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Old Jan 13, 2012, 12:49 PM
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nano battery


I have a strange acting 3s. It shows 4.19 4.20 4.17. I'm balancing it now. The battery has not preformed well. My Acromaster airplane won't hover at all with this battery. Any ideas on why this battery has no output?
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Old Jan 13, 2012, 01:59 PM
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If other packs of similar size will hover the plane, the simple answer is it's had it's day and needs to be retired.
Some ways to kill a battery:
Store at full voltage
Run till the LVC cuts in or lower.
Discharge at very high current rates.
or, simply, it has been run correctly for a lot of cycles and it's now just an old tired pack.
Old Jan 14, 2012, 09:46 AM
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Thanks Hoppy. I've read alot here but nothing seemed to match my battery problem. I charged, balanced, and discharged/ recharged and nothing really seem to help. It shows 4.20v on all three cells but never has output power. It will only produce half power while flying so I afraid to use it much. I'm thinking it may short out something.
Old Jan 14, 2012, 12:02 PM
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I've got a whole bunch of packs just like that.....charge up nicely but just can't provide good current levels anymore. I don't think there is a high risk with using them, they just aren't much fun.
How old are they?


IMO, Time to discharge and toss.
Old Jan 14, 2012, 05:48 PM
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That pack was just bought in July and only used maybe twenty times! It's a nano-tech so I thought it would be a good battery. Oh well, that's the way it goes. I may use it in a park flyer sometime. Hey, when we talk about storage... how long do you normally leave a fully charged battery stored? It's getting to be winter time in the Louisville, Ky area and it may be a month or two before I can fly again. I can pull some out and fly if need be right? I mean if I hae them charged for storage this week and next week it's sunny and 50 well I'm fully charging and flyin'. Do you thinkthat hurts them any?

Amos
Old Jan 14, 2012, 05:58 PM
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Personally I don't leave them fully charged for 24 hrs. I won't even leave them over night unless for some reason they are charged and I am certain I will fly the next day.
Old Jan 14, 2012, 06:09 PM
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A fully charged pack degrades much faster than a 1/2 charged pack. A couple of days is my max.
I have a HK Quattro 4 channel chzrger and can have 4 packs ready to fly in under 30 min.
Old Jan 15, 2012, 09:46 AM
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Awww man! That might explain why my packs don't last but one summer! I charge them when I'm done flying for the day so they will be ready for the week end. Lesson learned. I thought it was ok to have them fully charged for a month but from what you guys say... I'm toasting money! I thought it would be harder on them to storage charge then turn around the next day and full charge them.
Thanks Amos
Old Jan 15, 2012, 10:05 AM
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In case it hasn't been said yet, you don't want to leave them discharged either. Store some where near 50% charged. And don't discharge them too low. Generally leave 20% in them at the end of a flight. I think that is somewhere near 3.7 volts/cell.
Old Jan 15, 2012, 03:43 PM
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Storing charge


I have a "store" program on my charger. I can't remember the exact voltage reduction but that will surely be a safe storage amount for them. I did not realize that I should not be leaving them fully charged. After I was done flying for the day I always recharged so I was ready for the next time. So if I understand this right... even if I'm not using them for a couple of days I should put them on store charge?
Old Jan 15, 2012, 04:28 PM
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At least under 4v/cell for short term storage.
Old Jan 15, 2012, 06:32 PM
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Quote:
Originally Posted by AMOS5 View Post
I have a "store" program on my charger. I can't remember the exact voltage reduction but that will surely be a safe storage amount for them. I did not realize that I should not be leaving them fully charged. After I was done flying for the day I always recharged so I was ready for the next time. So if I understand this right... even if I'm not using them for a couple of days I should put them on store charge?
Most chargers will charge or discharge to 3.8 or 3.85 volts/cell in storage mode. I tend to charge mine to 3.9 and it falls back a bit. At 3.9 it's also a little quicker to charge.
Old Jan 16, 2012, 12:31 AM
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( WallWart ) Idea
I am experimenting with charging ideas thinking of adding a load resistor and zener diode last will be a Led multi diode that turns green when ready off my wall wart
This is a final one way lock style it will not allow over charging ...
Old Jan 16, 2012, 09:52 AM
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Quote:
Originally Posted by Airlady View Post
( WallWart ) Idea
I am experimenting with charging ideas thinking of adding a load resistor and zener diode last will be a Led multi diode that turns green when ready off my wall wart
This is a final one way lock style it will not allow over charging ...
What your final aim is, is not clear. Are you talking about bringing an overdischarged cell up to 3 +/-V or about charging to 4.2V?

If you are proposing a 4.2V charger design, be very careful and think about all the the what ifs. If it were that simple, manufacturers would be offering items with that circuit design. They however all use CC (constant current)/CV (constant voltage) circuitry.
Chargers are just too cheap to risk a fire using non-lipo chargers. Several members have used precision DC power supplies where the max voltage could be set very accurately but even they have had problems with voltage variations and the practice has been dumped.
Old Jan 17, 2012, 01:00 PM
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Quote:
Originally Posted by Turner2 View Post
Most chargers will charge or discharge to 3.8 or 3.85 volts/cell in storage mode. I tend to charge mine to 3.9 and it falls back a bit. At 3.9 it's also a little quicker to charge.
My charger puts it at 3.80/3.81. This is gonna stink trying to keep up with remembering to go charge before I fly. I'm just used to keeping them charged and ready for every weekend! Oh well if it will save some money then it'll work.


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