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Lipo batteries..will only charge at low rate

Old 08-11-2012, 08:30 AM
  #1  
liposucker
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Default Lipo batteries..will only charge at low rate

I have two 3s 5000mah battery packs and both are showing the same unusual behaviour.

The 2 packs are about 2 years old and have been used about 60 to 70 times each. They have never been run down to low, theres usually about 30% to 40% in them after the flight.

I have always charged them at 4.0A and they record about 97% to 99% capacity and the cells are always balanced.

Recently when I have charged them at 4.0A my charger beeps with an "Input voltage error" warning. Its only on these 2 packs it gives this warning.

I find I can now only charge these packs at 1.0A...any higher and I get the warning message. The resulting charge gives 97% to 99% charge and the cells are balanced and they packs perform as normal in the planes. The packs do not get warm during the charge.

Basically there is no differance to how they use to be, just the low charge rate.

Whilst this is not a problem as it just simply takes longer to charge, I was wondering if a more serious problem exists.

Any advice/thoughts appreciated.
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Old 08-11-2012, 10:30 AM
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JetPlaneFlyer
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'Input Voltage Error' means that the voltage being supplied to your charger is either too high or too low... Usually the cause is voltage falling too low under load, probably caused by an inadequate / failing power supply.

It might be happening only with those two batteries because they are larger and take more power to charge than your other batteries.

Steve
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Old 08-11-2012, 10:36 AM
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liposucker
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Originally Posted by JetPlaneFlyer View Post
'Input Voltage Error' means that the voltage being supplied to your charger is either too high or too low... Usually the cause is voltage falling too low under load, probably caused by an inadequate / failing power supply.

It might be happening only with those two batteries because they are larger and take more power to charge than your other batteries.

Steve
Hi Steve

Thanks for the quick reply.

I'm not experiencing similar problems with my other 3s 5000mah...they still charge as they have always have, which is why I was leaning more towards a battery problem than a power supply problem.

Do you think my charger is possibly failing?
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Old 08-11-2012, 12:15 PM
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Perhaps it is a charger issue - what are you using for a power supply?

One test - attach the charger to one of your car batteries and see if they same behavior exists.

I suspect your power supply...
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Old 08-11-2012, 05:48 PM
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liposucker
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Originally Posted by rcers View Post
Perhaps it is a charger issue - what are you using for a power supply?

One test - attach the charger to one of your car batteries and see if they same behavior exists.

I suspect your power supply...

Thanks for the reply.

I'm using the charger from the mains. I tend to charge at home as opposed to the flying field. I can certainly check the charger on my car battery next time I'm at the field when I've used one of the batteries. At the moment they are fully charged.
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Old 08-11-2012, 07:06 PM
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I assume it is an AC/DC charger then.

O - and by the way - not good to leave LiPo's fully charged when stored. Leaving them at 3.7v or so while stored will likely keep them lasting longer.

Mike
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Old 08-11-2012, 08:41 PM
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kyleservicetech
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Originally Posted by liposucker View Post
I have two 3s 5000mah battery packs and both are showing the same unusual behaviour.

The 2 packs are about 2 years old and have been used about 60 to 70 times each. They have never been run down to low, theres usually about 30% to 40% in them after the flight.

I have always charged them at 4.0A and they record about 97% to 99% capacity and the cells are always balanced.

Recently when I have charged them at 4.0A my charger beeps with an "Input voltage error" warning. Its only on these 2 packs it gives this warning.

I find I can now only charge these packs at 1.0A...any higher and I get the warning message. The resulting charge gives 97% to 99% charge and the cells are balanced and they packs perform as normal in the planes. The packs do not get warm during the charge.

Basically there is no differance to how they use to be, just the low charge rate.

Whilst this is not a problem as it just simply takes longer to charge, I was wondering if a more serious problem exists.

Any advice/thoughts appreciated.
Do you have access to a digital multimeter? Places like Harbor Freight has them for under $5.00. (I've got a full range of these meters from several HF meters to two Fluke 87 $$$$ meters) Use one of these meters to monitor the output voltage of your power supply to see if it is sagging during the charging cycle. If it is a 12 Volt DC power supply, it should hold very close to 12 Volts DC. (If it's a Computer Power Supply, that's another issue!)

If you've not used a digital meter before, take a look:
http://www.wattflyer.com/forums/showthread.php?t=52821
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Old 08-11-2012, 10:22 PM
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Denny sounds like he has a built in supply? Not sure...

I guess even then the charger should show input voltage too.
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Old 08-12-2012, 02:47 PM
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which charger you talkin' 'bout?

Beeps with an "Input voltage error" doesn't sound familiar to me.
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Old 09-19-2012, 02:48 AM
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Default LiPo batteries only charge at low rate

I have two LiPo batteries, 11.1v, 1000mAh and about two years old with few charge cycles on them that also charge very slowly compared to other similar LiPos that I have. My charger is a Triton2 and is fully automatic, I can't adjust the charge current; the charger does it. My power supply to the charger is perfect, no problem with it. I suspect the batteries are perhaps "on their last legs"! After the very long charge time, this charger will end the charge and indicate that the battery is fully charged. A digital voltage check of each of the 3 cells confirms this. The battery flys normal in my airplane, however. Crasher
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Old 09-19-2012, 02:58 AM
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nidly
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It is true that older worn out batts will take longer. They spend proportionately more time and capacity in the slower CV stage of charge.

ps. The only way to change the cc part of the charge current (the set-point) on T-2 is to lie to it about capacity.
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