Brand new battery bms problem

[Oursoul]

Hi, here's another plea for help identifying the bms in a battery!

Recently bought this 48v frog battery from ebay, charged it up all good, but think I've buggered the bms as it's not charging anymore (light on charger stays green when plugged in), and pressing the test button on battery does nothing. If I press it while charging it briefly flashes red.

Anyway I've opened it up and tried to reset it by plugging the charger in with bms disconnected then reconnecting but that didn't work.

So now I'm looking at replacing the bms, but can't see any useful info on it and looking up the specific codes on it yield no results.



Did a Google translate too:



(Love how it's also translated the wires to WWVW!)

Tbh I don't really know what I'm doing. It's to connect to a 36v 500w voilamart front wheel which I bought after trying to connect the battery to my existing 36v 250w motor and it didn't improve performance.

Any help would be greatly appreciated

 

[lnanek]

BMS are fairly interchangeable. Make sure to determine your battery chemistry, e.g. LiIon vs. LFP (lower voltage per cell), figure out how many cells your battery has in series, e.g. 13S means 13 cells in series, and make sure to match or exceed your previous 30A discharge capability and 5A recharge capability if putting it back in the original system. You can get a new one for as little as $35.

That said, it's more likely the battery is out of balance or has a bad cell than that the BMS is fried. Many BMS will refuse to run if, for example, one cell is 3.4V and the rest are 3.7V. their balancing ability tends to be fairly limited. That mass of a bunch of cables coming out of it are called the balance wires. They go to the individual cells so the cell voltage can be measured separately.

 

[amberwolf]

As noted above, it's much more likley to be a cell problem than BMS problem. See below for some questions that may help us help you find the root cause:

Recently bought this 48v frog battery from ebay, charged it up all good, but think I've buggered the bms as it's not charging anymore (light on charger stays green when plugged in), and pressing the test button on battery does nothing. If I press it while charging it briefly flashes red.

What specifically happened just before it stopped working? (usually some combination of events or symptoms occurs before a problem is noticed; listing such events/symptoms often leads to a solution).

For instance, it could be related to below:

It's to connect to a 36v 500w voilamart front wheel which I bought after trying to connect the battery to my existing 36v 250w motor and it didn't improve performance.

If the battery isn't able to handle the current (A) demand of the new kit (regardless of whatever specs the seller said it could do), and it was used with the new higher power motor enough it could have caused a problem. Which of several problems it might be depends on the actual pack capabilities vs the actual loads.

Or if the 36v controller itself failed from too high a voltage (48v nominal, 52v full)) on it, and internally shorted, it could've damaged the battery pack in one of several ways.

A link to the pack's purchase page may have helpful info.

Anyway I've opened it up and tried to reset it by plugging the charger in with bms disconnected then reconnecting but that didn't work.

What are the voltages between each pair of wires on the sense wire connector of the BMS? A 48v pack is usually 13s, so there are usually 14 wires on it, and using a voltmeter to measure between each pair of wires will give 13 voltages, which are the individual cell groups the BMS monitors.

(Love how it's also translated the wires to WWVW!)

FWIW, it actually translated them to "WYWWA". (attention to detail in troubleshooting is important, especially with batteries. )

 

[docw009]

What is the problem? Does the battery not run the bike any more? Or is it just not taking a charge?

As far as replacing it, seems like you need a 10S BMS, rated for 30A if I believe those translations. However, Frog batteries are pretty small, and one could probably get by with a 20A BMS. What really matters is whether a 30A BMS will fit in the case.

Also, if your frogger battery has a on/off switch, you probably want a BMS with an on/off switch to match,

However, you should follow advice given above, and check the cell voltages, all ten of them. It's convenient to unplug the BMS and use the balance connector. I steal my wife's safety pins to do it. I also insulate the pins so they won't short circuit if they touch.

 

[Oursoul]

Thanks for the intelligent replies, and sorry for the delay, didn't get a notification!

Right, before I post all the technical details I'll explain what happened.

The old 24v battery lasted about 7 years, but kept conking out when going uphill - it would come back after a minute, or if I turned the ignition off and on. This situation got worse over time so assumed it was probably the age of the battery.

I bought the 48v battery thinking it was the same form factor as my old one and would just slot into place and would get years of use with extra range due to the higher power/voltage (told you I didn't know anything). Anyway it didn't work out, and the bike would conk out as soon as I got to the pavement and turned uphill out of my driveway, so worse than before.

Then I assumed it must be the motor, did a bit of research and found this 36w voilamart kit. Also read somewhere that they were OK but it was advised to get a sinewave controller rather than use the one supplied, so got one of those too.

The wheel arrived first, and straight away noticed that it had different connectors to my existing controller which has julet waterproof ones so I had no way of connecting it to the battery. This controller is also way too large to fit in the battery mount, but did come with a bag thing you attach to the frame (no idea where to put it though as the battery is mounted inside the frame currently, there's no way to do it tidily in any case)

So I tried putting in the new sinewave controller which does fit AND has the right connectors for the existing wheel, but again cut out as soon as I started going uphill.

Finally I connected the new battery to the new motor using the supplied controller and nothing happened. Its got an indicator light on the throttle which didn't light up, so tried the battery test light and got nothing - it did work when I first charged it. Then I plugged my old battery into the new motor and the throttle did light up, so I'm actually not sure at what point the new battery stopped working.

As you say, the next thing would be to test the cells (I like the idea of using pins in the ribbon connector, very clever) I do have a multimeter but don't really know what I'm doing with it, so if you can point me to something on this site that covers that please do! I'm a bit scared of blowing myself up/burning the house down but am kind of out of ideas.

Anyway here's the specs for the parts:



https://www.ebay.co.uk/itm/283856333695?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=TnVP7Zf7Som&sssrc=2349624&ssuid=B7ruB3mXQhG&var=&widget_ver=artemis&media=COPY

Controller:



https://www.ebay.co.uk/itm/394207072321?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=4hhh-mporc-&sssrc=2349624&ssuid=B7ruB3mXQhG&var=&widget_ver=artemis&media=COPY

Wheel:



https://www.ebay.co.uk/itm/385045069713?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=ps1r00e9tri&sssrc=2349624&ssuid=B7ruB3mXQhG&var=&widget_ver=artemis&media=COPY

Hope that's enough info, thanks so much for your help, I feel like I've been a bit stupid and wasted a lot of money for nothing (though I do have a battery with lots of fresh cells in it!)

 

[amberwolf]

This situation got worse over time so assumed it was probably the age of the battery.

That is pretty likely, but would need testing to be certain. Unbalanced or incapable cells sagging in voltage beyond the limits the BMS allows for safety, resulting in BMS shutting power off, is a common pack problem.

Anyway it didn't work out, and the bike would conk out as soon as I got to the pavement and turned uphill out of my driveway, so worse than before.

Don't know which of a few possible reasons, why it would in this case. Other testing would have to be done, but kind of irrelevant at this point.

This controller is also way too large to fit in the battery mount, but did come with a bag thing you attach to the frame

FWIW, it's better not to put a controller in a bag, because it generates enough heat inside itself to age components inside faster than usual. Lower power controllers probably won't fail from it, but as you go up in power level and pack voltage the internal design tends to make enough heat to start causing issues over time.

But if you have to ride in a lot of water/rain/etc, controllers are usually only water resistant, not waterproof, and a bag might help protect it more against that (depending on conditions).

Sometimes you have to compromise which thing to protect against. :/

So I tried putting in the new sinewave controller which does fit AND has the right connectors for the existing wheel, but again cut out as soon as I started going uphill.

If it actually turned power off completely, it means the BMS in the battery shut off to protect it. It can be from an imbalance inside causing some cell(s) to drop too low in voltage, *or* it can be from an overload such as too high a current draw from the controller, if the BMS has this protection as well.

If it didn't turn power off, it's not the battery itself (or at least, not the BMS shutting down), and is more likely to be a controller self-protection, possibly from a wrong phase/hall combination, for one example. Not all controller/motor combinations use the same connection pattern, though many of the ones that use the same connector will--you may have to use the controller's self-learn or auto-detect feature (often a pair of wires that only connect to each other).

Finally I connected the new battery to the new motor using the supplied controller and nothing happened. Its got an indicator light on the throttle which didn't light up, so tried the battery test light and got nothing - it did work when I first charged it. Then I plugged my old battery into the new motor and the throttle did light up, so I'm actually not sure at what point the new battery stopped working.

The not-working battery could be a fuse blown, or the BMS may be in "protect" mode for whatever reason. May require opening it up to find out.

As you say, the next thing would be to test the cells (I like the idea of using pins in the ribbon connector, very clever) I do have a multimeter but don't really know what I'm doing with it, so if you can point me to something on this site that covers that please do! I'm a bit scared of blowing myself up/burning the house down but am kind of out of ideas.

There are many battery troubleshooting threads that have good step by steps on testing, if you need to do it now, and have time to do a fair bit of reading around. But we can write up some specific directions for yours if you have time to wait for them.

 

[docw009]

Running a 24V controller on 48V? I don't think the 24V controller has an overvoltage circuit to protect the circuitry, but it may have an internal DC-DC converter that fails at that voltage,

I have a frog battery. It's 36V, the case holds around 40 cells For a 48V battery in the same size package. I think 52 cells for a 13x4 array would be pretty tight, and too heavy to mount on a seat p[ost. In face, I never used my frogger much, because I didn't trust the clamp on the seat post. Well, if it is 48V 10.4AH made with 2.5AH cells, it should be enough to run the Voilamart.

Does the wheel spin OK with no load?

 

[Oursoul]

The not-working battery could be a fuse blown, or the BMS may be in "protect" mode for whatever reason. May require opening it up to find out.

It's not the battery fuse, I've checked it and swapped with the one in the old working battery, which still works with both fuses.

Wouldn't doing the aforementioned bms reset get it out of protect mode if that was the problem?

 

[Oursoul]

Running a 24V controller on 48V? I don't think the 24V controller has an overvoltage circuit to protect the circuitry, but it may have an internal DC-DC converter that fails at that voltage,

I have a frog battery. It's 36V, the case holds around 40 cells For a 48V battery in the same size package. I think 52 cells for a 13x4 array would be pretty tight, and too heavy to mount on a seat p[ost. In face, I never used my frogger much, because I didn't trust the clamp on the seat post. Well, if it is 48V 10.4AH made with 2.5AH cells, it should be enough to run the Voilamart.

Does the wheel spin OK with no load?

1. The battery is mounted inside the frame, as putting it under the seat post means raising the seat by several inches so my feet no longer touch the ground!



I did used to worry about the old one as it got a bit rattly, but somehow clung on for 7+ years. The new one weighs about twice as much, so took the opportunity to put the new mount on.

2. No the wheel doesn't spin at all with the new battery but still works with the old one. Something has caused the battery to shut off completely.

 

[amberwolf]

Wouldn't doing the aforementioned bms reset get it out of protect mode if that was the problem?

Depends--some BMS just don't "reset" properly.

Also, if there is actually a condition the BMS is detecting outside it's limits, it will still detect that and stay off.

You'd have to open up the battery to test what might be outside it's limits. Cell group(s) too low, or too much difference between them, broken-off balance wire, etc.

 

[Oursoul]

Thanks, I've tried to do a bit of research into battery testing after a few days away and again got quickly confused, so am back to humbly ask for help please!

It seems there are different methods of doing a BMS reset - i've already tried unplugging the BMS, plugging in the charger then plugging in the BMS to no avail. Another suggestion was using the discharge port, and while trying to identify where the discharge port was on a frog battery found this on an amazon page - not exactly the same model as i've got (this is 36v) but am assuming the setup is the same:



I can't actually see a 'socket' there, but this reminded me of another incident that may or may not have contributed to my woes. When i had the battery attached to the holder, i was having terrible trouble removing the battery again, to the point where i stuck a screwdriver in between the battery and the holder to lever it out, which snapped the plastic bit with the 2 prongs on it (imagine my delight - brand new £260 battery that i've just busted because i didn't fully turn off the ignition key, thereby not disengaging the lock). Anyway i glued this back together and added electrical tape to hold it in place and it appears ok, stays together when i slide the battery on and off in any case.

I didn't think this was important before, but if it is indeed a discharge port maybe this would have contributed somehow?