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Old Oct 27, 2010, 11:16 AM
Expat
Japan
Joined Apr 2010
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LIPO care for lazy people...

Hi all
I gather the majority of people who use lipos don't know anything about their care, and learning too much will ruin the fun of the hobby for them. So the trash can gets filled with lipos. With prices these days, no body really cares.

So I thought it might help to make a easy hit list which will help a lot.

Can someone answer these questions?

1) Proper voltage at full charge (and acceptable variation).
2) Proper voltage at full discharge (and acceptable variation).
3) Proper voltage when not in use (acceptable variation, and how long is "not in use").

Thanks!
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Old Oct 27, 2010, 11:24 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
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4.2 per cell ,4.1 to 4.20
3.8 , 3.7 plus

3.7 to 4.0 , not being flown,ran etc. and not about to in the next few hours.
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Old Oct 27, 2010, 11:34 AM
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Japan
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Thanks
Hours?! wow, I thought it was weeks.
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Old Oct 27, 2010, 12:37 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
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so do many others thus

http://www.rcgroups.com/forums/showthread.php?t=1329171
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Old Oct 27, 2010, 01:15 PM
Scratch building addict
rotagen's Avatar
United States, CA, Felton
Joined Jan 2005
660 Posts
Lazy people? Someone call my name?

Well they're still expensive in my book, cuz I just threw away 3 very weak 10 dollar batteries that gave me only around 4 flights. Course that was over the course of 2 years.

I'm gonna start freezing the bastards.
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Old Nov 26, 2010, 08:35 AM
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Brighton, CO
Joined Jun 2009
899 Posts
Does anyone know anything about MaxAmps batteries ? Are they any good ?? I was thinking about getting a lipo for the transmitter
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Old Nov 26, 2010, 08:44 AM
Southern Pride
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Haralson County GA. USA
Joined Oct 2004
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IMO the best battery for a Transmitter is made from Sanyo Eneloop AA cells.
Why have to remove the battery for charging,have tio worry about it being ruined if you forget and leave transmitter on, etc..


Sanyo Eneloops have extremely low selfdischarge similiar to LiPoly, you can ues the stock OEM charger, they will power a DX7 Transmitter for around 10 hrs. per charge . Charge them today let them set for two months or longer and they are still good to go.
Charles
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Old Feb 17, 2011, 04:02 PM
Expat
Japan
Joined Apr 2010
3,023 Posts
Hi all, Lazy Lipo guy checking in again.
Couple of questions if you have the time.
Is (near) freezing temps bad for lipos? All winter I have used, stored, and charged them at or near freezing. I noticed they seem to take a LONG time to charge as compared to summer.

Also, what causes them to discharge unevenly during a flight?

Thanks!
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Old Feb 17, 2011, 06:53 PM
Frankenstein recycled packs
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USA, AZ, Gilbert
Joined Jan 2006
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Charge slower when under 50F.
Charge to 4.1 volts per cell when under 50F.
Uneven voltages across the cells is normal after a flight.
Even voltages across the cells when charged is normal.

My guess is either your supply voltage is lower when cold, the packs are taking longer to balance or your charger is taking care of the cold charge condtion for you.
What charger are you using?

Rick
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Old Feb 18, 2011, 10:16 AM
Expat
Japan
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I'm using 2 simple slow chargers:
http://www.rccarmax.com/esky-part-00...851-p-959.html
http://www.hobbyking.com/hobbyking/s...idProduct=7637
This to test:
http://www.hobbyking.com/hobbyking/s...idProduct=6589
The former is slower, but balances almost perfect everytime. The latter is faster, but always a bit off.

I was using this:
http://www.hobbyking.com/hobbyking/s...idProduct=5548
As in once. The display stopped working the second time I used it.
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Old Feb 18, 2011, 06:56 PM
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LeszekJ's Avatar
Poland
Joined Nov 2010
462 Posts
Quote:
Originally Posted by rampman View Post
Uneven voltages across the cells is normal after a flight.
I don't agree.
It happens only when battery is overdischarged or it's worn.
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Old Feb 18, 2011, 07:13 PM
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So. Cal.
Joined Oct 2004
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Quote:
Originally Posted by LeszekJ View Post
I don't agree.
It happens only when battery is overdischarged or it's worn.
Not necessarily true. Many manufacturers do not expend great effort to ensure that packs are comprised of perfectly matched cells with respect to capacity and internal resistance. Cells of different capacity will have different voltage when discharged. It's for this reason that it's most efficient to balance only when approaching full charge.

Mark
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Old Feb 19, 2011, 05:53 AM
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Poland
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Quote:
Originally Posted by mrforsyth View Post
Cells of different capacity will have different voltage when discharged.
True but when a battery is healthy the imbalance stays within a very reasonable limit. When I apply the 80/20 rule it's within 10mV and a charger shows the same numbers after a few minutes of resting. If cell voltages differ significantly under load or after a flight it's a warning signal.
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Old Sep 02, 2011, 06:36 PM
Expat
Japan
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Lazy guy here
How about fridge storage? Any merit to keeping them there all the time? And does this mean that cold weather flying is better than hot weather?
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Old Sep 02, 2011, 07:13 PM
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EricJ320's Avatar
Knoxville, TN
Joined Dec 2005
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Quote:
Originally Posted by TheNiceGuy View Post
Lazy guy here
How about fridge storage? Any merit to keeping them there all the time? And does this mean that cold weather flying is better than hot weather?
Think of them like a nice tall glass of beer, just because it's best when it's been stored cold, doesn't mean it's best enjoyed out side in the cold!

Lipos will discharge best when warm, although too hot will damage them. Cold temps on the other hand cause their voltages to drop more under load and prematurely. So warm days are better for power from a lipo. The only caveat would be, if the ambient temperature is too hot for them to get proper cooling from airflow, you could potentially over heat them, when otherwise they wouldn't on a cooler day. In the winter I take mine to the field in a portable electric cooler that does cooling and warming, to keep them nice and warm for good strong discharges in cold temps.
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