How to wire up a dual battery to your Isuzu Dmax Smart Alternator

Does your DMAX have a smart alternator?

There is a lot of confusion about whether or not modern vehicles have a smart alternator. The easiest way to check is to look closely at the earth terminal of the battery. If the earth has a direct contact to the body without any sensors then it is not a smart alternator. If there is a module connected straight onto the terminal then it mostly is a smart alternator system.

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Does my DMAX have a smart alternator?

Locating an ignition source for a DMAX

Beside the battery, in between the battery and the guard is a fuse box. On here you will find a main power source and the ignition source.

On vehicle with a smart alternator a ignition feed will tell the DC Charger to keep running even if the vehicle is in low voltage mode.

Isuzu DMAX Ignition Fuse Location
Ignition source isuzu D-max

On the late model Isuzu D-Max there is a engine fuse in the fuse box that is only live when the ignition is on. It is extremely important that you check the fuse as  it can change with vehicle updates and model changes. The images within this article are only a guide and vehicle manufacturers can change the position or use of the fuses. Please use a multimeter to check prior to removing.

With all additions to the fuse box you need to test use a multimeter, check there is no voltage when the vehicle is off and then check again when the ignition is live. You should only see voltage at the fuse when the ignition is on and no voltage when the vehicle is turned off.
If you are finding voltage at that fuse source, then you need to use your mulitmeter and check each fuse to find one that has no voltage when off. This will mean that when you stop your vehicle and leave for the day the aux battery system will not drain your start battery.

isuzu DMX jumper Fuse Location

No Splice Wiring

Using a JTS Jumper fuse you can tap into the fuse without any splicing. This means there is no interference with the factory wiring harness protecting your warranty.

Simply remove the 10A fuse and place into the bottom (spare) slot of the JTS Tap Fuse Holder. Then relocate into the same spot you removed the fuse from. Now you have a clean ignition souce for your Isuzu D-Max.

Midi Fuse Holder

On the Isuzu D-Max, behind the battery you find a great location to cleanly mount a midi fuse holder. Midi fuses are highly recommend for fitment when using a BCDC Charger. DO NOT fit thermal fuses, circuit breakers or Maxi fuses. They will give you trouble down the track.


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Does my DMAX have a smart alternator?

Isuzu D-MAX Midi Fuse Power

Using the main power supply the the fuse box is a great location to power your BCDC in an Isuzu D-MAX. This location will keep clutter to a minimum and give you a great “factory like” look.

Always use good quality terminals and the right cable size for the job. Most installations use 8 gauge or 8 B&S Cable. A little heat shrink on the terminal and you will have a professional finish.

Now The Hard Work Is Done

Now that you have a reliable power feed and a clean ignition source you are ready to go. Simply run your 8 B&S Twin with the ignition wire to the rear. We recommend installing your cable into split tubing for protection and running down the chassis.

Terminate to a Anderson inside your vehicle for your dual battery system.  If you are needing power to your caravan a new cable run is required as the dual battery cable kit is not heavy enough to push power all the way to your caravan’s DCDC.  For this kit you are needing our “Power to TowBar” or give us a call and we can help you with your system requirements.

For more information call the team at JTS On 1300 377 128

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