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HelicopterRadio - Servo - Gyro - Gov - Batt › new to A123's. Not sure if im having problems
07-10-2008 03:30 PM  9 years agoPost 1
helirulz

rrVeteran

Singapore

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Hi guys I've just gotten a 2cell 1200mah A123 pack and im cycling them at the moment to get them up to shape.

Im using a Hyperion 1210i charger and I notice something weird.
After a complete charge, I discharged my pack at 2A using a setting of 3V/cell and managed to discharge roughly 650mah out of the pack.

I then tried charging the pack at 1.2A and managed to pump back about 700mah which is pretty close to what i managed to pump out of these cells. However, these values are absolutely no where close to the 1200mah capacity rating. Is there anything wrong with them?

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07-10-2008 03:40 PM  9 years agoPost 2
BrainDrain_dx

rrKey Veteran

Wichita KS

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I set my LVC to 2V/cell on my 2300 a123s, your not letting them go low enough. At 2 amps maybe 2.5v/c should be enough. If you can, drain the pack to 5 volts and you should get the proper mah out of them.

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07-10-2008 03:42 PM  9 years agoPost 3
JKos

rrProfessor

Redondo Beach, CA

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The smaller A123 cells (such as from VPX packs) are spec'd at 1100 mAh, not 1200 mAh. That said, they've never delivered their rated capacity. Folks have done well to get 900 mAh out of them. There is a general disappointment in their performance. Lots of info on them over on RCG (such as here: http://www.rcgroups.com/forums/showthread.php?t=768729).

Also, manufactures rate the capacity at given discharge current (typically C/5) and cutoff voltage. Any deviation from that will yield a different result.

Have you been balance charging them?

- John

RR rules!

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07-10-2008 03:59 PM  9 years agoPost 4
helirulz

rrVeteran

Singapore

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Braindrain:
I didn't realise that 3V/cell is too low.
The lowest my charger can go is 2.7V/cell so I'll try those settings.

JKos:
The previous 2 charges were without a balancer. I've finally found a suitable connector to fit the A123 pack i have. I'll do a discharge down to 2.7V/cell and balance charge from there and see how many mAh i can pump back in.
The pack that im using probably contains generic A123 cells...not sure if they're from A123...

I'll report back once Im done with another cycle

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07-10-2008 04:11 PM  9 years agoPost 5
JKos

rrProfessor

Redondo Beach, CA

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> The pack that im using probably contains generic A123 cells

If the pack is spec'd at 1200 mAh then, no, it's not real A123 cells.

- John

RR rules!

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