Question re charge rates on auto chargers  
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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> Question re charge rates on auto chargers
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Question re charge rates on auto chargers - 6/19/2002 5:41:03 PM   
mrbonk



Posts: 600
Joined: 2/18/2002
From: BundabergQueensland, AUSTRALIA
Status: offline 		Greetings,
What determines the charge rate that an automatic charger settles on? I've got one of these supernova250 things and I notice that different packs will charge at different rates if I leave it set on auto. Even 2 packs of the same capacity (1000mah) charge at different rates. I've also got 2 single 1.2v cells that I use for onboard glow. One of them (1400mah) ends up charging at less than .5A continuous, while the other (1250mah) settles on 2A continuous! How does the charger work this out?


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MrBonk
http://www.mrbonk.com
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Question re charge rates on auto chargers - 6/19/2002 7:54:31 PM   
HitecRedneck



Posts: 215
Joined: 12/22/2001
From: Kingsland, AR, USA
Status: offline 		I have the same charger and it does the same. Hopefully the charger is measuring the amount of charge each cell or pack can handle and at what rate. This is my understanding of the charger. I have one pack that charges very low and it showed up that one cell was bad. Maybe low charge represents the condition of a battery while high rate represents the battery being ok. My thoughts.

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Question re charge rates on auto chargers - 6/19/2002 9:43:58 PM   
Steve Lewin


 

Posts: 904
Joined: 3/18/2002
From: Reading, UNITED KINGDOM
Status: offline 		It's trying to check the internal resistance of the battery. Different types (not just sizes) of cells have different values and will tolerate different charge rates. An increase in resistance is also one sign of a battery going bad. One consequence if this is that batteries on their way out also often charge to a HIGHER voltage than normal (bigger numbers are not always better).

Steve

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Question re charge rates on auto chargers - 6/20/2002 7:01:24 AM   
mrbonk



Posts: 600
Joined: 2/18/2002
From: BundabergQueensland, AUSTRALIA
Status: offline 		[QUOTE]Originally posted by Steve Lewin
An increase in resistance is also one sign of a battery going bad. One consequence if this is that batteries on their way out also often charge to a HIGHER voltage than normal (bigger numbers are not always better).

Steve [/QUOTE]

So, this brand new 1250mah Sanyo SCR sub-C cell I've just got, which is the one that sucks up 2A continuous, could be buggered? It's a regular cell (not solder tag) and I soldered directly onto the ends of the battery......could this have killed it? I didn't get the ends of the cell red hot or anything (I *can* solder) when I did it. How much heat does it take to kill a cell anyway?


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MrBonk
http://www.mrbonk.com

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Question re charge rates on auto chargers - 6/20/2002 1:03:27 PM   
Steve Lewin


 

Posts: 904
Joined: 3/18/2002
From: Reading, UNITED KINGDOM
Status: offline 		I think you've got that the wrong way round. Higher resistance means lower CURRENT but higher VOLTAGE. The bad cells are usually the ones that will only charge at very low currents.

OTOH my 1250SCRs happily charge at up to 4A (on a Schulze charger) but if yours is taking 2A for more than about 45minutes something's wrong.

Soldering can be tricky, but I can't give you a definite answer as I haven't managed to kill a cell yet. But then I'm ever so careful. You need a hot iron with a heavy bit so it doesn't lose heat. If you are leaving the iron on the cell button for more than about 5 seconds you're doing it wrong.

Steve

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       Post #: 5

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