Dual Battery vs Portable Power Supply

Submitted: Tuesday, Jan 01, 2008 at 19:26
ThreadID: 53016 Views:9321 Replies:6 FollowUps:0
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Hi - I have been thinking of getting a dual battery for my Pajero (NS SWB) and was wandering what peoples thoughts were on

a) Getting a dedictaed dual battery installed
b) Getting a portable power supply using a batery box setup which is charged like a dual battery.

My use would be for
1) run a fridge in my camper and/or
2) run a fridge (which I want :))) in the back of the Pajero.

I can see benefits/disadvantages with both solutions but being new at this I would like to hearwhat other people with more have done.

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Reply By: Member - Vince B (NSW) - Tuesday, Jan 01, 2008 at 19:59

Tuesday, Jan 01, 2008 at 19:59
I have used a dual system in 3 vehicles & found them to be quite adequate for my needs.

Contact Derek at ABR 4wd accessories(he advertises on this site).
He will give you valuable info on both set ups.
AnswerID: 279262

Reply By: Boobook2 - Tuesday, Jan 01, 2008 at 20:02

Tuesday, Jan 01, 2008 at 20:02
I originally had a portable battery in my NM pajero but went to a dedicated dual battery system because

a) the capacity of the portable system was not quite a day for my waeco 50l and got worse over time. Also I had to get the wiring upgraded to get it fully charged in the back anyway.

b)It is heavy and takes up space, also hard to tie down and it moved, often getting unplugged and not charged.

c)you have to remember to disconnect it and reconnect it.

Hope this helps.

If you can do a lot of the work yourself it could be cheaper to have a dual battery. If not it is probably about $250 more.
AnswerID: 279264

Reply By: Member - Mike DID - Tuesday, Jan 01, 2008 at 20:05

Tuesday, Jan 01, 2008 at 20:05
We're lucky that the Pajeros have been designed to install a second battery beside the existing one.

Those studs and the socket are there to hold a 10" N70 battery - and you won't have to worry about the mudguard cracking like other brands when you add a battery.
AnswerID: 279266

Reply By: Sand Man (SA) - Tuesday, Jan 01, 2008 at 20:17

Tuesday, Jan 01, 2008 at 20:17
I'm greedy, I have both.

If you are running a fridge in your camper, you would be better served with having the battery in the camper and maintaining a charge with an Arrid Twincharge controller. This controller boosts the charge being received from the vehicle alternator, to correct any voltage drop resulting from a long cable run.

If you intend locating the fridge in the back of your vehicle, you would be better served by a fixed, dual battery system.

If you have any thoughts about removing the fridge from the vehicle and storing it in your camper or annex, a portable battery system may be a better choice.

In my situation, I have the benefits of both, running the fridge of the auxiliary battery while driving and maintaining a charge in the portable system with a second in-car charging unit and swapping over to the Thumper when I camp. The portable system also powers a couple of 12 volt lights and is further charged while stationary with a solar panel.

You just need to determine your own needs, then implement one or more of the solutions as you go.

Regardless of the method you employ, protect the battery with a low voltage cutout unit connected to your fridge. A fully drained battery can be destroyed in short order if you let it go below 11.6 volts, or 30% of its capacity, on more the a couple of occasions.


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AnswerID: 279269

Reply By: Mainey (wa) - Wednesday, Jan 02, 2008 at 00:26

Wednesday, Jan 02, 2008 at 00:26
Oldman, enjoy what you "want"-> 2) run a fridge in the back of the Pajero.

Use a 'quality' battery isolator and decent battery cable to connect the (AGM Deep Cycle) battery via the isolator to the Cranking battery, if the two batteries are side by side all the better.
( don't forget some type of 'fuse' system )

Run a thick power cable to a fused termination block in the vehicle so the fridge (and lights etc) can be safely plugged into the Auxiliary power supply.
Does the fridge have a 'low battery cut-out switch' ?

AnswerID: 279296

Reply By: Oldman - Wednesday, Jan 02, 2008 at 19:30

Wednesday, Jan 02, 2008 at 19:30
Many thanks for the replies.

I reckon a permanent dual battery is probably the best for me.

I have a SWB and so do not have that much storage in the back.

The portable is certainly more flexible option but I reckon I would use it mainly for running a fridge in the car while driving and or one in the camper.

AnswerID: 279423

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