Batribike Breeze - cuts out after a few minutes

[vfr400]

Quicker to charge the low cell with any old 5v or USB type charger.
In older batteries like yours, they sometimes powered the BMS from one cell, so if you didn't use the battery for a long time, that cell went down - typically a cell at the end of the pack.

You can use any similar silver fish battery. If the terminals don't match, you can swap the bottom plastic piece. Always make sure you have the correct polarity using a meter.

A re-cell will be too expensive on a battery like that. A new one will be cheaper.

 

[Nealh]

The balance feature is top end balance depending on the BMS specs it can be anywhere between 4.15 - 4.2v per cell, also the cells have to be very close voltage wise for the balance to occur.

 

[Cancunia]

More progress..
Many thanks for all the replies, special thanks to @cyclebuddy for the halogen bulb test load idea, to @Tony1951 for pointing me in the right direction re the low cell & to @vfr400 @Nealh for the tip about charging up the low cell.
I first tried to discharge the other cells via a single bulb but after 3 hours, the result was that I just did not get enough drain on the good cells so I switched to charging up the low cells. It turned out that there were 2 cells that needed a top up. After disconnecting the BMS, I used a variable AC-DC transformer at 4.5 volts which took a couple of hours to bring the low cells up to approx 4.1v. I hadn't checked the transformer output before doing the top up, but it turned out to be 1250mA max @ 12v.
After the top up, I ran the test load again for 30 mins & recharged the battery via the normal charger, all cells came back up to just above 4.1v I tried the load test again for 2 hours followed by a recharge & then for about 3.5 hours until the charge indicator on the battery pack showed red, a recharge took about the same amount of time, with all cells returning to about 4.1V So, my battery has gone from shutting off at about 30 mins on the test load to 3.5 hours and still going.
Next test will be on the bike, when it stops raining..

 

[Nealh]

Pleased you have got a good result so far, out of balance cells is something a lot of people don't understand. All they look at is the end voltage and led indicators, they simply don't replace good old proper digital voltage readings to see where the issue may lie.

It is why on another note any battery with a BMS one should not routinely just charge to 80% - 90% alone as once a cell starts straying the balance feature never does it's job. If one wants to experiment then the ability to track/check the individual cell groups periodically is required or carry out 80/90% charges and and a full charge once in while.

Once top end voltage, battery cutting out under load or lack of range shows it head then one has to firstly look at the battery balance as this is often where the crus of the issue lies.

 

[Nealh]

Often when this scenario crops up the indications are the battery may be past it's best and for most the opening and testing of a battery appears daunting, in fact with common sense and able to follow good advice anyone can undertake simple cell testing to see where the issue may lie.

 

[sjpt]

they simply don't replace good old proper digital voltage readings

Good old proper voltage readings are analog; these new fangled digital meters are handy but don't give the same 'feel' for the voltage.

 

[Cancunia]

OK, roadtest this afternoon. Got a lot more out of the battery than before, but still only about 3 or 4 miles before cut out. My house is on a hill so I'm not sure how much I'd get on a totally flat road but for sure a lot less than with a new battery. On the plus side, I now know that the bike works ok and that I also need to make the pedal gearing higher.

 

[Nealh]

Even though the battery is balanced it does now indicate that the pouch cells are knackered and likely have high internal resistance, time to replace the battery with one that has li-on cells.
Again if you can rig up a the volt meter to read whilst riding you will see the voltage collapse, most likely those same two low cells being the culprit.

 

[Tony1951]

@ Cancunia....

Oh - that's a disappointment. I thought when I first started reading your update that it was going to work, especially when the on load test seemed to be working.

This shows how lucky my partner was when she bought the Somerby with a battery that would not charge and had been left unused for over a year. Once the voltage was raised a bit by unorthodox means (bypassing the BMS briefly) it started charging normally. My fist run on it I expected it to do what yours did on the hill, but no - it works and she has ridden it 35 miles on a single charge and it still showed three lights out of 4 on its rather crude battery indicator. Hers goes really well up very steep hills. We won the lottery there, I think.

 

[Cancunia]

I can't deny that I'm a bit disappointed, but to be honest I'm not too surprised. I bought the bike cheaply as it had a problem & had the expectation that it would need a battery so while my luck was not as good as @Tony1951 above so far as the battery is concerned, it's not a total disaster.
I've learned a lot about batteries in the process of trying to fix this problem & learned enough about the bike to feel reasonably confident about getting a new battery for it.
Yesterday's ride was not conclusive in terms of range as the battery did recover enough after stalling on the hill to run for long enough to get me home and test the speed limiter on the way back. Another problem with the bike is that the gear change cable is broken so it's only possible to pedal in top gear which is too high for the hill I was going up. I'll try again when the cable is replaced.
I'm now under no illusion that the old Lipo Pouch battery will need to be replaced, but I may get a bit more use out of it yet.