Monday, Mar 26, 2007 at 08:32
Hi
Its not helped by the fact that many people use different terminology for the same things.
Most of the salesman are hardly professionals !
In making you dual battery decision I think one needs to ask a why ?
In your case you say fridge then maybe spotlights !
I would use spotlights with the engine running and in my case the
normal car battery can run a fridge overnight so no need for 2nd.
If I was a little unsure of capacity I'd put in a bigger or better type
battery(this was my solution), or carry one of those jump starters as re-assurance.
(does your fridge have low voltage cut out?)
If you decide you need one - is it to assist with heavy current loads like winch
or much lighter, but usually longer camping loads ?
From here people usually go down one of two paths--->
1/ To add a second battery in parallel (perhaps with manual switching) (low cost )
2/ To add second battery via a dual battery setup via a management unit. (Most common solution)
In case 1 its fairly easy but you need a battery of the same type and you should not
mix standard lead acid with an AGM as AGM requires a higher voltage (0.2).
In case 2 you add a dual battery controller and there are basically two types
A/ Voltage sensitive relay (or equivalent) (most common solution)
B/ Voltage stepup 2nd battery charger (best but costly)
Case B is more often used with camper trailers because of the long leads needed - you don't mention this so we will forget B option.
When you have decided to use a management unit then you have more freedom with battery typesand an AGM can be used although I prefer not because most management units still just switch 2nd battery in parallel when charging is available, and they don't charge optimally.
Robin Miller
AnswerID:
229747