Pardon me if I seem completely ignorant. I hve a question on what can be used in a li-ion charger as a spacer. I see some people buy the ready made 15 mm slug spacers, while others say they just use stacks of rare earth magnets or stacks of pennies. Am I right in assuming that just about any old hunk of metal will work as a spacer? I'd hate to spend $2-3 on a ready made spacer if I can just use an old bolt of the right length out of the bolt bucket. What do people use as spacers? Are there risks associated with spacer use?
Not really, but you should wrap them with electrical tape just to be on the safe side.
I use copper stuff out of the plumbing bits and pieces that really should have been thrown away years ago but you never know when you will need it bin. Works great
I would only use a bolt if something better wasn't available. You want to use something that is as electrically conductive as possible. Copper and aluminum are good here. I've used the neodymium rare earth magnets. They are a tad less conductive than aluminum, but their advantage is that once in place between a cell and the charger, they are unlikely to move. A roll of copper coins may not stay in place. I now use the aluminum dummy cells that are sold for the purpose.
I use the neodymiun magnets sold at DX
http://www.dealextreme.com/c/rare-earth-re-magnets-1105?r=43033281
The 8mm 20 pack is interesting. But you have from 8 to 20 mm in diammeter
Always usefull
unprotected or IMR 18500 + spent .22 casing = 651mm
The neodynium magnets do have some resistance, this is visible when charging with hobby charger, the magnets soak up voltage thus the charger will terminate earlier.
But really, not that big a deal, the convenience of magnets outweigh the oh-so-tiny capacity difference IMO.
You can find almost any size on ebay, most are even cheaper.
Short of having a lathe to make your own, this is the winner.