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Old Jun 21, 2003, 3:45 AM   #1
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Default This can't be good... Batteries hot enough to burn

I have one those Sony 1 Hour Quick Chargers you can get at Circuit City, Fry's ETC for $20-30...

popped in my Digipower 1800mah... after about maybe 2 hours the red light went out and I pulled the batteries out. You could hold them for 10 seconds at the most before they felt to hot to hold.

Anybody have experience with this charger? Good, bad?

I assume if the batteries get this hot, they wont last that long?
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Old Jun 21, 2003, 5:09 AM   #2
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What brand is it?

According to what I've read the internal temperature would need to be about 200 degrees celcius to damage the batteries. You wouldn't be able to hold them anywhere near 10 seconds!
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Old Jun 21, 2003, 5:20 AM   #3
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It's very normal that batteries run hot when quickcharged.
I race 1/10 electric and after a 7 minute heat you can't hold the batteries for more than 5 seconds, they really cook.

Nothing to worry about.

But do take care of them, never use them straight after charging, let them cool down for about half an hour/hour.

When I really need I charge my batteries in about 60 minutes and that works also, so 2 hours meaning probarbly a charge of 900Mah and that should be no problem, NiMh's can be charged with their own capacity so taking only one hour.

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Old Jun 21, 2003, 2:23 PM   #4
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jbailey wrote:
<
According to what I've read the internal temperature would need to be about 200 degrees celcius to damage the batteries. You wouldn't be able to hold them anywhere near 10 seconds!
>

200 deg. C is above the melting point of the 60/40 solder used for most electronics.

NiMH battery makers recommend limiting the maximum temperature to 45 deg. C (113 deg F).
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Old Jun 21, 2003, 2:55 PM   #5
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just remember is you all use these very convenient 1hr chargers you are reducing the lifespan substantially on your batteries. it's better to have 2-3 sets and 2 chargers and let them go slow at around 5 hrs or so you'll never run out that way. patients is a virtue.
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Old Jun 22, 2003, 5:36 AM   #6
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You don't get something for nothing, and don't forget the outside temperature (which you can't hold) is much lower than the core temperature.

I think the best thing with chargers is to use the fast charge when you really need to, not as a routine. And keep batts permanently on trickle, which is usually at about the self discharge rate. That avoids a fast charge when you need them in a hurry.

But it's been said before, AA batts are pretty cheap and it seems always needing replacement with newer bigger one's coming along.

I read somewhere recently about a new battery technology, really small, with big output that runs on gasoline!
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Old Jun 27, 2003, 3:14 PM   #7
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I am more concerned with a fire hazard then the batteries life. Since like it has been said... high cap rechargeables are dirt cheap nowdays.
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Old Jun 30, 2003, 7:08 PM   #8
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I'm ready to replace my Rayovac chargers as on a couple of occasions they've gotten cells so hot the plastic jacket split and blistered. I'm looking at a Maha or Lenma fast/cool charger to see if it makes a difference.
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Old Jul 11, 2003, 8:22 PM   #9
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Quote:
Originally Posted by padeye
I'm ready to replace my Rayovac chargers as on a couple of occasions they've gotten cells so hot the plastic jacket split and blistered. I'm looking at a Maha or Lenma fast/cool charger to see if it makes a difference.
Then I would suggest not using cheap batteries anymore. The jackets are not supposed to melt even with Quick chargers. Quick chargers are known for getting batteries very hot (it's very normal). I use Energizer NiMH AA's and never had a problem with them in my Rayovac. Also there is no proof that quick chargers will kill or reduce the batteries life. NiMH's prefer a quick charge. It's just the nature of their chemistry. The supposed reduction in life by using quick chargers is a myth propagated by a few companies so that you will buy their "slower" chargers to make you feel more satisfied with their "slower" and "cooler" charging products. Why would you want to downgrade your charger? The Rayovak 1 Hour is currently KING in quick charging. Try Energizer 1850mAh's. You will not be disappointed. $11 for 4 AA
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Old Jul 11, 2003, 11:41 PM   #10
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Quote:
Also there is no proof that quick chargers will kill or reduce the batteries life. NiMH's prefer a quick charge. It's just the nature of their chemistry.
I should like to see some references to the academic literature about this. As an electrochemist retired from electricity industry research, who once wrote a batteries review (internal only!), I find the allegations and counterallegations about fast charging of Ni-MH surprising. I should expect the batteries to tolerate it to a degree, but not necessarily 'prefer' it.

It's completely dependent on accurate detection of the end point, otherwise there is violent overcharging. Severe heating is obvious evidence of overcharging.

Ideally a battery won't heat up much during charging because the energy going in is being *stored* as chemical energy. The heat comes from dissipation in its internal resistance, which is small but significant.

You're converting one chemical to another at a dispersed 2-D interface (where the electrons leave the electrode & enter the reactants), but the products & reactants are dispersed in a 3-D matrix through which things must diffuse. This miracle is difficult to arrange in practical terms, so it takes time for this to go to completion.

Quote:
reduction in life by using quick chargers is a myth propagated by a few companies so that you will buy their "slower" chargers
All manufacturers will quote evidence in favour of their kit, so myths arise on both sides of the argument! Third party 'slow' chargers for camcorder batteries were heavily promoted a few years ago, because camera manufacturers all supplied fast ones.[/quote]
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