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Old Mar 17, 2012, 09:52 AM
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LiPo Charge/Storage question

So I've always read not to store LiPo's fully charged for long term. In practice, I usually fly, then charge when I return, and usually fly again within a couple of weeks.

This warning, in bold print on the XPS site, concerns me a bit, the part about 'a few hours'. Does this apply to just the batteries they sell, or is this how folks generally handle LiPo's, or is this CYA on their part?

WARNING!! LIPO BATTERIES CAN NOT BE STORED IN A CHARGED STATE FOR MORE THAN A FEW HOURS OR THEY WILL BEGIN TO SWELL. STORE ALL LIPOS AT NO MORE THAN 3.75v PER CELL.

-= Dave
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Old Mar 17, 2012, 10:17 AM
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Warning is correct

Store them at 3.85v / cell or thereaboutrs when not in use

They start to degrade if left fully charged and the effect is cumulative

Cheers
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Old Mar 17, 2012, 10:25 AM
A man with too many toys
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That’s correct in that you don’t want to have a full charge until you are ready to fly. The warning does have an error (or maybe just a typo). The voltage needs to be between 3.80 and 3.85 NOT 3.75v).



This applies to ALL LiPo batteries.




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Old Mar 17, 2012, 11:46 AM
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Most of today's smart chargers that incorporate a storage function are set at 3.8 volts/cell.

mw
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Old Mar 17, 2012, 01:51 PM
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The 3.75 is not a typo as today's 65c Lipolys are best stored lower than the typical 20-45C ones but 3.85 is still OK for even 65c ones IMO.

Problem is that there are many levels of LiPoly users and many more levels of LiPols so 3.85 is simplier to get across to the masses perhaps. Hopefully those purchasing 65C LiPolys know a bit about LiPoly management but then perhaps not.


LiPoly Storage voltage by Charlie Wang (Mr. Thunder Power) from years ago

http://www.rcgroups.com/forums/showp...&postcount=148


Quote:
3)we recomment 3.8V (50% charge for 2 to 3 years storage)
3.5V allows 9 to 18 month storage (18 months at optimium condition)
3.3V allows 6 to 12 month storage (12 months at optimium condition)
3.0V bad idea

Regards,
Charlie
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Old Mar 17, 2012, 03:54 PM
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Quote:
Originally Posted by everydayflyer View Post
The 3.75 is not a typo as today's 65c Lipolys are best stored lower than the typical 20-45C ones but 3.85 is still OK for even 65c ones IMO.

Problem is that there are many levels of LiPoly users and many more levels of LiPols so 3.85 is simplier to get across to the masses perhaps. Hopefully those purchasing 65C LiPolys not a bit about LiPoly management but then perhaps not.


LiPoly Storage voltage by Charlie Wang (Mr. Thunder Power) from years ago

http://www.rcgroups.com/forums/showp...&postcount=148
WOW 3.3V for 12 months! I always thought that anything below 3.6v for any period of time will degrade batteries. Looks like I really donít need to put everything at storage charge after a weekend of flying. Sounds like itís ok to just let them set until I am ready to go flying again.

Has anyone actually tested this or is it just Charlie Wangís theory?


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Old Mar 17, 2012, 04:16 PM
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First off remember that was from years ago and Thunder Power Pro Lites were 13C at that time.

Charle never posted anything without full data to back it up. As to if the 3.3 is still as valid today with 45-65C Lipolys I have read no data on this.

Main issues I have with LiPolys as low as 3.3 these days is that number one they are completely discharged which I do not believe is good for them at all. I do not believe in even 1C charging with cells below 3.7 so for me to store at 3.3 or 3.5 and then have to charge at 1/2C or less until they reach 3.7 and then do my normal 3 to 5c charge would be to much time and bother.

One feacture I always liked about the Thunder Power 1010c charger was that if the cells were low it wouklld automaticly do a reduced charge until they reached 3.7 then increase(ramp up) to the set rate. Most chargers these day hit the cells with the set rate in very short order.

If I over fly a LiPoy and it shows cells below 3.7 at the field I reduce the charge rate and wait till they reach 3.7 then bump it back up. If I really do not need that one again for that flying session I just do a low rate to Storage Charge at 1/4C or so.

Charles
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Old Mar 17, 2012, 10:24 PM
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All great info. Thanks for everyone's contributions!

-= Dave
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