Prius NHW10 (MK1) Hybrids - How to test and resurrect them

Batteries, Chargers, and Battery Management Systems.
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Mr. Mik   1 kW

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A Phoenix with a clipped wing....easily fixed!

Post by Mr. Mik » Mar 29 2010 7:42am

The deeply discharged NHW10 battery described earlier has now undergone further testing which has shown that it is in in good health, except for a single "stick" out of the 40 sticks (with 6 cells each)!

In short, the test is a full charge followed by about 3 weeks rest to allow self-discharge to occur. This is then followed by a stick-level capacity test at 12A with the CBAIII.

Here are the results for HP1:
Image
Image

And here the results for HP2:
Image
Image

A nice battery except for the one stick (S34) that dropped off early in the self discharge test! And that is most likely due to a single cell in that stick. One cell out of 240, but the NHW10 ECU will detect it and limit vehicle performance severely each time the cell hits empty. And because I have spares, it is easily fixed!

I am quite certain that I will use this sort of test as the main testing procedure for the other batteries I have lying around. It requires a lot of time, but relatively little operator input during this time.

With hindsight this result was already apparent after the first capacity test (after HP2 charge number 5), in which stick S34 was the worst:
Image
Image
These test were done from 10hrs to 42hrs after end of charging; S34 was tested 40hrs after end of charging.

But the result was not as clearly visible, and I think I would have been worried that there might be other sticks with problems hiding. The three week test satisfies me that this S34 is the only problematic stick in the battery.

The optimised procedure to test an unknown NHW10 battery half-pack:

1) Slow charge to up to 140% capacity. Depending on ability to actively cool the batteries one may use up to C/10 = 0.6A charge current. But it may go up in flames without active cooling at that charge rate! 100mA is much safer until the battery is known to be good. If both half-packs are left in the battery housing, then the cooling impellers can be used to provide powerful active cooling.

2) Discharge half-pack through a 400W incandescent light globe array. Monitor for sudden 1.2V drop (within a minute or so) by recording with a DSO or similar device, drawing a graph.
For a single reversing cell it looks like this on the PoScope monitor graph (in this case in a Vectrix 102s NiMH pack):
Image
Channel A (red): Voltage measured by x100 probe (1/100 x battery voltage).
Channel B (blue): Voltage measured by x1 probe across a 10 Ohm resistor (10 x discharge current).
X-achsis: time in hrs:min:sec:msec
Using a scope this way makes it clearly visible when a single cell reverses in such a long string! Of course, other forms of monitoring would also work. It is also possible to build a relatively simple circuit which detects such a small voltage drop and automatically terminates the discharge.

3) Repeat 1) and 2) several times to exercise the battery. How often depends on how long it had been left unused (and other factors).

4) Leave battery to rest for several weeks after a full charge (temperature dependent). So far I figure 3 weeks is a good amount of time to wait in 25degC. This test will find out the bad cells which may have good immediate post-charge capacity, but increased self-discharge rate.

5) Capacity test after the rest period. Ideally individual sticks, but one could also discharge Half-packs (to find the weakest stick quickly) whilst monitoring with the scope as above. Once a reversing cell is being detected by the sudden drop in the discharge graph, the 20 sticks of the HP are voltage tested (still under load); the stick with the weakest cell will have a voltage of about 1.2V below all the others.


But only individual stick testing can give you the detailed information you need to decide how to best repair the battery. In the above example of the NHW10 BlueCar battery it is clear that the one outlier stick can be replaced and then the battery will be good. Testing HP's will only find the weakest stick, but will not tell you if another one has only slightly better capacity then the worst one.
With individual stick capacity testing you would also be able to identify the few good sticks in a badly damaged battery.
Last edited by Mr. Mik on Aug 25 2010 5:13am, edited 7 times in total.
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Re: Prius Mk1 Batteries - How to test and resurrect them

Post by Mr. Mik » Mar 29 2010 8:05am

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Re: Prius Mk1 Batteries - How to test and resurrect them

Post by Mr. Mik » Mar 29 2010 4:28pm

The post https://www.endless-sphere.com/forums/v ... 75#p211975 was edited to show how to clean the MAF sensor of the NHW10 Prius MK1.
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Re: Prius Mk1 Batteries - How to test and resurrect them

Post by grindz145 » Mar 30 2010 8:14am

In you're experience are these packs easy to find at junkyards etc? I am assuming they air fairly cheap. I am quite interested in getting some of the commutation inverters and possible even an electric motor out of one... :twisted: Very nice work!

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Re: Prius Mk1 Batteries - How to test and resurrect them

Post by Mr. Mik » Mar 30 2010 3:35pm

grindz145 wrote:In you're experience are these packs easy to find at junkyards etc? I am assuming they air fairly cheap. I am quite interested in getting some of the commutation inverters and possible even an electric motor out of one... :twisted: Very nice work!
This depends very much on where you are!

AFAIK, the NHW10 has been exported as used vehicles in significant numbers to the UK, Australia and New Zealand. The does not seem to be a shortage of broken ones around Australia; I have two working ones now and one "Research Vessel" which I hope I will get into a good enough state to run it around on private property to test batteries, other components and maybe PHEV conversion options. All were very cheap because of problems with the main battery. The last two also had accident damage and needed to be re-combined into one good vehicle and one that's just for spares if needed later on.
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A link to the Powe Split Device (PSD)

Post by Mr. Mik » Mar 31 2010 8:18am

This is very neat! An animated simulation of the Prius PSD where you can alter the parameters and see the result.

http://www.wind.sannet.ne.jp/m_matsu/prius/ThsSimu/

The heart of the Prius, so to say....

Is there any good reason to not use the PSD with a powerful electric engine instead of the ICE?
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Re: Prius Mk1 Batteries - How to test and resurrect them

Post by Mr. Mik » Apr 16 2010 9:25pm

Something new about the battery which came with the car I bought in Dec 2009 posted above at: https://www.endless-sphere.com/forums/v ... 69#p252369

Looks very repairable!
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by peterperkins » May 16 2010 12:53am

Interesting thread.

Identical cells are also used in the Honda IMA based vehicles Insight/Civic etc. They also suffer from imbalance issues over time mainly as a result of self discharge variations. Heat in the centre of packs also causes IR and self discharge variations between subpacks (a stick of six cells) The honda cars have no balancing or cycling capability so the imbalance fault is inevitable in the end.

The insight forum have a few members now who have considerable experience with repairing these packs. I repair them in the UK for Insight owners. The subpacks respond well to aggresive cycling on the bench with a decent charger such as the Overloader or similar. It can take upto 10 cycles to restore capacity with apparently poor subpacks. www.insightcentral.net

In order to repair packs here in the UK I dissasemble the batteries and cycle/exercise all the sticks noting capacity under charge and discharge until it recovers to an acceptable level. Critical is the self discharge rate which can be determined by leaving the sticks for a week and then discharging them to the cutoff point and working out lost capacity. Then I select/match the closest 20 sticks from my stock and reassemble them into a pack.

The temp sensor strip is a PTC resistor sensor and changes resistance rapidly as temp gets upto 70-90C. The cutoff PTC cell overheat alarm point in the Insight is an amazing 90C. The Insight battery fan which is controlled by four other sensors does not operate until the battery reaches 55C. This is too high IMO and leads to excessive heat in the batteries.

The completed packs respond well to CC low current charging and we use 250-350ma at 170V to charge a 144V nominal pack.

The sticks used in the Insight can deliver 100A or accept 50A regen.
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by Mr. Mik » May 16 2010 5:14am

peterperkins wrote:Interesting thread.

Identical cells are also used in the Honda IMA based vehicles Insight/Civic etc. They also suffer from imbalance issues over time mainly as a result of self discharge variations. Heat in the centre of packs also causes IR and self discharge variations between subpacks (a stick of six cells) The honda cars have no balancing or cycling capability so the imbalance fault is inevitable in the end.
Do you know if they are 6.5Ah or 6Ah cells?

The imbalance can be fixed (temporarily) by EQ charging. I'm working on an EQ charger to do the whole 240s pack at once, it's almost ready.

The insight forum have a few members now who have considerable experience with repairing these packs. I repair them in the UK for Insight owners. The subpacks respond well to aggresive cycling on the bench with a decent charger such as the Overloader or similar. It can take upto 10 cycles to restore capacity with apparently poor subpacks. http://www.insightcentral.net

In order to repair packs here in the UK I dissasemble the batteries and cycle/exercise all the sticks noting capacity under charge and discharge until it recovers to an acceptable level. Critical is the self discharge rate which can be determined by leaving the sticks for a week and then discharging them to the cutoff point and working out lost capacity. Then I select/match the closest 20 sticks from my stock and reassemble them into a pack.
I have a charger that can do up to 5 charge/discharge cycles (discharge at only 0.7A) for a 6-cell stick. But I find it so very tedious and time consuming to do each stich that way!
How many cells are in the Honda packs? IIRC it 120cells, right?

I prefer to charge a 120s half-pack, then discharge it (also in series) for cycling. The problem is of course that I have no automated shut-off mechanism yet to detect a single cell dropping to zero V, and to stop the discharge automatically at that point. I have some suggestions (from someone who has given me lots of good advice and seems to know what he is talking about!) about how to build such a device, but have not had time to build it so far. I have managed to use a USB Digital Storage Oscilloscope in such a way that I can spot the 1.2V drop when a single cell in 120 cell string (or in 102 in my Vectrix) drops to zero V. But, I need to sit there and watch, and that is not good!
The temp sensor strip is a PTC resistor sensor and changes resistance rapidly as temp gets upto 70-90C. The cutoff PTC cell overheat alarm point in the Insight is an amazing 90C. The Insight battery fan which is controlled by four other sensors does not operate until the battery reaches 55C. This is too high IMO and leads to excessive heat in the batteries.
The EQ charger I am building can (on the bench so far...) detect a 120 Ohm rise from the 640 Ohm of a 20degC 240s pack. That equates to a battery temperature of 55degC or a single cell reaching 75 -80 degC. The charger automatically turns off the charge current (but continues the power supply to the cooling impellers) when the resistance of the PTC resistor sensors gets too high.
The trouble I am struggling with at the moment is how to turn off the charge current when the cooling impeller is not running. I want that double safety in the charger, because charging at 0.6A can possibly set the battery on fire.
The completed packs respond well to CC low current charging and we use 250-350ma at 170V to charge a 144V nominal pack.

The sticks used in the Insight can deliver 100A or accept 50A regen.
For regular EQ charges (every few months or so), I want to charge the entire 240s battery at 0.6A to keep the time for a complete EQ charge as low as possible. It will still take an entire day and night that way!

Measuring the current in and out of my NHW10 Prius battery I found this:

Maximum current draw: 108A

Maximum regen current: 60A
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by peterperkins » May 16 2010 12:16pm

The cells are 6.5ah although only 4ah is used by the honda system 20-80% soc approx.

The robotronic overloader can charge at 8A and discharge at 20A so gives them a good workout.

I am working on a multisubpack balancer which has 20 subpacks fitted to it, and then uses a pic to manage charging each one in turn, all automated and dumps data to a netbook running excel. I'll post details when it's finished. it will have a 50A charge/discharge capability to really give them a work out.

It's a reaL doddle to make a high voltage CC supply to charge the cells in a complete pack at 350ma.

You need one of these

http://www.meanwelldirect.co.uk/product ... efault.htm

and as many of these as reqd in series with the above to bring the total output voltage upto you pack charged voltage.

http://www.meanwelldirect.co.uk/product ... efault.htm

Total price under £100 if you shop around.

The LED CC supply does all the work ;)

Total time for a full pack balancing charge assuming one cell in the pack is completely empty and needs a full 6.5ah < 20hrs

We tend to only do full pack balancing monthly or weekly maximum. if the cells/pack are going out of balance faster than that then the pack needs ovberhauling.
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by Mr. Mik » May 16 2010 4:58pm

Interesting idea!

But, it does not do all the work!

It also needs to power the cooling impeller and turn the charger off when the battery is getting too hot, the impeller is not running and/or the charging time is over.

Otherwise one risks setting the battery, car and garage on fire!
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by peterperkins » May 16 2010 11:05pm

In testing on numerous insights unless you live in arizona then the packs do not heat up to dangerous levels with 350ma charge current.

Some people do power the fan, most do not. We don't bother with a charger cut off, a simple plug in timer can do.

Guestimate soc from car soc gauge, dial in suffcient charge hours using timer to balance pack and let it get on with it.
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by Mr. Mik » May 17 2010 2:46am

Thanks for the explanations! I have never seen the Insight battery pack. Does it allow for spontaneous convection cooling?

When I charge Prius NHW10 half-packs onto the bench, with relatively good spontaneous air flow through the half-pack (due to putting it on wooden "spacers"), then the top layer of cells still heats up to 35degC in 25degC ambient temps @ 100mA charge current.

I had to terminate attempts to charge at higher rates because I did not want the cells to go above 40degC. They self-discharge a significant part of their charge in such circumstances while they cool down. The self-discharge is not necessarily bad if you want to achieve equalisation, but I think the heat also ages the cells.

Have you actually used the current limiting SMPS and the other "booster" SMPS' which you suggested for this application? I ask because some SMPS seem to be producing a fully isolated or "floating" DC output, and others do not. I may work with some, but not with others!
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by peterperkins » May 17 2010 7:39am

Have a look on Insight central for details/pics of the battery pack / chargers etc it has limited convection cooling.

Bear in mind the insight normal battery fan does not start operating until the pack reaches 55C. The PTC strip alarm for an individual cell overheating and the IMA shutting down is an incredible 90C

So you are being very conservative.

Yes the psus do work correctly and are fully isolated floating DC output I've sold quite a few as pack chargers for Insight owners.

I would say the insight does tend to let the pack get a bit hot, I think 45c as a normal maximum is more realistic and probably better for it in the long run.
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by Toorbough ULL-Zeveigh » May 17 2010 3:54pm

Mr. Mik wrote:Do you know if they are 6.5Ah or 6Ah cells?

chart on this Prius page sez 6.0 Ah for the NHW10.
confident enuf to correct wiki?

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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by Mr. Mik » May 23 2010 5:18am

peterperkins wrote:Have a look on Insight central for details/pics of the battery pack / chargers etc it has limited convection cooling.

Bear in mind the insight normal battery fan does not start operating until the pack reaches 55C. The PTC strip alarm for an individual cell overheating and the IMA shutting down is an incredible 90C

So you are being very conservative.

Yes the psus do work correctly and are fully isolated floating DC output I've sold quite a few as pack chargers for Insight owners.

I would say the insight does tend to let the pack get a bit hot, I think 45c as a normal maximum is more realistic and probably better for it in the long run.
Thanks for the explanations!

Encouraged by this, and some information from a Panasonic battery reconditioning patent which claims that a few days at 50degC is good for the cells, I am testing my charger under simulated fault conditions....

I disconnected the cooling impeller and plugged in another identical impeller (which is running but not blowing air at the battery), to fool the safety mechanism
which shuts the charger down when the impeller is not drawing current. The batteries are heating up under the 0.4 to 0.55A current (depends a bit on fluctuations in the grid voltage) without any active cooling. So far, the top layer is 60.1degC hot and rising, it smells a bit funny, too!

This is a one-off experiment to test my freshly built charger, not a recommended charging procedure! Time might tell how the battery coped with this abuse(?) in the longer run!

The temp sensor resistance has gone from 322Ohm to 350Ohm per half-pack and I expect the charger to shut down sooner or later. It did shut down at around 100Ohm increase (50Ohm per half pack) in preliminary tests, but that was simulated with a trimpot. The real deal test is running now...

Very interesting to see the reduced peak voltage of NiMH cells in action when they start to get hot!

The peak at about 21degC cell temp was 353.7V, minus 1.4V for the diode drop, makes 352.3 V, makes 1.468V/cell (under 0.45A charge at Full SOC).

Now, at about 60degC, the charge voltage is only 342.5V, minus 1.4V for diode drop, makes 341.1V, makes 1.421V/cell.
And the other interesting thing to watch is the current increase that this causes: This is now at 0.55A, and rising. A runaway scenario in the making...

Of course, this would not be an issue with the strictly current limited setup you were suggesting. I am running this test with 30min timed intervals and very frequent measurements/observations being done, because my charger can increase the current further if the voltage drops.

Time to wear safety goggles when approaching the battery ...

OK, 64.5degC now, started another 30min of charging....@ 0.58A.

All this is happening at about 22degC ambient temperature.

Half-pack temp sensor strip resistances now: 361Ohm + 356Ohm = 717Ohm.

.
.
Charging voltage now down to 341.4V...0.58A...

The pack temperature seems to stabilize in the low 60's - around 62degC.

Another 30min interval started, after this I'll give up unless the temperature continues to rise.

.
.
Seems so far that you are right about my charging being very conservative.

However, this is a cool Autumn evening with the battery on the concrete floor in the garage. The heating will most likely be much more of a worry when one does an EQ charge of the battery inside the car and in Summer.

I hope to get to a stage where I only do these EQ charges at leisure, every few months, preventatively, but the imbalance problems are bound to be worse in Summer and I think I will need to do one EQ charge per year per car in hot weather. The safety temp cutout mechanism might come in handy then!

The other result from this test is this: The cooling impellers are quite capable of keeping temps down when powered at 6V in 21degC ambient temperatures during a 0.6A EQ charge. Again, this may be quite different when hot cabin air is used to "cool" the battery in Summer.
Last edited by Mr. Mik on Jun 12 2010 5:39pm, edited 2 times in total.
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Re: Prius NHW10 (MK1) Hybrids - How to test and resurrect th

Post by peterperkins » May 23 2010 11:35pm

try a 350ma cc supply your current is too high imo for continued use
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Prius NHW10 Equalisation Charger - Special Freddy

Post by Mr. Mik » May 24 2010 4:23am

peterperkins wrote:try a 350ma cc supply your current is too high imo for continued use
I don't think so!

The heating was exclusively due to the deliberate creation of a fault condition - namely that the impeller motor draws current, but no air flow results. It could easily happen in real life due to a number of scenarios. For example, a cable or other foreign body drops into the impeller intake and stops it from turning.

When it's all running normally, the current always stays below 0.6A and the 6Ah (or 6.5Ah) cells can cope with that very well. This will limit the time required for an EQ charge and will for example allow to achieve a full EQ charge overnight in Arizona or Australia in Summer. Start when the heat is easing off at 1800pm, finish in the early morning before it gets too hot again!

Here is the schematic of my charger, it is now "matured" enough to publish, BUT, it is not fully tested and may have significant safety issues!

Click the thumbnail for large resolution schematic: Image
Image

I hope I'll get some feedback from knowledgeable members here - please point out if you see any issues or problems with this charger!

It can be adapted to many other specialised charging applications, too!
Last edited by Mr. Mik on Jun 11 2010 11:31pm, edited 1 time in total.
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Special Freddy NHW10 EQ charger 8.0 description

Post by Mr. Mik » May 25 2010 6:34am

Here is a description of the SFreddy NHW10 EQ 8.0 charger with some pictures:

Image

Image

Image

.
Remember: This is an experimental design and not fully tested. If you are considering to build something like it then it is entirely at your own risk! Get someone with the appropriate qualifications to check and build it for you! I am posting this to get some peer review and to iron out the possibly still present dangerous design faults!

Click the thumbnail for large resolution schematic: Image
Image


The charger is designed to perform about 6 functions:


1) Provide 6V DC to run the cooling impeller continuously. It can therefore also be used for cooling the battery after driving when needed.

2) Provide about 0.6A at voltages between 320V DC and 355V DC to EQ charge a NHW10 battery.

3) Shut down the charging current if the cooling impeller motor is not drawing current (to prevent any overheating).

4) Shut down charging (but continue cooling) if the battery temperature (or a single cell temperature) becomes very high despite the cooling impeller drawing current (like when the impeller blades were blocked by something, or if something is blocking the air intake holes, or if the car is parked in the sun and hot air is sucked in for "cooling").

5) Terminate charging automatically and redundantly, at the desired time. This is done by two timers working independently in series. But cooling continues in-definitively (unless a third charger is used to turn everything off).

6) Automatically ground the car chassis whenever connected.

(The next stage of the charger development will introduce a further function:
7) To automatically disconnect the temp sensor strips from the stock system by switching a number of relays (using the 6V supply). This will allow EQ charging without
opening the battery and will cause an error if the car is started while still connected to the grid. The ECU would see the battery as terribly hot and probably refuse
to do anything apart from running the cooling impeller at full bore. But that next stage is not included in the schematic, yet!)
.
.

Now to the individual parts:

The 1:1 isolation transformer is the single most expensive, large and heavy part of this charger. It is there because the DC output of the charger would be "balanced" without it. That means that the electrical potential between the positive output and earth would be 1/2 of the output voltage, and the same for the negative DC output. The result of this is that touching just one pole of the chargers output would cause a potentially lethal electric shock through the body of someone who is grounded. One hand behind the back would not prevent this!


With the 1:1 isolation transformer the DC output is "floating" instead of balanced. With a floating voltage one would need to touch both positive and negative output
cables to get electrocuted.
.
.
The grid supply is 240V AC, 50Hz, but the actual voltage at my place is often around 250-255V AC.

The heart of the charger is a bridge rectifier. It turns AC to DC, with the resulting DC voltage being 1.414 x AC voltage.

In my case, 250V x 1.414 => 353.5V DC .

That is too close to the voltage which is needed to charge a full NHW10 battery with 240cells x 1.45V = 348V (at least if using a charger such as this one).

Therefore, the isolation transformer has an additional "Volts-up" transformer in series, following the Isolation transformer. It has tabs to add an additional 9V, 12V, 15V, 18V, 21V or 30V to the AC supply. This is much cheaper than having a dedicated 1:1.x isolation transformer custom made. I have this second transformer connected so that it adds 21V, bringing it to just below 277V, the maximum rating for several of the used components.

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The switch-mode power supply (SMPS) produces 6V DC (but can be set to various voltages). This 6V DC is used to power the cooling impeller motor, which draws about 2A at this voltage and the SMPS needs to be able to produce this continuously. Jaycar have just recently begun to stock a suitable SMPS, previously they were all
underpowered for this task.

The 6V DC supply is also used to provide a measurement current through the temperature sensor strips (TSS1 and TSS2) along all 240 cells in the battery.

The 2kOhm trimpot (accessible through a small hole below the red momentary-on pushbutton) reduces the current flowing through the TSS1+TSS2 to a level close to the "must-open current" of the first relay in the circuit (5V coil, 18V/0.5A contacts). When the resistance of TSS1 and/or TSS2 rises due to heating up, that relay opens and turns off the power to another relay (5V (should be 6V) coil, 277V/5A contacts). I found it too difficult to find a single relay with appropriate ratings for this job, so I used two to achieve 6V switching of 277V AC.

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The "momentary on switch" is used to trigger the first relay to close, because the current needed to close the relay is much higher than the current needed to hold it closed.

The third job for the 6V DC supply is to close a reed switch (400V / 3A rated). I broke several of these reed switches while attempting to get this to work. The glass tube cracks easily when any force is applied, and the contacts stick together due to the brief but high inrush current into the motor run capacitor if the reed switch is directly connected to the motor run capacitor. Therefore I changed the set-up to include a further relay, with higher inrush current tolerance. This relay was left over from the attempts to find a single relay for the TSS sensing circuit, anyway! So the reed relay closes when 2A flow through the about 30 coils wound around it, that turns on the solid state relay (3-32V "coil", 280V/3a contacts, 80A inrush current tolerance).

Only when all 4 relays are switched on will the motor run capacitor be connected to the 277V AC supply. This in turn provides the rectifier bridge (1kV rated) with power and starts to charge up the smoothing capacitors (electrolytic, 100uF each).
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The motor run capacitor "throttles" the current flow
. The maximum DC voltage will always be 1.414 x input AC voltage, irrespective of the capacitance of the motor run capacitor. But the Farad value of the motor run capacitor determines the maximum current flow when the DC output is shorted. For the 48uF motor run capacitor (the big white cylinder in the aluminium box of the charger) the shorting current would be about 3.6A. The current is a linear function between the maximum current when shorted at zero V and the maximum voltage with zero current when nothing is connected to the charger.
The motor run capacitor is connected with push-on connectors so that it can be exchanged for other capacitors. For example, a 8uF capacitor could be used to start charging a totally empty battery with about 0.6A.
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The resistor in parallel with the motor run capacitor serves to discharge the capacitor when the charger is turned off. The charger must not be turned on again for a minute or so after having been turned off, depending on this resistor value. This is because the sine wave of the AC grid supply could happens to be at the opposing extreme to then the charger was turned off. In that case there could be 277V x 2 = 554V, and this could cause large current flow and damage to the capacitor.
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The two resistors in parallel with the smoothing capacitors serve a similar purpose: Discharge the capacitors so they become safe to connect a battery for charging.
The charger needs to be connected to the battery before turning it on, and with the smoothing capacitors at a voltage at or below the battery voltage. Connecting it with the capacitors charged to 390V DC could cause a spark and damage components!

The diode between the smoothing capacitors and the ammeter prevents inrush current into the smoothing capacitors when the battery is being connected.

It's probably overkill to have a further diode in each connection cable to the battery terminals at the positive and negative end of the string, but it will not do any damage, I think.

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Connection procedure:

1) Remove mid-pack circuit breaker (the orange handle at the back of the battery).
2) Connect up the cables (TSS1 and TSS2, impeller motor, charging cables), set the timers as desired, but do not plug the timers into the 1:1 isolation transformer output, yet.
3) Put mid-pack circuit breaker back in. From now on it's all really dangerous!
4) Plug charger into the grid supply.
5) Turn on the ON switch, the impeller should start to run now.
6) Press the momentary ON switch and then push the plug with the timers into the 1:1 transformer output to start the charge current.
7) Gradually increase the trimpot setting until the charger turns off (ammeter drops to zero). Do not turn it back on for about a minute, see above!
Then turn the trimpot back down about 2 full turns. This depends on the type of trimpot used - I used a multi-turn type.
8) Best way to turn the charger back on is probably to remove the timers and go back to step 6). One can also just press the momentary ON button, but this might sooner or later affect the relay due to the inrush current which it is switching. Better to have all relays closed before the inrush occurs!

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So much for now, I hope it makes sense to you, ask if you have any questions, I'll try to explain it as far as I understand it.
Last edited by Mr. Mik on Jun 11 2010 11:33pm, edited 1 time in total.
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Special Freddy NHW10 EQ charger V15.3

Post by Mr. Mik » May 25 2010 8:05am

Here is the "final" (HAHA!) version 15.3 of the Special Freddy NHW10 EQ charger. It has been working quite well for some time now but it still needs to be considered an experimental design. Don't just build one like it unless you know what you are doing!

A permanently installed harness (removable) allows to plug the charger in without any opening of the battery. Diodes protect against electrocution risk.

Click to enlarge: Image

The next part is not yet built and will allow the cooling impellers to be run by a solar panel when the car is parked in the sun. This should reduce imbalance due to differential heating of cells. It will need another diode somewhere I think.
Click to enlarge: Image
Last edited by Mr. Mik on Apr 27 2011 9:38pm, edited 2 times in total.
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Honda used the same sticks!

Post by Mr. Mik » Jun 11 2010 11:55pm

It turns out that the Honda Civic and Insight use the same subpack sticks as the Prius NHW10!

And there are others out there with much better equipment, knowledge and ability than myself to test them!

Check out this site (and all the other fantastic pages in there): http://www.99mpg.com/blog/batterypacksexpose/

And this forum: http://www.insightcentral.net/forums/mo ... eries.html

and http://www.insightcentral.net/forums/mo ... al-issues/

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Back to my own little corner: I have started to make a sort of index of this thread in the first post at the top: https://www.endless-sphere.com/forums/v ... 14&t=12764
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Panasonic Patent on how to do it.....

Post by Mr. Mik » Jun 12 2010 7:24am

Here is a patent by Panasonic which describes a method of detecting bad cells in long battery strings and replacing them.

It may be of some use, and many NHW10 owners believe it is about these batteries.
Attachments
Matsushita-Panasonic advice re Prius NiMH battery US6573685.pdf
(1.3 MiB) Downloaded 648 times
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First real world EQ charge with Special Freddy 8.0

Post by Mr. Mik » Jun 12 2010 7:43pm

The Special Freddy 8.0 charger is now charging the battery in my Blue NHW10 for a preventative EQ charge.

It's been seven weeks since I placed the reconditioned battery (with one stick exchanged) back into the car. It was "bottom balanced" at the time, i.e. all sticks empty but just capable of starting the car once. The car then charged the battery up to wherever it saw fit.

The warning triangle has not come on again. The car is working perfectly.

There have been two occasions when the car started to charge the battery (by mildly revving the ICE) until the battery was shown as full on the Multi Function Display (MFD).
No turtles, no power restrictions. Battery SOC on MFD never dropped below 1/2 in 7 weeks of driving (at least I did not see it).

The battery has no wiring harness for external charging, yet. Therefore I had to take the seat out and open the battery cover.

It takes 30min to get to the start of actual charging, all hooked up and ready. Definitively an incentive to work on the battery-internal part of Special Freddy and install a harness! Too much hassle to do it this way every few months!

Image

The earth connection is still a rigged-up part - the red alligator clip cable, that needs fixing! The connector for the gray cable coming from Special Freddy has plenty of empty poles for that, eventually the orange and grey cable will both terminate at the same single connector, so one cannot forget to connect some part or another.

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The EQ charge is still running, here are the problems encountered so far:

The charger turned off the current twice and I cannot tell with certainty when it happened. That makes estimation of total EQ charge time difficult. After the first time, I added a DMM with Min/Max function. That way, I will have some indication how far it got. I also reduced the resistance of the trimpot by a 1/4 turn each time. Eventually it will be set low enough to never turn off unnecessarily.

And that's it as far as problems go!

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Now to the unexpected good results so far:

The charge current turns off immediately if the car is turned on during charging! I do not quite understand how this works, but it does. That can only be good, unless you forget to turn it back on and stuff up the EQ charge. But usually one would avoid turning the car on during EQ charging.

Another (hopefully good!) result is that the master warning triangle and the Car with exclamation mark come on when the car is turned on with the charger attached and powered up. I expect this to disappear as soon as the PTC strip is reconnected to the stock system. If the warning symbol remains on, then this is of course a bad outcome. I will know in a few hours.
The ICE did start (I just had to try it!), but I did of course not try to drive with the charger plugged in!
I think it is essential to reset the EQ charge request warning symbol if a permanent EQ charge harness is to be installed into a good or reconditioned battery.

Otherwise the risk of someone attempting to drive off with Special Freddy connected would be very high.

The grid plug should also be connected in such a way that it gets pulled out clean if the car is driven off - automatic disconnect! :lol:
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DiPoD - Is the ICE burning Dino Poop right now???

Post by Mr. Mik » Jun 13 2010 5:55am

I used the extra time ("created" by the delay to the EQ charge) to finish a little project which I have had in mind since a while:

A visual indicator that says:"The ICE is burning Dino Poop".

Now, how do you turn that into an acronym....Hmmm......TIbuDiPoo????? ROTFLMAO

EDIT: Came up with "DiPoD" for Dino Poo Detector.....

Anyway , it works now!

I floated the idea on the Yahoo Prius MK1 group a while ago, and a number of ideas were proposed. I though this particular one was most likely to succeed; it was suggested by Peter R. the group "owner".

Today I finally tackled the job by having a look at the "Research Vessel" with a DMM.

Aim: Plug into the fuel pump power supply and hope that the fuel pump is always (and only!) on when the ICE is running.

I found 5 or 6 wires entering the plug on top of the fuel tank under the rear seat. One of them is white-black and I think that is the battery common ground wire. This might be the same as chassis ground when the battery is installed in the vehicle, but I am not certain about it. So I stay right away from it when I can!

Somehow most of the other cables looked like sensor wires to me (for fuel level measurement) so I decided to hone in on the black-red-black-red with silver dots wire.

I followed this wire towards the front of the research vessel - and after putting in a 12V battery and the HV circuit breaker I cranked the ICE and found 13.5V between this wire and chassis ground! BINGO!


While the blue NHW10 was finishing it's EQ charge, I searched in it and found the same black-red-black-red-silverdots cable under the plastic trim at the bottom of the driver door (amidst many other cables!). I measured the length of cable I would need, then soldered cables to a "12V LED courtesy light" (which I had snatched up for cheap at a Dick Smith "Get rid of all the interesting stuff sale" together with several bags full of other treasure), making sure the polarity is right. Then covered it with clear shrink-wrap to avoid any shorting and added hot-melt glue as needed. A ring-lug was soldered to the negative cable, then I fed both cables through the slot underneath the bonnet release lever. Next I bolted the negative lead to chassis ground together with all the other ring-terminals under the corner plastic trim. The positive cable was hooked up with an insulation displacing splice-connector to the black-red-black-red-silverdots cable midway underneath the plastic strip at the bottom of the driver door (not on the door, but between the seat and the lower "door-frame" so to say. I bet there is a proper name for that part of a car....)

Three cable-ties and a little bit of electricians tape later, it was all tied up and now looks like this:

Image

It just sort of dangles there and the LED's intense light can be directed as needed for almost any lighting conditions.
The two different plastic panels mentioned earlier can be seen in this picture.
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The results from a single test drive:

The LED's come on seconds before (and after) the MFD show energy flow from the ICE starting or ceasing. The time delay is gone, there is immediate feedback rather than waiting 2 seconds for the next MFD refresh.

So far, I have not been able to test the device with a cold ICE. I ran the ICE after completing the EQ charge and to test the new gizmo until it was warm enough to turn itself off while parked. The test drive followed this, starting with a warm motor.

But the results have already been very very interesting and I think probably very useful as well!
Last edited by Mr. Mik on Jul 22 2010 4:00am, edited 1 time in total.
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Re: Burning Dino Poop right now??? Part 2

Post by Mr. Mik » Jun 13 2010 11:15pm

I had another very interesting test drive with my 07/1998 Blue NHW10 today, learning what it does by way of watching the "DiPoD" (Dino-Poop Detector).

It was most enlightening!

The drive started with a cold engine, which makes my 07-98 NHW10 behave differently from times when the ICE is being turned on when it is already warmed up.

I do not know if this is a malfunction or if Toyota changed the design / programming at some point in time, because my white 12-1998 NHW10 behaves quite differently!

The blue NHW10 will never stop the ICE if it is turned on and the car is left parked in "P".

The white NHW10 will run the ICE under the same conditions for about 5-10 minutes and then it turns itself off automatically. The white car will also turn the ICE off at traffic lights once the ICE is warm, even when the ICE was only started once when still cold.

The blue car, however, will not turn the ICE off at traffic lights, even when it is well and truly warm, unless the ICE is turned off and then on again when already warm. From then on it will continue to behave just like the white car and turn the ICE off at every occasion.

Before installing the DiPoD I could not determine if the ICE was running whenever the car was moving faster than about 20km/h due to road and wind noise.

I assumed that the ICE in the blue car would also run continuously while coasting downhill when the trip started with a cold motor, because as soon as I had slowed down enough to hear the ICE, I would always find it to be running. The DiPoD showed me that this assumption is incorrect!

I have not tried it out in the white car yet, so the following only reflects the behaviour of the blue 07-1998 NHW10 with DiPoD:

Even after a cold ICE start, the ICE gets turned off when coasting at speeds higher than 60km/h. If the shifter is changed to "N", the ICE starts to run immediately while the car is coasting. There goes my theory that coasting in "N" might increase km/l results!
When I let the car coast in "D", the ICE will stay off until the speed drops to 49km/h - the ICE starts to run each time when this occurs.
The ICE does not run when coasting at 100km/h, I will have to test higher speed on the highway sometime later.

When I turn the blue car off and on again with already warm ICE, then the ICE does not start any longer when coasting at or below 49km/h; it turns off whenever I take the foot of the gas pedal.

That insight alone was worth the effort of building the DiPoD - :lol: but wait, there is more....!!!! :lol:

It turns out that it is possible - contrary to what I have read somewhere - to use electric propulsion at speeds at least as high as 80km/h!
Because the DiPoD gives immediate feedback (rather than the 2-3s delay for the MFD) it is possible to give just the right amount of (feather light!) gas pedal action to add a bit of power to the glide without running the ICE.
Pulse and extended glide, so to say!
In practice this is going to be most useful on moderately downhill stretches of road, when drivers behind you are in a hurry and want to push you to drive at the speed limit. Depending on terrain this might make a significant contribution to km/l values!

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Can anyone tell me if the different behaviours between cars described above are typical for NHW10's of a certain age or serial number? Or is it a fault that can be fixed somehow? Where in the electronic system is this behaviour stored or determined?
Mr. Mik

There is always a way if there is no other way!
The writer of this post accepts no responsibility or liability resulting from attempts to repeat or perform the procedures described in this post. This information may be used at your own risk.

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