jump start a car with a cordless drill battery?

Rocksy · Post by **Rocksy** » Fri Jan 22, 2010 6:55 pm

Well i found myself at work the other day with a flat battery in the Brumby, the same day i chewed the power cord off the belt sander with the belt sander.

3pm rolls around and dead battery, so i have a McGuyver moment and tried to jump the car from the 19.2v Makita drill battery using the power cord from the belt sander.... and masking tape.

It didn't work, now i'm not sure if its possible with the type of batteries that cordless tools use, or i was just doing it wrong??

Defeated, and had to ask for a jump start (every mans nightmare)

Can it be done, and what do you need...?

Gannon · Post by **Gannon** » Fri Jan 22, 2010 8:01 pm

There isnt enough peak current in a cordless drill battery to jump start a car.\

And also, hooking up a 19v drill battery to a 12v car battery will flatten your drill battery before you have a chance to turn the key

The internal impedance of a car battery is very low, which is why you can pull several hundred amps from one.
Cordless batterys (NiCd, NiMh or Li-ion) have a higher internal resistance and can only manage a peak current of maybe 10-20 amps

Rocksy · Post by **Rocksy** » Fri Jan 22, 2010 8:38 pm

bugger

phantomD · Post by **phantomD** » Fri Jan 22, 2010 9:43 pm

Next time I'll loan you the battery out of my mobile phone and see if it does you any better!!!

steptoe · Post by **steptoe** » Fri Jan 22, 2010 9:59 pm

I have trouble with those start ya car via ya cig lighter plug gadgets. Do you have to wait hours for the charge to get through the piddly circuits?

AndrewT · Post by **AndrewT** » Fri Jan 22, 2010 10:15 pm

shoulda just roll started!

Rocksy · Post by **Rocksy** » Sat Jan 23, 2010 4:30 am

flattest street ever, and the brumby requires the choke on and i was by myself.
It had to give it a whirl:)

AlpineRaven · Post by **AlpineRaven** » Sat Jan 23, 2010 3:31 pm

steptoe wrote:I have trouble with those start ya car via ya cig lighter plug gadgets. Do you have to wait hours for the charge to get through the piddly circuits?

you cant really start via ciggie lighter unless you slowly "balance battery voltage level"
You will just burn the wires if you just try jump start via ciggie lighter..

Only thing I'm just glad to have is manual transmission.. roll start! but if the battery is DEAD flat, there is no power for ECU to start up... havent actually tried this, but i did that in other car and didnt work..
Cheers
AP

fredsub · Post by **fredsub** » Sat Jan 23, 2010 6:38 pm

as others say, as expected you can't jump start the car with your 19.2V cells....

starting needs about 400amp (lets say) for 10sec,
the drill batteries whilst able to supply a good current, won;t be able to stretch it that far.......

but

in amp/hour terms that energy is quite small, only about < 2Amp/hour

so if the OPost'er had left the cells (that were fully charged,right ?) to equalize with the car battery, then it would have started certainly.

This only works with a flat car battery, not a dead one.

Had tried this very trick myself once....
flattened the battery using the stereo and the laptop and charging a small 12amp/hour sealed battery (laptop running via it).

caught me by surprise! engine wouldn't even turn, just the grr noise and thats it.

so, my McGuyver moment was to use the small battery to return charge to the car battery,
this was possible because the small battery is not directly connected to car's 12V,but via a small inverter,
this one in fact...
http://secure.oatleyelectronics.com//pr ... cts_id=223
(a bit modded ,but)

so after hooking it up to charge the car battery, waited about 20minutes.
And sure enough, it started, without hesitation.
And I tell ya, I wasn't real sure it would work, because the small 12V wasn't fully charged either....
was a grim moment when first tried.

so if its a myth, its busted:p

RSR 555 · Post by **RSR 555** » Sat Jan 23, 2010 10:08 pm

phantomd wrote:next time i'll loan you the battery out of my mobile phone and see if it does you any better!!!

rotflmfao

steptoe · Post by **steptoe** » Sun Jan 24, 2010 7:22 am

don't laugh, he may still have one of the original bricks from 1985 just as a rechargeable power source. $720 bucks a year line rental back then, real STD rates back then and text messaging was one way only - to your pager. Still got my pager somewhere...

Never read instructions for those "start ya car thru cig lighter" probably quite a wait while it trickles. Yeah , imagine starting ya car through a 15A fuse

last celtic warrior · Post by **last celtic warrior** » Sat Jan 30, 2010 5:35 pm

I have tried "pull starting" my Subie one time, but the battery was too low to power the ignition. (Mine is an auto, and was stuck in an awkward position off road).

Simply undid a strand from a Telstra rope, wrapped it around the spare crank pully, braced my foot against the front wheel and pulled like buggery. Need strong arms for this though...

Ended up deciding to call for help, but mobile was flat, so jumped it with the AA batteries out of my camera, some spare speaker wire and masking tape to hold the connections. Worked a treat.