eBike stopped working

[Deleted member 4845]

Video does not work, but not needed.

Check the main leads where they attach to the bms. These are seperate from the balance wires.

If you have 42V going in to the BMS, then look HARD for a fuse, if none, then the BMS is bad. Unusual from impact alone, maybe a broken component lead or smashed chip?

Check carefully the connection for the main leads to the pack itself if not 42 at the BMS connection. This is where I would expect the breakage from shock damage to occur.

It is feasible to just totally bypass the BMS, but then you have NO protection from over-discharge, or over-charge, and no balancing. Old battery, take some safety precautions, but use it as a learning experience.

 

[johneakin]

The battery has a screw out fuse from the case, I tested this and it's working.

With the unplugged wire harness on the BMS, the voltage from the discharge port was still 4.xV. Not sure what meaning this has (of any).

I checked all the wires and they look good, tho quite a few are in casing and most are glued so structurally it looks fine.

Not sure how/where else I could test the charge to try and narrow down the issue.

 

[Deleted member 4845]

Check the main leads where they attach to the bms. These are seperate from the balance wires.

Big heavy honkin wires from the battery. Likely a huge solder ball where the pos and neg wires from the battery attach to the BMS.
If covered in hot glue, carefully remove enough for the probe to test. You could also test the connection points on the battery itself, basically the same test, isolating the BMS.

Not the ports. The raw feed from the battery.

The reason for this is to test the connections for the main output from the battery. Balance wire results show the serial grouping is at least correct. Last major connection is from battery, to BMS, then BMS to ports. You have already tested the ports.

 

[johneakin]

Some more info.
I suspect this means the BMS is definitely at fault?

 

[Deleted member 4845]

that's the one. Yep, this is confirmation. Also means the battery itself is functional.

Might be worth investigating the connection of the discharge port cable to the BMS itself. May have cracked there.

A good look at the other side of the BMS might be useful.

Now you can play with stuff like individual string charging, replacing the BMS with one that will talk to a smartphone app with Bluetooth, programmable balancing at 80% or 90% charge, etc. Likely not worthwhile for an old battery, but the new BMS can be re-used on another battery.

Get thru that, then you are ready for building your own battery, using an N.E.S.E. kit. Avoid Vruzend and Soldering to cells.

While in there, check brand names on your cells. Though these can be easily faked.

 

[johneakin]

The bottom arrow in the image above I tested right at the connection to the BMS, So its def not an issue with the wire to the discharge port.

I suppose it still could be the switch not actually working, failing that its def a more generic problem with the BMS
The switch has two wires that run to the BMS, not quite sure how to test that though as they are well glued to the BMS.

Can I order any 10S BMS (does the amp reading matter?
I'm looking at this https://www.amazon.co.uk/Jadeshay-Protection-Battery-Balance-Function/dp/B08HZBLC3J/
Though not sure if they all come with connections for the on/off switch? presume they do?

Or this one is cheaper, but with no balancing function but not sure the original (below) had that either

10S 36V 30A Lithium Battery Protection Board 3.7V Li-ion Cell BMS PCB Board suitable for 10 series Li-ion Cell Support over charge protection, over discharge protection: Amazon.co.uk: Business, Industry & Science

10S 36V 30A Lithium Battery Protection Board 3.7V Li-ion Cell BMS PCB Board suitable for 10 series Li-ion Cell Support over charge protection, over discharge protection: Amazon.co.uk: Business, Industry & Science

www.amazon.co.uk

I think this is the exact replica, but would take an age to get delivered from china

This product is no longer available.

This product is no longer available.

www.alibaba.com

 

[Deleted member 4845]

AMP rating should be low enough to protect your battery, and high enough to give necessary performance.

On/off switch is not standard, one last test on existing battery is to bypass or hotwire that switch.

10S is main standard you need to match, consider some of the advanced features to possibly use on your next battery.

 

[johneakin]

Thanks for all your help
you're incredibly informative
Is it a problem if you don't have a switch? Thats not really needed is it?
Some also come without balancing function? Is that essential? (Given this battery life may only last another few years I wanna buy a cheap BMS just to ensure it works)

 

[Deleted member 4845]

The switch can help to avoid sparks when connecting, at 36V is not a huge problem, but good to have with a removable battery.

Without the switch, I would disconnect controller when mounting battery, maybe get some spark-arrest cables for the final connection. The danger is the spark could pop the controller, again at 36V, not much risk. Done this many times with no problem, if at 48V would really want a switch or the anti-spark connectors.

Standard BMS only balances at or near full charge. Most, that is, some do not balance at all. For best battery life, newer chargers can charge to 80% or 90%, where normal BMS will never balance. "advanced" BMS can balance at whatever point you choose. Also communicate, live, individual parallel group info, lots of other data, to a smartphone or display. Not much more money, but reusable on your next battery, if you build it.

Which I will now encourage you to look into. If you had built your first one, all you would need now, is new cells. AND..... YOU pick the type and quality of cells you want. Huge savings. Well, you would still likely need a new BMS, due to the crash. Although, the protective box and security of the mount would be to YOUR standards, not someone else's.

Kit I mentioned earlier involves no soldering to cells, just tighten nuts, solder main wires to BMS, can get these premade, also balance connectors, fairly easy. No, I have not done one yet, but have followed these kits for a while, this designer knows what he is doing and it is thoroughly tested.

Also, IF you want to go faster, then next battery you could go to 48V or higher. Check if controller supports, most do, if not they are fairly inexpensive. Roughly 20-30% speed increase.

 

[johneakin]

I've ordered a cheap controller and soldering kit off Amazon for delivery tomorrow. Will keep you posted how this goes...

Once again, thanks for the help and sharing your knowledge. Hopefully this thread is helpful to others in the years to come

 

[johneakin]

Just to check before my new BMS arrives

1) The positive battery to -P reading 4.xV
2) The reading across the -B and -P on the BMS is 33.5Volts


What does #2 tell us? Does that still suggest a BMS issue?

 

[Deleted member 4845]

#2 is the same one that read 42V just yesterday?

Is anything on the BMS very warm or hot? Did you move, bump, or even touch the battery between readings?

Take this reading more than once?

Should not have dropped that much. Either BMS is bleeding power, or a cracked solder connection or spot weld moved when battery moved, or some really, REALLY bad cells. That drop represents roughly 40% to 60% of the total energy stored in the pack, maybe higher considering its age.

When BMS balances, all is does is bleed higher parallel groups by heating some small components while charge is going on. This is what the balance wires are for. These do occasionally get stuck on and bleed constantly. Not real common, but something is going on to lose that much voltage that fast. Would have to be more than one, though.

You could charge the pack, take readings, then remove the BMS and take more readings. Also, CAREFULLY, move the pack a bit, similar to previous re-arrangements, and take some more DVM measurements.

Gotta take it off for the new one anyway.

Actually, I would leave it on for one more charge cycle, without touching it or even breathing hard on it, test for loss and confirm, THEN charge once more, remove BMS, and test THAT.

There is an old axiom I use a lot for diagnostics. "Once is bad luck, twice is coincidence, THREE TIMES is enemy action", meaning a direct cause and not just a mistake or accident.

 

[johneakin]

Fitted new BMS
Battery and bike is now working again.
All fixed for £11, Many thanks for all your help.

if you PM me your PayPal I'll tip you a coffee

 

[neilskiier]

I've ordered a cheap controller and soldering kit off Amazon for delivery tomorrow. Will keep you posted how this goes...

Once again, thanks for the help and sharing your knowledge. Hopefully this thread is helpful to others in the years to come

Looking back at may post. Do you remember what controller was suggested

 

[neilskiier]

The switch can help to avoid sparks when connecting, at 36V is not a huge problem, but good to have with a removable battery.

Without the switch, I would disconnect controller when mounting battery, maybe get some spark-arrest cables for the final connection. The danger is the spark could pop the controller, again at 36V, not much risk. Done this many times with no problem, if at 48V would really want a switch or the anti-spark connectors.

Standard BMS only balances at or near full charge. Most, that is, some do not balance at all. For best battery life, newer chargers can charge to 80% or 90%, where normal BMS will never balance. "advanced" BMS can balance at whatever point you choose. Also communicate, live, individual parallel group info, lots of other data, to a smartphone or display. Not much more money, but reusable on your next battery, if you build it.

Which I will now encourage you to look into. If you had built your first one, all you would need now, is new cells. AND..... YOU pick the type and quality of cells you want. Huge savings. Well, you would still likely need a new BMS, due to the crash. Although, the protective box and security of the mount would be to YOUR standards, not someone else's.

Kit I mentioned earlier involves no soldering to cells, just tighten nuts, solder main wires to BMS, can get these premade, also balance connectors, fairly easy. No, I have not done one yet, but have followed these kits for a while, this designer knows what he is doing and it is thoroughly tested.

Also, IF you want to go faster, then next battery you could go to 48V or higher. Check if controller supports, most do, if not they are fairly inexpensive. Roughly 20-30% speed increase.

Hey 4845 what Bms or controller were you suggesting to johneakin in May 2022

 

[johneakin]

Don't think one was suggested
But I did buy https://www.amazon.co.uk/dp/B08DQLVH3K and it worked a treat.

It broke once on me (think I got some water in there)
Bought another one and its been working fine since.

 

[ozzie21]

On my Trinx ebike I have two batteries. I don't use a Battery blender so at the moment I use each separately. The bike came originally with a 48V x 13Ah battery and I bought another Hailong 48V x 20Ah battery. Anyway a few weeks ago when using the 48V x 20Ah battery the bike would run for maybe 2-3 minutes then shut off. After rebooting it would shut down after only a few seconds. I tried the original 48V x 13Ah and all was fine. I suspected the BMS module. I brought it to a shop and they confirmed it was the BMS. So a new BMS and the labor all in was $135. All is good now.

 

[johneakin]

Yea those chinese BMS's seem flaky.
So many people must throw out their batteries when they break, such a shame as the cells are likely fine and its just the BMS that has packed in.

In reality its a 5 minute job to replace the BMS with a soldering iron and a new BMS from amazon

 

[ozzie21]

Yea those chinese BMS's seem flaky.
So many people must throw out their batteries when they break, such a shame as the cells are likely fine and its just the BMS that has packed in.

In reality its a 5 minute job to replace the BMS with a soldering iron and a new BMS from amazon

If I was at home I would have probably fixed myself but I'm away overseas where I work. There's a bit of a language barrier, I don't have much for tools here and I wouldn't know where to find another BMS either. I believe I should have been able to get a new BMS for around $40 if I was still back in Canada. I wouldn't even know where to start to try and find a BMS here. I bought the 48V x 20Ah Hailong battery here last summer for around $300 and I didn't want to trash it. I've been using it for 6 days since the repair and it seems like it's gonna be OK.