Tips for making an 18650 battery holder

So I'm looking to setup a bank of 16850s to push 2 P7s on my bicycle. I don't feel like spending big $$ on a battery space pack (though they look nice). I know I am taking some risk without a dedicated protection PCB but its still what I plan to do. The cells are individually protected and I'll ensure that when first installed, they will have identical charges as to prevent voltage balancing currents causing trouble. I'll also avoid charging it unattended on my pile of dried hay.:shrug:

After deciding not to solder the 6-8 batteries together (which was tough since I'm almost a soldering enthusiast) I figured I'd need some other way to do this. All batteries will be in parallel. For some reason you can't buy an 18650 battery holder, it seems like a useful item to me

Anyhow, I need a way to set this up. The big thing I'm having trouble with is how to get the contacts to reliably engage some kind of connector. I'm reasonably inclined in terms of building things and have plenty of tools so that gives me more possibilities. I'd like something I can mount to my bike with velcro fairly easily as well, I was thinking some kind of tube with end caps complete with conductors but wasn't entirely sure what would reliably grip the batteries.

Wiring is easy enough, I'm connecting some 14 gauge speaker wire with power pole disconnects which will allow me to charge the pack while still on the bike.

Anyone here have any ideas?

I got some plastic tubing for hot water heaters, its a perfect fit for the 18650s, and also picked up caps meant for furniture bottoms that fit great on the ends. I think I'll use some Pre-1997 Canadian pennies (98% copper or so) to engage the positive and the negative will be one of those battery pack springs soldered to a penny. Then wires will connect to the other ends of the pennies (which are glued into the caps) and run out and wired in parallel. I'll report back with some serious innovation I think I can keep the resistance low enough to not present much problem.

Sounds an interesting project - let's see some pics.

I'm glad you decided not to solder the cells together - this is something that should never be attempted unless the cells have tabs.

Wiggle said:

I got some plastic tubing for hot water heaters, its a perfect fit for the 18650s, and also picked up caps meant for furniture bottoms that fit great on the ends. I think I'll use some Pre-1997 Canadian pennies (98% copper or so) to engage the positive and the negative will be one of those battery pack springs soldered to a penny. Then wires will connect to the other ends of the pennies (which are glued into the caps) and run out and wired in parallel. I'll report back with some serious innovation I think I can keep the resistance low enough to not present much problem.

Click to expand...

I have been using a similar sort of setup for about a year now. I found some plastic plumbing tubing that's a perfect fit. I got some small joiners for this tubing which I have glued end pieces into then put springs in from stanndard AA battery holders. I run a 4S 2P setpup with a boost driver for my 6 led light and a 6S made made from 2 three long lengths for my 4 led light with a buck driver. I have tubing lengths cut for 1 and 2 18650 as well but don't tend to use them.

I am failing to link the image but there are a couple of shots of the 4s2p setup with my light pictures from the link below.

Ifor

DM51 said:

Sounds an interesting project - let's see some pics.

I'm glad you decided not to solder the cells together - this is something that should never be attempted unless the cells have tabs.

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How do the tabs make it much safer, it seems like any decently connected tab would still sink heat into the battery quite rapidly?

ifor powell said:

I have been using a similar sort of setup for about a year now. I found some plastic plumbing tubing that's a perfect fit. I got some small joiners for this tubing which I have glued end pieces into then put springs in from stanndard AA battery holders. I run a 4S 2P setpup with a boost driver for my 6 led light and a 6S made made from 2 three long lengths for my 4 led light with a buck driver. I have tubing lengths cut for 1 and 2 18650 as well but don't tend to use them.

I am failing to link the image but there are a couple of shots of the 4s2p setup with my light pictures from the link below.

Ifor

Click to expand...

Very nice setup, I wish I could run a bunch of them in series, so much easier.

Does rare earth magnets solder? Or, what kinda magnet can be soldered to? (where to buy locally?)

If the above is feasible, industrial velcro on batt sides could hold into place.

What I can't imagine, is how to afix springs into a resin to push against poles reliably. I can imagine piping only useful for putting cells in series.

degarb said:

Does rare earth magnets solder?

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Yes, but it has to be done quickly enough not to heat up the magnet too much, or it will lose much of its magnetism.

I'm making some 4 x 18650 holders, check here for details.

Cheers, Rich

Is it ready for sale?

I have some of these plastic bottle preforms. A preform is basically a soda bottle before it has gone through the blow molding process to convert it into a full size bottle.
They make a pretty good fit for 2 x 18650 cells with a little room to spare at the top/bottom.
They are practically indestructible, waterproof & the screw on lid provides a means to ensure a snug fit for good contact with the terminals.

I have yet to actually put them to practical use. I am very new to the whole light building scene - ordered my first batch of goodies from DX and am expecting delivery in the next day or 2.
So far I have used these as storage containers for some 18650 cells I salvaged from laptop batteries.

Once I get started with my DIY light building, I will certainly come up with some more innovative ways to put these things to use.

Here are some pics.





http://picasaweb.google.com/bradjackson78/DIYLightsHostedImages?feat=directlink

Hi bradjackson, and welcome!
Care to reveal your source for those soda bottle preforms and their cost?

...(and double your post count by doing so?)

There is one retailer if you put plastic bottle preforms into google. 5"x1" The novelty factor is high. They'd make nice pill bottles, etc etc.

I just found these at DigiKey, 18650 holders with pressure contacts. For two bucks you can save a lot of time and trouble !

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=bk-18650-pc2-nd



http://www2.electronicproducts.com/...tected_cells-article-incd11_nov2009-html.aspx

I think this is a mostly dead thread ...but I make some 18650 holders that may suit you.

https://www.candlepowerforums.com/threads/240139

yes they do as long as the are nickle plated. You need to be quick though.

degarb said:

Does rare earth magnets solder

Click to expand...

DM51 said:

Yes, but it has to be done quickly enough not to heat up the magnet too much, or it will lose much of its magnetism.

Click to expand...

3/16" thick 1" x1" Square tabular magnts are out there in the surplus electronics marketplace that have a convenient hole right in the center for a screw mount that I use to screw on a solder lug. Then I don't hafta heat up the magnet to hook a wire to it.

BTW, I have a nice source of $2.00 18650's from BG Micro in Garland texas and knowing these cells can put out as much a 3 amps under load, i decided to forgo making my own battery holder,cause I found then easily enoug with google, 1 cell, 2 cell, and 4-cell holders for 18650s all for $% or leass. I ordered two 2-cell holders from Amazon for $9.00

Yodar who started his portable lighting with PR-2 bulbs.
L.E.D. are MAGIC to this O.F. ;>)
Bets regards
Yodar in Fl.