Hi. Looking at a basic dual battery setup in a Trailblazer (Colorado 7), and believe I need some help.
Last time I did this was in an old vehicle 10+ years ago, and I see a lot of "*Will not work on vehicles with smart alternators " now. I assume the current model trailblazer has a smart alternator? Can Holden disable this so I can use a basic cheap dual battery kit?
I'm getting confused by VSR vs DCDC chargers, and not sure what's most suitable for our situation.

My Trailblazer is a lease car, so I need to carefully consider what I can install (and remove later) with little visible damage.
We will be towing a van with 2x 150W panels and a couple deep cycle batteries on it, and the vehicle will have a waeco CF50. I had planned to put a simple battery box in the back, and wire up as a second battery, with an external anderson for adding a portable solar panel when we camp without the van (for potentially a few days at a time), with appropriate solar controller.

I had considered just installing the same battery as in van, and wiring up to use the van system for charging on the road (ie treat as third van battery electrically), and rely on solar when detached. But I'd prefer to wire up as a second vehicle battery with isolator etc for trips away without the van to charge on the road.

Has anyone here done a similar setup in a Trailblazer/colorado 7? Or have some experience to share?
Trying to keep costs down, and understand what options I have to DIY.
Seems the cheap kits are mostly not suitable for smart alternators.
Thanks,

Thanks Dougwe.
I will be avoiding the engine bay - have seen someone wedge another yellowtop behind the main battery, but as I have a lease car, I don't want to do modifications. Happy to run some cables to the cargo area and use a portable battery box there.

It's just picking a suitable system that has me stuck currently.
I looked at a cheap dual battery kit (and MPPT regulator), but the kit says not suitable for smart alternators, which I've read will drop voltage when not under load in an effort to save a little fuel?
Is so, wasn't sure if lights and/or aircon would be enough load on it to keep pumping sufficient volts for a basic wiring kit, or if I needed to step up to a better unit (DCDC chargers have been suggested - CTEK D250SA? Projecta Idc25?).
Cheers.

Hi Wimma,
I have a January 2016 Colorado7 (assembled in Thailand) and have just finished the installation of a VSR to power my Caravan's fridge. Like you, and a lot of others, I did wonder whether my vehicle had a 'smart' alternator. Apparently some earlier models did, or so some folks reckon. I could find no definite info re my vehicle's alternator. So, I got a multimeter and an old 12v cigarette plug and wired them together so I could see the voltage at various stages. i.e. pre-start, at start, at shortly after start, at 1500rpm, at 80kmph out on the road, after 20 mins running, at end of run etc. What I found was that immediately after engine start the voltage increased to 14.94v , then after a minute or so the voltage decreased to 14.3 ish. It stayed at that reading for the rest of the test. From that I deduced that the alternator fitted was NOT a 'smart' one.

As you will have found there is not a lot of spare room under the Collie's bonnet. In fact, I could only find one place where a VSR could be mounted relatively easily. That spot is between the battery and the firewall. In that spot there is a bracket with a raised, and unused captive nut. Just to the left of that captive nut the aforementioned bracket is bolted to another captive nut in the left wheel arch. I mounted my VSR on a small metal bracket that I made up to use both those captive nuts. The VSR is mounted horizontally. I used 6AWG twin cable to connect the VSR to an Anderson socket at the rear of the vehicle. The twin cable is protected within 6m of 16mm corrugated split tubing - from the big orange shed - and is zip tied along the underneath of the vehicle. I recommend first attaching the Anderson Socket and zip tying the cable forward from there. I purchased 7m of cable and ended up cutting 700mm off. I have a inline 30A Maxifuse fitted between the Battery +ve and the the VSR. The -ve of the 6AWG is terminated at the body earth point down by the battery (below the horn mounting). The small Earth line from the VSR (use a 'fork' terminal) is terminated at the body earth terminal just to the rear of the windscreen washer filler tube.

In preparation for a trip in a couple of days I put the fuse in today and ran some voltage tests. 14.6 volts on the multimeter plugged in a front cigarette socket with engine idling gave 13.8v at the fridge terminals. That should ensure that a 'cold one' is ready for me when I park.

Thanks Brian.

I did look at one of those as well, and my parents have one in their xtrail for then fridge too (60AH I think). Good little units, and come with the car kit. I'd still need to install that, but not bad value, though I thought it might be handy to have solar input also, so on the weekend just bit the bullet and ordered a Projecta Idc25 unit and a heap of 6B&S cable. Should do the job, and I'll remove from the vehicle when I hand it back.

In theory I should be able to wire up for a portable solar panel, and at a pinch could move the projecta to the van if the van unit has a failure. It also means I could grab the van battery and pop in a cheap battery box and get a matched pair for the van (only coming with single battery).
Time will tell if it was a good decision or not :)

Worth having a go myself anyway.
Cheers.

Wimma wrote:

---

Thanks BaldEd, sounds like just what I'm planning!
Not a bad idea to grab a multimeter and do some tests too, as mine is a new vehicle (since Nov) so unsure if it's smart also. Might call holden and see what they say too ... and I just did, and mine apparently DOES have a smart alternator. Bummer.
Would love some more details of your setup anyway if not too much trouble - what VSR did you use? And all cabling, connectors/plugs?
Where did you get it all from?
Sounds like I have to find a revised solution.

Have seen where to mount the VSR in engine bay (some come with a very handy L shaped bracket to suit too) but I'm yet to work out how to easily get some cables through the firewall and through the cabin - was going to try and snake along under the plastic moulding on the floor next to the door, else go your route and put underneath the vehicle.

I did want to put some cabling into the rear left of the cargo bay, where you can easily unclip the cup holder and get access to the existing cable runs for lights/cig lighter socket, so thought connections there to second battery might be the go. Ideally need something from there to rear of vehicle for plugging in solar too though.
But I also need a couple rear anderson plugs (van & ESC), and underneath from main battery might be best there.
I did talk to an autoelec, but $100/hr for 8+hrs got shot down pretty quick. Ouch. Happy to at least run the cabling myself if I can. Sadly I also need a 12 pin flat to match the new van (currently have a 7pin), so may need to consider some help anyway.
Thanks again for the info.
Cheers.

---

 Hi Wimma,

Sorry for the delay - I've been away with the van for a few days. The new 12v supply to the fridge worked just dandy.

To answer your questions. I bought the VSR, the 7m of 6AWG twin cable, a 50Amp Anderson socket mount (screwed to the tug's back 'bumper' alongside the tug's 12 pin socket),  and a 50A Anderson plug (fitted to the van's fridge wires). I bought all the above from Jaycar. I also purchased 6m of 16mm corrogated split tubing to give further protection to the twin core cable during it's run underneath the Colorado7 from the rear of the vehicle to the engine bay. 

I didn't bother trying to pass the twin core through the firewall and along inside the vehicle. I believe in the KISS principle. This cable is solely to provide fridge power. To get the cable from one end to the other,  I removed the spare wheel and ran the cable along the bottom of the vehicle, as high up as I could, zip tying it almost every 30cm. I followed the wiring loom that is on the left side of the vehicle that goes high over the rear axle and then passes between the driveshaft and the fuel tank and zip tied to all convenient points. The cable comes up into the engine bay following the 3 or 4 small diameter metal pipes (brake lines?) there. Thus the twin core enters the engine bay right close to where I have bolted the VSR (on a small bracket I made for it). The bracket is bolted to those 2 captive nuts to the rear of the battery. It probably took me the best part of a day to thread and zip tie up the cable, but then my labour is cheap. I used a pair of ramps on the left side to give me crawl room.

Be aware that you need a proper heavy duty crimper to crimp 6AWG cable. I soldered the rear Anderson 50A pins (both tug and van) but got my local auto leccie to crimp up the earth lug and the VSR +'ve lug at the engine bay end. Cost me $20 and he provided the lugs.

The van's fridge had been wired to the pins 9 & 10 of the 12 pin plug, with all wires enclosed within a plastic sheath leading from the A-frame. I removed the sheath, extracted the 2 heavy fridge wires and resheathed the 7 pin wires. I used an old bike inner tube to sheath the fridge wires.

All the best.

Wimma,

I have a waterproof, 30A inline Maxifuse between the battery and the VSR. The rubber Maxifuse holder comes pre-installed in a short length (approx 30cm of 8AWG cable). I cut the cable so that fuse holder was central. The length of cable was just long enough to reach from the battery +ve terminal to the input side of the VSR, mounted on that little metal bracket I made. Phew! I soldered the lug at the VSR end as my crimper was not really man enough to crimp 8AWG lugs. The battery end I left for the auto leccie to crimp, when he crimped the 2 x 6AWG lugs to the twin core cable under the bonnet. I also got him to connect the fuse cable to the battery +ve, as I couldn't get the +ve battery protective cover off - I was scared of breaking something. The fuse I didn't put in the holder until after everything was in place. The only thing the VSR controls is the fridge supply.

To keep to the KISS principle I didn't bother with connecting the VSR to the ignition switch (the VSR comes with contacts & instructions that allow this). Thus, after engine shutdown the fridge will draw from the tug's battery until the tug's battery voltage drops down through 12.8v. It can take quite a few minutes for the battery voltage to drop down through 12.8v. With the normal resting tug battery voltage being around 12.5v there is no danger of not being able to start the tug engine, if one stops en-route for a meal. Once at my destination I disconnect the Anderson and fire up the 3 way fridge on gas.

When I first got the C'7 I got an auto electrician to wire the vehicle up for the Jayco 12 pin socket and connect up the brake controller I had (Tekonsha P3). If I was doing it again I would use a Redarc Elite Pro controller as it would be easier to mount, and be less of a danger to my left knee.  The brake controller is powered through a 30A auto-reset CB.

My new Jayco came with the  AL-KO ESC already fitted - powered through the Jayco 12 pin plug.

If you are running 2x 6AWG cables then run them separately - to retain flexibility. There is not a lot of room beside the fuel tank, so the cables will need to be stacked along there.  The largest split protective tubing I found (at the Orange shed) was 16mm ID. The 6AWG twin core is a tight fit in that tubing. You will need 6m of tubing for each cable. Place the twin core within the tubing before you start threading the cable(s) along the bottom of the vehicle. I recommend you start at the back and thread forward, zip tying as you go. Leave plenty of spare cable at either end. Note that the cable's -ve earth termination is quite a way forward - I used the one near the front of the battery (below the horn).

Cheers.

Wimma,

Regarding whether or not your vehicle has/has not a smart alternator I'd do my own checks if I was you rather than rely on the local Holden dealer. At least that way you will know. The checks can be quite easily performed as I  stated in an earlier posting. You just need a multimeter - easily plugged into one of the 12v sockets. Then you will see the voltages produced by the alternator as you run down the road. My alternator drops down from just after engine start to give a steady reading of 14.4v as I cruise along.

Cheers