# How can I charge a 12V Car Battery?

J

#### [email protected]

Jan 1, 1970
0
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
http://www.davidbevan.co.uk

T

#### Tom Biasi

Jan 1, 1970
0
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
http://www.davidbevan.co.uk

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

B

#### Ban

Jan 1, 1970
0
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
http://www.davidbevan.co.uk

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.

S

#### Steve Banks

Jan 1, 1970
0
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).

F

#### Funfly3

Jan 1, 1970
0
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

J

#### John Miller

Jan 1, 1970
0
Funfly3 said:
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

Beware of cheap (unregulated) chargers used routinely. They will boil
your electrolyte, and generate excess hydrogen while they're at it.

A

#### Andrew Mawson

Jan 1, 1970
0
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
http://www.davidbevan.co.uk

I OK I'll 'fess up - I don't know - WHAT'S a LIPOS ??????

AWEM

F

#### Funfly3

Jan 1, 1970
0
Andrew Mawson said:
I OK I'll 'fess up - I don't know - WHAT'S a LIPOS ??????

AWEM
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

F

#### Funfly3

Jan 1, 1970
0
John Miller said:
Beware of cheap (unregulated) chargers used routinely. They will boil
your electrolyte, and generate excess hydrogen while they're at it.
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

P

#### Poxy

Jan 1, 1970
0
Funfly3 said:
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.

Exhibit A:

D

#### Doug McLaren

Jan 1, 1970
0
| > 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:

J

#### [email protected]

Jan 1, 1970
0
I think its one of these...

....the output from my charger is 12V/450mA so I guess it would take
100h to fully charge a flat /70Ah car battery?

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
http://www.davidbevan.co.uk

T

#### Tim Auton

Jan 1, 1970
0
Funfly3 said:
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

You're getting Amps and Amp-hours confused. A 10A charger can charge a
100Ah battery.

Tim

T

#### Tim Auton

Jan 1, 1970
0
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).

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

http://www.sussex-model-centre.co.uk/Pro+Peak+Power+supply-5167.htm

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

J

#### [email protected]

Jan 1, 1970
0
1. Walk back to your car to charge the lipos (or the lead battery)

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 £50 each) laying around on the floor where someone might walk off
with them.
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.

Not too sure if thats a serious suggestion?
4. Buy more lipos and pre-charge them?
At £50 each I have bought 3 batts and 2 chargers as this allows for
almost continuous flying.

Thanks

David Bevan
http://www.davidbevan.co.uk

J

#### Jim Slaughter

Jan 1, 1970
0
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.

J

#### Jim Slaughter

Jan 1, 1970
0
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.

J

#### [email protected]

Jan 1, 1970
0
Decide how many charges you want, then buy cyclic or deep-discharge rated SLA 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
http://www.davidbevan.co.uk

C

#### colin

Jan 1, 1970
0
Doug McLaren said:
| > 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:

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 =^.^=

T

#### Tim Auton

Jan 1, 1970
0
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.

you'll find loads of suppliers. One at random:

http://eurobatteries.com/sitepages/sla.asp

Tim

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