I got 2 1,800-mAh 3-cell LiPos the other day, one with a Parkzone
foamie I bought to replace one I totaled and the other off the shelf
of the LHS. I charged both then realized the new plane was missing
parts so I decided to discharge both to 11 volts because they'd
probably be unused for a few weeks (I'm not looking to start the "how
to store LiPos" discussion again -- last time was pretty thorough).
Anyway, I discharge by attaching a 12-watt 13.8 volt automotive lamp
with a voltmeter in parallel and watching while compensating for the
drop from the lamp.
One battery discharged normally. The other dropped a bit, then went
immediately to about 6.5 volts. Couldn't miss it -- the bulb went
I tried the questionable battery again, and it did the same, dropping
suddenly to about 7 volts.
My question, obviously, is Do I have a bad battery? Seems to me the
sudden drop is one cell going virtually dead. But I'm new to all this
and pretty ignorant. Any suggestions?
It's 1 for charge, 15 for discharge. Instructions on battery say to
charge at no more than 1.75 amps, so I charge at 1.5. It's a balancing
charger that comes with the plane and battery, supplied by Parkzone.
Batteries are identical.
Sounds like it.
If you're careful, you can measure each cell with a voltmeter. Access it at
the balance socket.
I had a cell go bad on a 3 cell lipo. It was an end cell. Gave it to my
mate, who chopped off the dud, and is still using the 2-cell battery..