Old bottle battery help needed

[jaggs]

I've got an old 36V bottle battery I bought for my DIY electric bike in 2011 which is now showing signs of wearing out. My electrician friend tells me I could try reconditioning it by running it flat/recharging a couple of times, but I'm not sure I have the ability to do that. So my questions are:

1) Are there any battery reconditioning options or do I have to buy a new battery?
2) If so, where can I get a battery at a decent price here in the UK? I originally bought my unit direct from a Chinese supplier.

Specs:
Li-ion battery model - #GA-36088
Voltage:36V
Capacity:8.8Ah
Samsung cell

Thanks very much.

 

[Deleted member 4366]

It's done well to last that long. Unfortunately, it's not possible to recondition it in any way. The only thing you can do is take the top off to check how well balanced it is. You might be able to claim back some capacity by manually balancing it if it's gone so far unbalanced that the BMS can't cope with it. For a replacement, try Cyclotricity, otherwise get one from China again. BMSBattery have them.

 

[jaggs]

Thanks very much for the fast reply. The balancing stuff sounds interesting. I only use the bike occasionally, and it hardly ever gets fully discharged on a run. Mostly just half way. At the moment it still works, but I've noticed less power and it discharges much quicker.

How could I tell about balance, and how would I get a manual balance done? (I know zero about battery tech).

 

[Deleted member 4366]

You have to take the top off and measure with a voltmeter. When you get the top off, take a photo to show what's there because there's differences inside.

 

[jaggs]

Thanks again. Here's the photo.

 

[Deleted member 4366]

That's the BMS with the cells crossing from side to side. If you look on the two white multipin connectors, the pins are numbered 1 to 10, but the sequence keeps changing sides. First, disconnect those thin red and black wires because they'll break off, then, after charging the battery, put your black probe on the place where one of the thick black wires are connected (B-, ch- or P-), and with your red probe, check each of the pins in sequence B1 to B10 to get the voltages from 4v to 40v (approx.). Post them here. Be careful not to short adjacent pins with your probes.

 

[jaggs]

Awesome. Thanks again. Here they are:

B1 - 4.18
B2 - 8.34
B3 - 12.51
B4 - 16.63
B5 - 20.76
B6 - 24.86
B7 - 29.03
B8 - 33.23
B9 - 37.43
B10 - 41.62

 

[Deleted member 4366]

That gives 4.18, 4.16, 4.17, 4.12, 4.13, 4.10, 4.17, 4.20, 4.20, 4.19.

It's a little out of balance, but nothing special. Ideally, you should now to put it back together and run the bike until it's fairly low, then check them again; however, whatever that shows, you won't be able to do anything about it. I would guess that the battery is getting tired and saggy. Replacements are not too expensive if you get one from Greenbikekit.com or BMSBattery. Make sure you look for the same type of connector on the bottom because there's three different types. Cyclotricity might also be able to help you out. Wherever you get one from, check that the connector is wired the same way before connecting to your controller because there's no standard. Use a voltmeter to check the two positive pins and the two negatives. There's 6 possible combinations!

 

[jaggs]

Thanks that's very useful. I'll do what you say and have a look around. It may do me for a little longer I'm hoping.

I have a round 4 pin connector on the bottom of mine, I assume that these are all connected the same, or is the same issue about wiring relevant?

 

[Deleted member 4366]

4 pins, 2 positives and two negatives gives 6 possible combinations. You'd better check them, like I said.

 

[awol]

Not bad lasting from 2011, any ideas how many miles you've done with this battery, or aprox number of charges?
My 10ah bottle from 2013 and used daily is on it's way out and has done about 5500 ish miles on about 280 ish charges