[altusmetrum] Bulging LiPo battery

Keith Packard keithp at keithp.com
Wed Sep 11 13:13:16 MDT 2013

Peter Hackett <peter.hackett at cal.berkeley.edu> writes:

> 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
> OK.

Should have been, unless the battery was broken.

> 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".

If it's been with this same battery, then I suspect it was damaged some
time ago.

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

Right, any 3.7V lithium polymer battery should be fine; you can get
these at many hobby stores that sell RC vehicles. Just take the wire off
the dead battery and stick it on a good one and you should be in great shape.

> 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
>   http://www.altusmetrum.org/Documents/SeparatePyroBattery/
> - (don't plug the TeleMetrum into USB)
> OR
> - Use 3 AAA batteries to power the TeleMetrum.
> - Use my StratoLogger to fire the e-matches.
> - (don't plug the TeleMetrum into USB)

Hrm. There's a LTC1682 5V charge-pump supply on TeleMetrum for the
accelerometer and that appears to be rated to only 4.4V. 3 AA batteries
will nominally run 4.5V; I'd assume at full charge they'd be slightly
higher, which doesn't bode well for the health of this power supply...

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