Alternator Output - Coolbox

Post by **Titus A Duxass** » 17 Jul 2008, 12:59

Okay, my Leisure Battery is Donald and after much thought I would rather not replace it.

We never camp without of an electric supply in one form or another, so the LB is only to power the interior light and the in-car stereo.

We have just acquired a laptop and some good speakers so no longer need the in-car stereo. We can live without the light.

My plan is to power the Coolbox (via the splitter relay) only when the engine is running. I have the cable already there and the relay.

Will the alternator/starter battery cope with the load that the Coolbox will require?

Note: I will not be running the Coolbox at max (pos'n 1 will be enough).

Post by **High Peaker** » 17 Jul 2008, 13:57

Your twin headlights are consuming around 250W of power (drawing nearly 20A of current, so a 40W or so coolbox drawing 3A is peanuts in comparison.
I had a portable coolbox which you could leave running off the starter battery for a few hours before it became a risk to your starting ability.

Genuine fridges only run off the car battery, as their current draw is too high for a leisure battery. So long as you do not leave it connected when stopped (easily arranged if the feed is only live with the ignition on).

Post by **Titus A Duxass** » 17 Jul 2008, 14:01

Cheers High Peaker,
Completely forgot about the Headlight power requirements.

You've just saved me a lump of cash.

Post by **Grun** » 17 Jul 2008, 14:56

Don't know if one of these might be useful. If a coolbox only draws 3 amps you could run it from the battery for a while without the engine, and this gadget will cut off the supply to the coolbox and keep enough juice in the battery for a start, at least that is the theory.

Maplin Car Battery Protector

Mike

Post by **Titus A Duxass** » 17 Jul 2008, 15:03

Grun,
Thanks that looks useful, I'll have to try and source one over here.

Post by **Bowton Lad** » 17 Jul 2008, 23:47

High Peaker wrote: Genuine fridges only run off the car battery, as their current draw is too high for a leisure battery. So long as you do not leave it connected when stopped (easily arranged if the feed is only live with the ignition on).

Fridges are powered by the alternator when the engine is running but receive no power once the engine is turned off. They should not be connected to the starter battery. I'm not sure if that's what you were trying to say in above quote.

Post by **High Peaker** » 18 Jul 2008, 09:50

Yes indeed - meant it is connected to the vehicle battery via a relay so is only live when when igntion is on, rather than to the leisure battery.
Exactly like some cigarette lighters are only live when the ignition is on.

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