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Old 11-28-2008, 11:54 PM   #1
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Default battery charging question.

hi guys i am a nitro 1/8 buggy off-roader and dont know alot about batteries and have a question about charging batteries ok here goes.

when charging a battery does charging at lower amps or trickle charge make the battery hold its charge/power for longer?

its just that i was using a normal car battery charger to charge up a 12 volt gel cell battery and the battery isnt lasting very long when in use and it is a 7 amp/hour.
could the charger i am using be too much for the gel cell?
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Old 11-29-2008, 01:10 AM   #2
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First, a car charger should charge the gel cell just fine, and charging at a lower rate usually won't make a difference except to take longer to charge it. Personally, if were charging a 7amp battery, I would charge it at no less than 5amp.

Now, the question I have for you is, what are you using the gel cell for that is draining it so quickly? Perhaps it is to small for your application?
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Old 11-29-2008, 12:41 PM   #3
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Gel cells are intended to be trickle charged at charge rates like 0.6 - 0.8amps. If you're just connecting the gel cell to auto batt, its charging at rates far higher than intended. Are you controlling the charge rate in any way? Something like zip charging the plane guys are doing with a123s off a car batt - the wire gage used to connect the two controls the charge rate. If not, the short time may be telling you that you've damaged your gel cell.

They are also somewhat notorious for not lasting too long. I've had good luck with mine using a float style charger and keeping it hooked up all the time.
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Old 11-29-2008, 07:34 PM   #4
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Listen to Duster , he knows what he is talking about for your gell cell . Downunder , buy the wall charger for it and you will be good .
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Old 11-30-2008, 01:35 AM   #5
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to da wizard - i am using the gel cell for a nitro off-road starterbox.

and guys i do believe i have damaged the cell is why i bought 2 venom 3600 mah stick packs connected in series i think to get 14.4 volts.

now i just found out i think there is a short in my starterbox because the 2 stick packs i recently bought were charged up fully for the first time on the friday arvo and connected and installed to the starter box and worked fine for friday when i was testing and moving the pins on top of box for car position.... but went flat by sunday morning (race day)and i have heard other guys getting like 2-3 race meets out of one charge for their stick packs so something is wrong and i think now i should have to disconect the batteries when box is not in use. they should hold charge longer than 2 days especially when the batteries are fully charged and not being used?

which leads me to believe the possible short in the bump box is contributing to the gel cell i was using previuosly was discharging so fast but i did think it may be due to the car charger i was using i think i may get longer out of it if it was trickle charged for longer im not sure its just that when i use the car charger the gel cell is warm after like 4 hours but im not sure what amps it is putting out.

how would i go about finding the short in the starter box?if so. and how would a short drain power when it is switched off and the starter motor isnt being used. im just not an electrics fan haha thanks for ya help guys.
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Old 11-30-2008, 08:10 AM   #6
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If you had a short your packs wouldn`t even lasted an hour , weather alone a day . What charger did you use to charge the Nimh packs ? I hope you used a hobby grade peak charger .
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Old 11-30-2008, 03:18 PM   #7
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yes i got my local hobby shop to charge them.
but now i just bought a supernova charger.
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Old 11-30-2008, 04:17 PM   #8
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Small SLA's (gel cells) are best charged with automatic float charger, like those used for motorcycle batteries. Basically, they charge at a low rate (.5 - 1 Amp) until ~14.5V and then go into float mode. SLA's should always be recharged as soon as possible after use since letting them sit discharged will cause sulfation and shorten their life. A wall wart will also work, but you would have to make sure not leave it on too long or it will dry out the electrolyte and kill it. A car battery charger may charge it too fast, which would also be bad for it.

To find a short or drain, you'd need to connect an ammeter inline with the battery and see if it reads any current flowing when there shouldn't be any.
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Old 12-01-2008, 09:41 PM   #9
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thanks pserve.

i just bought a supernova 250s charger and it charges nicd,nickel metal hydrid and pb batteries i know the first 2 but what exactly is a pb battery?
i will have to guess that is a 12 volt gel cell but im not sure am i correct?

if so then i can charge it using my new charger and it will check if its faulty and it can charge at a very low amp rate so i may be able to save it and use it to supply power for the charger i am using to charge it up with on race days for reciever packs etc.. instead of leaving it in the car connected to the 12v acid battery i can charge on the bench.
as far as the starter box goes i think i might just buy a new one mine isnt the best of boxes but it done the job id rather a newer slimmer style box anyway. thanks for your help guys.

oh and one question that didnt get answered was the first question i asked on this thread was that, will charging a battery preferably a nimh battery at low amps will the battery hold its charge longer rather than if charged at high amps. for eg: if charged at 0.3 amps compared to say 3.0-5.0 amps. will the lower amp rate make the battery hold its charge for longer when being used??
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Old 12-01-2008, 11:13 PM   #10
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Yes, the Pb battery type is for Lead-Acid batteries. Just make sure you set it for 6 cells (12 Volts). A gel cell is an SLA (Sealed Lead-Acid) battery.

For your other question, I think the consensus is that charging a Nimh at lower rate will make it last longer, while faster charge rates will make it more powerful, for a shorter time.
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