RE Bay Area Rocketry I've sent e-mail to Mike but I think he may already be at Black Rock for ARLISS.
RE pull a battery from a bundle: Yes. Mike is an *AWESOME* vendor! I wouldn't be surprised if he was willing to do that. I think give that it's late in the day (and even later at SparkFun (Colorado)) and my "Scottish" blood bristles at paying $25 to get an $9 battery, I'll go to Black Rock and "expect a miracle" If my backup "other possibilities" are deemed "not too wacky" by Keith, I might prepare for one of those in case a miracle doesn't happen :-) On Tue, Sep 10, 2013 at 3:39 PM, Sam Fineberg <[email protected]> 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 <[email protected]> > <[email protected]> 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 > [email protected]http://lists.gag.com/mailman/listinfo/altusmetrum > > >
_______________________________________________ altusmetrum mailing list [email protected] http://lists.gag.com/mailman/listinfo/altusmetrum
