Battery issues

stevet2233

New Member
So my bike has been out of commission for a while and i finally got everything fixed and tuned up. The controller was booting, the motor was taking off with both the pedal assist and the throttle. I finally take it out to go for a ride annnndddddd... the battery immediately dies. The battery meter says 100%(i think this is always the case for this computer when the motor isn't under load, but this is new to me so I cant say for sure) but as soon as I start moving with any amount of weight on the motor it plummets down to 50% and then shuts down. When I unplugged it from the charger the little indicator lights on the battery showed 100%, but after this little "ride" it agreed with the bike that it was now dead.

I had a little bit of worry something like this might happen earlier today because I had charged the battery a couple weeks ago and this morning it was reading dead on the indicator lights, i plugged it in and it went to 100% suspiciously fast, i wasnt there watching it, but it when i came back about an hour later it was full, which is very abnormal. There was a long period of time(at least a couple months) while the bike was out of commission where i had left the battery plugged in, hopefully that isn't my issue, but wouldn't be shocked.

Anyway, moral of the story I'm wondering what people think my issue is, bad BMS or blown battery cells?

Thanks!
Steve
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
So my bike has been out of commission for a while and i finally got everything fixed and tuned up. The controller was booting, the motor was taking off with both the pedal assist and the throttle. I finally take it out to go for a ride annnndddddd... the battery immediately dies. The battery meter says 100%(i think this is always the case for this computer when the motor isn't under load, but this is new to me so I cant say for sure) but as soon as I start moving with any amount of weight on the motor it plummets down to 50% and then shuts down. When I unplugged it from the charger the little indicator lights on the battery showed 100%, but after this little "ride" it agreed with the bike that it was now dead.

I had a little bit of worry something like this might happen earlier today because I had charged the battery a couple weeks ago and this morning it was reading dead on the indicator lights, i plugged it in and it went to 100% suspiciously fast, i wasnt there watching it, but it when i came back about an hour later it was full, which is very abnormal. There was a long period of time(at least a couple months) while the bike was out of commission where i had left the battery plugged in, hopefully that isn't my issue, but wouldn't be shocked.

Anyway, moral of the story I'm wondering what people think my issue is, bad BMS or blown battery cells?

Thanks!
Steve
Test the battery with a voltage meter at the first connector and the charge port if possible. If it has a switch be sure to cycle it off/on
Check all connections from the battery to the motor for loose and or dirty pins.
 

stevet2233

New Member
Test the battery with a voltage meter at the first connector and the charge port if possible. If it has a switch be sure to cycle it off/on
Check all connections from the battery to the motor for loose and or dirty pins.
Connector read 52V, charge port read 48V. all connectors are clean.

I would assume if I am getting the proper voltages then that means the batteries themselves are just fine and that this would be BMS, yes?
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Connector read 52V, charge port read 48V. all connectors are clean.

I would assume if I am getting the proper voltages then that means the batteries themselves are just fine and that this would be BMS, yes?
Not necessarily, but maybe... You could have bad cells and when put under load the voltage drops sharply causing a Low voltage shutdown.
You should have the same voltage at both the charge port and battery connector.
You also should have near 54.6 v on full charge.
Have you tested the charger output when not connected to the battery? That should be 54.6v
 

stevet2233

New Member
hhmm so not getting a stable reading off the charger at all when it is plugged into the wall and never even approaching 54.6v, jumping between 5v-28v, so maybe my charger is junk?
 

stevet2233

New Member
hhmm so not getting a stable reading off the charger at all when it is plugged into the wall and never even approaching 56v, jumping between 5v-28v, so maybe my charger is junk?
also the charge battery is supposedly a 48v battery, so the 48v at the charge port makes sense to me, not sure the deal with the 52v
 

tomjasz

Well-Known Member
Can you tell us more? Who sold the battery?

In a frame case with a removable base?

How old is it?

Has it spent time in storage?
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
hhmm so not getting a stable reading off the charger at all when it is plugged into the wall and never even approaching 54.6v, jumping between 5v-28v, so maybe my charger is junk?
Not necessarily. Some chargers pulse a voltage as you say to wake up the bms... These are harder to measure the output voltage as they need to be connecter to a load. Full charge voltage of a nominal 48v battery is 54.6v.

Toms question can help with us having more info... Maybe a pic of the battery as well.

Have you tried leaving the battery attached to the charger for a few hours after the light turns green. If you do this, just keep an eye on it and make sure nothing is getting too warm.
I'm thinking the battery wasn't stored correctly and/or at the correct storage voltage and some cells have shut down by thier internal safety feature when voltage drops too low.
 

stevet2233

New Member
Alright, so here's the full backstory:

I bought a bike built by some enthusiasts who enjoyed building/selling e-bikes, the battery came with this, so I do not have much history on it beyond what i can see. First frost 2019 it didnt seem icy at my place, but on my commute to work there was some slick paint in the city and the bike slipped out from under me and landed directly where the cable came out of the hub motor and sliced right through it right where the cable came out of the motor, so no possible way to fix it. Before i got around to actually fixing it i broke my ankle and this was the furthest thing from my mind for a while.

This entire downtime the battery was stored in an open climate controlled room at room temperature, it really should have been ideal storage conditions, but it is at this point where i believe the battery was plugged in for an extended period, potentially a few months.

When i finally got back to this we were already in the pandemic and I couldn't for the life of me figure out what motor it was to replace it. The guys i bought it from weren't sure which specific one mine was to help replace it either, but helped point me to a new one that should have at least been compatible with the battery, and they thought the controller as well. I got that but it just didnt seem like the wiring of the new motor could be paired with the old controller, after many hours and much frustration i gave in and just bought a full ebike kit of bafang hardware that was all prematched. Hooked it all up, tested everything with the bike on the stand and all seemed great, but never tried it with load indoors for obvious reasons.

Today i took it outside, powered it up and it was dead by the end of my driveway :'(

So any ideas why there is the difference in readings between the charger port on the battery and where it connects to the bike? Getting 52.6 at the connecter and 47.2 at the charging port.


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Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Alright, so here's the full backstory:

I bought a bike built by some enthusiasts who enjoyed building/selling e-bikes, the battery came with this, so I do not have much history on it beyond what i can see. First frost 2019 it didnt seem icy at my place, but on my commute to work there was some slick paint in the city and the bike slipped out from under me and landed directly where the cable came out of the hub motor and sliced right through it right where the cable came out of the motor, so no possible way to fix it. Before i got around to actually fixing it i broke my ankle and this was the furthest thing from my mind for a while.

This entire downtime the battery was stored in an open climate controlled room at room temperature, it really should have been ideal storage conditions, but it is at this point where i believe the battery was plugged in for an extended period, potentially a few months.

When i finally got back to this we were already in the pandemic and I couldn't for the life of me figure out what motor it was to replace it. The guys i bought it from weren't sure which specific one mine was to help replace it either, but helped point me to a new one that should have at least been compatible with the battery, and they thought the controller as well. I got that but it just didnt seem like the wiring of the new motor could be paired with the old controller, after many hours and much frustration i gave in and just bought a full ebike kit of bafang hardware that was all prematched. Hooked it all up, tested everything with the bike on the stand and all seemed great, but never tried it with load indoors for obvious reasons.

Today i took it outside, powered it up and it was dead by the end of my driveway :'(

So any ideas why there is the difference in readings between the charger port on the battery and where it connects to the bike? Getting 52.6 at the connecter and 47.2 at the charging port.


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The difference in voltage between the charger port and the discharge port both on the battery leads me to think it's the bms... If so, this might be preventing a proper charge.
If you feel that you are experienced enough to open up the battery and test each group of cells and then plug in the charger and see if the BMS is outputting to all groups. This will give you some insight on the cells, bms and charger.
You must be very careful not to short circuit anything and if you are unsure... Take it to a professional.
I can't think of another way to test that charger other than wiring in a voltage/watt meter between the charger lead and the battery.
You could buy another inexpensive charger as a test as well.
I'd also take a very close look at the Discharge port on both the battery and the bike that all the pins are equally shiny and clean as this is the most common battery problem.
I say wait a day or so and let's see if someone else chimes in with some ideas as well. Maybe there's some easier test that can be done.
 

stevet2233

New Member
popped the battery out of the case for now, nothing looks out of place, not that i would expect it to at this point, going to see if anyone else responds on here and maybe unwrap it in a few days. with the size and shape for a brief moment I thought it was a stack of Li-Ion packs and I got excited, that'd be a super easy replacement if there was a dead cell, but upon further inspection I could feel the individual humps of the 18650s, gonna be a royal PITA if there is a dead cell, I'm not feeling buying like fixing that myself... I'm not in any way worried about swapping a BMS, its just a couple plugs and a little bit of solider. Reconstructing an 18650 pack is... involved.
 

David W

New Member
One of my Genze e102s died suddenly yesterday - battery voltage is only 5 VDC at the terminals. This is the second battery pack I've had to replace this year, the other being an Ecoreco L5+ scooter. I'm increasingly suspicious of the low-end chargers some of these vehicles use - so far I don't (knock on wood) have the same problems with my Bosch batteries. My understanding is that batteries from Bosch, BionX, Shimano, Yamaha, etc. have a data line that (I'm guessing) tells the charger what it can handle and then eventually shuts off the current. The Genze uses Panasonic 18650 cells, so I suspect the charger killed the battery more than I suspect the cells.

Emailing with Genze support now, not sure how much luck I'll have as they were supposedly going out of business, but I actually did get a human reply within 24 hours. I'm also planning to compare pricing with an ebike battery repair/repacking service like FTH Power. It's clear to me that battery repair/repack is going to be big business in the future. It's also clear to me that buying cheap ebikes off Alibaba or such ultimately results in tears and sadness - you're making an investment in a vehicle and you want to be able to get support.

...dtw
 

stevet2233

New Member
So I finally broke down and cracked the wrapping for the battery open and checked the individual parallel loops. I'm having trouble diagnosing, but my gut reaction is to assume the worst and that I have a dead cell, but I really have no clue

Battery is in 13s4p, there is no noticeable physical damage to either the battery or the BMS. All the clusters(cant remember the proper term at the moment haha) except 1 seem to be charged, but I cannot see anything at all that would point to which cell it is. if you look at the attached image of the side of the battery it is the 5th row from the left. this one is coming in at .8V, all the others are reading 3.25-4.0V. The BMS wires appear to be attached to the cells well, when the wire is given a light tug the banding between cells moves with the wire.

Any ideas?
Thanks!
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Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
Even 0.75v seems to be too large a variation between groups.
0.8v is far below the low voltage shut down for a cell which is really 4 cells in parallel.
I'm wondering if the BMS is bad and in turn killed the that group. Or possibly the group drained and shut down during storage.
Have you tried plugging in the charger and reading the output of the BMS.
This also may be tricky as a safety feature of the BMS it may not try to charge a group with too low of a voltage. The way to test would be to swap charging leads between groups.
On a not new pack, I'm not sure it's worth any repair efforts.

@harryS
Any thoughts?
 

tomjasz

Well-Known Member
If you use Facebook there are very good battery pages there. This isn't the best place to sort battery issues. I missed who built the battery.
47.2 at the charging port.
Charging port voltage is irrelevant. Testing charger output may be irrelevant with some chargers. A three-year-old abused battery may be just plain worn out. Buying used batteries can be problematic.
 

Gionnirocket

Well-Known Member
Region
USA
City
Y. O.
If you use Facebook there are very good battery pages there. This isn't the best place to sort battery issues. I missed who built the battery.

Charging port voltage is irrelevant. Testing charger output may be irrelevant with some chargers. A three-year-old abused battery may be just plain worn out. Buying used batteries can be problematic.
All available information trying to help someone online is not irrelevant.
Knowing if the charger is working properly is not irrelevant.
Charger port voltage should be equal to discharge port. If not this can indicate a BMS issue... Again, not irrelevant.
Working on a tired, abused battery... I agree , problematic 🙃