used(dead?) batteries !(SOLD)

[larryKay]

SOLD

[Mr. Protocol]

At the engineers' Q&A at the Sacramento Segfest, I asked Doug Field et al. about refurbishing battery packs. He said that would be difficult as the packs are welded shut. I pointed out that I was an amateur radio operator, and that they are "the most tightwad bunch of techno-freaks you could ever hope to meet. We have extreme methods of getting into battery packs."

This got quite a laugh from Doug and the others, but he then went on with somewhat more discouraging news. The cells in the battery packs, like most "internal" cells, have tabs on the end for permanent connections. In most everyday battery packs these tabs are soldered to a bus. In the Segway battery pack, they're resistance welded. Solder won't take the punishment that Segway packs receive. Now, soldering equipment is easy to come by, but resistance welding equipment is something else again.

Taken together with the lack of substantial outboard electronics in the packs to make refurbishing worthwhile, Doug said, it's mostly a losing proposition, unless you have a relatively small number of dead cells with the rest in good condition...and access to resistance welding equipment.

[Freddy]

Larry you have mail
Freddy

[Stan671]

quote:Originally posted by Mr. Protocol

[Doug] said that would be difficult as the packs are welded shut ... The cells in the battery packs, like most "internal" cells, have tabs on the end for permanent connections. In most everyday battery packs these tabs are soldered to a bus. In the Segway battery pack, they're resistance welded. Solder won't take the punishment that Segway packs receiveSee, this is one of the many hidden reasons why the Segway HT is so expensive.

Stan Dobrowski

[W9GFO]

Uh, resistance welded? The cells are resistance welded to each other by their tabs (common way to make packs) but the tabs that make the connection to the circuit board are soldered. I have replaced two blocks of cells so far. Everything is working just fine.

It's not easy, but certainly doable.

Rich H

The Un-Official Segway Battery FAQ
http://www.spinfoot.com/SegwayBatteryFAQ.html

[Mr. Protocol]

How'd you make up the blocks?

[W9GFO]

The bad blocks were replaced with blocks from another battery pack.

Rich H

The Un-Official Segway Battery FAQ
http://www.spinfoot.com/SegwayBatteryFAQ.html

[W9GFO]

Making up a block would be easy enough, even using just solder. RCers do it all the time and they also tend to take a fair bit of punishment.

Side note - the Segway batteries are tabbed together with fairly thick tabs - about twice the thickness that you see in production RC packs even though RCers will pull 30 amps or more from them. The HT doesn't even come close to that kind of draw. They are also resistance welded at four spots per cell - not two like is common.

Rich H

The Un-Official Segway Battery FAQ
http://www.spinfoot.com/SegwayBatteryFAQ.html

[Mr. Protocol]

I'm just curious: did you use solder yourself to make up the packs, or do you have welding equipment? As I mentioned above, Segway doesn't use solder to do this because Segways get pounded a lot, at least statistically - I'm wondering what the failure rate of solder might actually be.

[W9GFO]

quote:Originally posted by Mr. Protocol

As I mentioned above, Segway doesn't use solder to do this because Segways get pounded a lot...


Segway DOES use solder to attach the blocks of cells to the circuit board. Ten cells are tabbed together (using resistance welding) to form a block, six blocks in each battery and each block has soldered connections (two) to the circuit board where all the current flows through.

I do not have resistance welding equipment. I desoldered the blocks from a bad battery pack and resoldered them into the repaired pack.

Maybe I'll post a pic...

I currently have no need to solder individual cells together to form a block, but if I needed to I wouldn't hesitate to do so.

And yes, my Seg does get pounded a lot. :D

Rich H

The Un-Official Segway Battery FAQ
http://www.spinfoot.com/SegwayBatteryFAQ.html

[Mr. Protocol]

Good to know! Y'all have heard my theme that in the worst case, we'll have to self-maintain these things some day, so it's good to know we don't have to obtain exotic equipment to do so...even if our "refurb" jobs aren't up to factory standards. If they work and hold up, that's good enough for me.

Thanks, Rich.

[terryp]

Doug's point when he answered Mike's question about replacement of individual cells was that, lacking spot welding equipment, you'd have to replace welded joints with soldered ones. I think he was really trying to discourage even 'tightwad hams' from doing anything to compromise the safety of the HT. But if you're willing to do the work and take the risk, and considering that if a joint comes loose in one pack, the other pack will bring you to a safe stop, I don't see a problem with it. (I wouldn't do it myself though.)

Segway - What's holding you up?