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Charging Lipos

Old 01-09-2007, 04:13 AM
  #1  
DamianWalker
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Default Charging Lipos

Hi All

Am I right in assuming that you charge a 1000Mah Lipo at 1amp, a 2200Mah Lipo at 2.2amps, a 4200Mah Lipo at 4.2amps, etc, etc? My Lipo charger reduces amps the closer the battery gets to full charge, but I want to make sure I start the charge at the right amps.

Cheers
Damian
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Old 01-09-2007, 05:57 AM
  #2  
Rugar
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Originally Posted by DamianWalker View Post
Hi All

Am I right in assuming that you charge a 1000Mah Lipo at 1amp, a 2200Mah Lipo at 2.2amps, a 4200Mah Lipo at 4.2amps, etc, etc? My Lipo charger reduces amps the closer the battery gets to full charge, but I want to make sure I start the charge at the right amps.

Cheers
Damian
Yes, you have it correct.
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Old 01-09-2007, 06:00 AM
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peterkron
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thats correct but if you are not in a rush to get them charged it is better to charge them at less than 1 c because they will then last longer
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Old 01-14-2007, 10:52 AM
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David_Aus
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Default More questions on charging Li Po's

Hi all.

I'd like to add to Damian's query as I have noticed some variances with charging Li Po's.

First let me open by stating that I use the Swallow 2 (AC/DC) charger to charge a 7.4V 2,600mAh Li Po pack.

I was told to charge the pack at 1C, which I understand to require me to limit the current on my Swallow charger to 2.6 Amps.
It does this fine, with the current draw of the battery decreasing as it progresses through the charge. It takes about 110 minutes to complete the charge.

I later read that it is better for Li Po's if they are charged at less than 1C. I therefore decided to lower the Amps that the charger would provide from 2.6 Amps to 1.0 Amp.

After commencing the charge, the display reads 1.0 Amp being provided to the pack but then things seemed to not progress as I would have expected.
The charger cut off after about 60 minutes. Therefore the pack was only partly charged and useless in the plane. I would have expected the charger to continue charging until the pack peaks (which is about 8.4 volts reading on the display of the charger).

So what I am missing here? If I charge at 1C I seem to get a full charge but if I charge at 1 Amp I end up with a partly charged battery.

Damian, is this also your experience?
Does any one else have any information on this that can help.

Cheers,
David. Melbourne - Australia.
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Old 01-14-2007, 03:46 PM
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jooNorway
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I don`t use Swallow (Schulse is my brand) but I suspect you set the capacity of the battery and when the charger have delivered that amount of mAh it stops... It just want to charge at 1C...
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Old 01-15-2007, 01:18 AM
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DamianWalker
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Hi David

I use the Swallow 1 charger and charge my 2250MaH 3S batteries at 1Amp and they have charged fully. Mind you I don't think they're have ever been discharged below about 60-70%, so charges take less than 60 minutes.

Cheers
Damian
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Old 01-15-2007, 01:03 PM
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David_Aus
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It appears that charging at 1 Amp should work which leads me to believe that my battery is suspect. It is an EBay battery out of Hong Kong (I can just imagine that your eyes are rolling back into your head about now) so I can't be 100% confident about the quality.

I have a new 11.1V 2,200mAh pack here that I haven't used yet as it will be used in my new Ultimate Biplane when I get around to actually completing it. I'll check how it goes with charging at 1 Amp.

Cheers,
David
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Old 01-16-2007, 04:52 AM
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DamianWalker
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Some of my best batteries come from Hong Kong, in fact I've had most trouble with named brand lipos.
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Old 02-09-2007, 10:17 PM
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The charger you have may be using the charge Amp rating to also decide what capacity the cell is. Therefore by entering say .5A it is assuming the battery is 500mAh as many chargers have this safety feature I would recommend charging at 1C if the Li-Po is of good quality then 1C will not decrease the lifespan of the battery in any noticable level.
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Old 02-10-2007, 06:26 PM
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I heard that 1c equals 2 amps not 1 amp. Is this correct?

Mike
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Old 02-10-2007, 06:30 PM
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AEAJR
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1C doesn't = 1 Amp unless the pack is a 1000 mah pack. 1C doesn't equal any specific amp rating.

1C= 1X the capacity rating of the battery. So 1C differers depending on the pack. If you charge a 650 mah pack at 1 amp, you may be calling Allstate about fire insurance. :o

As stated earlier in the thread, if you have a 1500 mah lipo then you would charge it at 1500 mah, or 1.5 amps which equals 1C.
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Old 02-10-2007, 06:34 PM
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Huntermd14
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Thanks for the info Ed. So my lipo battery rated at 2100 mah = 2.1 amp = 1c. Interesting.
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Old 02-10-2007, 06:37 PM
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Huntermd14
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Another question. My younger son has a rc truck and the battery is 3000 mah nimh. How many amps would you charge that at for a reasonable time and doing no damage to the pack.
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Old 02-10-2007, 08:30 PM
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AEAJR
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For a motor pack, 3 amps would be fine.

4.5 amps would probably be OK.

If they are high quality, high output cells, maybe even 6 amps, but that might be pushing it.
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Old 02-12-2007, 10:35 AM
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Originally Posted by Huntermd14 View Post
Another question. My younger son has a rc truck and the battery is 3000 mah nimh. How many amps would you charge that at for a reasonable time and doing no damage to the pack.
If it is a good quality pack you can safely charge at 6amps but it will effect run time and shorten the life of the pack. I would suggest around 4-5amps would be fine.

I race 27 Turn Touring Cars & charge my IB4200's @ 6amps & discharge at 20amps (should be 30amps). You have to keep a very specific schedule to get the best out of the batteries.

Generally speaking you charge at a higher rate for POWER but sacrifice runtime, & visa versa.

Hope this helps

Cheers
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Old 02-12-2007, 10:29 PM
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JoshGordon
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Originally Posted by DamianWalker View Post
Hi All

Am I right in assuming that you charge a 1000Mah Lipo at 1amp, a 2200Mah Lipo at 2.2amps, a 4200Mah Lipo at 4.2amps, etc, etc? My Lipo charger reduces amps the closer the battery gets to full charge, but I want to make sure I start the charge at the right amps.

Cheers
Damian
You are correct.

Joshua Gordon
Common Sense RC
www.CommonSenseRC.com
Toll Free 866-405-8811
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