A couple random battery q's

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fisc0319

1 µW
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Mar 10, 2016
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I have been researching batteries for my bike but am just a beginner for sure. I had a couple q's that I thought some of you may have an answer for.

Why isn't there a preformed pack that the lithium cells can be put into like AA batteries? It seems to be such a pain to spot weld all these things together when you could possibly just snap them into something like this that is prewired:
http://www.parts-express.com/8-aa-cell-battery-holder--140-978?utm_source=google&utm_medium=cpc&utm_campaign=pla

Why is there such a fire risk with these hobby lipo packs but you don't hear about it (at least I haven't) when using lithiums in power tools/devices?

Thanks, sorry if these are stupid q's
 
There are spring-contact battery holders like that for li-ion 18650 cells but they are only suited for low power applications as the spring contact is of too high a resistance for something like an ebike battery.

Power tool batteries are high quality 18650 can cells. RC Lipo is arguably inherently less stable due to differences in chemistry/construction, but they are also of much lower quality and consistency.
 
Here is what I have, location is western Wisconsin, had another post but no replies yet:
I have a mid drive kit installed on a fat tire bike, the stats on the motor are: Multiwatt (650~1680W), with controller:48V continuous 840~1680W, 40A continuous, Max 100A, and am working on getting the battery set up to meet my needs and am looking for recommendations.

The vast majority of the time I think I will need to travel under 1 mile, and do have some big hills to climb. I would never be going over 5 miles for sure. I am looking at 3-5ah hobby king packs, but wanted to ask to make sure I am getting what will meet my needs. I would like to try 36v first to see if its enough to climb the hills, if not them Ill bump it up to 48V. Whats the most economical, simple set up for my needs?
 
Rechargeable lithium AA batteries exist, I have some, and they are called a "14500". It means 14mm in diameter, and 50mm long.

You question goes to the lack of "loose cell" battery packs, where you buy the box of the size and shape you want, and then buy the cells and simply pop them in, like refilling a flashlight. many small one/two/multi cell holders draw current through the spring that maintains pressure on one end of the cell. Cells get warm and then expand slightly, then they cool and shrink. It's been mentioned that those coil-springs are a poor conductor at high currents, but several loose cell boxes have been made where the current was carried by a separate copper tab, while some type of spring (or spongy "compression pad") maintained the pressure over the cell warm/cold cycles.

To date, snaths version is the best so far (IMHO), and it is what I'd copy right now. Agniusm is currently making a version to sell that looks reasonably good. Why didn't snath pursue sales? I would guess that he fears customers inserting the cells wrong, and the pack catching on fire. That's why I don't make them for sale.

As to the cells, it would take several 14500's to equal the capacity of one 18650, and there are several high-current models of 18650 cell available right now at reasonable prices. I don't know of any 14500 cells that provide high current, not much of a market for them.

"Another No Solder/Weld 18650 Build" (snath, 6 pages [plus more links to other no-solder/no-weld builds])
http://endless-sphere.com/forums/viewtopic.php?f=14&t=57810

"18650 battery Kit development and discussion" (agniusm, 4 pages)
https://endless-sphere.com/forums/viewtopic.php?f=14&t=63190
 
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