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Old Aug 01, 2007, 01:17 PM
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Calgary, Canada
Joined Jul 2007
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Question
How long do LIPOs hold their charge on the shelf?

I have a stock CX2 LIPO battery pack and I am wondering how long it will hold a charge. I charged up my battery pack yesterday afternoon but did not get a chance to fly as my son woke up early from his nap. So I decided to plug it in to top it up this morning and it is taking quite a while to top up. Is it the charger or does the battery pack lose that much of a charge sitting on the shelf overnight? If it is the battery is it the stock battery pack or the technology as a whole. NiMH were bad but it was only 2-5% per week.

Thanks,
David
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Old Aug 01, 2007, 02:42 PM
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Joined May 2007
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I checked some of my batteries. (I have a bunch).

1 Brand new, never used, never charged, got it over a month ago 7.40v
1 old battery charged last evening 8.30v
1 old battery charged a week ago, not used 8.28v

So based on my experience, they don't lose much of a charge over time.
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Old Aug 01, 2007, 03:05 PM
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Lipos have a very low self discharge rate when compared to nimh and nicads. There are established storage procedures that are believed to prolong the life of these types of batteries. All new lipos are shipped at a storage voltage of approx. 3.8-4.0V per cell and they should be stored that way if they won't be used for more than 2 weeks. Storing lipos fully charged is believed to shorten their life span.

Doubletap
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Old Aug 02, 2007, 11:57 PM
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According to what I know, Lipo batteries (newly bought) take a few recharges before they can be charged up to their fullest capacity. At their fullest charge, their durations last from 10 to 12 mins. I own a Blade CX2 myself.

How long did it fly for?

Does anybody know if the Blade CP/CP Pro batteries last longer? Just a curious question since their voltages are at around 11 volts instead of 7.4 volts.
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Old Aug 03, 2007, 02:50 AM
CSI
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Just adding a couple of additonal thoughts about your lipos.
I can definitely confirm that they hold their charges for quite some time...months even. Charging them to full, and then leaving them sit like that for several weeks or more is definitely very bad for them. I had about 8 common sense lipos of all sizes...800mAh up to 2000mAh and let them sit at full charge for as long as a month or so waiting on the winds to die down. I KILLED about 8 lipos too!!! All of them quickly lost their ability to push amps under load. They would charge up fine, but when in use would quickly drop down to minimum amp outputs, then just stay there for the duration of the runs. I talked to the business owner and he confirmed that leaving them sit like that really hurt their performance. Take this as you will.......
David, your situation doesn't sound right. You shouldn't need to, or even be able to top off your lipos the very next day. Either you have a bad charger or something wrong with the pack. I suppose it could just be the charger itself, not able to do anything when it reads a full pack, and maybe it just sits there confused? Lot's of possibilities, but no, your packs, if charged, should be holding.
I have also encountered what Xen said about the lipos taking several discharges before they start to produce at peak efficiency. Definitely don't cycle them, just run them normally and they seem to get better after a few uses.
I have learned my lesson and changed my lipo charge, storage procedures. It was a very expensive lesson....
Ken
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Old Aug 03, 2007, 08:36 PM
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Since we are on the topic of lipos. What do we do with the packs that are no longer good. How should you dispose of them?
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Old Aug 03, 2007, 11:43 PM
MK
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Take it to a place that takes dead cell phone batteries like Radio Shack, Circuit City, etc.
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