Dual Aux Batteries

Submitted: Sunday, Mar 25, 2007 at 17:58
ThreadID: 43630 Views:2058 Replies:4 FollowUps:2
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Hello all.
I realise that this subject is raised quite abit.

Recently I have being chasing prices and information on what type and brand of batteries to use as my Aux under the bonnet in my 91 80series landcrusier.

I have being reading up about AGM. Wet celled, Gell Deep cycle and quite frankly I am confussed. Also I have being told 4 different stories from the so called professional @ battery World that im not to sure who to believe.

The question I am asking is if someone could give me a simple explantion as to what the different types of batteries ( AGM DEEP CYCLE WET CELLED & GELL ) are and what would be the best way to go with an underbonnet duel battery system that will be running a 70ltr Explorer fridge freezer and is the future spotlights.

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Reply By: Alloy c/t - Sunday, Mar 25, 2007 at 18:21

Sunday, Mar 25, 2007 at 18:21
AGM= absorbed glass mat , comes in 2 types ,deep cycle + HGL which is a semi deepcycle ,, all AGM batts can and do take recharging faster than any other Type of battery ,originally designed for millitary ,you can drop it /shoot it/ turn it upside down ect and lose no liquid

Conventional deep cycle is just as your standard starting car batt with thicker internal plates ,is a "wet cell", best use is long slow discharge as in running 12v fridge ,due to nature takes longer to recharge than Agm.

Gell cell are generally classed as "non spillable" ,come in both deep cycle and starting ,,

price varies from lowest "wet cell " then "gell" through to AGMs ,
have a read at www.batteryweb.com
AnswerID: 229635

Follow Up By: Member - Peter R (QLD) - Sunday, Mar 25, 2007 at 18:54

Sunday, Mar 25, 2007 at 18:54
Some info that may assist

Pedro
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FollowupID: 490445

Follow Up By: Crakaphat - Sunday, Mar 25, 2007 at 19:26

Sunday, Mar 25, 2007 at 19:26
What is the better way to go
I was told that AGM is no good under the bonnet due to heat created it can cause the plates inside to buckle.

but with the deep cycle if you drain it to far you have little change of getting the battery back to a safe charge unless using smart chage like a solar panel.

Can anyone recommand I brand of battery to use that would be suitable to my needs.
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FollowupID: 490451

Reply By: Battlecat - Sunday, Mar 25, 2007 at 23:19

Sunday, Mar 25, 2007 at 23:19
Hello,

All depends on how much power you need / how long you need power before the engine recharges the batteries / where you car goes.

CCA is what you need to start a car or winch where AMPS per hour and capacity come to play for the fridge etc

I have a Rotronics Dual battery setup and I run three batteries - one crank and two for everything else. Optima are the way to go for me as I live in the Pilbara and have to deal with corrugations and high temps. They last heaps longer and although there are cheaper batteries out there you cant put a price on being stuck miles away from help with no power because your battery dropped a cell etc the cost of the tow etc will pay for batteries for 30yrs or so. The yellow top can be used as a dual purpose or just get a red top and a yellow.

If you are $ constrained then a marine battery will do the trick - Exide are good

Hope that this helps - remember that dual batteries management kits are not equal either.
AnswerID: 229713

Reply By: Robin - Monday, Mar 26, 2007 at 08:32

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

Reply By: Mainey (WA) - Monday, Mar 26, 2007 at 11:04

Monday, Mar 26, 2007 at 11:04
NOT a SEALED battery in the engine bay heat, reason being you can't replace the lost fluid... will cause the battery to die early.

Run the spot lights direct off the Cranking battery.

Look at a Calcium/lead Deep Cycle battery. (Delkor brand or similar)
However, AGM's will give you superior performance to all other types
AnswerID: 229781

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