Amperage load on battery springs

veloman

veloman

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I'm wondering how many amps these little springs will transmit?

http://www.mouser.com/ProductDetail/Keystone-Electronics/211/?qs=sGAEpiMZZMupuRtfu7GC%252bV5k6zVTq3YUfHt8nhDUQyY%3d

There was a pic on one of these battery building threads here, I think.

My motor is capable of pulling about 20amps peak, 15 sustained, and I have only 2 cells in parallel. So that means a peak of 10 amps through these springs, or 7.5 sustained. Also, the cells are not tab welded or soldered together, just pressed by spring tension contact.

Do you think I'll run into any problems if I'm going up a hill at 600watts or 15amps?
 

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Unless there are cu tabs and wires connected directly to the battery contacts, the springs are a bunch of resistors in series that will glow and loose their temper, then loose their connecton when the current gets too high. Also when you bump them in the direction that will load the spring above the springs load, you will get a interuption of power, springs are not a good idea on moble equipment that sees any shock.
 
So the only way to build a battery is with a tab welder? lol


Anyone want these 24 konion cells? $20 + shipping (US)
 
Not so likely that it will become a problem at 15 amps. But I do agree, any poor connection in there will get hot.

Not like you are a fat no pedaling kind of guy either. So I bet you have no problems with you riding the bike.
 
Well I do have that going for me, the most power I will draw from the pack for a minute would be 400watts or so.

But I really worry about the connections. The cells are simply just resting against each other's ends, held by spring tension.


Maybe I should try soldering wires to make the cell connections, completely changing the layout back to the original Makita pack design??? There would then be no forces on the connections. I have a flux pen, that should help make a stronger solder?
 
I've measured the resistance of those type of spring contacts when used in those black plastic AA battery holders. They were over 0.1 ohms!. At 15 amps, you would drop 1.5V in the spring alone. I have seen them act as circuit breakers with AA NiCd batteries. They get hot, contract, the connection opens, residual heat warps the plastic to make it permanent.
 
texaspyro said:
I've measured the resistance of those type of spring contacts when used in those black plastic AA battery holders. They were over 0.1 ohms!. At 15 amps, you would drop 1.5V in the spring alone. I have seen them act as circuit breakers with AA NiCd batteries. They get hot, contract, the connection opens, residual heat warps the plastic to make it permanent.
Click to expand...


This explains why I had voltage sag when running the motor with the wheel off the ground...... :roll:

I am taking apart this battery tonight, it's definitely not staying that way.

Thanks.
 
Ready to learn how to solder cells now? hehe.
Don't feel to bad; i get to learn how to do surgery on a zippy flightmax pack thanks to 1 dead cell.
 
veloman said:
texaspyro said:
I've measured the resistance of those type of spring contacts when used in those black plastic AA battery holders. They were over 0.1 ohms!. At 15 amps, you would drop 1.5V in the spring alone. I have seen them act as circuit breakers with AA NiCd batteries. They get hot, contract, the connection opens, residual heat warps the plastic to make it permanent.
Click to expand...


This explains why I had voltage sag when running the motor with the wheel off the ground...... :roll:

I am taking apart this battery tonight, it's definitely not staying that way.

Thanks.
Click to expand...

Yeah, I once had the brilliant idea of using them in a 4xAA nicad app that needed to supply like 10 amps for a second. Should be no problemo, correcto? Nopeo... too make matters worse, it took a few hours to figure out what was going wrong... :oops:
 
Those batteries + and LED + a little electrical tap make great little emergency flashlights. Also, there are high power LED flashlights that use 18650 cells and make nice Christmas presents, plus you already have the batteries and spares. Laptop battery packs often are filled with 18650 cells, so you also have spares to do a repair. I don't think that's enough cells to jump start a car, but it may be enough to provide a little extra boost on a really cold sub zero morning.
 
My laptop could use a battery. The one that came with it was dead. (refurbished laptop from ebay 4 yrs ago).


I might try out the battery tomorrow around the neighborhood just for the hell of it...lol.
 
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