18650 Battery Holder

[marty]

Want to build a battery for this scooter. Currie Phat Flyer had 2 - 12V lead acid batteries.

Got lots and lots of defective Makita 18V power tool packs. Been studying Doctorbass battery building projects.
I ripped off the metal strips with needle nose pliers. Suspect it is stainless steel? Older Makita batteries had 2 spot welds per connection. They used plated steel strips. [Removed green cover just to see em naked :wink: ]

Want to build a 6P, 8S battery. 6 cells in Parallel, 8 groups of 6 in Series if I am thinking correctly? Do we say 6P/8S or 8S/6P?

You guys all solder your battery packs together. I got nothing against solder. Got a bunch of soldering irons and about 40 years experience soldering everything from big to little. Just think that heating these batteries with soldering irons is wrong.

Here http://endless-sphere.com/forums/viewtopic.php?f=14&t=28285&start=15#p533659
Doctorbass say:

Spring tend tobe too thin fo rthe current demand...

I used already some copper braid... wich is a little soft and conduct alot more!

What i suggest to prople who dont want to solder or spotweld is to use soft copper braid and a little foam under it to keep pressure on the copper braid.

These braid can be used like a buss bar to parallel and serie them.

For testing cells before the assembly i made some neodium magnet test lead for testing the capacity at 1C of each cells. this is a really quick connect way and still conduct more than i expected.

you can solder on the chrome layer on the magnet.. but dont heat them too much to keep their magnetism. :wink:

Doc

Here is my preliminary plan. Grind off them tiny remains of spot welds with some type of tiny grinder. Tried a file but it was too easy to damage the green coating and black insulating washer. Buy some 18650 Battery Holders. Experiment with copper braid. Makita cells are steel. Steel and copper corrodes. Dielectric grease might be a good idea?

See these 18650 Battery Holders at batteryholders.com Buy battery holders from batteryholders.com Duh!
View attachment 3

Here are drawings:
View attachment BK-18650-PC6-datasheet.pdf
View attachment BK-18650-PC8-datasheet.pdf
If mechanical connection between battery and contact is tight will this work? I say yes? Would anyone like to see some "Safe" style charts and graphs explaining this? Any one got any other 18650 Battery Holder ideas?

 

[parabellum]

Since you ripped off the tabs and soldering can damage the cells now, there is not much of choices left.
You will need to experiment with the holder to see where to limit the current, contact to cell will not be great and SS is not very good electric conductor resulting in excessive heating at certain current levels that can and will melt the holder. Anyway, it may work for low power setup with little mods on the holders. I personally, solder them together on stock tabs.

 

[pwbset]

Yeah just dremel off the remaining spot weld remnants. Easy peasy. Why not build your own tab welder marty? Super easy to do, relatively cheap and gives really good results once you get the hang of it. That's what I did with my "duct tape strap packs" a few years ago and I'd routinely slurp 7-8kw bursts out of those without issue.. and that was with mixed V and VT cells... oops... LOL. I've just reserved one of the hubzilla motors for this upcoming season and plan on building another konion pack since they are so bloddy easy to charge etc. Once you've tab welded it's hard to go back to solder.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=9691#p169386

 

[pwbset]

Got lots and lots of defective Makita 18V power tool packs.

Any more recently or are these from your big score a few years ago? I've been outta the ebike game for a year or so, but I'm looking to source about 34 packs for this coming summer (assuming the 8 "good" cells per pack is still applicable). Let me know what your supply is like and if you want to sell some again. Thanks.

 

[marty]

Since you ripped off the tabs and soldering can damage the cells now, there is not much of choices left.
You will need to experiment with the holder to see where to limit the current, contact to cell will not be great and SS is not very good electric conductor resulting in excessive heating at certain current levels that can and will melt the holder. Anyway, it may work for low power setup with little mods on the holders. I personally, solder them together on stock tabs.

Only riped off the stainless steel strips on the 4 batteries in my picture. At this point I am really not sure how I will construct my battery. Proper Planing Prevents Poor Preformace.

 

[marty]

Yeah just dremel off the remaining spot weld remnants. Easy peasy. Why not build your own tab welder marty? Super easy to do, relatively cheap and gives really good results once you get the hang of it. That's what I did with my "duct tape strap packs" a few years ago and I'd routinely slurp 7-8kw bursts out of those without issue.. and that was with mixed V and VT cells... oops... LOL. I've just reserved one of the hubzilla motors for this upcoming season and plan on building another konion pack since they are so bloddy easy to charge etc. Once you've tab welded it's hard to go back to solder.

http://endless-sphere.com/forums/viewtopic.php?f=6&t=9691#p169386

Will look into the $100 spot welder idea. Here is a battery spot welder that cost way more then $100
[youtube]F5ThF32YlW4[/youtube]

 

[marty]

Got lots and lots of defective Makita 18V power tool packs.

Any more recently or are these from your big score a few years ago? I've been outta the ebike game for a year or so, but I'm looking to source about 34 packs for this coming summer (assuming the 8 "good" cells per pack is still applicable). Let me know what your supply is like and if you want to sell some again. Thanks.

There was no big score. More like lots of little scores. Not selling any batteries now. Might sell them again in the future.

 

[parabellum]

Only riped off the stainless steel strips on the 4 batteries in my picture. At this point I am really not sure how I will construct my battery. Proper Planing Prevents Poor Preformace.

Will post some pictures, of what I did with my konions, today in the evening (pictures are at home). It is the simplest way I can think about, John in CR did same thing and is happy for years by now.

 

[parabellum]

I started with 54 used makita packs, 5s2p each.
First sorting out , balance charging and letting sit for 2 weeks then capacity testing.
In following example are only better compete packs, but if pair or two of cells is not good I combine it with other (similar capacity) packs cells, cutting them out carefully letting original tabs then soldering in needed place using strips from positive side of monitoring circuit.

Sub packs classified and ready to assemble

packs in shape

Paralleling on pack and cell level. (some people do not use balance connections on this cells, I do)

5s 12p pack ready and balanced.

Finally, needed quantity of 5s packs is connected in series. 1of the packs can be less then 5s if other voltage needed.