What's the most 'universal' low-cost battery format?

[Nealh]

My first one was the Korea Boss arduino model about $80 it worked ok but got quite warm so added a fan to keep it cooler, then something went wrong and it stooped working. The guy in korea said it was likely the arduino so I bought a new one for about $15 and swapped it out, still refused to work so called it a day/

I then bought the malectrics 4 -5 years ago and it has been great, using the copper nickel sandwich method one can spot weld copper with it, I use a high rate 3s 65c lipo for power. The malectric is a good shout for buying one, the K weld is a step up.

 

[Nealh]

BAK and lishen look like they will become more familiar names in the years to come with shortages on the main branded cells become even scarcer.

 

[Nealh]

These are dirt cheap, how well they work is any ones guess.
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[Nealh]

My 12s2p uses Hg2 genuine cells and for my low current draw of about 2.6a in PAS 1 the capacity is approx. 5200mah out of the 6000mah. Max I have had is 30 miles typically though I charge after 25 miles at about 3.55v per cell.

 

[harrys]

I have this one. It tops out at .12mm strips, which I believe are nickel plated steel. I need to keep the copper probes clean. It seems to punch a lot of power, but it doesn't translate to automatic good welds. Blows holes in thinner strips, I get burn marks on my 50 year old formica desk top transferred thru the strips when I weld test strips.

By the well, test strips is not necessarily a good test. They don't adhere to each other, but if I weld to a battery, the current appears to go thru the strip better. It must have to do with resistance. Pressing down hard makes a poorer result than a light touch. WHat I do is do a couple of test runs on a dead cell. and test the welds for pull strength,

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I woder how it would do if I opened it up amd used my own battery instead of the 4.2V internal cell.