Potential hack solution... I have several times taken apart old laptop batteries to repurpose the individual cells inside. Quite old ones will have cylindrical Li-Ion cells, 4.1V charge cutoff. Newer will have several Li-Poly cells. In almost all cases, the protection circuitry is centralized on a piece of PCB. So (carefully!) cut the leads and you can get at individual unprotected cells. While these are bulky, at old age they still have quite a lot of capacity and into a short can still put out pretty amazing current.
Personally I'd go to the RC store and find something that has a high current rating, such as for small RC helicopters, and just pay careful attention to polarity as already suggested. Since you are using ematches, you probably don't need much current to set them off, and they are fairly likely to be open-circuit after they are fired, so *likely* you never draw more than the protection circuit is rated for anyway. However, lots of variables, and easy to armchair advise from here... Good luck in any case. -Bryan On Tue, Sep 10, 2013 at 5:31 PM, Plugger Lockett <plugger.lock...@gmail.com>wrote: > I'm pretty sure I packed a 600mAh spare if you think that will suit your > needs. I'm Andrew Hamilton and will be in the Australian camp. See you on > the playa! > On 11/09/2013 8:40 AM, "Sam Fineberg" <s...@fineberg.net> wrote: > >> Peter, >> You might ask Mike @ BAR. He had some Telemetrium gear the last time I >> looked. He might be able to pull a battery out of a bundle kit if you >> asked nicely. >> >> Sam >> >> On 9/10/2013 3:23 PM, Keith Packard wrote: >> >> Peter Hackett <peter.hack...@cal.berkeley.edu> >> <peter.hack...@cal.berkeley.edu> writes: >> >> >> I'm off to Black Rock on Thursday. Not sure I'll be able to replace it by >> then. >> (I'm assuming it would be hard to find the right battery locally) >> >> Yeah, we use the same connector as some helicopter batteries, but the >> polarity is reversed, which would destroy both battery and board if you >> plug them together. >> >> Bdale has a pile of current stock, but he's in California until tomorrow >> evening. I don't have any of the larger size left at this point or I'd >> offer to ship one from here. >> >> We get them from SparkFun though, and they do offer overnight shipping: >> >> https://www.sparkfun.com/products/341 >> >> However, if you want to use them to fire charges, you'll need to remove >> the current limiter board. If left in place, the battery will shut down >> as soon as you try to fire a charge, leaving the board dead in the >> air. Older SparkFun batteries had a different protection circuit which >> worked fine with TeleMetrum, newer SparkFun batteries nearly always fail. >> >> It's a pretty simple soldering job, if you're up for the adventure. >> >> http://www.altusmetrum.org/Documents/FixBattery/ >> >> Anyone want to chime in on whether AAA's will be big enough? >> >> Also, I guess I should be concerned about battery internal resistance. >> Will 3 standard alkaline >> batteries in series be able to provide enough current to light the >> e-matches? >> >> Not recommended for a couple of reasons: >> >> *) TeleMetrum will try to charge them when plugged in over USB. There's >> no way to disable the charger, and the board cannot run without a >> battery in place. >> >> *) AAA batteries have a higher internal resistance than lithium >> polymer batteries, which means if you try to fire an e-match, the >> voltage seen by the board will drop low enough to reset the board. >> >> >> RE over-charge: >> >> Can that happen using the TeleMetrum to do the charging? >> >> The charge controller on TeleMetrum shouldn't be able to overcharge an >> undamaged battery. I've left them plugged in for weeks at a time without >> problems. >> >> -keith >> >> >> >> _______________________________________________ >> altusmetrum mailing >> listaltusmet...@lists.gag.comhttp://lists.gag.com/mailman/listinfo/altusmetrum >> >> >> >> _______________________________________________ >> altusmetrum mailing list >> altusmetrum@lists.gag.com >> http://lists.gag.com/mailman/listinfo/altusmetrum >> >> > _______________________________________________ > altusmetrum mailing list > altusmetrum@lists.gag.com > http://lists.gag.com/mailman/listinfo/altusmetrum > >
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