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How to test AA rechargeables... - 7/20/2008 1:31:20 AM   
fasstrevo



Posts: 97
Joined: 3/15/2007
From: Rancho Cucamonga, CA, USA
Status: offline 		Does anyone know the best way to test AA rechargeables. I've got a lot I've accumulated over the years and I know some must be bad, but they all look the same and I need a way to test and weed through them.

Should I just throw them on the charger then test for 1.2v with a meter? Please help.

Thanks

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RE: How to test AA rechargeables... - 7/20/2008 1:58:38 AM   
exeter_acres



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Status: offline 		IMHO, the best way would be to cycle them.....

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RE: How to test AA rechargeables... - 7/20/2008 2:51:37 AM   
fasstrevo



Posts: 97
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Status: offline 		Thanks. How would I go about "cycling" them? Sorry if it's a dumb question.

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RE: How to test AA rechargeables... - 7/20/2008 5:02:59 AM   
guver


 

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From: LaGrange, OH, USA
Status: offline 		This device is perfect for testing them http://www.westmountainradio.com/CBA.htm

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RE: How to test AA rechargeables... - 7/21/2008 1:58:47 AM   
kcobra


 

Posts: 31
Joined: 2/21/2005
From: , MO, USA
Status: offline 		Are you talking loose cells? If so, pick up a La Crosse BC-900 charger. It takes 1 - 4 AA's or AAA's and will individually discharge, cycle, etc each cell. Charger goes for ~$45 shipped on Amazon.

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RE: How to test AA rechargeables... - 7/21/2008 2:35:43 AM   
fasstrevo



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quote:

ORIGINAL: kcobra

Are you talking loose cells? If so, pick up a La Crosse BC-900 charger. It takes 1 - 4 AA's or AAA's and will individually discharge, cycle, etc each cell. Charger goes for ~$45 shipped on Amazon.


Yes I'm talking loose cells. So are you saying they might not necessarily be bad just need to be properly discharged and cycled? I'm not a pro at electric RC so please school me. Thanks!

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RE: How to test AA rechargeables... - 7/21/2008 3:12:28 AM   
kcobra


 

Posts: 31
Joined: 2/21/2005
From: , MO, USA
Status: offline 		Yep. A lot of times cycling Nicad/Nimh cells will bring their capacity back up. The La Crosse charger is nice because it keeps cycling each cell until it sees that the cell is not taking more juice than the previous time(s) is was cycled. Then it terminates the cycling for the cell. All cells are treated individually. Basically, put the cells in the charger, hit start and then come back 1-2 days later.

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RE: How to test AA rechargeables... - 7/21/2008 4:48:33 AM   
fasstrevo



Posts: 97
Joined: 3/15/2007
From: Rancho Cucamonga, CA, USA
Status: offline 		I'm sold, thanks so much! I'm sure the cheap "fast" charger I've been using is killing my batts.

Unless someone chimes in with a different suggestion I think the La Crosse unit is the one.

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RE: How to test AA rechargeables... - 7/21/2008 4:03:22 PM   
SilverFoxCPF


 

Posts: 58
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From: Bellingham, WA, USA
Status: offline 		Hello Fasstrevo,

When the LaCross BC900 came out, it was at the top of the heap. However, since then, Maha came out with their C9000 unit. It actually has a Break-In function that will charge your cell at 0.1C for 16 hours, then do a 0.2C discharge to determine the capacity of the cell, and finally charge it back up at 0.1C for 16 hours. This feature is not available on the BC-900, and I think it makes the C9000 much more attractive, even though it costs a little more.

Tom

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RE: How to test AA rechargeables... - 7/21/2008 6:54:38 PM   
fasstrevo



Posts: 97
Joined: 3/15/2007
From: Rancho Cucamonga, CA, USA
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quote:

ORIGINAL: SilverFoxCPF

Hello Fasstrevo,

When the LaCross BC900 came out, it was at the top of the heap. However, since then, Maha came out with their C9000 unit. It actually has a Break-In function that will charge your cell at 0.1C for 16 hours, then do a 0.2C discharge to determine the capacity of the cell, and finally charge it back up at 0.1C for 16 hours. This feature is not available on the BC-900, and I think it makes the C9000 much more attractive, even though it costs a little more.

Tom


I'll check it out, thanks Tom!

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RE: How to test AA rechargeables... - 7/22/2008 2:37:11 AM   
kcobra


 

Posts: 31
Joined: 2/21/2005
From: , MO, USA
Status: offline 		Thomas Distributing is a good place to get the Maha chargers or the La Crosse if you don't want to go through Amazon. About the same price after shipping.

I'm a bit confused on the usefulness of the Maha cycle method described above. If the charger charges at 0.1C, wouldn't the batteries roughly be charged in 10 hours for completely discharged batteries? Even less time for partially charged batteries. Why the additional 6 hours? Everything I have read says trickle charge is not good for NIMH.

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RE: How to test AA rechargeables... - 7/22/2008 4:06:38 AM   
fasstrevo



Posts: 97
Joined: 3/15/2007
From: Rancho Cucamonga, CA, USA
Status: offline 		Well I ended up ordering the Maha charger today. I hope it wasn't a hasty decision, but I really wanted to get it quick rather than risk messing up any more batteries. This is a good discussion though and I enjoy reading.

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RE: How to test AA rechargeables... - 7/22/2008 4:28:04 AM   
SilverFoxCPF


 

Posts: 58
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From: Bellingham, WA, USA
Status: offline 		Hello Kcobra,

When charging at 0.1C, the charge efficiency is not all that good. You actually need to put in around 150% to come up to a full charge. The "forming" charge goes for 16 hours to make sure the cell is fully charged. The damage done by the extra hour of charge at this rate is minimal.

The battery manufacturers follow an IEC standard when determining the capacity of their cells. The standard calls for charging at 0.1C, allowing the cell to rest for from 30 minutes to 4 hours, then running a discharge at 0.2C.

The same standard also is used to determine cycle life. One of the methods used to determine cycle life involves charging at 0.1C for 16 hours.

You are correct in that extended trickle charge is not good for NiMh cells, however a couple of hours at 0.1C is not considered extended trickle charging.

Tom

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RE: How to test AA rechargeables... - 7/22/2008 6:58:54 AM   
kcobra


 

Posts: 31
Joined: 2/21/2005
From: , MO, USA
Status: offline 		Cool. Thanks for the explanation.

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RE: How to test AA rechargeables... - 7/22/2008 4:29:55 PM   
guver


 

Posts: 8975
Joined: 3/7/2003
From: LaGrange, OH, USA
Status: offline 		That looks like a neat deal, put them in and come back a few days later not having to do any switching, logging, ect. Simply write a number on ther cell or organise them together. I'm in the market for a new AA charger, maybe I'll get this one.

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