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mitchelljames - 2012-01-26 13:10

Does anybody have any idea if something like this will power a car radio, i know its 12volts but i know nothing about amps etc?

Cheers

http://www.ebay.co.uk/itm/1-pcs-12V-1300mAh-Ni-MH-Rechargeable-Battery-Pack-RC-/280801671645?pt=US_Batteries&hash=item41611579dd

nak.d - 2012-01-26 23:40

I have sucessfully used a 12v sealed Lead Acid battery to power my Nakamichi TD 400 when testing indoors (small size, possibly a motor bike battery, can't remember as it was borrowed from a friend) ...just to be kinky, I hooked up the pre-outs to my Arcam A75+. With superb results I might add. Obviously you'll need a mains charger as well, but going this route proved easy and conveinient.

isolator42 - 2012-01-27 05:46

That item on eBay is rated at 1300mAh at 12V, meanuing it can maintain 12 volts while supplying 1.3 amps for one hour.

Considering power (watts) = volts × amps, so the power available is 15.6 watts. That doesn't sound like enough to power a car stereo head unit. Most head-units I have seen need a 5 amp fuse, which indicates a power comsumption of at least double what a 1300mAh battery can supply. It will power the car radio up, but if you crank the volume, that battery won't be able to supply the power.

Short answer: No

This one might be nearer the mark:

http://www.ebay.co.uk/itm/2-x-12V-3800mAh-Ni-MH-Rechargeable-Battery-Pack-RC-M1-/280802184603?pt=US_Batteries&hash=item41611d4d9b

samsnite - 2012-01-28 13:30

It will probably run the car radio for a while, car radios usually take 1A. So you would be good for 1,3 hours with a 1300mAh battery, in theory.

I have had my eyes on this:

http://www.dealextreme.com/p/r...ie-camera-more-73774

for good portability...

isolator42 - 2012-01-28 14:58

I used to have one of those Kenwood car stereos where the whole unit pulled out of the dash. I worked for a power supply manufacturer, so I made my own small, simple 12V dc supply for it which could supply not much more than 1 amp without the voltage collapsing. I got a spare chassis for the Kenwood car stereo on my workbench, so I could listen to tapes & the radio (I wired up a headphone socket to the speaker outputs). Not 100% ideal but it worked well. I measured it & the current when powering the headphones with the radio on was indeed less than 1 amp (0.8A, I think). When I put a tape in, the lights on the car stereo would dim as the tape started up: the voltage falling as the extra power needed to start the tape exceeded what my little power supply could provide. When the tape was playing, it was OK again.
This is where I get the idea that a car stereo might need more than 1300mAh.
Of course, this was 20 years ago & car radios might well be more efficient now...

samsnite - 2012-01-29 08:37

Well, you can not compare a battery with a power supply, as they work in different ways. The battery capacity is measured in Ah (ampere per hour) as the power supply is limited to its maximum current output measured in amperes. Depending on the battery technology discharge current can be tens of amperes.