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View Poll Results: Do you keep your LiPos at Storage Charge?
Yes 183 61.00%
Sometimes 50 16.67%
No 67 22.33%
Voters: 300. You may not vote on this poll

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Old Jul 26, 2011, 11:11 AM
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Here is a good question Charles what's the downside of leaving your batts at 1/4 charge,that's how mine end up i do put them in storage but just for curiosity what's the downside for a week.
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Old Jul 26, 2011, 11:14 AM
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I can't give you any rational reason, just the fear it "helps."
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Old Jul 26, 2011, 11:25 AM
still learning
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west Georgia, USA
Joined Nov 2007
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I posted a similar question at wattflyer a few weeks ago.

The strategy I liked most as a weekend flyer, during the flying season, is to fully charge and store in refrigerator - almost as good as storage voltage in a refrig.

I just use cheap batteries and fully charge.
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Old Jul 26, 2011, 12:07 PM
Southern Pride
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Haralson County GA. USA
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Quote:
Originally Posted by The Tug View Post
Here is a good question Charles what's the downside of leaving your batts at 1/4 charge,that's how mine end up i do put them in storage but just for curiosity what's the downside for a week.
Depending on who's chart one uses that could be a range of X to X but going by this one it would be approx. 3.77 volts per cell

http://www.rcgroups.com/forums/attac...mentid=3842605

which is fine. Storage voltage is not rocket science. The good range is 3.7 to 4.0 per cell . To many get bent out of shapre when their charger does not storage chare / discharge to exactly 3.85 per cell.

Charles
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Old Jul 26, 2011, 02:46 PM
Too much is just not enough...
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Joined Jan 2009
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This is my third season of electric flight. Here's how its worked out for me:

First season, all batteries left fully charged as soon as day was done.
By the beginning of the second season, many of the cells didn't have the output they did the first season, puffed a little during use, and smelled of slight venting when stored.

Second year, I listened to the input of others and stored at storage charge when done for the day.

Beginning of the third season, I'm still using the batteries from season two, they don't puff when used, and no odor of slight venting.

My none scientific results of using storage charge when not in use. YMMV.
These were all on HK batteries.

The only drawback I have from using storage charge is what to do with the brand new batteries I bought in season two, since none of mine are failing (as I just jinxed myself)
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Old Jul 26, 2011, 05:38 PM
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Houston, TX
Joined Jan 2008
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I charge mine to 4V after flying. That way I don't have long to go to get them ready. While I would love to charge and fly, I fly at the crack of dawn so no time to get up charge and head to field. I charge what I will use the evening before flight day.

Considering how cheap these lipos are getting, I'm not certain I care too much anymore. I've got 3S 2200 20C that are 3 yrs old and still won't puff. I would love to replace them with newer 40C and 5C charge rates...but those old ones just won't die. I do notice this season that they are getting warm after a flight but that's about it. In fact, I'm mistreating my 20C lipos now so I have an excuse to replace them with better but they keep on going.


Charles,
I've heard that these newer 40C or better lipos shouldn't be fully charged until ready to use else they'll be damaged much more quickly than the 20C. Seems like leaving them fully charged overnight is a bad thing. Is this true?
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Old Jul 26, 2011, 08:00 PM
Southern Pride
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Haralson County GA. USA
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Quote:
Charles,
I've heard that these newer 40C or better lipos shouldn't be fully charged until ready to use else they'll be damaged much more quickly than the 20C. Seems like leaving them fully charged overnight is a bad thing. Is this true?
The longer a LiPoly is at full charge the faster the IR increases. The higher the IR the lower the true C rate.

If you need highe C rate (lower IRs) and pay more for them then why abuse them? If you get 6 minute flights then that is an avaeage 10C discharge rate which most likely means that 20 or 25C is all you need. Question now becomes do you purchased 20-25C LiPolys and take care of them or replace them often or do you purchase higher C ones such as 40 to 65C and abuse them and hope they still deliver the reall 10C avg. 20 to 25C burst you need.

I have read that some of the 65C ones should be only charged right before use. That would fit my logic if one needs their max. capabilities.

Charles
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Old Jul 26, 2011, 08:08 PM
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Quote:
Originally Posted by everydayflyer View Post
The longer a LiPoly is at full charge the faster the IR increases. The higher the IR the lower the true C rate.

If you need highe C rate (lower IRs) and pay more for them then why abuse them? If you get 6 minute flights then that is an avaeage 10C discharge rate which most likely means that 20 or 25C is all you need. Question now becomes do you purchased 20-25C LiPolys and take care of them or replace them often or do you purchase higher C ones such as 40 to 65C and abuse them and hope they still deliver the reall 10C avg. 20 to 25C burst you need.

I have read that some of the 65C ones should be only charged right before use. That would fit my logic if one needs their max. capabilities.

Charles
Do you know exactly why the resistance increases?
VP
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Old Jul 26, 2011, 10:09 PM
Southern Pride
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Trick question or do you really expect me to compose a wWhite paper on it? There is tons of such data on the world wide web for those who care to do the research. In simple terms all rechargeable cells start to age as soon as they are assembled. Electricty is produced due to chemical reactions , the higher the state of charge and the warmer the temperature the faster the aging occures.

A thread start here earlier today.

http://www.rcgroups.com/forums/showthread.php?t=1477911

Note the only commonly used rechargable cell type that I am aware of that fairs best at full charge is Pb.

Charles
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Old Jul 27, 2011, 03:54 AM
BrainFart RC-Pilot
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Echt, Netherlands
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there is a big amount of energy inside a charged pack
IMO logic that the pack suffers from it, if you keep it charged

it is very different with a car gasoline tank
there the energy is stored in another substance

so to me it is logic that it suffers from a full charge...and this for a longer time
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Old Jul 27, 2011, 11:22 AM
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Charles,
I hand launch my EDFs so need the max ooomph I can get at toss. While you're right that 20C is all I need for the set ups I have based on max amps at WOT, there's a big difference on how easy it is for the plane to get airborne. 30-40C gives me much better success toss rates than 20C.

Don't want to abuse the lipos but flying at dawn means I have to wake up at 4am to start charging lipos...so I rather not abuse my sleep time Then again, 5C charge rates would allow me to use a deep cycle and charge at the field as I fly...
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Old Jul 27, 2011, 12:54 PM
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United States, IL
Joined Jul 2009
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I'll sometimes parallel balance charge them up the day or night before I want to use them, but generally I just balance charge them up to 4.1V per cell right before I use them, discharge them down to around 3.75V per cell stabilized during use, then balance charge them up again to use again, or balance charge them to 3.85V per cell stabilized for storage.
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Old Jul 27, 2011, 03:40 PM
I hate waiting for parts
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Yes, always. No exceptions.
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Old Aug 10, 2011, 02:09 PM
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Raleigh, NC
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I do now... Not sure what's the deal with Nanotech batteries but my recent batch didn't last long at all before they started puffing. I'm thinking maybe it was because I always left them fully charged. I fly regularly so no battery would stay fully charged more than a week or two but I'm wondering if that contributed to the early death of my Nano-techs...
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Old Aug 10, 2011, 03:00 PM
BrainFart RC-Pilot
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Quote:
Originally Posted by cjbucher View Post
I do now... Not sure what's the deal with Nanotech batteries but my recent batch didn't last long at all before they started puffing. I'm thinking maybe it was because I always left them fully charged. I fly regularly so no battery would stay fully charged more than a week or two but I'm wondering if that contributed to the early death of my Nano-techs...
which size did they have? I mean...was it 2200 or 4000mah or 5000mah?
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