Would you please help me diagnose my 48V 15AH Ping V2.5?

[NeezyDeezy]

Hi guys, my Ping isn't working. It's seen 200 or so cycles. I reluctantly removed the outer layers of the Ping, opened it up, but I don't see any problems. I'm not sure what to do next. I bought the Ping for plug-and-play, so I'm brand new to this, but I'd appreciate any advice you can give me! I can take and upload photos if it helps, but I'm not seeing anything peculiar.

Thanks!

 

[dogman dan]

Assuming all the led's lit means all your cells charge to 3.7v, then the only thing left is the bms is not turning on.

What's the voltage reading on the big wires leading into the bms from the battery? 59-60v?

 

[NeezyDeezy]

Well, I have a $5 analog voltmeter, I'm not sure if that makes a difference, but I tried it and it shows only 50V. I'm not sure if I'm measuring them correctly, but it also shows most of the cells are 3.5V. There is one cell that sometimes doesn't light up on the BMS. But, if I leave it on the balancing charger overnight, it will sometimes come on. That cell, near the middle, right now reads a little less using the voltmeter, like 3.2 maybe.

 

[DAND214]

First thing is a good digital meter. Even a cheap one from Hf works fine.

I have a pack just like that. One cell in the middle doesn't light up at all. In my case the cell is shot, I can single cell charge it and it works but if i don't charge it the BMS shuts down the pack with a 5 amp load.

Let it charge till all the leds are lit. Then check your voltage. It should read as Dogman said almost 60v. If it reads that then the BMS has a problem. Check the solder joints to the BMS and at the battery.

If it's the BMS contact Ping about it, or contact him anyway. He is a great guy to have for support. Ask him what he thinks might be the problem. I am sure he hears this a few times a day. As we all say about him, great guy to deal with.

Dan

 

[dogman dan]

Well, even with dogman math 50v divided by 16 isn't 3.5v. Sounds like you have at least one weak cell, and the others are not getting fully juiced if they are only 3.5v. My bms cuts out at about 48v, so at 50v you are close. If your weak cell that is actually 3 pouches has two dead pouches in it, It may sag that two more volts instantly and be causing the bms to trip.

What kind of voltage is the charger putting out? 60v?

the really common problem is a charger that broke at the plug. Disconnected, the led turns green. But you say the led's light, so a charge is happening. One possibility is an intermittent bad connection at the plug. I've rode off half charged with that problem. But that was on an early ping, without the led's to give me a clue the charge never happened.

 

[NeezyDeezy]

Damn, I was wrong. All the lights aren't coming on, but I think maybe I just wasn't noticing that one on the end wasn't lighting up. I'm not sure I'm measuring this right, I'm measuring the reading across each square of solder at the top of the cells? I'm getting 3.9V for all the cells except for 2 (3.2V), 7 (3.2V), and 16 (1.5V). But I still get a 50V reading for the pack.

I just emailed Ping.

 

[DAND214]

1.5v IT's A GONNER.

Ping will help you out.

Dan

 

[dnmun]

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[dogman dan]

Sounds like that one cell is the culprit then. Bummer. I'd try to bring that last bad cell up some with a cellphone charger or some other kind of 4-5v wall wart. If it comes up to about what the others do, then then try charging it for nearly forever and see if the light ever comes on. Your voltmeter may be off a bit, explaining why the lights come on when they shouldn't till about 3.6v or more.

Chances are, you need three new cells from ping, and will have to do some soldering. But you might be able to baby that last cell for a few more short rides.

 

[mst3kpimp]

What if he removed just one cell or enough cells to make it a 36v pack? would the bms still work?

 

[dnmun]

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[NeezyDeezy]

Ok thank you guys so much for trying to help me. I've read all of your posts. I'm a little new to this. I am now certain I'm measuring the cells correctly, and here's what I get, starting with the end of the pack with the black wire:

2.7 (not lighting up on BMS)
3.5
3.5
3.5
3.9
3.7
3.7
3.7
3.5
3.6
3.7
3.7
3.8
3.7
3.1 (not lighting up on BMS)
3.6

The other 14 cells light up on the BMS. When I measure the total pack I have to change the scale to 300V, but it looks like it's about 51V. By the way, it's been on the charger for about 60 hours now.

Ignore what I wrote before, I'm sure of these measurements here.

what was the pack used for?
A mini-might motor with 20 amp controller. Note, I had a 25 amp fuse that never blew, so the amps were NEVER high.

Did you leave it sitting for along time uncharged?
I think this is my problem. I charged the battery, then I left it for 7 weeks in my apartment without using it or charging it (it wasn't connected to a controller or anything). But, I never would have thought it would cause these problems.

When did you buy it?
May, 2009

do you have a picture?
yes
http://img690.imageshack.us/img690/2619/img8007ol.jpg
http://img221.imageshack.us/img221/3126/img8008etb.jpg


are all the sense wires connected to the cells?
yes

do you have a harbor freight store you can go buy a digital voltmeter for $5 from? they are more accurate than you think.
I will try to do this soon, but I think my analog is easy to read precisely when it's on the 10v scale

what is the output voltage on your charger?
60V

did you use it under load while that cell was low?
Definitely not

I really want to fix this because other than not using it for a little while, I really babied this battery.

What should I try next?
Thanks again!

 

[docnjoj]

I would first try to charge those 2 low cell groups with a lipo phone chager. You will have to watch them as they charge so as not to go over about 3.7 volts. Then wait and see of those 2 cell groups drop in their own, maybe a few hours. If they hold their charge go ride a short distance <2miles? and then put the battery back on the charger overnight. If those 2 cell groups drop on theri own accord before the test ride or if they charge immediately first during recharge they will probably need to be replaced. Ping can help with pre made cell groups. I decided to turn my 48 volt 20 ah Ping into a split 36 volt 20 ah battery since 4 cell groups were bad. It is a fair bit of work but there are threades on how to do this. Check out Dnmun's suggestions on using wires instead of reusing the circuit board connectors. Good luck with this as it can work well. My battery is still putting out 15-16 AH about 2 years after surgery,
otherDoc

 

[dogman dan]

Agree with all Doc just said. Try to charge up the low ones by connecting a 4-5v power supply to the same place you took the reading from. It's possible the bms drained the end cell, but the middle cell should have been ok. That far out of whack, it could take weeks for the bms to bring up those weak cell groups.

Another approach, you could take a headlight and use it to drain the highest cells one by one some. Then put it on the charger and see if the weak cells charge any, or just stay the same.

The key thing will be if they can hold a charge.

If you store a ping, you need to unplug the bms during the storage. It uses a tiny trickle all the time.

 

[dnmun]

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[NeezyDeezy]

Well, I replaced the bottom cell group and the same exact thing happened again (just the bottom group is dead and tripping the BMS).

I think the problem might be that the bottom cell group was never attached the BMS and so doesn't balance...? How can I confirm this? When I replaced the group weeks ago, I charged it up to 3.8V but it wouldn't cause any light to come on on the BMS.

I guess one question I have is why it seems that the bottom cell group does not have its own balancing wire? It never has (see photo). Maybe I am getting confused and the black wire is the correct balancing wire...?

 

[dnmun]

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[dogman dan]

I think on another thread we saw a ping where the last wire to the bms was the big negative wire to the bms. So it also looked one wire was missing.

My guess? The bms has a short in it, and discharges that last cell group. I'd want to charge up the whole battery manually to 3.7v then disconnect the bms and see what happens. Any group dropping voltage? If not, then plug in the bms and look again.

How long did it take for the last cell group to drop? Was it days or months? We haven't heard from you since october, and now it's almost July. It's pretty normal for a bms to kill an unattended battery in 6 months or more if you don't unplug it.

 

[dnmun]

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[NeezyDeezy]

Thanks guys, the original cell group was dead. It would drop to about 0.2V after sitting idle. One of the cells had also puffed up.

The battery did not sit unattended for six months. I replaced the cell group and then resumed using the battery. Eventually though, the bottom group died again (although it might not be in as bad shape as the original).

I'm sure the BMS is not discharging the cell group when at rest. I just think it is not balancing it. Dogman, the large black wire can serve to balance the bottom group?? That seems strange. All other groups, including the top cell group, have their own balance wires. Also, there is no light on the BMS that corresponds to the bottom group (only 15 when there should be 16).

I guess I'll ask Ping what to do...

 

[Tench]

Dogman is probably refering to my 36v ping pack, it only had 12 wires in the balance plug which would indicate an 11 cell battery, it turned out to infact be a 12cell battery and did used the heavy negative lead as the bottom connection to the first cell which then gave the BMS enough cell connections to balance the whole pack.

 

[dogman dan]

Yep that was the one. I tend to remember stuff, and forget who completely.

Moving on, Ok, it worked normaly for awhile, and then it seems to be happening again. At this point, more guesses will take more info. Exactly what is your normal routine? Most importantly, do you ever leave it on the charger long enough to balance it? Do you do discharges likely to unbalance it, as in till the bms shuts it off?

 

[dnmun]

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[NeezyDeezy]

Exactly what is your normal routine?
8 miles round trip, often much less, then charge after each ride

Most importantly, do you ever leave it on the charger long enough to balance it?
Yes, the battery stays on the charger overnight

Do you do discharges likely to unbalance it, as in till the bms shuts it off?
Never

the BMS only balances the pack while you are charging, not when the charger is off.
Correct

the pack looked like it would not charge because you had a cell at 3.9V which you never drained down to let the others catch up
I used a single cell charger to top off the lagging cells

now you have replaced the lowest cell and the BMS is still cutting out?
It cuts out after a short ride because the bottom cell group goes below LVC

can you put the pack on the charger and measure the cell voltages so we can see if it is because it is now outa balance again?
I can charge the pack up to 60V (more or less balances), but if I let the pack sit off the charger overnight, the bottom cell group drops below LVC

usually it is the high cell that is the bad one. not the low one.
I don't have any super high reading cell groups

you need to do a bench test into a dummy load to find the cell that has lost the capacity.
Is there any way you might please link me to info on the easiest way to do this?

THANKS!

 

[dnmun]

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