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Old Mar 04, 2006, 01:18 PM
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How Long Do You Wait Before Charging LiPo's?

After a flight, I wait until the pack gets below 100F and then recharge. Some say wait longer. What is best for cell life?
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Old Mar 04, 2006, 01:42 PM
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Haralson County GA. USA
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Ambient temp or around 75F. You can use a battery cooling fan tube to speed it up. Remember inner cells take longer to cool.

Quote:
What is best for cell life?
Thunder Power's Safety sheet says 32 to 113F however I have read in several places not to charge them when cold and especially do not charge while cold and bring into a heated area.
Sometime I think we are all learning together and that information is obsolete by the time it becomes common knowledge.


Charles
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Old Mar 04, 2006, 03:11 PM
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Makes sense to me, thanks!
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Old Mar 04, 2006, 06:34 PM
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As soon as the wheels touch down

Dan
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Old Mar 04, 2006, 07:27 PM
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I generally wait until the battery feels cool in my hand which is usually around 10 min or so.
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Old Mar 04, 2006, 07:41 PM
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Quote:
Originally Posted by supi7
As soon as the wheels touch down

Dan
Yes but you have a very good wholesale source.
My guess is that most vendors could have an endless supply just from customer returns that really have no major problems or by salvaged good cells from used returned packs.
The summer of '04 I charged and flwew non stop with some E Tec 1200 6C classic packs but they were my learning packs. I try to take better care of mine now and they seem to do much better.

Charles
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Old Mar 04, 2006, 08:45 PM
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Quote:
Originally Posted by everydayflyer
Ambient temp or around 75F...Charles
Dang, my flying season is almost over for a good 9 months. I won't see 75F here in AZ again until November.
I am going to have to set up a place inside my home to charge these things in another month.
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Old Mar 04, 2006, 11:57 PM
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Quote:
Originally Posted by everydayflyer
Yes but you have a very good wholesale source.
My guess is that most vendors could have an endless supply just from customer returns that really have no major problems or by salvaged good cells from used returned packs.
The summer of '04 I charged and flwew non stop with some E Tec 1200 6C classic packs but they were my learning packs. I try to take better care of mine now and they seem to do much better.

Charles
Hi,

yes we do., but... The most important thing is to choose a correct battery . If your battery is coming down hot, guess what, you are drawing too much and the battery you are using is not sufficient.

I have been running anything from 5C to 20C packs and because of tools like whattmeters/ amp meters, I am able to choose the battery that is just right for my power plants.

Best Wishes,
Dan
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Old Mar 05, 2006, 12:03 AM
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I usually wait about 10 minutes, but it depends on the setup. My 10s2p heli packs come down warm, but only warm enough to be able to feel they are above ambient's (which is pretty high for winter .. between 60-80..).

Rhett
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Old Mar 05, 2006, 12:22 AM
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I usually charge at home, when the packs are nice and cold.. and a 1/2 C rate and I use a hyperion balancer...yes I have lots of packs..

yes I wear suspenders and a belt

Herm
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Old Mar 05, 2006, 07:41 AM
Southern Pride
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Haralson County GA. USA
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Quote:
Originally Posted by supi7
Hi,

yes we do., but... The most important thing is to choose a correct battery . If your battery is coming down hot, guess what, you are drawing too much and the battery you are using is not sufficient.
I have been running anything from 5C to 20C packs and because of tools like whattmeters/ amp meters, I am able to choose the battery that is just right for my power plants.

Best Wishes,
Dan
I agree Dan but I have not been able to find a LiPoly ,or any other rechargeable battery that weighs less than 3 oz. delivers 20A C and 30A burst of 10 seconds and provides 6Ah capacity.

If the vendors say they are 20C cont then we should be able to run them at 30C without rthem getting to hot and being damaged.
IF you purchase8 a rope rated at 500 lbs. tensile strength it has been tested and pasted at 1,000 lbs..
If you purchase and consume super size orders of fries from Super Mac Chicken you will become Super Sized.

If everyone looked at LiPolys as a means to fly longer instead of lighter many of the probvlems would vanish.

Example I just checked one of my many years old Sanyo SCR 1,000 mah 8 cell NiCad packs. IT weighs 12.1 ounce. It delivered approx 1 volt per cell at 30 amps with burst to ????? . So it flew a .05 (1/2A) pylon racer for 1.5 min. or provided 3 climbs to altitude in a 2 meter glider or provided 3 minute sports flying in an Electra Streak or a SkyVolt, well the SkyVolt uses a 10 or 12 cell.

So now days a 3S 10.5 volts under load of approx. 3500 mAh would weight approx the same and provide better than three times as long of lights and
would only need to be 10C with 15C burst. If however you used a 2500 mAh 3S then weight would be lighter, flight would be much better and the original NiCad flight times would not strain the LiPolys.

Problem is everyone want the lightest weight, highest cont C most capacity in a given size and at least 300 cycles.


Charles


Charles
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Old Mar 06, 2006, 11:09 AM
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Hello Charles,

Are you aware of any studies on charging hot cells?

It would seem to me that if you are running at 5-8C, you should be able to charge at 1C as long as the cell temperature remains below the damage temperature (whatever that is - this week ) of the chemistry. The constant current portion of the charge would allow for further cooling as well.

I let my packs cool down before re-charging, but am not sure there is a technical reason for doing that.

Tom
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Old Mar 06, 2006, 11:21 AM
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Quote:
Originally Posted by SilverFoxCPF
Hello Charles,

Are you aware of any studies on charging hot cells?

It would seem to me that if you are running at 5-8C, you should be able to charge at 1C as long as the cell temperature remains below the damage temperature (whatever that is - this week ) of the chemistry. The constant current portion of the charge would allow for further cooling as well.

I let my packs cool down before re-charging, but am not sure there is a technical reason for doing that.

Tom
Hoppy is the one with all the tech. links.
During the 450 plus Kokam life cycle test 3C charge 9.5C disch I think but could be off a bit it was stated they used forced cooling after the discharge and before charging, why? As you say they would have cooled durning the 20 min. charging time would they not?

Brad S. for whatever reason lets cells set for 15 min. after a 1C discharge and as the discharge rate is increased the resting period is increased. I believe that at 10C it is approx. 60 minutes. Not sure why but I imagine he has his reasons.
I have seen may references to using a battery cooling tube with LIPolys prior to charging..

Charlie Wnag while charging at 3C and discharging at 4C (600 plus cycles )on the TP PL 910 allowed a 5 min. ( I believe) resting period , why , again I do not know.


I guess I should take one pack which I can fly almost daily and abuse(?) the you know what out of it. Use one to small say 900 mAh so that it will be flown at approxly 5C avg. with burst to 16C (if it can do it) ,throw it right on the charger at 2-3C and see how long it takes to kill it. Some will then say that one sample proves nothing. Next month better cells will be availabel, etc., etc. I only offer advise based on my experience which works for me.If cost / life of LiPolys is unimport then everyone should fly them like they stold them. Let them live fast,die young and then buy better replacements , take better care of the next ones or just keep the vendors rolling in green backs.


Charles
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Old Mar 06, 2006, 01:34 PM
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I use many packs, so they r usually rotated one flight only, seldom do any fast charging at the field
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Old Mar 06, 2006, 04:24 PM
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Quote:
Originally Posted by everydayflyer
it was stated they used forced cooling after the discharge and before charging, why? As you say they would have cooled durning the 20 min. charging time would they not?
Charles
Charles, there was report of pack failure when charged fast when it was hot, somewhere in the past.
Even in graphs of newest 100C cells from a123systems, everywhere there is a time left to cells cool down.
I know really nothing more about this, but I would better be safe and let the pack to cool down if it is warm, before starting next charge.

To anwer topic question : 2 packs for a plane are sufficient for my needs.
I am charging allmost immediately after a flight (after pack is cold ), if there is enough time to probably fly again with that pack.
Otherwise I am charging in the morning before going to field.
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