Zippy Flightmax / Turnigy lipo testing

[methods]

Great time to remind everybody that Lipo chargers are nothing more than power supplies.
Dont let them give you a false sense of security.

My charging setups may be down right hazardous but I respect them so they keep me on my toes.

-methods

[SpeedEBikes]

The iChargers aren't just power supplies. They are far more sophisticated and therefore possibly more prone to bizarre and sudden failure. Has anybody else had these go up in flames for no apparent reason?

I love the damn things but realize that when critical functions such as regulating output voltage are under active software control it opens up the possibility for software bugs to result in catastrophe. I'm not saying that's what happened here, but I could easily imagine a scenario that involved no hardware failure at all or perhaps a minor hardware failure that resulted in inaccurate readings for voltage or current leading to meltdown.

I'd encourage everyone who encounters trouble with these chargers to report it in as much detail as possible. The company seems fairly responsive to posts made on the HobbyKing board and if there is a pattern of failure it will emerge more quickly if we do a good job reporting the failures

[methods]

The iChargers aren't just power supplies.

My point was that they are not some sort of magical device that when used properly will protect you from lipo failure.
I have owned and blown up just about every version of the icharger and its variants btw.

I would argue that they are just power supplies in how they charge - nothing sophisticated going on - nothing like what happens with lead or Ni.
Simply CC/CV
That's why I advocate saving your money and charging with a simple power supply and manual balancer.

I am however not ready to point the finger at modern technology and say that we should go back to vacuum tubes.
Power supplies pop and that is that - any number of passive or active components in a regular power supply can fail causing meltdown.
How many opamps and comparators and PWM sources do you suppose are in a modern supply?

Being a firmware expert I have no firmware phobia - once programmed - they are just another active component as far as I am concerned.
No different than any integrated circuit on the board.

Software bugs are another issue.
I will bet my balls this was not a software issue.
I have personally seen crap solder joints on these units. Pop yours open and look.
I put my money on a heated up cold joint.

-methods

[mwkeefer]

Methods - forget LiPo failure - this could have been far worse...

After dissection (not much) it's clear the LOW side FETs of the switching power supply burned clean through the PCB (yep all 3 of the low side - closest to the power input) and took out the cap and a good bit of crap above. That said...

Educated guess on cause - LOW side fets tried to turn on while HIGH side was fully on already... odd, gates should have been logic level controlled for hardware based "short" (or crossover if you prefer controller terminology) protection but I guess they weren't just like there was no internal fuse or diode to BLOW before the gates cooked the PCB like a plasma cutter (no crap, the insides are blackened bad - top and bottom and two of the three fets burnt so badly they came right off as I pulled the PCB - crispy cajun style one with a big messy hole in it the rest just extra cooked - toast you wouldn't eat.

It's kinda sad when you think about it... If the exact same thing (input side issue with gates/fet/etc) causes a short on a Meanwell it blows the fuse if hiccup mode doesn't cover the damage - on better supplies the likes which Methods uses - probably no pop fuse, no blown fet, resettable breaker? LOL

Seriously the only issue is balance - right now I can get about 30mv difference bulking 3 x 5S as a 5S3P pack (balance taps paralleled before charging).. this pack was getting to 20mv but then the iCharger incident, it should correct back to 20mv within a cycle or two.

Methods... what resistor do you use to short your cells out for balancing (kidding but I've thought of a simple 4v dissipator, single cell to draw down the higher cellls in a manual process durring charge until the slower cells catch up).

-Mike

[MrKang]

Funny, i had the same experiences with my IMAX B6 which is probably the same manufacter of the ICharger. All China Stuff.
I bought 2 of those units cause they were very cheap and did there job done for the money. But after 2 cycles i connect my normal 13.8V power supply and then i heard a sparkle/sissing sound together with the smell of burned resistors. A small smoke fume came out of the box....
After that i opened the box to see what was broken...I still didn't figure out what the hell was happened. I suspect a FET on the output of the charger which has type : IRF 540N but while measuring it i didn't detect a shortcut. Then i measured the two large diodes on the input. One of them had a measuring of 0.179mV , i don't know if this is normal. I thought all diodes are arround 0.450mV




I'm gonna measure some more components and find out who's to blame.

[MrKang]

So i measured from the start where the 14V come in. then i stumped on this 8pin smd IC. I am wondering if this is a FET in a different eclosure. I think it is.
I measured zero ohms. so i think it's broken. on the ic is printed: PF6BJ / FDS / 6675

[Hyena]

The board layouts are a little different but that looks to be the same IC that friend in mine. Like Mike described above, mine burned a hole right through the board.

Mike if you want a good 4v load for ghetto balancing cells whack a cree LED on there. That's what I've done a few times and drawing 1-2 amps quickly pulls high cells back a notch!

[MrKang]

Does anybody know what kind of IC this is ? can i replace it with a normal TO220 FET type ? and if so which can i use ?

[methods]

.... - on better supplies the likes which Methods uses - probably no pop fuse, no blown fet, resettable breaker? LOL...

pffft... yea. My Lambda supplies are modular. Each module has access to a shut-down breaker via an isolator.
If any module detects Over/Under Voltage it hits the shutdown line and the power supply latches "off" until the ac power is cycled
I once drove 100V DC into a 50V output module and absolutely destroyed that module but the mama power supply was not damaged at all.

Methods... what resistor do you use to short your cells out for balancing (kidding but I've thought of a simple 4v dissipator, single cell to draw down the higher cellls in a manual process durring charge until the slower cells catch up).

-Mike

6.2 ohms - 6.8ohms
When I have no resources I just hook all the cells in parallel to make a 1S 15P and hook up a standard RC balancer
Now I have 12 of Garys Balance boards tuned to 650mAh. 4 are tuned to 4.1V and 8 are tuned to 4.15V.

Anyhow - I hear what you are saying about the charger - it is definitely lacking in redundant features - but the name of the game is cheap right? How cheap can we get a full featured charger. * I am personally willing to take on more risk if it means that I can get my hands on technology for a noticeably lower price*

-methods

[GCinDC]

In light of recent 1010B failures, and considering I toss my Charger, PSU and spaghetti of wires in and out of the backpack several times a day, I thought I needed to at least protect them better against the unnecessary wear & tear, so...

I cut the sides off an old video camera case to create a charging 'toilet kit':

gutted_camera_bag.jpg

Sides cut off video camera bag

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I left a flap between PSU and charger to protect them:

mostlyopen.JPG

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Open and charging (5s8p @ 10A) under the desk at work - stays nicely balanced, btw, all within .015V after several months). Yet to put a nametag in it... PSU's gonna come out of that mesh, BTW. Even though there's plenty of air, it gets warmer than I'd like.

under-desk_charging.JPG

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i've now got fixed 'ports' on the front of the pack for the power & balance leads. After unplugging charge & balance leads, I plug in serial discharge cable and DB25 with 4 pigtails for chargery BM6's (which have a little slot to live in)...

IMG_3732.JPG

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And now that I'm a member of the 40 mph club, I got a (methods spec?) helmet, which I can lock along w/ bike & batts.

locked_batts_onbike.JPG

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Hope that's not TMI for this thread...

[methods]

That helmet saved my ass

-methods

[geoff57]

That helmet saved my ass

-methods

Hi
I use the same model, with the cold weather and long rides I go on I fitted it out with a visor for the rain and wind.
For music and keeping in contact with people I fitted earphones and a mic that work with my Iphone, just keep the volume down so I can hear the cars, I can also turn off the music in traffic a good idea.

Geoff

[rscamp]

That helmet saved my ass

-methods

Hmmm. Are you sure you put it on correctly?

[methods]

-methods

[mwkeefer]

Hey guys!

Love the helmets - those are what full face bike helmets for BMX? Or are they lightweight motorcross helmets - personally I have a shoei and a bell full face which I've been wearing alot lately (rain).

The IC chip (8 pin smt) is actually a TTL->USB level adapter used to interface to the MCU of your charger.

Although I'm still looking for the last shipment of power supplies which UPS has lost ( a few 48v units to confirm earlier findings) I did get a new surprise delivery today - the first prototype of my new geared hub design (steel straight cut, oil bath, enclosed) was on my step along with some nice extras I wasn't expecting. I will get details up tommorow - I have my son this weekend (he's tired and 3 - I'm lucky he's letting me type this up while dora is on).

If anyone cares - my 3yr olds review of the new motor: "kewl"

-Mike

[MrKang]

The IC chip (8 pin smt) is actually a TTL->USB level adapter used to interface to the MCU of your charger.

I just found out with your hint what this IC does. it is a circuit breaker connected (on the right of the photo) with a temparture circuit.
On that pins you connect the temperature sensore which finally gives a logic signal to cut the power off.

I will hook up my Lab supply and find out what is wrong..

[mwkeefer]

Mr Kang,

Sorry about that... I couldn't find the chips #s anywhere in my references and it looked as if it ran to the 3 pin connector interface on the PCB - I guess thats your temp not USB connection to your PC.

Glad you figured it out.

-Mike

[Toorbough ULL-Zeveigh]

That helmet saved my ass

-methods

Hmmm. Are you sure you put it on correctly?

it's probably a gaye thing.

[mwkeefer]

Todd,

That's just wrong = )_

As requested... here are the pics of the iCharger - post flame out:

This is the PCB near the power input side and the large CAP.










As I stated in my initial report, you can clearly see from these photos the level of damage and the apparent cause.

The good news:

I have lots of cool spare parts I can pull off the UNBURNT side, even the LCD (been looking for a nice LCD - I have lots of 2x16 and 2x12 but these are nicer).

-Mike

[methods]

Pffffft.....

If you cant fix that you are weak-sauce.

I - personally - would spend the 36 hours it would take to repair/rebuild/reverse engineer all that.

150 / 36 = $4.16 / hour for your efforts!

-methods

[mwkeefer]

Pffffft.....

If you cant fix that you are weak-sauce.

I - personally - would spend the 36 hours it would take to repair/rebuild/reverse engineer all that.

150 / 36 = $4.16 / hour for your efforts!

-methods

Methods,

I couldn't fix it - 3 or 4 layer board and no way to reconstruct the burnt PCB inner layers.... assuming I could in 36 hours - my minimum labor rate is 65.00 per hour (contract) wiht the upper being > 100.00 per hour - so to spend 36 hours to fix it would really be a cost of: 36 * 65 (minimum) which works out to: 2340.00 - much cheaper to buy a new one and far less aggrivation.

[hurricaniac]

Does anyone see any red flags in using the following cheap bulk charger setup for a 12s3p Lipo 15ah (Using six Turnigy 6s1P 5000mah 20C packs)?

- 48V 20A server power supply with 20' of 17ga lamp cord to limit current
- CellLog8s to trigger a HVC device ("Improved simple auto disconnector for battery charging/testing" -- a DIY circuit in RC Groups: http://www.rcgroups.com/forums/showthread.php?t=1131817)

Thanks for any fire alarms you can pull in advance,
Bruce

(My wife made me write this after seeing lipo fires on youtube)

[mwkeefer]

Does anyone see any red flags in using the following cheap bulk charger setup for a 12s3p Lipo 15ah (Using six Turnigy 6s1P 5000mah 20C packs)?

- 48V 20A server power supply with 20' of 17ga lamp cord to limit current
- CellLog8s to trigger a HVC device ("Improved simple auto disconnector for battery charging/testing" -- a DIY circuit in RC Groups: http://www.rcgroups.com/forums/showthread.php?t=1131817)

Thanks for any fire alarms you can pull in advance,
Bruce

(My wife made me write this after seeing lipo fires on youtube)

Bruce,

Honestly my friend if your using the Turnigy packs... yes I could see an issue.
At empty those packs will attempt to sink/source (damn I wish i could remember the right word, but you understand) as much current as they can. If your planning to attempt to charge less than 4 6S packs (connected via seperate cords) you will be pulling 20A through these lines - DC current (I recall you have to cut the rating by 1/2 when going from AC to DC conversion the scale for voltage - could be wrong).

Biggest issue I see is if your planning to actually use the little guage for current limiting, sure they will block a huge portion of current but that results in HEAT and will melt them if you just ran 20' of lamp cord to teh eBike. Good news it's only the lamp cord which will heat up and melt.

Given this knowledge - we need to look at the C rate:
5AH @ 20C (I think you mean the 20C/30C packs - slightly different, lower internal resistance)
That means in continuous discharge they can provide 100A (they will get warm at this level, hot even) and peaks for a few seconds of 30X5A 150A.

These packs recommend a charge rate of 1C so.. that is 1 x Capacity or 5AH however you seem to be wanting to charge all 6 6S packs so - the question is...

Will you be charging them all at once?

Here's the break down -
6P6S (what your charging in parallel mode) is actually 5Ax6 = 30AH Capacity so first there is no need to limit current for the safety of the LiPo.. that's 10A under 1C (which also means you could charge 4x6S in parallel for 1C charging.

If you planning on using a seperate lamp cord to each pack positive and negative, sure that would mean 6 lamp cords and each would only carry a portion of the current total. So if charging in 6P it would be 1/6th total current or 20 / 6 = 3.33 A per cord over 20' - should be okay (should I still wouldn't do it - too many individual wires, too small a guage and too long a run) - 18G cable gets warm after a while at 36vdc and 22A continuous and for the first 70% of the charge cycle your current will be similar but the voltage higher.

Consider lamp cord is rated for use with 100-150w lamps at 110v so (110 / 100) = 1.1A , this is not the limit but really I wouldn't use lamp cord... id use at a minimum 10 guage harness of less than 20'... if you need to run a charge cable from an outlet to the eBike or charging station - please use a 20A rated outdoor extension cord of 20' - the drop will be less and the wires are insulated better to prevent shorting or overheating.

If you can be more specific about how many of these packs you plan to charge at once... if you plan to parallel the balance taps durring the charge or just the discharge wires, etc... I can provide you with a much more accurate electrical requirement - be a bit more specific on the power supply type too... it may have adjustable current limiting internally (variable resistor pot) or ... you could limit/reduce the current by increasing the internal shunt resistance - there are many more ways you could do this which would be safer and more efficient (heat is always wasted energy).

Hope this helps,
Mike

[mwkeefer]

Methods,

I had figured as much on the Lambda supplies - should I even google them to find a price or are they far beyond reasonable in terms of "normal joe" purchase?

You really do use a resistor? I was actually kidding but that's pretty cool (although I would need to use needle nose pliers cause otherwise... actually I could build up my guitar callouses).

Ahh cells in parallel - Would be nice if it were an option but as these are pack level... its a no go, good idea for headaway or actual built up lipo packs. I still haven't ordered gary's balance boards but I would like to in the next days. For an interum solution I use a small array of high power LEDs (sort of what Hyena suggested) to draw down individual cells from the balance taps... it seems to measure between 500ma and 800ma which is fine for the kind of drag down I needed.
That and doing every third charge @ 1C waiting for C/20 to quit the process seems to keep them within 15-20mv of each other.

Yea the chargers we want are to be cheap but... I look at a pair of 24 or 36v meanwells - figure 40.00ea (prob less on eBay) so that's 80.00 but what more do we need? The iCharger seems to balance as it charges draining small amounts from the higher cells at each .25 or .50v point until 4v then it begins to do this more often to obtain a < 10mv differential. I have done the research into the chemistry (I wasn't sure of the effects of this type of charging) and these little drain offs so that the remaining cells can be brought up don't count as cycles and should not really reduce the pack life (contrary to my concerns).

That said.... if we can interface a good cell level drain with cell level voltage monitor and a simple MCU to monitor and control the whole thing - we acheive the "bulletproof" quality and safety we need.

1.) The supply is fused and if we replace them with lower fuses (ie: 6.5A @ 110) and limit the current so the units produce no more than their 350w rated power they should last forever... a failure would be at fuse level and would cause nothing more than a voltage drop which would be detected.
2.) An iCharger like charge / balance scheme can be implemented in software with simple logic gates to prevent any possible error conditions which would be considered "fatal" to the charger or pack.

You get the idea ... so 80.00 + about 20.00 in external parts... for a much higher quality and serviceable unit.

-Mike

[drewjet]

So I ordered myself 6 of the 6s 5000 MAH 20C Turnigy's. Got them in less than a week, WOW! Shipping at $69 kinda hurt, but even so, still a great price. Of the 2 I have charged so far, they are showing an Internal resistance of 1.3 to 1.6

Now the bad news.

1 Came with a slight puff on an end cell, and one came with a cell at 1.0 volts.

What should I do? Charge and see what happens? Send em back?

Good news and bad news. I got my replacement pack in. I chose to send only the one with the 1.0 volt cell as it really didn't seem all that puffy and I intend to wrap them very tightly. The bad news it cost me $20 to send back and took about 2 months to make the round trip. But hey that's better than getting nothing. Sure would be sweet if they would allow us to send returns to the US warehouse.