Lead acid battery problems (Full Version)

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9c -> Lead acid battery problems (9/23/2007 7:16 PM)

hello everyone,
I have a 2 year old 12V 7.5A hobbico "flight box" battery. After charging with a 12V .5A "wall wart" charger yesterday for 18 hours, i went to the field and tried to start my helicopter, but to no avail. The starter wouldn't even turn over the enging one time. I'm positive the engine wasn't flooded. After i hooked it up to my mini-vans starter batter (car battery), the starter easily turned over the engine, and started. After i came home i discharged the flight box battery with a Triton Jr. (no small feat, it discharges at a max of like .3 A for this battery) and it only had around 200 miliamps left in it. is it just me? or does 7.3 amps of power go away in trying to start a .50 size helicopter engine just once? what going on here, and can anyone help?



Red Scholefield -> RE: Lead acid battery problems (9/23/2007 7:53 PM)


quote:

ORIGINAL: 9c

hello everyone,
I have a 2 year old 12V 7.5A hobbico "flight box" battery. After charging with a 12V .5A "wall wart" charger yesterday for 18 hours, i went to the field and tried to start my helicopter, but to no avail. The starter wouldn't even turn over the enging one time. I'm positive the engine wasn't flooded. After i hooked it up to my mini-vans starter batter (car battery), the starter easily turned over the engine, and started. After i came home i discharged the flight box battery with a Triton Jr. (no small feat, it discharges at a max of like .3 A for this battery) and it only had around 200 miliamps left in it. is it just me? or does 7.3 amps of power go away in trying to start a .50 size helicopter engine just once? what going on here, and can anyone help?


There is a good chance that your 2 year old battery has breathed its last. You might give the Triton a shot at it, but don't be surprised if it doesn't get well. A 2 year life on these batteries is not at all uncommon. You might try another source as these are as common as dirt in the battery world. Some place that sells emergency lighting batteries. Also much to my surprise I found them at Farmer's Tractor and Supply. I guess they use them for electric fence or gate openers. Anyway a farm supply place might be a good place to look. Office Depot might be another source as these are the same batteries they use in computer UPS systems.



mrasmm -> RE: Lead acid battery problems (9/23/2007 10:28 PM)

once you get a new pack a good way to prolong its life is to put the SLA on a float charger. You can get one from harbor freight for 6 bucks, or a better quality one from walmart for about $20 bucks or so. I put all my SLA's in a bank on a float charger, and that just keeps them in top condition and keeps the plates from getting too low of voltage which keeps the plates from suplating. They'll last alot longer that way.

Basically if the volts go to low on any lead acid battery the suplur perminantly deposits in the lead which decreases the acid (ie sulphuric acid) which slows down the electrochemical process, and it also ruins the patch of lead where it perminantly gets deposited which decreases surface area which is basically is the Ah and CC.



Red Scholefield -> RE: Lead acid battery problems (9/24/2007 1:01 AM)

Float keeps them from going dead (below 1.8 volts/cell), but if you watch the voltage and charge when it gets down to 12 volts (no load) you will get even better service out of them. Fortunately the self discharge is fairly low, so a fully charged battery should last for 2 or 3 months minimum before you need to charge it.



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