gonna try my hand at

[rcjordan]

li-on battery terminal welding.

My power tool ecosystem is 18v Porter Cable, long obsolete. Battery pack replacements are getting crappier & crappier.  Over the last couple of years, well-rated nickel tab spot-welding machine has come down from $250 to $130 ...about what I spend every 2 years on crappy battery packs. Worth a try so I can use quality 18650 batteries and rebuild.

[ergophobe]

I just saw an article about soldering titanium using ultrasound... maybe that's the next wave. Are lithium-ion battery terminals extra hard?

[rcjordan]

>soldering titanium using ultrasound...

That article was the catalyst to go looking at battery welders one-more-time.  Voila' prices have way down as more and more people start building their own ebike battery packs.

>Are lithium-ion battery terminals extra hard

Both ends of the battery is smooth and ready for spot-welding the nickel strip that bridges to the next battery.  I guess they have to be welded due to the high heat they generate when under load.

[ergophobe]

Ah. Makes sense. Solder would melt.