8fun battery wont charge!

[Furbadurba]

Hi all, in august I tool delivery of a 36V 9Ah bottle type battery from 8fun.. (replacement for a previous one which had died).

Anyway yesterday I went to charge the new battery and the light on the charger stayed green as if charging was complete, even though battery indicator showed nearly empty.

I checked both fuses in the battery and they seem good.

Emailed 8fun and the just suggested a BMS issue.

Any advice on next steps appreciated!

Furba

 

[Deleted member 4366]

If two batteries won't charge, it seems more like a problem with the charger. Presumably it charged OK before it was sent to you, or was it empty when you got it?

 

[KirstinS]

from your post it is not clear if you got the battery and not used it/charged since august until yesterday ?

or wether the problem appeared yesterday but has been working fine since August ?

Do you have a multi meter and, if so, is there any voltage reading from the battery ? What is it please ?

Same goes for charger ? does it read 42v ?

Finally my 8fun charger has a tiny little hole with access to a switch. The switch means the charger can be used to charge 24v battery or 36v battery

I'm thinking that if the switch has been flicked accidently from 36v to 24v then everytime you plug it into a depleted 36v battery the charger thinks it is a full 24v battery and goes green

 

[Furbadurba]

Thanks for the reply d8veh. The previous battery had what I think of as a separate problem - it just died straight out.

I received this replacement battery a couple of months ago and have been using it daily since then without trouble. Then last night it wouldn't charge.

Fuses are fine. I did find some moisture inside the housing after recent heavy rain, not sure if this could have shorted something on the BMS?

Measured Vs across the power supply = 42, so it seems to be working...

Im not sure how possible it would be to replace a BMS on this??

 

[Zebb]

What is the voltage on the battery.?

 

[Deleted member 4366]

That makes it a bit clearer. Not a charger problem, but water inside the battery is very bad news. A little bit of moisture wouldn't be a problem, but, if it's getting in, it wouldn't take much to short the cells at the bottom. Where exactly did you see the moisture? If you took the top or bottom off, there'es an "O" ring around the top and the bottom of the aluminium tube. Make sure that each is sitting in the groove
properly.

If you want to check it yourself, take the top off (3 screws) to get access to the BMS. The LED board in the top is connected by very thin wires, which nearly always break off through handling, and then you have to solder them back on, so be very careful with the top, which will dangle by those two wires.

The BMS might be wrapped in tape or something, so peal it off to get access, then you can pull out the multipin connector, and carefully check the voltage between each pair of adjacent pins until you have 10 results. If you've only got 10 wires, you get nine results. The tenth will be between the battery internal negative and the lowest pin or between the highest pin and the positive main wire.

Here's a photo. The connector is on the left edgeways on, so not so easy to see. This one pulls out upwards. Some pull out horizontally.

 

[banbury frank]

Hi you can buy BMS from link below

bottle battery BMS
Frank

 

[Furbadurba]

Great - thanks. I'll check those voltages tomorrow. There were droplets inside the housing at the top around the wires to the BMS, as well as in the bottom around the switch and fuses. The rubber seal didn't stand much of a chance - it's pretty flimsy.. Seemed properly seated though.

The voltage across the battery read at 36v after first leg of my commute this morning, which surprised me - the battery was only half charged when I left home. Should I see a drop in V or current as the battery charge drops?

 

[Deleted member 4366]

When it's fully charged, It'll be about 41.5V. When empty, it'll settle to about 33V. The voltage drop as it discharges if fairly linear until about 35V, and then it starts to accelerate downwards. Also, as the voltage drops, power goes down in proportion. That's why it's best to keep it charged if you can.

 

[Furbadurba]

OK, I have only 9 wires going to the multipin.

I measured 3.51V across each adjacent pair, 3.51V between +tive and last wire, and 3.51V between -tive and first wire.

Im hoping this means my battery cells are intact...!