Individual replacement cell availability

[freewheeler]

Hi Everyone

Any battery experts here?

I picked up a nice looking e-bike battery for free from my local recycling center. It is a 36v 16ah unit which fits behind the seatpost as used on many Chinese ebikes. I believe this battery type is known as a 'silverfish'.

Anyway, there was no voltage showing on the output pins so I opened it up and probed the voltage on each cell pair (it is a 2p 10s configuration) and one pair showed 0 volts with all the others near to 4v.

If I could find two replacement cells it looks like it might be worth attempting to repair the battery. Trouble is I can't seem to find a source.

The battery uses Li-Po pouch cells which are approx 168x70x8mm, each cell is nominally 8000mAh and 3.6v

They look much like this:

If anyone could suggest a source I would be very grateful

Mark

 

[anotherkiwi]

Those kind of LiPos should be searched for in China on alibaba. How are they welded/soldered?

If you like to live dangerously... https://hobbyking.com/en_us/zippy-flightmax-8000mah-2s1p-30c.html

 

[freewheeler]

Thanks for the reply

The cells are soldered into the pack using the nickel tabs as in the photo above.

I see the dimensions of that 2S hobby king pack are close enough to what I have and would actually fit quite well.

I wonder if using such cells would be so dangerous if used with the original BMS - I know they have a terrible reputation....

 

[anotherkiwi]

Thanks for the reply

The cells are soldered into the pack using the nickel tabs as in the photo above.

I see the dimensions of that 2S hobby king pack are close enough to what I have and would actually fit quite well.

I wonder if using such cells would be so dangerous if used with the original BMS - I know they have a terrible reputation....

Because they aren't in an aluminium silverfish battery box when the drone they are powering crashes into the block of flats across the street? What were you filming?

If they are taken care of by a BMS they are just as dangerous as the other ones you are sitting above.

 

[freewheeler]

Yes I see your point! I like the youtube videos where people poke their LiPos with a sharp implement - I think the technical term is 'venting with flame'!

Well seeing as the cost of the Hobbyking battery is quite reasonable I may as well order one up. The cells on Alibaba seem to have minimum order quantities in the 100's.

I am thinking to bring some balance wires to the outside of the case so I will be able to make basic checks on the cells without having to dismantle anything and if the BMS is faulty, at least I will know about it.

 

[anotherkiwi]

Be very careful when you do the wiring, cut one wire at a time! 8 Amps packs a lot of punch and even the balance wires make lots of sparks - yes I have had a JST-XH come off when unplugging...

 

[awol]

yes I have had a JST-XH come off when unplugging...

You need something like these, I use them and find they make it much easier when handling the balance wire plugs.
http://www.ebay.co.uk/itm/Balance-Plug-Savers-AB-Clip-2S-3S-4S-6S-Li-Po-for-JST-XH-plugs-5pcs-UK-/201246540742?var=&hash=item2edb3a83c6:m:mNNhBGuNUxFTGeUpadhL-Eg

 

[anotherkiwi]

Total: £23.46

For 4 bits of plastic... I know I need them I am just looking for an honest source.

 

[Topdonkey]

Total: £23.46

For 4 bits of plastic... I know I need them I am just looking for an honest source.

You get 5 of them in a pack for the price shown, so not too expensive