Powering cooler from a car battery

beer enigma

Ok I know that its a car battery, but this is a more likely place to get an answer:

I'm running a cooler box for camping - its 12v 46w - I presume that means 46w/hr ?

If amps = w/v - that gives me a draw of 3.83amps ?

Does anyone know what the output of a car battery is & from there how long I could run the cooler for :eek:

Stoner

I don't know, but this might help, I have a 22W DC lamp for 3 hours from a standard car battery. I could be wrong or they could be wrong (the manufactures of the solar kit) but you might be able to use this as a ratio, based on that a fully charged battery would be 1.5 hour (ish) of cooling, like I said I could be wrong but it's a start, obviously there are different sizes batteries etc too.

Raggaroo

Depends on size of car battery, Normal petrol 1.6 l petrol engine would take a 50 AH battery. That is 50 Amp Hours which is 1 Amp for 50 Hours or 50 amps for 1 hour. In your cae it would be 3.83 Amps for 13.05 hours (In Theory) In Practice it would probably be less (maybe 12 hours). But a cooler box is quite well insulated so maybe it doesnt draw a current all the time to stay cool.

Bruthal

Andip wrote: »

Ok I know that its a car battery, but this is a more likely place to get an answer:

I'm running a cooler box for camping - its 12v 46w - I presume that means 46w/hr ?

If amps = w/v - that gives me a draw of 3.83amps ?

Does anyone know what the output of a car battery is & from there how long I could run the cooler for :eek:

Its about 4 amps alright for powering that. It is correct saying its 46 watts. 46 watt hours would only be for every hour the cooler box is run, and is the amount of units of energy used.

A standard car battery for a 1.4l car would be around a 45 amp hour battery, and would in theory run the cooler for 10 hours, but car batteries are not deep discharge batteries, although at its capacity/10 which would be about 4.5 amps in this case, and you should get 7 or 8 hours without over discharging it.

Are you thinking of powering it off the actual car battery in your car? If your using it camping you can use a 5 amp 12v power supply plugged into the sockets on the sites. That will use only 0.2 amps from the 230v socket.

Billy Bunting

Better to wire in a split charge relay and second battery, discharging batteries by 50% will soon buck them up. :eek:

fred funk }{

I think them cooler boxes use a heat sink and a fan to dissipate the heat from that, so to answer the earlier question whether it cuts out when cool, it doesn't.

Bruthal

fred funk }{ wrote: »

I think them cooler boxes use a heat sink and a fan to dissipate the heat from that, so to answer the earlier question whether it cuts out when cool, it doesn't.

Yea they probably use that thermoelectric effect (peltier effect), which the fan assists, rather than just a heat sink. And they run continously alright.

beer enigma

Thanks for the input guys, someone had offered to lend me a fairly new battery, so I'll wire it up and try

beer enigma

50Amp battery

just over 10hrs...............