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Gel cell battery charger?

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qquake2k

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I use a small 2.4 ah gel cell battery for my launch control system. What is the best and easiest way to charge the battery? Can I use a 12 vdc AC adapter? Does it need some sort of circuitry? Or can I just hook it up to my car battery?
 

j.a.duke

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I use a small 2.4 ah gel cell battery for my launch control system. What is the best and easiest way to charge the battery? Can I use a 12 vdc AC adapter? Does it need some sort of circuitry? Or can I just hook it up to my car battery?
I use a charger from All Electronics. Inexpensive but good. Keeps all my 12v batteries in peak condition. It's intended for the small batteries that we'd use in rocketry, not an auto battery.

12VDC 500MA 2-STAGE CHARGER

And shipping is reasonable as well.

Cheers,
Jon
 

Handeman

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You can't use just any charger on a gel-cell battery. If you charge it with to high a voltage, it will shorten the live of the battery dramatically.
 

bobkrech

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I use a small 2.4 ah gel cell battery for my launch control system. What is the best and easiest way to charge the battery? Can I use a 12 vdc AC adapter? Does it need some sort of circuitry? Or can I just hook it up to my car battery?
Batteries need to be charged with DC, not AC, so you can't use an AC adapter.

You can recharge a gell cell using a cigarette lighter adapter as a charger in you car, however you do not want to leave it connected for long periods of time. Make sure you use polarized connectors so you can't reverse the leads, or you will destroy the battery.

Gell cells must be charged more carefully than a liquid lead acid battery because the gell will trap any gas generated in the event of an overvoltage and greatly decrease battery capacity and lifetime. The use of a multi-step charge such as the one mention in this thread is highly recommended. Most two step chargers first recharge in a current limited mode, one mentioned charges at 0.5 A, and the once the current drops to a certain rate, it will switch over to a constant voltage charge of 13.8 vollts. When the current drops to some low value, if it has a charged light, it will turn on.

Leaving a gell cell on a trickle charger is not recommended due to the potential for gassing, but 13.8 volts DC is the absolute long-term holding voltage if you do this.

Bob
 

Micromeister

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I've been using AC/DC wall pack adapters for years with the clubs gel-cell batteries. They work wonderfully. or for about 9 bucks you can pick up a 12v trickle charger from Harbor freight that also does a fine job.
 

davel

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I just got one of these from Harbor Freight. Had a coupon for $4. Think it'll work?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=42292
Don't see any specs listed, so hard to tell. Do you have a digital volt meter available? If so, check to be sure the float does not exceed 13.8 volt MAX.

Ideally, you want to charge a lead/calcium plate battery (a Gel Cell uses lead/calcium plates) at a current not to exceed c (where c is the AH capacity of the battery) to a voltage of 2.35 volts/cell. Anything above 2.35 volts/cell and the battery will begin to gas, and you run into the problems bobkrech mentioned.

Hold that 2.35 volts/cell until the current drawn falls to c/10. Then drop to a float. Theoretical ideal float is 2.17 volts/cell, but in practice 2.2 - 2.25 volts/cell is more common and will 'top off' the battery a bit quicker. 13.8 volts for a 6 cell battery works out to be 2.3 volts/cell, which will accelerate battery aging, but is low enough to prevent gassing.
 

Micromeister

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By AC adapter, I meant a transformer that provides 12vdc.
They work Perfectly. Our club has been using 500 and 1000 ma Adapters and those HF trickle chargers for DECADES, without a single problem on 4.5, 5.5, 7 and 26 amp/hr gelcells since the early 90's.
That's a great discount coupon you got there. the Harbor freigth chargers do a wonderful job on the little Hobbico 7amphr batteries full charge in about 8-12 hours.

Gel-Cell Charger-b_HarborFrt 12-15V Charger_04-12-02.jpg
 
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