[NSRCA-discussion] Power batteries

[Jay Marshall]

I seem to have seen a mfg's instruction to store at 80% charge. I think this
is what my TP charger does (when asked). Indoor temps should be fine.

Jay Marshall

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dave
Sent: Wednesday, February 11, 2009 7:51 PM
To: 'General pattern discussion'
Subject: Re: [NSRCA-discussion] Power batteries

Ideally, the lipos would be at 3.7-3.8 volts per cell when not in use, and
only charged just prior to use.  Higher voltage equals higher chemical
activity in the cell which leads to more deterioration.

You are most likely to damage cells when they are older, have sat at high
voltage for an extended period of time, and then are deeply discharged at a
high rate.

I'm intentionally not giving specific durations or rates - because it is all
relative, and there are not any absolutes so for as what will definitely be
safe, or definitely be a problem.

In practice, I try to charge the night/morning before I fly, and don't worry
about leaving a battery charged for 1 week.  If I don't fly a battery for
more than about 3-4 weeks, I go easy on it for the first 1-2 flights (use
less throttle, don't fly as long) - this seems to recondition the packs to
an extent, even though they may not show any loss of performance (after
sitting for an extended period of time).

Regards,

Dave


-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ron Van Putte
Sent: Wednesday, February 11, 2009 7:22 PM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Power batteries

I got to thinking that I might not be the only one who is not sure  
about the proper way to store Lipos.  How about expanding on the  
thought Verne?

We don't actually have to store Lipos down here in Florida, unless  
you think a week or two without flying requires that you store them.
I'm going flying tomorrow:  Partly cloudy, 70 degrees, 6 MPH wind out  
of the northeast.

Ron

On Feb 10, 2009, at 2:57 PM, Verne Koester wrote:

> My limited experience (3 seasons) in electric is that most packs  
> will run strong the first year and then drop to unacceptable levels  
> the second, at least, that was the case with the batteries I flew  
> my first two years. In fairness, and I won't mention the  
> manufacturer, I didn't store them properly out of ignorance, so  
> that might be a reason, or the reason the power dropped off the  
> second year.
>
> Verne Koester
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