[altusmetrum] Bulging LiPo battery

Peter Hackett peter.hackett at cal.berkeley.edu
Tue Sep 10 16:49:41 MDT 2013


I charged the battery by plugging it in to a USB charger.
I *did* leave it for (I think) two days. But it sounds like this should be

I've always had "trouble" with charging (at the very least "confusion")
I've had situations where I know it needs charging (software says the
voltage is
low) but the charge light doesn't go on (usually.)
So I now just "plug it in (for a long time) and check it".

So it looks like the only (quick, complete) solution is a new battery that
I modify
by removing the protection circuit.

Given your information, it seems like other possibilities are:

- Use 3 AAA batteries to power the TeleMetrum.
- Use a separate Pyro battery as documented at
- (don't plug the TeleMetrum into USB)


- Use 3 AAA batteries to power the TeleMetrum.
- Use my StratoLogger to fire the e-matches.
- (don't plug the TeleMetrum into USB)

On Tue, Sep 10, 2013 at 3:23 PM, Keith Packard <keithp at keithp.com> wrote:

> Peter Hackett <peter.hackett at 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
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