Deep cycle charging - trickle charge?

[slowhilux]

Just started on fitting a deep cyle battery purely to run the fridge ( 3rd battery ). It will be a sealed type, in a battery box, sitting on the fridge slide between the fridge and cargo barrier. It will be independant of everything else, ie, earthed to the fridge slide (which i had to then earth to the drawer chassis), and the only time it will be connected to any other part of the car is when it needs to be charged.

Now, my question is, do i need a special type of charger for a deep cycle battery?? The charger will sit on the cargo barrier. I have heard that deep cycle batteries dont like being charged straight from the alternater??

Any help would be great

Phill

[chimpboy]

you could put one of these in and forget about it:

http://www.outerlimits4x4.com/PHP_Modul ... hp?t=19402

but i am biased.

Jason

[-Scott-]

Phill

The typical method to charge an automotive sealed lead acid battery is to apply around 14V DC and let it take all the current that can be delivered. The flatter the battery is, the more current it will take (normally...) If your starting battery has had a hard time, when the engine is up and running it may take most of the current your alternator can put out - my alternator is rated at 75A, and it's a small one.

Deep cycle batteries don't like high charge currents, so putting them straight across the alternator will kill them real quick - probably faster than a starter battery will be killed by repeated drainings.

Jason is spot on - the Jaycar controller is ideal for your application. It will detect when the second battery is trying to draw too much current, and switch to a low charge mode to protect it. Great for a deep cycle battery, but it really sucks when you're a cheapskate using your old starting battery as the auxiliary.

Cheers,

Scott