?Super NiCads?

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Bad Dawg
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Joined: Fri Jul 18, 2003 3:27 pm
Location: Solomon Islands

?Super NiCads?

Post by Bad Dawg »

I've just gotten some strange RX. battery readings, and I had to check with somebody.
I bought four battery pacs from SErvo City. They are HItech 600mah four pacs of AA's. They were on sale eight months or a year ago, and I didn't do anything with them till now. I've just charged them for the first time and they are taking a lot more than 600 ma. Using a Super Nova 250 the first tow took 840 and 960 ma each. I have the third on the charger now and it's taken 1420 ma and still going up.
The first two read 5.45 and 5.38 v on the voltmeter (loaded) after charging.
Is there something I should be worried about?
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Which_way_is_up
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Location: Dallas, Texas

Post by Which_way_is_up »

Are they really nicads or are they NiMH batteries? Batteries, either nicads or NiMH are not 100% efficent and so you will see 20% or 25% more charge go in then the battery is rated for. So seeing 840mah or 960mah for a slow charge is not unusual. But the 1420mah charge and still going is not normal. I see that happen on cheap NiMH batteries that the charger will not see the delta v occur and so it'll just keep charging until you catch it. I use a charger that can be set to a max charge and so if it doesn't see the delta it will stop charging after the max is reached. So that it doesn't damage the battery. So for a 600mah battery I'd set it for around 800mah to stop.
Bad Dawg
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Location: Solomon Islands

Post by Bad Dawg »

They are NiCads. They are still taking a charge. It's been 8 hrs and 19 min and taken 2384 mah. There has got to be something wrong with this pac.
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Which_way_is_up
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Post by Which_way_is_up »

Not necessarily, but by now they've been seriously over charged. You see as soon as the batteries have gone through the "delta v" of the battery pack then the charger will never see any further indication that it needs to stop charging. So unless you stop the charger manually, it'll just keep charging the batteries forever and finally ruin them.
Pat_Willcox
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Post by Pat_Willcox »

Mark,

You might give FMA tech service a call and run this by them. I use the Super Nova "automatic" for Nicads and "manual" for Nmh and Pb.
Bad Dawg
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Joined: Fri Jul 18, 2003 3:27 pm
Location: Solomon Islands

Post by Bad Dawg »

Roy,
I took your advice and stopped the charge. I discharged them and got 698 mah out of them. I recharged them on auto and they took 670 when the charger cut off. Like so many things in life, "It's a mystery."
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Which_way_is_up
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Post by Which_way_is_up »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Bad Dawg</i>
<br />Roy,
I took your advice and stopped the charge. I discharged them and got 698 mah out of them. I recharged them on auto and they took 670 when the charger cut off. Like so many things in life, "It's a mystery."
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

With any new NiCad or NiMH battery they need to be slow charged and cycled three times or so to "form" them. Before they'll be consistent. Batteries that have sit around not being used for a period of months will have a tendancy to act the same way as new "unformed" batteries and need to be cycled a couple of times to "exercise" them back to full capacity. Depending on the quality of the battery they may not produce a good "delta V" transition for the charger to see on the first charge or two. I've got a Super Nova also but it's been relegated to being my secondary charger and instead I use a "Triton" charger for several reasons. In addition to being able to have it act as a "Delta V" charger I can also tell it to stop charging after a specific amount of time and or after a specific amount of charge has been put into the battery. I've noticed that my chargers (both the Super Nova and Triton) don't seem to like a lot of brand X NiMH batteries and don't stop charging correctly. A lot of times they want to stop after only charging a 100mah or so and some other times they will not stop after what should have been a full charge. This seems to be more the case in small capacity and AAA batteries. So I add 20% or so to what should be the max charge amount in the "max charge" setting and that way I know that it will get a full charge but not be over charged. I've noticed that brand name batteries like Eveready don't seem to have the problem. So I only buy Eveready for my devices like digital cameras, etc. I even made my own transmitter pack from a set of 2300mah AA Eveready NiMH batteries. It took a little work soldering the pack up but now I've got a quality 2300mah battery pack that charges and cycles to the rated value and lasts forever in my transmitter. I buy the Eveready batteries at Wal-Mart. You can get a 2300mah 8-AA package for around $16 to $18. Which comes out to a little over $2 per cell. Not much more then what you pay for brand X cells with lower capacity. Of course they're not perfect for all situations, like a light weight receiver battery pack for SSC or 1/2A but would be good for Open B, Limited B, 2548, etc.

Where weight and lower capacity comes in, you can use Eveready NiMH AAA batteries and they are now coming out rated at 800mah. Again, available at Wal-Mart in 4 packs. Great capacity, small size and weight. Just a case of whether or not you're comfortable building your own battery packs.
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