akschu

My Feedback: (5)

I bought a 5 cell pack with Sanyo NIMH HR-AAAU 720 batteries for my twist 3d for the purpose of getting average runtimes with as little weight as possible. The pack has been fine, but a couple of days ago I left my plane on and ran them stone dead. I know this is really bad for batteries so I turned the plane off then waited a few minutes for the voltage to come up before charging them at the slowest rate. The voltage did come up and I charged them at 100ma (slowest my charger will go) until they peaked at around 550. The charger is a duratrax ICE so I can see on the graph the batteries taking a nice uniform charge, so then I cycled them a couple of times and every time I get around 550ma charge and about that in the discharge (at 800ma). The batteries seem completely reliable on the cycler, but I'm worred about battery failure in the plane, and the lower reported capacity is making me wonder.

Anybody have any thoughts on this?

Thanks,
schu

marcellus

Have you slow charged (1/10C) with a charger that does not voltage peak detect, e.g. a wall charger, to balance the cells in the pack? They are unlikely to fail in the plane, they just don't have the capacity they had. They are best dumped when they get down to below 80% of their original capacity but see if you can recover them with a form charge 2 or 3 times.

akschu

My Feedback: (5)

I didn't know I could use my futaba charger for a slow charge (because it's a 6v nimh pack), but I talked to Dave at radicalrc and he said the same thing. I'm going to leave them on the futaba wall charger all night then tomorrow I'll cycle them and see if they look better. If they don't I'll just pitch the pack and buy another, $20 isn't work risking a plane.

schu

richrd

Set the ICE peak detect at max 25 mV, capacity at 140% and it becomes a very good form charger PS current @ .1 Amps
Charge now should get up to 900 mAH for 700mAH baterries. Looking for max capacity cutoff on screen not delta peak.
Rich