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How do you determine what amps to charge LIPO's?

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Fiddy$Trainer View Drop Down
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  Quote Fiddy$Trainer Quote  Post ReplyReply Direct Link To This Post Topic: How do you determine what amps to charge LIPO's?
    Posted: 07/Mar/2009 at 10:44am
Ok I've got several batteries now and I don't know how to figure out at what amperage I need to use with various batteris. Is there a chart somewhere or some sort of calculation to figure this out.
 
I've got the Turnigy ACCUCEL-6 charger.
LIPO:
I know that for a 3S 2200mAmp I charge at 2.0A
3S 1800mAmp= 1.5a
3S 2200mAmp=2.0a
 
What about a S3 1500mAmp?
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  Quote SeaComms Quote  Post ReplyReply Direct Link To This Post Posted: 07/Mar/2009 at 10:58am
Damn new forum - just typed up a nice long explanation and it kicked e out when I hit post...

Anyways, Take 2.....

Most currently available LiPo's should be charged at 1C and no higher.

The Turnigy 6 charger allows you to charge in increments of 0.1 amps, so I always charge the batteries at 1C or the next step under if thats not possible.

So, a 2200ma (or 2.2 amp) battery would be charged at 2.2 amps, the 1800 at 1.8, the 1500 at 1.5.

Never charge a normal LiPo above 1C, but you can charge them at less than 1C. Charging at a lower current will extend the life of the battery a little, at the price of taking longer to charge.  I personally use the balance charging option when preparing the batts the day before going flying, when out on the field, I use the quick charge option as this will drop the charge time by up to 25% at the sacrifice of the last hundred or so milliamps of charge.


Edited by SeaComms - 07/Mar/2009 at 10:59am
Cheers, Dave.
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  Quote W3FJW Ron Quote  Post ReplyReply Direct Link To This Post Posted: 07/Mar/2009 at 11:00am
Charge all your batteries at the 1C rate. If it's a 2200mah battery, charge it at 2200mah or the next lower charge rate if 2200mah is not a value with your charger . Charging at more than that will shorten the battery life.
 For a 1500mah, charge at 1500mah or the next lowest charge rate available.
With that said, there are newer lipos that can be charged at more than 1C but if so, it will be written on the pack.
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  Quote Fiddy$Trainer Quote  Post ReplyReply Direct Link To This Post Posted: 07/Mar/2009 at 9:25pm

Thanks guys

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  Quote emsnaz Quote  Post ReplyReply Direct Link To This Post Posted: 13/Mar/2009 at 1:29am
How to take Care of your Lipos
 1) Always charge at 1C or less with a Lipo charger ( 2 cell 1250mah is charged at 7.4volts 1.2amps,  a 3 cell 2200mah is charged at 11.1volts 2.2amps) Heat kills lipos and a faster charge generates more heat. Even if the manufacturer allows a higher rate of charge, stay at the 1C rate. ( its your call, Lipos are expensive ) Note each cell is 3.7 volts

2) Balance Lipos often it takes a little longer but they last longer.  ( The minimum I balance mine is after every day at the flying field, and just prior to going the night before.  The night before I balance charge them at 200mah it only takes a few minutes each because they are already charged )

3) Never draw more than the recomended current from a lipo. If it is a 3 cell 20C do not go over 60 amps ( I wouldn't go over 40 amps with it) Higher current draw equals more Heat and we already know that is Bad..

4) Stay nearby your Lipos when charging. I haven't burn't one up yet, but I have heard my charger giving me warnings and stopped the charge to correct the error. ( commonly wrong charge voltage ) Some chargers are easily knocked into a wrong setting be careful.

5) Charge in a safe location. Some people use a Pyrex container, Lipo sack, and other great ideas. I charge mine outside on the patio on good old Concrete ( its reasonably fire proof )

6) Store your Lipos where they are safe (no bumps or falling objects) preferably in a Container that will keep your home safe.. ( Old Steel ammo cans lined with contact paper work great and are cheap ) Also the ammo can is easy to carry to the flying field. If you don't plan on using a Lipo for a while (2 months) store them in the discharged state recomended by the manufacturer. ( I have killed a few by not following this advice )

7) When purchasing Lipos get the ones with Balance Leads. That dollar or two extra is worth it. A balanced Lipo gives you more than twice the use.

8) If you have a lipo, that is so far out of balance that it doesn't charge plug a balancer into it ( I use an Astro Blinky ) and charge at your Lowest charge rate ( around 100mah ) More often than not you can get it back to working condition. This takes a LOOOOONG time..






Edited by emsnaz - 14/Mar/2009 at 4:38am
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  Quote fiftythree33 Quote  Post ReplyReply Direct Link To This Post Posted: 14/Mar/2009 at 2:57am
interesting that the temp of my Flightmax 3s 2200's stay exactly the same when charging at 1c and 2c
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  Quote emsnaz Quote  Post ReplyReply Direct Link To This Post Posted: 14/Mar/2009 at 3:52am
Just a thought but wattage is a measure of power, and if your power increases you Heat increases.   So 11.1volts  x 2.2 amps = 24.42 watts  so then 11.1 volts x 4.4 amps = 48.84 watts.   I guess that simple physics doesn't apply at your location, or maybe something isn't being accurate...Just a thought, anyway I was clear in my earlier post they are YOUR batteries do what you want. I don't like buying alot of them, been using quite a few that I have for 2 years and some longer.

Edited by emsnaz - 14/Mar/2009 at 4:42am
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  Quote aerofreak Quote  Post ReplyReply Direct Link To This Post Posted: 14/Mar/2009 at 4:52am
Originally posted by fiftythree33

interesting that the temp of my Flightmax 3s 2200's stay exactly the same when charging at 1c and 2c

Do you have a long term experience charging that lipo at 2C - is there a much shorter lifetime?
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  Quote motogman Quote  Post ReplyReply Direct Link To This Post Posted: 14/Mar/2009 at 8:42am
To answer the actual question asked figuring out the charge rate is a simple matter of moving the decimal point 3 places to the left example a 1000 mah battery would be charged at 1 amp (1.000) a 1300 mah at 1.3 amps (1.300) 1800 mah at 1.8 amps (1.800) 2200mah at 2.2 amps (2.200) or a 5000 mah at 5 amps (5.000)

Your discharge rate has nothing to do with how many cells are in a pack it's based on the C rating and the mah of the pack  to figure this out move the decimal of the C rate over 3 places to the left and take that times the mah of the pack example a  1000 mah 20 C pack would be (1000X.020=20amp discharge) a 2000mah 20 C would be (2000X.020=40amp) a 2000 mah 25 C would be (2000X.025=50amp) and a 2000 mah 30 C would be (2000X.030=60amps) it doesnt matter if its 1 cell or 12 cells in a pack the amps are always the same the only thing that changes is the voltage


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  Quote Wheels Quote  Post ReplyReply Direct Link To This Post Posted: 12/Nov/2009 at 7:51am
Originally posted by emsnaz

Just a thought but wattage is a measure of power, and if your power increases you Heat increases.   So 11.1volts  x 2.2 amps = 24.42 watts  so then 11.1 volts x 4.4 amps = 48.84 watts.   I guess that simple physics doesn't apply at your location, or maybe something isn't being accurate...Just a thought, anyway I was clear in my earlier post they are YOUR batteries do what you want. I don't like buying alot of them, been using quite a few that I have for 2 years and some longer.
 
You never know..... maybe instead of turning into heat some of the watts you're so worried about are going.... into some kind of storage.... almost like......... a............... battery?
 
Just because someone doesn't agree with you, or finds a different result than you do doesn't mean they are being deceptive.
 
Maybe you could tell us about the comparisons you've run that make you so sure?
 
I charge my zippys at 2c as well and they don't get warm.
 
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