Sourcing 18650 cells

[Hightechpete]

I have a non functioning 10s 5p battery that hasn't seen alot of use. Detailed investigation revealed one parallel group at zero volts, one cell in this group has leaked some electrolyte and appears to have taken down the other cells in that group. The other nine groups are taking and holding a charge so I would like to attempt a repair. I can't identify the cells, I assume they are 2200 mah (50 cells in an 11ah pack) no idea what C rating.
Can anyone suggest where I might get half decent 18650's in small quantities?.

 

[Nealh]

A pic of the cells.

 

[Hightechpete]

Thanks for the speedy reply Neal. Can't provide a pic at the moment, cells are pale blue with a white insulating disk, some are marked with a barode and KA2FK12 318399. Most have no markings whatsoever. I assume they're Chinese knock offs.
The battery casing is marked JDXQT INR36111712770614, I've checked on various 18650 databases and can't find a reference to either number.

 

[Hightechpete]

Update - An email to ebikebatteries.co.uk has solved my problem. Immediate response from Jimmy who is going to a lot of trouble for very little reward. All the positive feedback they have had is well deserved.

 

[Ray Winder]

Update - An email to ebikebatteries.co.uk has solved my problem. Immediate response from Jimmy who is going to a lot of trouble for very little reward. All the positive feedback they have had is well deserved.

That's good to know, I would be interested to know more about your repair and about the cells you found. Repairing a battery is something I'm curious about as it seems continuity of battery supply is poor, and as cells get better can we update tired batteries with better ones?

 

[Hightechpete]

First a caveat, I am no expert, there are members of this forum who are far more qualified. It could be said that I know enough to be dangerous, but with advice and research I'm learning.

I've had a non functioning battery laying around for some time, before I recycle it I thought I'd take it apart to see if I could get my head around the workings.

Long story short, I discovered 1 leaking cell which had taken down the CID of the other 4 cells in the P group, all the other cells in the pack appeared to be OK, so a cheap welding kit was obtained together with 5 compatible replacement cells. I will now adjust the voltages and weld in the new cells and hope this will fix it. If so I'll have fixed a £200 battery for 30 or 40 quid, if not it's been well worth it as a learning experience, it's been fun.

Do your own research with regards to the technicalities and especially the safety aspects, there are plenty of resources on the net, it's not rocket science.

 

[Ray Winder]

I have been looking at videos of people spot welding packs of cells using pure nickel strip and it seems pretty logical (I worked in engineering) sometimes the efforts of people learning the process can be helpful as they don't usually assume people know things.
I bought my wife a hopper shopper which was not used so I am wondering about checking that out, seems logical to look at upping the power of the battery if I do it
Just wondered about welding machines and cell suppliers, probably it would make sense to buy a ready made battery but still curious

 

[Nealh]

For the diy battery builder who is only doing repairs or builds for himself, then a decent mini arduino welder is best with a good high current discharge lipo 3s as a power source. This gives a lightweight highly portable system that takes up very little space in use and storage.
Two of the best systems are the Malectrics and the Kweld systems both Eu made /designed. For a power source a very good 65c or better 3s lipo, my one is a Turnigy 4500mah. I use the Malectrics with a foot pedal as an option so not to displace a weld when/where not needed.

Cost though is going to be about £200 all in.
DIY Arduino Battery Spot Welder Kit V4 Full Bundle For Lipo Battery - Malectrics

kWeld – complete kit – Ecycle Revolution

I use the Malectrics and it spots copper/nickel sandwiches as does the K weld.

 

[Nealh]

It isn't cost effective to do your own if only a one off but for the inquisitive or someone wanting to learn/know more then it is a worthwhile venture for a couple hundred £££'s.
I build all my own packs and have done so for 4 years or so, first I started by just making small 1s -3s batteries for small items to work.

 

[Hightechpete]

I bought my wife a hopper shopper which was not used so I am wondering about checking that out, seems logical to look at upping the power of the battery if I do it

Did exactly that to a friends 24v shopping bike with a 36v battery, controller and display. Well worth the effort.

 

[Ray Winder]

Thanks for the input, it doesn't seem to be cost effective to set up just to do one cell pack, but interesting nonetheless I wondered about buying a ready assembled pack like the ones on Ali express but don't know what quality cells they use, I've often wondered why someone who has invested in a good welder doesn't offer bespoke packs.
I need to keep digging, I'm sure the little shopper bike is worth a bit of an upgrade and it it's in the car so easily.

 

[soundwave]

.https://www.fogstar.co.uk/collections/batteries/Size_18650

decent cells are not cheap atm and in short supply.

 

[Ray Winder]

decent cells are not cheap atm and in short supply.
[/QUOTE]
Thanks that's interesting, wonder if they will come back down as supplies pick up. Probably worth paying for quality cells if you are going to do it.

 

[Nealh]

Thanks for the input, it doesn't seem to be cost effective to set up just to do one cell pack, but interesting nonetheless I wondered about buying a ready assembled pack like the ones on Ali express but don't know what quality cells they use, I've often wondered why someone who has invested in a good welder doesn't offer bespoke packs.
I need to keep digging, I'm sure the little shopper bike is worth a bit of an upgrade and it it's in the car so easily.

One has to ideally set up as business and have good insurance, then there is the certification requirements and getting them from A2B. One can't ship cells/batteries willy nilly.
There are 3 or 4 guys in the UK who carry out such bespoke builds or re-celling,
there have been at least four mentioned on the forum and two I know are members.

 

[Nealh]

.https://www.fogstar.co.uk/collections/batteries/Size_18650

decent cells are not cheap atm and in short supply.

Fogstar have had some new genuine stock deliveries lately from the likes of Molicel, Samsung, Vapcell, BAK, Eve, Sinowatt & Sanyo.
However if one wants to build a battery the FS retail is the wrong place to buy, if one spend over £75 on cells (which isn't hard) then one should buy from FS wholesale where the cells are some 50/60 % cheaper.

For instance Moli 26A retail site £6.49 vs £2.99 wholesale site.

 

[Ray Winder]

Fogstar have had some new genuine stock deliveries lately from the likes of Molicel, Samsung, Vapcell, BAK, Eve, Sinowatt & Sanyo.
However if one wants to build a battery the FS retail is the wrong place to buy, if one spend over £75 on cells (which isn't hard) then one should buy from FS wholesale where the cells are some 50/60 % cheaper.

For instance Moli 26A retail site £6.49 vs £2.99 wholesale site.

The wholesale site is pretty interesting, starts to make the project more viable

 

[Nealh]

When I get around to my next battery build The BAK 1850cnp 25a cell at £2.15 has peaked my interest and according to Mooch on ECF it is a damn good alternative to the Sam 25R and performance wise is near perfect match.
Also the Sinowatt 20a cell at £1.70 it again is a good alternative to the Sam 30Q.
The best cell though today on the market is regarded as being the Moli P26A.

Fogstar have a very good rep for only dealing with genuine cells from verified sources, i.e. direct from the factory.

 

[Hightechpete]

I've had a non functioning battery laying around for some time, before I recycle it I thought I'd take it apart to see if I could get my head around the workings.

Just to put everything in perspective, the cell replacement was a success. The pack now accepts and holds a full charge, well worth the effort. The amount of time spent was considerable, suffice to say I won't be attempting a scratch build at any time in the near future, all things considered an off the shelf battery seems like a bargain.

 

[Ray Winder]

Just to put everything in perspective, the cell replacement was a success. The pack now accepts and holds a full charge, well worth the effort. The amount of time spent was considerable, suffice to say I won't be attempting a scratch build at any time in the near future, all things considered an off the shelf battery seems like a bargain.

Its very interesting to get the opinion of someone who has actually taken this on, I am still in the research stage but your input interests me. I was wondering about buying a welder something like:
Welder

To upgrade the shopper bike using higher Amp hr cells , and which I may use to re cell some expensive battery tools at a later date

Or just to go with a new battery which should fit :
Battery
Much easier, and no extra tools cluttering my Garage

By the way approx how many miles do you get from your battery now?

 

[Hightechpete]

By the way approx how many miles do you get from your battery now?
[/QUOTE

Not been tested yet, I suspect the range will have suffered somewhat, the battery is 4 years old and fitted to a ladies bike that is seldom used, which is why I did a repair rather than investing in a new battery. I was hoping that I might get my wife to join me for an occasional gentle ride.
I got a 36v frog battery direct from Yose for around £115 and a £20 controller to upgrade a friends 24v shopper, quite a simple swap but very effective.