2011 D40 Navara 2.5, Dual battery system

[ROnEM]

POD,

Exactly how I have mine set up - works a treat as I have a LC200 with "Smart Alt" and two (2) factory fitted batteries behind each headlight, just connected with a "big" cable between them. My auto elec says they have to run two batteries just to kick the thing over!

After many beers, ideas and wiring plans, my auto elec and I finished up with the following:

For the purpose of the van and the Tekonsha P3 brake controller, all power is taken from the battery on the driver's side.

Brake Controller:
The P3 brake controller +ve is connected via 20A auto reset circuit breaker and 6mm cable to the battery's +ve terminal.
The electric brake voltage feed "blue cable" is again 6mm from the brake controller and feeds back to pin 5 at the 12 pin plug. The thin blue wire in the factory loom is not used, but not removed from the loom, just disconnected at the rear plug.

To charge the van batteries:
There is a twin core 6B&S cable running directly from the +ve & -ve battery terminals to the Anderson Plug at the rear. There is 50A auto reset circuit breaker and low voltage solenoid mounted near the battery. In the van is a CTEK 250S Dual DC-DC charger that is connected directly to the Anderson Plug to charge the 2 x 100AH Gel batteries in the van.

To power the 150Lt fridge:
There is a single 6mm cable directly from the +ve terminal on the car battery, via the same low voltage solenoid and 50A auto reset circuit breaker as the Anderson Plug.
This is connected to pin 9 on the 12 pin plug.
There is a 6mm earth from pin 10 of the 12 pin plug to the main chassis rail.
Voltage drop to the fridge is now only 0.6v and it keeps the drinks super cool.
Contemplating connecting it directly to the van batteries via a low voltage solenoid, but it works really well as it is.

To recharge the breakaway unit battery:
Pickup the 6mm +ve from pin 9 and loop a short 6mm to pin 2

To improve other earth lead:
At the vehicle's 12 pin plug, disconnect the thin factory loom white earth cable from pin 3.
Replace with 6mm and earth to the main chassis rail.

Off Grid:
6B&S cable connected from one of the van’s 100AH Gel batteries to a red Anderson plug at the front of the extended draw bar.
200W 10.4A solar panel to recharge when off grid and sunny.
2,500W (5,000W Peak) Pure Sine Wave Inverter connected to both batteries to run the express/cappuccino maker and other AC appliances as required. Happy wife = great trip
Red Anderson Plugs used so as to avoid accidentally connecting the wrong things together.

Have always driven with head lights on, even when not towing - Just habit!

Hope this helps others with some ideas.

Cheers,

Rohan

 

[boots33]

OK, so to combat these so-called "smart" alternators, why can't we "dumb" it down? Here's my idea/plan: if you run the positive power from the starting battery (instead of the alternator) to the relay, which then goes to the auxiliary battery, why won't that work? You are taking voltage from the starting battery, the alternator will sense a drop in the starting battery's voltage and then increase its output to the starting battery, which will then charge the auxiliary through the relay.

Hi Pod
It will make no difference to the charge rate whether you take your power from the start battery or the alternator. The problem is related to the fact that smart alternators rely on more than just the current state of the battery to determine their rate of charge and also generally have a lower float voltage setting as well.

Also, has anyone actually run a volt meter on their starting battery to make sure that what you are being told is the truth and not just some guys attempt to up sell you a new whiz bang dc-dc charger??

If you have a look at some of the four wheel drive and van forums you will find a lot of discussions on this subject, so it is a real issue for many people. A lot will depend on an individuals style of vaning. For example if you charge the van battery before you leave and your type of trips usually consist of a few hours driving and then a stay at a van park on 240v you may well have no problems at all. On the other hand if you were a heavy power user and travelling around oz with lots of long runs and off grid stops you might need to look at dc-dc chargers etc. Also there is no real standard to smart alternators so units from different manufactures will likely not behave the same.

 

[POD]

Hi Pod
It will make no difference to the charge rate whether you take your power from the start battery or the alternator. The problem is related to the fact that smart alternators rely on more than just the current state of the battery to determine their rate of charge and also generally have a lower float voltage setting as well.

Hi Boots,
Was wondering how long it'd be before you weighed in on my post!! (Please, no offence!) So if my ScanGuage is saying that I'm getting 14.0 to 14.2 volts charge at the battery then surely I won't have an issue. Is it possible I DON'T have a smart alternator?? How do you find out? I have a brand new 2012 Navara ST-X V6 , if anyone knows??



If you have a look at some of the four wheel drive and van forums you will find a lot of discussions on this subject, so it is a real issue for many people. A lot will depend on an individuals style of vaning. For example if you charge the van battery before you leave and your type of trips usually consist of a few hours driving and then a stay at a van park on 240v you may well have no problems at all. On the other hand if you were a heavy power user and travelling around oz with lots of long runs and off grid stops you might need to look at dc-dc chargers etc. Also there is no real standard to smart alternators so units from different manufactures will likely not behave the same.

I had heard of the Ranger guys having issues but I still can't see how the alternator will not charge if it senses a drop in the starting battery's voltage. Its like the government and their up-the-@r$e surplus. It just doesn't make any basic sense.

 

[Feldty]

OK, so to combat these so-called "smart" alternators, why can't we "dumb" it down? Here's my idea/plan: if you run the positive power from the starting battery (instead of the alternator) to the relay, which then goes to the auxiliary battery, why won't that work? You are taking voltage from the starting battery, the alternator will sense a drop in the starting battery's voltage and then increase its output to the starting battery, which will then charge the auxiliary through the relay.

I know it sounds too simple but why won't that work?

Also, has anyone actually run a volt meter on their starting battery to make sure that what you are being told is the truth and not just some guys attempt to up sell you a new whiz bang dc-dc charger??

Hi Pod,

I had my setup exactly like your suggestion and my dual battery was never fully charged. It in fact sulpherized my AGM and probably halved its life according to a local Auto Electrician. I needed to put it on a rejuvenation charger to get a decent capacity back which touch wood seems to have worked.
The really hard thing for me to understand was that every time I pulled over and had the vehicle idling, it would be charging the dual battery at 13.4v ???? it was only when I checked it while driving that I noticed a drop back to 12.2v. The local Nissan dealer did not even have any specs on the alternator etc that could help me with the problem.
While the coin was frustrating, I am very happy with my setup and in particular the DC-DC charger. It simply take the guess work out of it.

Kev.

 

[boots33]

Hi Boots,
Was wondering how long it'd be before you weighed in on my post!! (Please, no offence!)

None taken, we are too laid back on this forum to get in a tizz

So if my ScanGuage is saying that I'm getting 14.0 to 14.2 volts charge at the battery then surely I won't have an issue.

If you are getting 14v then you should be ok. But remember that smart alternators will usually go onto boost mode for a while after the vehicle has been started and deliver a higher voltage so you should try and check the voltage after you have been driving on the open road for a while. It's when they cut back to cruise mode that they reduce the voltage.

I had heard of the Ranger guys having issues but I still can't see how the alternator will not charge if it senses a drop in the starting battery's voltage.

The alternator will ramp up it's output to try and cover any extra load it detects but don't confuse amps with volts. The problem is that once the alternator goes into it's cruise or float mode it will deliver all the amps your vehicle needs but only at a maximum voltage of around 13v. this is to reduce the amount of drag the alternator places on the engine