Reawaken battery?

[Scuba Steve]

Hi All,

New to the world of assisted cycling and I have recently purchased a converted mtb with mid motor Bafang 8fun 36v 500w kit.

The bike is great and running well but it came with two dolphin type batteries, one of which will not accept a charge. Charger plugs in and shows green light and the charge display on the battery itself will illuminate as if charged when the button is pressed to check it’s status but only when plugged into the charger.

The previous owner had kept it as spare and believed it didn’t have enough charge in it to awaken it.

Is there a way to give the battery a helping hand and possibly get it running again?

I have had a look for battery repair folk in the Manchester area online as it’s not something I am comfortable with tackling myself.

Any help would be appreciated

 

[wheeliepete]

If you don't want to open it yourself, it would be worth the postage to let Jimmy at Insat Int. have a look at it for you. He will give you a very honest opinion and arrange a courier to pick it up. Give him a call.

https://ebikebatteries.co.uk/

 

[Scuba Steve]

Hi Pete,

Thanks for the reply and link.

I had a quick look at the internals but the battery appears to be well made and well padded and sealed so I didn’t want to start pulling the layers apart to get into something I have no clue about.

Sounds worth sending it off just on the off chance he can get it going again

 

[Andy-Mat]

Hi All,

New to the world of assisted cycling and I have recently purchased a converted mtb with mid motor Bafang 8fun 36v 500w kit.

The bike is great and running well but it came with two dolphin type batteries, one of which will not accept a charge. Charger plugs in and shows green light and the charge display on the battery itself will illuminate as if charged when the button is pressed to check it’s status but only when plugged into the charger.

The previous owner had kept it as spare and believed it didn’t have enough charge in it to awaken it.

Is there a way to give the battery a helping hand and possibly get it running again?

I have had a look for battery repair folk in the Manchester area online as it’s not something I am comfortable with tackling myself.

Any help would be appreciated

I know a way, because my bike arrived in that condition and the company lent me what they call "a 0 volt Charger", which corrected the problems completely.
Some questions for you:-
1) But my battery was new, how old is this battery right now?
2) Are you electrically proficient?
3) do you have safety goggles handy?
4) A place to work, with power, outside?
I may have an answer for you, but I cannot take responsibility if it goes wrong, even if its a lack of knowledge or understanding on your part!

A better alternative would be a bike shop who has such a "0" Volt charger, pay them to do it, but if they try and sell you another battery, go somewhere else. That is what they wanted to do to me!!!

I have a method in my head, that I would do if it ever happened again, but it needs a small 1-2 amp laboratory power supply with variable current and at least 30 volts variable.
Do you have a) the knowledge and b) access to such a power supply?
It is not without some danger.....Li-ion batteries can catch fire and/or even explode!!

I also have a copy of the documentation from the special charger, that details basically, how the charging is achieved. I can send it as a pdf, if you wish.....

Are you game?

The only supplier of such a charger that I know of, wants $120 plus transport!! But it should not cost that much, a standard charger is only around $40!! I personally would expect it to not cost more than about $65.....

I have several methods in my head, one even using the original charger and an small extra circuit!!

regards

Andy

 

[Scuba Steve]

Thanks for reply Andy,

I am usually game for attempting to repair most things although reading this made me think it’s best if I leave it to the professionals.

I once built my own kit car, the wiring was the only thing I didn’t take pleasure from. Now I just stick to changing the odd plug or fairy light bulb

I have the none functioning battery but I have the exact same battery that I am using that works fine. I may try the BMS from the working battery on the none charging one and see if that gives me any sort of encouragement.

 

[Andy-Mat]

Thanks for reply Andy,

I am usually game for attempting to repair most things although reading this made me think it’s best if I leave it to the professionals.

I once built my own kit car, the wiring was the only thing I didn’t take pleasure from. Now I just stick to changing the odd plug or fairy light bulb

I have the none functioning battery but I have the exact same battery that I am using that works fine. I may try the BMS from the working battery on the none charging one and see if that gives me any sort of encouragement.

I don't want to put you off, but a mistake could take the second battery down as well.
I will attach the infos from the Zero volt charger, you can see exactly how it works, the only difference between the chargers is the nominal voltage.the method is still the same.
That is a small two sided document, copied onto one side...Tell me what you think.

regards

Andy

 

[wheeliepete]

If you are going to attempt to remove the BMS yourself, then before you do, carry out some simple voltage tests on the battery. Check the output fuse. Measure the voltage on the output terminals, then the voltage on the battery side of the BMS. If you have voltage from the battery pack itself, then most likely your BMS is faulty. Next is to measure the voltage from the 10 wires on the connector from the BMS. Be careful, your battery may appear dead, but there could still be alot of energy stored in it. Post your results.

 

[Nealh]

If you have already opened the battery, can you see a white sense wire connector block with 10 or 11 thin wires connected ?
Or better still show us some pics of the opened battery.
By taking 10 voltage reading via the thin sense wire connector, we can ascertain if any of the 10 cell groups voltages are preventing the BMS switching on or whether possibly the BMS is faulty.

If unsure we can guide you to carry out checks that will not do you or the battery any harm.

 

[Andy-Mat]

If you are going to attempt to remove the BMS yourself, then before you do, carry out some simple voltage tests on the battery. Check the output fuse. Measure the voltage on the output terminals, then the voltage on the battery side of the BMS. If you have voltage from the battery pack itself, then most likely your BMS is faulty. Next is to measure the voltage from the 10 wires on the connector from the BMS. Be careful, your battery may appear dead, but there could still be alot of energy stored in it. Post your results.

All good advice!
Andy

 

[Nev]

Scuba Steve, if you haven't do so already have a read through this thread. It will give you a better understanding of batteries and charging systems used on pedelecs.

http://www.pedelecs.co.uk/forum/threads/battery-lost-capacity.32956/