Even Newer 4 to 24-cell Battery Management System (BMS)

Batteries, Chargers, and Battery Management Systems.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by GGoodrum » May 05, 2009 9:30 pm

Hey Bob, good to have you back. :) Hope the back is a bit more tolerable these days.

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by potatonet » May 06, 2009 1:25 am

ok because I cant handle reading through 77 pages of what would be a very long read...

Is there anyone that makes a 50A BMS for 16 cells? or do I have to get one of these boards and make my own

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by dnmun » May 06, 2009 9:46 am

pnet, mr li ping sells a 48V BMS, also Headway, and ecitypower all have cheap BMSes.

actually some of the better parts of this thread are in the previous ones, but maybe half of this thread is worthwhile. BOL, dm

great to see bob back here, the old bear is outa hibernation. looking forward to more meaningful discussions of electrical problems.

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by potatonet » May 06, 2009 12:56 pm

yeah I have 2 ping BMS but I need something that can put out more as they are both limited to 30A. its a shite BMS on a decent LIPO pack

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by bobmcree » May 06, 2009 1:49 pm

justin at ebikes.ca has just come out with an improved switched capacitor bms for the lifepo4 packs he sells. he might be willing to sell the bms separately, i have not looked into it yet.

as for a 50A bms, this depends on whether you want a system that can equalize charge on a 50 Ah system or just a bms that has a switching fet capable of 50A. If the latter i think you just need to beef up the fets. If you have a higher capacity system you might need more balancing current, depending on the balance state of your cells.

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by potatonet » May 06, 2009 8:55 pm

just a 25ah system but I would prefer to get 50-70 amps out

peak would be set below the capacity of the BMS on a CA.

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by julesa » May 06, 2009 9:05 pm

You could upgrade the FETs on one of the BMSs you already have and solder the shunt up a bit... or just solder the shunt, cross your fingers, and replace the FETs if they blow. :?

Either way though you'd need a way to test the new limit. I wonder if you can measure the shunt resistance and calculate exactly what the resistance needs to be to set the limit at 50A. Hmm...

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I can't get my 2.3 BMS to latch.

Post by Nate » May 07, 2009 6:08 am

Hi Guys, I can't get my 2.3 BMS to latch.
LVC is good. I'm connecting the charger w/o the battery. All LEDs come on evenly and the main is very red. I get 3.7v on each channel with my charger suppling 60.2v .5a. The shunts get very hot. Tested all resistors and they are fine except 1M and the 10Ks by Q1. The 1M reads .280 or .656 depending on lead +- placement and the 10Ks read 6.88. All diodes checkout except D1 and D2. I unsoldered them and they are ok, but when soldered seem to leak. Guessing that is ok... The back of the board is very clean. Lots of isopropyl and toothbrushing. I did have to replace one shunt resistor that read 3.4ohms...?
LiFePo4 BMS V2.3.jpg
Thanks for your help!
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 07, 2009 9:18 am

You can't get an accurate measurement of most parts when they are in circuit due to the effects of the other components. Comparisons from one cell to the next may be valid.


First try testing the charge control circuit by jumpering pins 7-8 on any optocoupler. Power up the board and stick a small screwdriver or something between the pins and you should see the main LED change from red to solid green. It should go back to red when you remove the jumper.
Board test 1.jpg
Board test 1.jpg (33.62 KiB) Viewed 2155 times
If the LED won't go green, then something is wrong with the bus line or the gate driver chip.

If the first test works, then try jumping the all shunts line to ground. This should cause the main LED to go solid green, but stay latched when you remove the jumper. The LED should reset back to red after you remove the power.

If this isn't working, try to measure the voltage from the ground bus to the any shunt line and the all shunts line.
Testing the Autoshutoff feature.jpg
Testing the Autoshutoff feature.jpg (159.12 KiB) Viewed 2156 times
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by Nate » May 07, 2009 10:44 am

Hi Fletcher. Sorry, I thought I posted the following but it was 3 or 4 in the morning and I rewrote the post four times. I forgot to add this:
I can get the main LED to go green using each opto, works correctly. The all shunts line latches correctly and a reset is required.

It is my understanding that without the battery hooked up the LEDs should flash then go off and the main goes green. All my LEDs stay on and the main is very red, no green tone at all.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by chessir » May 07, 2009 12:03 pm

Hi Bobmcree:

I purchased and received your Variable Power Supply Kit some time ago. At that time you promised to provide complete assembly
details complete with photos on bobmcree.com. I searched your website but could not find these instructions and photos. I now have an urgent need for this variable power supply as my Ping v1.0 24v10ah batt konked out on me. If you still have these instructions and photos could you supply them please???
bikeboy-silence is golden
ezip trailz dual24v10ah sla and/or ductape24v10ah lifepo4

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 07, 2009 1:22 pm

Nate wrote:Hi Fletcher. Sorry, I thought I posted the following but it was 3 or 4 in the morning and I rewrote the post four times. I forgot to add this:
I can get the main LED to go green using each opto, works correctly. The all shunts line latches correctly and a reset is required.

It is my understanding that without the battery hooked up the LEDs should flash then go off and the main goes green. All my LEDs stay on and the main is very red, no green tone at all.
I'd guess either your power supply voltage is just a tiny bit too low or the current is limited to less than the shunt current.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by Nate » May 07, 2009 1:54 pm

The current is 3.5a but the BMS is only taking .5 - .6. Wouldn't the Main LED be yellow at least? It is completely red and each channel is 3.7v and some are 3.8v... Not sure if I can up the voltage any more. This is a ping charger.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 07, 2009 5:42 pm

I'd guess the Ping charger voltage is set to max out just below where the circuit can trip. Just for a test, try putting a small battery (1.5v or 3v) in series with the charger output to boost the voltage.

There might be a voltage adjusting pot inside the charger.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by Nate » May 07, 2009 6:06 pm

I will try that tonight and post back. Thanks!
Electra Townie Black - Crystalyte 72v/40a and 5304 - Cycle Analyst 2.1 - A123 16S 5P - v2.3 BMS from GGoodrum and Fechter http://www.tppacks.com

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by Nate » May 07, 2009 8:59 pm

I tested it up to 63v, no difference... Any other ideas? Thanks.

*Edit: I just tested with the battery connected. I got it up to 60v before turning it off. channels 1,3,5,7 and 9 stay at or below 3.5 so the LEDs won't light up. Most other channels are at 3.9 and channel 15 gets up to 4v! This thing is an oven! I could get a serious burn on it if not careful. I know this will get better after the battery balances out. Now here is the weird thing. I disconnect the charger and the main LED goes off but the other LEDs stay on. Is that supposed to happen? I'm stumped...
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 07, 2009 11:11 pm

That's a problem. The shunts are coming on, but not sending the signal to cut off the charging current when they are maxed out, which allows the cells to over charge a bit. The shunts will stay on to drain off the excess voltage, then the cell LEDs will go out.

Yet, when you short the pins on the output side, it seems to work properly and the main LED goes green.

Any chance the optocouplers are installed backwards?

Edit: I can see from your picture that you have them installed properly.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by Nate » May 07, 2009 11:57 pm

Just rechecked the optocouplers again to be sure, they are fine. I left the battery on until it drained and the LEDs turned off. Should I be getting 3.75 - 3.8v per channel without the battery connected? Hoping someone can test this with theirs. Thanks.

Edit: Still need help... Is there another way to test the optocoulpers? What else can I do? Please, I need to get this working. Thanks.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by mimichris » May 10, 2009 8:58 am

M Goodrum or M Fechter,

Connected them on the transistor of opto " ebrake signal " and " controller ground " to manage the LVC on the BMS, are to plug on the GND and the BK of the controller Infineon for to activate the regen batterie when tension reached the doorstep of 2.1V ?
Exact or not exact ?
Thanks,
Maxime

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 10, 2009 9:32 am

mimichris wrote:M Goodrum or M Fechter,

Connected them on the transistor of opto " ebrake signal " and " controller ground " to manage the LVC on the BMS, are to plug on the GND and the BK of the controller Infineon for to activate the regen batterie when tension reached the doorstep of 2.1V ?
Exact or not exact ?
Thanks,
Maxime
Yes I think you have it right. When any cell drops to 2.1v, the opto comes on and activates the brake line, which stops the controller output.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 10, 2009 9:59 am

Nate wrote:Just rechecked the optocouplers again to be sure, they are fine. I left the battery on until it drained and the LEDs turned off. Should I be getting 3.75 - 3.8v per channel without the battery connected? Hoping someone can test this with theirs. Thanks.

Edit: Still need help... Is there another way to test the optocoulpers? What else can I do? Please, I need to get this working. Thanks.
You have me pretty much baffled by that one.
Yes, you should have around 3.7v per channel with no cells connected. If the circuit goes into throttling (main LED yellowish), the voltage readings may be off by quite a bit due to the switching.

With the circuit powered, try measuring the voltage from the control ground to the 12v bus line and verify you have 12v. Then try shorting pins 7-8 on any opto and see if the 12v remains at 12v while the pins are shorted (seems like it would have to if the main one switches to green).

Another test would be to measure the voltage on the any shunts line against the control ground when none of the channel LEDs are lit, then increase the voltage until at least one channel LED is fully lit and see what happens to the voltage. It should drop from around 12v to less than 1v. You can measure across R6 for this voltage.

When a channel LED is fully lit, also try measuring the voltage across pins 1-2 on the opto for that channel. The opto will turn on at around 1v.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by mimichris » May 10, 2009 12:31 pm

fechter wrote:
mimichris wrote:M Goodrum or M Fechter,

Connected them on the transistor of opto " ebrake signal " and " controller ground " to manage the LVC on the BMS, are to plug on the GND and the BK of the controller Infineon for to activate the regen batterie when tension reached the doorstep of 2.1V ?
Exact or not exact ?
Thanks,
Maxime
Yes I think you have it right. When any cell drops to 2.1v, the opto comes on and activates the brake line, which stops the controller output.
Hi Goodrum,

I can connect the transistor of the opto ILD2 directly, BK and GND :

1) to the yellow wire of the brake handle,
2) to GND

without particular precaution?

When do I brake, the switch of the brakes handle consignment a signal to cut the controller and to stop the motor, doesn't the transistor of the opto risk to receive an inverse tension to its terminal ? Because I don't know tension sent by the switch of the brake handle, it is can be the GND.....

Thanks,
Maxime
Last edited by mimichris on May 11, 2009 1:07 am, edited 1 time in total.

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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by Nate » May 10, 2009 11:18 pm

fechter wrote:
You have me pretty much baffled by that one.
Yes, you should have around 3.7v per channel with no cells connected. If the circuit goes into throttling (main LED yellowish), the voltage readings may be off by quite a bit due to the switching.

With the circuit powered, try measuring the voltage from the control ground to the 12v bus line and verify you have 12v. Then try shorting pins 7-8 on any opto and see if the 12v remains at 12v while the pins are shorted (seems like it would have to if the main one switches to green).

Another test would be to measure the voltage on the any shunts line against the control ground when none of the channel LEDs are lit, then increase the voltage until at least one channel LED is fully lit and see what happens to the voltage. It should drop from around 12v to less than 1v. You can measure across R6 for this voltage.

When a channel LED is fully lit, also try measuring the voltage across pins 1-2 on the opto for that channel. The opto will turn on at around 1v.
It has not done any "throttling" yet, always Red or Green.

The 12v bus is only 11.4v? Could this be the problem? I short the opto and it stays at about 11.35v. Latched it is about 11.35v.

I don't have a variable power supply so I can't test the any shunts as described above... I did test the voltage a different way: No battery all LEDs on 5v, opto shorted .65v and latched 1.4v. I opened up the ping charger and there are no pots. My Soneil 4808srf is down for the count at the moment.

I can measure the voltage across pins 1 and 2 of the opto. Without battery connected all the LEDs are on and main is solid red, some are above 1v some are as low as .85v.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 11, 2009 8:42 am

mimichris wrote:
I can connect the transistor of the opto ILD2 directly, BK and GND :

1) to the yellow wire of the brake handle,
2) to GND

without particular precaution?

When do I brake, the switch of the brakes handle consignment a signal to cut the controller and to stop the motor, doesn't the transistor of the opto risk to receive an inverse tension to its terminal ? Because I don't know tension sent by the switch of the brake handle, it is can be the GND.....

Thanks,
Maxime
You need to observe polarity. Yellow goes to BK, black goes to GND.
Both the opto transistor and the brake switch are doing the same thing by essentially shorting the brake wire to ground. You can connect them in parallel with no problem. The open circuit voltage should be 5v.

In some systems, the brake switch is used to power a rear brake light. In this case, you would not want to connect directly to the brake switch.
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Re: Even Newer 4 to 24-cell Battery Management System (BMS)

Post by fechter » May 11, 2009 9:02 am

Nate wrote: It has not done any "throttling" yet, always Red or Green.

The 12v bus is only 11.4v? Could this be the problem? I short the opto and it stays at about 11.35v. Latched it is about 11.35v.

I don't have a variable power supply so I can't test the any shunts as described above... I did test the voltage a different way: No battery all LEDs on 5v, opto shorted .65v and latched 1.4v. I opened up the ping charger and there are no pots. My Soneil 4808srf is down for the count at the moment.

I can measure the voltage across pins 1 and 2 of the opto. Without battery connected all the LEDs are on and main is solid red, some are above 1v some are as low as .85v.
11.4v is close enough.

Boy, that doesn't make much sense. When the LEDs are on, the voltage across R6 (input to the gate driver) should drop to around 1v. When you short pins 7-8, the voltage looks correct.

Check the board very carefully around U2 and R6 to make sure there is not a solder bridge somewhere. Hold the board up to a light and look through it from the bottom side. Measure the value of R6.

*edit*

If you run it with no cells and the LEDs lit for a while, does U2 get warm?
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