Used Makita pack teardown

[999zip999]

Syo do you have a spot welder ? Do you use a gasket on the positive end ? Hard to see in your blog. ??

 

[Syonyk]

Syo do you have a spot welder ? Do you use a gasket on the positive end ? Hard to see in your blog. ??

Yes, I have a spot welder. 788+, with a few blog posts talking about how it's built/failures/repairs/etc.

I don't use a separate ring on the positive end (the pack, as built, doesn't come with one, and I try to rebuild them as close to stock as possible), but I do trim the ends down on the positive pole to reduce the chances of a corner poking through the insulation and shorting things out. The recent posts on the BionX pack teardown & rebuild cover this.

 

[dequinox]

Yes, I have a spot welder. 788+, with a few blog posts talking about how it's built/failures/repairs/etc.

I don't use a separate ring on the positive end (the pack, as built, doesn't come with one, and I try to rebuild them as close to stock as possible), but I do trim the ends down on the positive pole to reduce the chances of a corner poking through the insulation and shorting things out. The recent posts on the BionX pack teardown & rebuild cover this.

How do you like that 788? I didn't know there was a tab welder available for that little cost...

 

[Syonyk]

Gee, if only I had a blog talking about this stuff. In my sig.

It's OK. It gets the job done. I did have to do major repairs on it after it blew up within 15 minutes of use. Like, literal, large bang, smoke, left my ears ringing type explode. The triac let go, hard.

I wouldn't push it very hard. I'll weld .15mm nickel, it'll probably do 0.2mm, but it's not likely to even tickle anything thicker.

 

[LyonNightroad]

I bought 400 of these used cells at $1 a cell from dr.bass all but 35 were still within 10% of original capacity. Although the capacity is rather low by todays standards and results in a heavy pack for higher capacities, they seem to tolerate abuse quite well. I haven't been running a bms for several dozen cycles now and they seem to'self balance' fairly well compared to other cells I have used. Still would not recommend doing the same if you don't know the risk and dont check on balance from time to time, but these are viable cells for making a no bms pack. And at $1 per 1.5 * 3.7 watt hours you cant go wrong. If money is unlimited then definitely get some of the sexy new 3.5 ah cells since it will be much easier to assemble and weigh less, building a 12p14s was a real pain.

 

[Syonyk]

Well, BionX doesn't use a BMS except bulk pack voltage on these.

http://syonyk.blogspot.com/2015/06/bionx-36v-96ah-pack-teardown.html

They seem to get away with relying on the self balancing characteristics without any problems - the only dead BionX packs I've run across so far are ones with stone dead cells from sitting for years.

 

[dequinox]

Ok so after half a year or more I'm back on this battery project, and the 1000lb teardown thread also, and I got some help in the mail today that will make this process go a little more smoothly and hands-off:


View attachment 1

 

[Doctorbass]

Here is something i'm sure peple will appreciate!

[youtube]Oz6Uis05ewA[/youtube]

Doc

 

[kriskros]

FORM to assemble multiple batterie cells for balance charging.... MATERIAL..2 pcs of wood 1/2wx1 1/2"x suitable length.. 2, 1/4" threaded rods,suitable length...two standard nuts,two wing nuts, 4 washers... drill one 1/4" hole in one end of each wood pc... make a 1/4 x4? slot in the other end// assemble with threaded rods// you now have frame that is adjustable in two dimensios that will hold batter cells of any size or quantity ...... ps,we are using a low power[110v].. spot welder 709a, that we foundon ebay..$342.00C.. it uses .1mmx.7mm nickel or nickel plated steel strips.. works very well.. because we have the spot welder we just tear the nickel strips off the cell packs.. quick and easy,,, package of 500.1mmx.7mmx 100m $15.00us on ebay