Dual battery system

Submitted: Wednesday, Sep 02, 2015 at 18:00
ThreadID: 130165 Views:2265 Replies:5 FollowUps:2
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Hi, we are about to pick up our new Izuzu D Max dual cab this week.
We are looking at a dual battery system from ARB. The one they suggested is under vehicle system with the battery mounted near the spare wheel with battery charger mounted near battery carrier and leads going into tub and also to rear power points.
I have never seen this system before{always had older vehicle with plenty of room under bonnet},those who have them has there been any problems with dirt, dust, water and mud?
Or am I better off going to a portable unit like the Thumper.I know it means taking up extra space in your vehicle but could be used for other things away from the vehicle
Hope I have been clear on what I need and looking forward to some advise.
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Reply By: Allan B (Member, SunCoast) - Wednesday, Sep 02, 2015 at 19:05

Wednesday, Sep 02, 2015 at 19:05
Hi Glyn,

ARB's arrangement sounds fine to me. Keeping the auxilliary battery (presumably an AGM deep-cycle) out of the heat of the engine bay is good sense for battery life.

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Reply By: Ross M - Wednesday, Sep 02, 2015 at 22:08

Wednesday, Sep 02, 2015 at 22:08
If it is a solenoid isolator system which you control OR it is a VSR type which switches on automatically, you shouldn't need a battery charger at all.
The vehicles alternator will deliver 14. 3v or14.4v to the battery and with appropriate sized cable supplying the battery, it will then become charged.
I have an in tub battery (AGM full River) and also one in the Tvan linked with an anderson cable. All batteries get charged.

Manual isolator/relay supplies main to the aux batteries. All has worked that way for more than 5 years. Original 2 x AGM batteries.
AnswerID: 589910

Reply By: Idler Chris - Wednesday, Sep 02, 2015 at 22:13

Wednesday, Sep 02, 2015 at 22:13
Batteries are heavy, I would not be putting them behind the back axle. I would try and place between the two axles if possible which gives for a more balanced vehicle.
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Reply By: Johnhu - Thursday, Sep 03, 2015 at 11:38

Thursday, Sep 03, 2015 at 11:38
What are your plans for the rear tub ? If you plan on a canopy and drawers, then there is plenty of room in the side wings of the drawers for the second battery. Of course if you want to keep the tub open, that's a different matter - just another option to consider.

AnswerID: 589924

Follow Up By: 901 - Thursday, Sep 03, 2015 at 12:20

Thursday, Sep 03, 2015 at 12:20
Thanks for all the replies. John, have a good canopy on it but no drawers so unit would be secure, so am thinking the Thumper type might e the way to go.
Think it could be more versatile in that when camping in one spot for awhile can have it hooked up to solar panels to run extra fridge.

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Reply By: Ken - Thursday, Sep 03, 2015 at 20:05

Thursday, Sep 03, 2015 at 20:05
Heavy leads might have been the way to go in the past but now most modern vehicles control the alternator voltage after a short period of running and lower the alternator output to around 13.2 volts which would never fully charge a battery even it this voltage was applied directly to the battery, ie. no voltage drop in the connecting leads.
There are a number of options available such as the diode/fuse booster or the best of all, a DC/DC charger. Unless you run extremely heavy wires the distance it is to the proposed battery location and stop the alternate voltage dropping you will never get the battery to full charge. In my view the DC/DC charger is the best option but bear in mind they are not cheap.
The maths [well Ohm's Law] tells the story. If your leads have a total resistance of 0.05 ohms [remember there are 2 wires and associated connections in the circuit] and the charge current is say 20 amps, there would be 1 volt dropped across the cables. If the voltage from the alternator was 14.4 volts [best case] you would have only 13.4 v at the battery.
I'd go with the ARB solution.
AnswerID: 589946

Follow Up By: 901 - Friday, Sep 04, 2015 at 07:25

Friday, Sep 04, 2015 at 07:25
Thanks for that Ken,have to work out cost compared to amount of use we would get from it.It was about $1200 fitted including optima battery.

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