How can I charge a 12V Car Battery?

This may sound a bit of a silly question, but currently I use one of
the small 12V 7Ah sealed lead acid batteries to charge my lipos with
(via a lipo charger) - but I only get about 3 charges before the 12V
has dropped too far.
...so the obvious solution is to buy a 12v car battery (about 70Ah).
The question is; will I be able to charge the 12V car battery with the
same charger that I use to charge the 12V sealed lead acid?
As I understand it a car battery is just a lead acid battery? So same
technology and same voltage just higher Ah. Will I blow myself up if I
use the small 12v lead acid charger on the big 12v car batt?
Thanks
David Bevan
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Reply to
junk1
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Hi David, The charger you have will charge the larger battery but will take longer. Car batteries are pretty heavy to be lugging around. Regards, Tom
Reply to
Tom Biasi
The voltage should be OK if it is the same kind of battery. There are Gel-cells around, that require less voltage. So make sure the charger is for liquid acid lead batteries. It might get more hot when charging and it will take forever with that car battery, but it should be suitable.
Reply to
Ban
Alternative sugestions:
1. Walk back to your car to charge the lipos (or the lead battery) 2. Since car batteries are huge, maybe another 7ah battery will give you enough charges. 3. How about some sort of foot pump like generator that you can pump the small lead battery back up, or possibly a lipo directly to save a few strokes, perhaps even while you are flying. 4. Buy more lipos and pre-charge them?
If you can shlep a battery to the pit area, then your car probably isn't that far away and is an excellent source for 12 volts (at least here in the states).
Reply to
Steve Banks
buy a cheap car charger from a car shop and buy a car battery from Macro for £17/£19 and its got 3 a year guarantee that's what I use
Reply to
Funfly3
Beware of cheap (unregulated) chargers used routinely. They will boil your electrolyte, and generate excess hydrogen while they're at it.
Reply to
John Miller
Lithium Polymer or LiPo for short at the moment these are the way forward for a lot of electric flying my 11.1v 2600mah LiPo weighs 140 grams, my 9.6v 2400mah NiCd pack weighs 500 grams, LiPo have a much greater charge density than normal packs or in other words are lighter and smaller for the same capacity
Reply to
Funfly3
What's the price of a regulated charger that will charge a car battery routinely??? a 10AH charger is around £45 so a 50AH is going to be a lot more and the battery has a 3 year warranty all for £17 cook it then take it back
Reply to
Funfly3
And they have an unfortunate propensity to spontaneously burn up SUVs.
Exhibit A:
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Reply to
Poxy
... | > Lithium Polymer or LiPo for short at the moment these are the way | > forward for a lot of electric flying my 11.1v 2600mah LiPo weighs 140 | > grams, my 9.6v 2400mah NiCd pack weighs 500 grams, LiPo have a much | > greater charge density than normal packs or in other words are | > lighter and smaller for the same capacity | | And they have an unfortunate propensity to spontaneously burn up SUVs.
And if you'll read the description of the story you linked to, they didn't `spontaneously' burn up that SUV. The pack was damaged -- that's hardly spontaneous, even if it was slightly delayed.
And to be fair, NiCd batteries can cause fires too when damaged.
Yes, LiPos do require that some care be taken with them, and if you fail to take proper care of them they can catch fire. But 1) under the right (wrong) conditions, other batteries can cause fires/catch fire too, and 2) they're not the sticks of unstable dynamite that people seem to make them out to be.
| Exhibit A: |
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Reply to
Doug McLaren
I think its one of these...
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...the output from my charger is 12V/450mA so I guess it would take
Is it safe to charge a car battery unattended? I usually just leave my current 12V on charge permenantly in the garage and just take it off charge to go flying. I always supervise LiPos when I charge them, but they only take 1h, I dont really fancy baby sitting a 12V car battery for 100h!
Thanks
David Bevan
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Reply to
junk1
Is this for charging in the field or at home?
If it's for use at home, get a 13.8V (or 12V) power supply. I've got the Pro Peak 20A one. £35 and it's got more than enough oomph for everything I need. I've not seen another PSU with similar capacity anywhere near the price, except in a PC of course :)
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If it's for the field I wouldn't get a car battery. Decide how many charges you want, then buy cyclic or deep-discharge rated SLA of appropriate capacity. Do you really need 30 charges out of a field battery? Lugging a car battery around is no fun, if you drop it acid pours out and they aren't rated for deep-discharge cyclic use so you'd be lucky if it lasts a year.
A cyclic-rated SLA will give you over 500 genuine cycles, which is several years of flying for most of us.
Tim
Reply to
Tim Auton
Charging from my car is an option I had thought about since it has got a 12V output in the back. The thing that put me off was that the LiPos are best charged outside of the car (since in certain circumstances they can catch fire) and I didnt really want to leave 2 or three LiPos (at =A350 each) laying around on the floor where someone might walk off with them.
Not too sure if thats a serious suggestion? :-)
At =A350 each I have bought 3 batts and 2 chargers as this allows for almost continuous flying.
Thanks
David Bevan
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Reply to
junk1
Buy a small tractor battery. They're about $18 at your local auto parts store. Buy a cheap auto battery charger for it. You should be able to get one in the $20-30 range. I have two tractor batteries. (They're not very heavy) I keep 'em both charged.
Of course the simplest solution is to use your CAR BATTERY to charge your lipos! That's what I do when I'm at the field.
A final solution is to buy a 12V power source to use your li-po charger in the house!
The little gel cells just don't have enough amp hours to last long.
Reply to
Jim Slaughter
You'll quickly ruin the car battery if you charge it constantly. You need to charge it and then put it on a trickle charger if that's what you want to do.
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Reply to
Jim Slaughter
of appropriate capacity.
Is SLA short for sealed lead acid? As thats what I have got now and I cant seem to find them over 7Ah? I am charging 1600mAh LiPo packs, and get 2 or 3 charges before the charger refuses to charge (as input voltage has dropped)
I guess if im realistic then I will go to the patch with 3 charged LiPos and probably wont want more than 10 flights which will mean 7x1600mA = 11Ah - so I guess I would need a minimum of 15Ah in the 12V. Please let me know if you can find such a battery.
Thanks
David Bevan
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Reply to
junk1
lead acid batteries can go with a hell of a bang too if they generate enough hydrogen gas wich then gets ignited. (like if u acidently short one out after over charging it !)
Colin =^.^=
Reply to
colin
of appropriate capacity.
Search for "sealed lead acid" on your favourite search engine and you'll find loads of suppliers. One at random:
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Tim
Reply to
Tim Auton

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