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Old Feb 06, 2016, 10:32 AM
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Safe charging current for old A123 cells?

I have some A123 cells which I've probably had for 7-8 years (since whenever they first became widely available, don't recall when that was). Their useful capacity is around 1600mAh now, down from 2300 when new. Just wondering what charging current would be deemed safe?
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Old Feb 06, 2016, 11:24 AM
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Well I don't think the age is an issue nor the useful capacity for a charging rate. I generally charge my A123's about 2C.

However, might I suggest that with only 1600 mah capacity remaining, the batteries should not be used for a model airplane anymore.
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Old Feb 06, 2016, 02:21 PM
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Originally Posted by natterjak View Post
I have some A123 cells which I've probably had for 7-8 years (since whenever they first became widely available, don't recall when that was). Their useful capacity is around 1600mAh now, down from 2300 when new. Just wondering what charging current would be deemed safe?
I've got some 6S2P A123's around six years old. And still charge those 4600 Mah packs at 19 Amps.

Strange thing about these cells. When they get old, they still hold voltage at 40 Amps per cell, but their Amp Hours drops off as you've found.

(My models have 140 A123 cells in them)
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Old Feb 07, 2016, 03:16 AM
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However, might I suggest that with only 1600 mah capacity remaining, the batteries should not be used for a model airplane anymore.
Thanks and no worries on that front - they are actually flying in a 7S configuration in one of these! An application they excel at and cheaper than a replacement Dyson battery pack
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Old Feb 07, 2016, 03:20 AM
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I've got some 6S2P A123's around six years old. And still charge those 4600 Mah packs at 19 Amps.

Strange thing about these cells. When they get old, they still hold voltage at 40 Amps per cell, but their Amp Hours drops off as you've found.

(My models have 140 A123 cells in them)
Thanks, sounds like I have no reason to worry about sticking with low charging currents, despite the diminished capacity. I've been staying on the cautious side and charging at 2.3A until now, but if your 6 year old cells still take 19A charges without issues then I'll ramp it up a bit. Useful info for me, thanks.
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Old Feb 07, 2016, 07:09 AM
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I was looking at the pictures I took of my planes yesterday and I noticed that I was using A123's in 2006. I am still using those packs.
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Old Feb 07, 2016, 07:50 AM
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Originally Posted by natterjak View Post
Thanks, sounds like I have no reason to worry about sticking with low charging currents, despite the diminished capacity. I've been staying on the cautious side and charging at 2.3A until now, but if your 6 year old cells still take 19A charges without issues then I'll ramp it up a bit. Useful info for me, thanks.
FYI reminder for readers of this thread. That's 19 Amp charge rate for a 2P pack, or 19Amps/2 which is 9.5 Amps per cell
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Old Feb 07, 2016, 07:54 AM
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I was looking at the pictures I took of my planes yesterday and I noticed that I was using A123's in 2006. I am still using those packs.
I'm kicking my self for not putting a 'new' date on the cells pulled out of those 36 Volt DeWalt packs. They are somewhere around 8 years old, and are still being used.
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Old Feb 07, 2016, 10:55 AM
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FYI reminder for readers of this thread. That's 19 Amp charge rate for a 2P pack, or 19Amps/2 which is 9.5 Amps per cell
That's a worthwhile clarification as I'd overlooked that distinction. Thanks.
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Old Feb 07, 2016, 06:39 PM
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Vollrathd,

I started out to build four 4s 2300's and did, but I found 4 somewhat weak cells so I bought for more cells and replaced them. I built another pack from the culls and it was about 1800 mah. That pack became marginal a couple of years ago so I ditched it. Last summer I had one cell fail(short out)in one of the four remaining packs. I needed a 3s cell pack for some smaller planes so I reconfigured it and it works fine. All the cells were bought directly from A123 when you could still do that for the full price. It shows the price per flight or even year is trivial. Just checked my log and 1020 flights were accumulated.
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Old Feb 08, 2016, 12:28 AM
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Vollrathd,

I started out to build four 4s 2300's and did, but I found 4 somewhat weak cells so I bought for more cells and replaced them. I built another pack from the culls and it was about 1800 mah. That pack became marginal a couple of years ago so I ditched it. Last summer I had one cell fail(short out)in one of the four remaining packs. I needed a 3s cell pack for some smaller planes so I reconfigured it and it works fine. All the cells were bought directly from A123 when you could still do that for the full price. It shows the price per flight or even year is trivial. Just checked my log and 1020 flights were accumulated.
Yeah

One of my club members is using a 2S1P A123 battery pack for receiver power in a $$$$ kerosene turbine model. That pack was purchased new in 2009. I just ran a battery analysis on the pack on my Western Mountain CBA battery analyzer.

At 15 Amps load, it checked out at the same voltage, and within 2% Amp hours of a brand new A123 pack.
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Old Feb 08, 2016, 07:03 AM
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And taking care of them does not take over your life if you want to be safe.
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Old Feb 08, 2016, 07:09 AM
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A123 cell can take abuse in charging and discharging..

I have A123 cells that are over 10 years old.. I always charge them at 5 amps. but in a jam charged them at 20 amps. cycle those weak batts and they should jump backup in capacity if not discard them..
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Old Feb 08, 2016, 11:45 AM
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For years I charged my A123s, while in the plane, with a Mastech 5020 @ 20amps.


With 2P planes that's effectively 10amps per cell; 20 for 1P.

Still do 20 via an iC3020 off 2Pbs in series; used for Zipping at 20 w/6S!
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Old Feb 08, 2016, 02:23 PM
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And taking care of them does not take over your life if you want to be safe.
Yeah, really agree. A few years ago, I really screwed up while charging a two cell A123 2300 Mah battery. It blew the top off of the cells.

(They were being charged with my variable voltage, variable current limiting power supply. Unfortunately, the power supply was set to 14 Volts DC while charging two cell A123 pack.

Right after that, I bought my first Cellpro PL8 charger.

Kyleservicetech A123 Screw Up
http://www.wattflyer.com/forums/showthread.php?t=58745
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