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Xplorer / GRX offgrid setup

Posted: 13 Mar 2019 17:27
by IR_Eddie
I have new Explorer (2019) which I tow with my Patrol 4.8 GRX. I need some assistance and advice in order to go off-grid while camping. I know there is a lot been discussed on this before but to be honest I'm even more confused than before after reading few threads. (This is obviously not my speciality).

Caravan is stock standard as it comes from the Factory - I've added only 1 deep cycle battery

Patrol have various mods (purchased it like this and did not do any of them myself). I’m not sure if a dual battery system was fitted (I know it only has one battery currently) however it has got some wiring and a Harrison plug at the back underneath the bumper.

I spoke to 2 x sales men and they gave me conflicting information. Please assist with the following:

  • How do I know if I have a duel battery system fitted or if the plug at the back is connected directly to the battery?
    If it is connected directly - can I use it like this safely?
    What must I look for under the hood to ensure the correct safety systems is also fitted
    if a battery management system is not fitted how do I know the caravan will not drain my starter battery - I see some people connect it to the ignition as well?

  • Is the standard factory fitted inverted and battery management system:
    Safe for DC to DC (Car to caravan)
    Solar ready
Solar setup
  • I intend to run the 90lt fridge freezer, caravan LED lights, ice machine, coffee machine (in the mornings), charging of phones / tablets
    Do I need an additional battery for long periods camping – if so, do I need anything else fitted other than the additional battery and cables to do this?
    What size panel is recommended for running this setup
    Some advice on the effectiveness of putting the Solar panel on the Patrols roof rack while driving rather than connecting it to the vehicles system (as an alternative to fitting a duel system on my patrol if it is non-existent)

Thanks in Advance (please don’t use acronyms in your replies as I don’t know the jargon for these)

Re: Xplorer / GRX offgrid setup

Posted: 13 Mar 2019 18:02
by Peter Connan
With regard to the car's system, unfortunately there is no shortcut. You need to crawl under the car and follow those wires from the Brad Harrison under the rear bumper to to see where they go.

To my mind, you want them to go directly to the power output of the alternator (the little screw where the thick cable going to the battery is connected) or to a bus-bar (just a sort of a multi-connector with bolts/screws into a copper or brass bar) to which the cable from the alternator is mounted, with just a heavy-duty fuse in between. One of these: ... U4QAvD_BwE

The negative wire should go to a common heavy earth, or to the engine.

If there is anything else in these leads, it's probably best to remove them. And while you are busy, make sure those wires are routed somewhere where they can't get pinched, bumped etc.

Whether or not the charging system in the trailer will drain your car's battery determines on that charging system, not on the wiring on the car.

With regard to using a solar panel on the car's roof while driving, forget it. You can't fit enough solar panel there to get even close to the power your car's alternator can produce.
And if you want to use it while the car is not running, then that means the car has to stand in the sun, which is to my mind a bad idea.

Now with regard to the van, I unfortunately have no idea what is fitted to those.

To my mind, you need to start with the battery or batteries. They are what determines how much charging capacity you need, at what voltage and how quickly the system will re-charge and thus how long it will last in real terms.

Unfortunately, the only way to really figure out what you need is to do some maths. Unfortunately there are many things that will complicate these calculations, such as how hot it will get where you camp, and how many days at a time it is likely to be cloudy, and how often you open that fridge...

Re: Xplorer / GRX offgrid setup

Posted: 13 Mar 2019 19:01
by IR_Eddie
Great thanks. It seems there a solenoid and the fuse fitted. Also traced the wite to another harison plug hiding in the boot.

It seems it will be a easy setup from hereon.

So will this sytem prevent the car battery from being drained when car is switched off?

Love my Car more and more :woo:
06BAF571-F68D-44EA-A082-D765C4410DD3.jpeg (2.11 MiB) Viewed 391 times
F9F65048-1885-42E7-943A-786D5A462FD9.jpeg (3.28 MiB) Viewed 391 times

Re: Xplorer / GRX offgrid setup

Posted: 13 Mar 2019 21:56
by NoPressure
Hi Eddie

Congratulations on your purchase(s).
I would like to mentiom something with regards to the power management for off grid camping.

Like Peter said you will have to calculate your power needs. You say this is not your field, but I'm unsure how indepth the explanations must be. So excuse if its too simplistic or even too complicated. First thing I want to say, is get something that you can use to measure the status of your battery - it is VERY important, because knowing. :think:

Some of the things you mentioned that needs to run/charge will have an indication on them what amps (A) they draw. Some will indicate Watts (W). The math goes as follows Watts = Amps x Volts. Everything is 12V. Your battery will have an Amphour (ah) indication on it ( for example 105ah).

Step 1:So convert all your power needs to Amps and then multiply those amps with the amount of hours they will draw power. Example: fridge draws 5amps for 12 hours = 60ah. Then add all these ah together.

Step 2: Now in a perfect setup your deep cycle battery must not discharge lower than 50%, example 105ah/2 = ~52ah. You did not mention which type of deep cycle you have. This will affect the info a bit.

Step 3: Go on the deep cycle manufactures website and look on the fact sheet to see how much amps your battery can charge at (max and min). (There are different phases of charging, but that gets too technical). Say for example its max is 8amps. Thus your deep cycle can only charge at 8amps per hour irrespective of the amount of amps your are sending to it (the regulator will regulate this). Again I'm only trying to help you calculate your power need and not your setup.

Step 4: Determine your minimum amount of charge (hours) you need to meet your ah "hunger" whilst only using 52ah(example) of your deep cycle battery. Please remember that you actually want to replace all the charge back into your deep cycle for the next day. When your voltmeter shows your battery is putting out 12volts, then you are in trouble, as 12volts indicate ~ 45% power left in the battery. Try and keep it atleast above 12.1volts (anywhere 12.7 volts and up is full - depending battery type).

Step 5: Is your charge supply enough. If you only have alternator - how long must you drive ( and when). If its solar, how much charge must it produce (sun availability).

Step 6: Your answer...well sort of.

This post is now long winded, if you want me to tell you what setup I have (regarding power charge need and supply I will post it for you).

Enjoy the math.

Re: Xplorer / GRX offgrid setup

Posted: 13 Mar 2019 23:00
by Peter Connan
The fuse is good, but take that solenoid and throw it as far as you can. Those things waste power when they get old.

The setup of the charging system in the caravan must be such that it either only accepts power when the car's engine is running, or if there is more than 12.8 Volt available. Either way will protect the car's battery.

Re: Xplorer / GRX offgrid setup

Posted: 14 Mar 2019 07:07
by Pieter B
I see you also intend to run a coffee machine and ice maker. If these are still 220V you'll need an inverter and probably a big one and a pure sine wave one at that.

Re: Xplorer / GRX offgrid setup

Posted: 14 Mar 2019 08:52
by Oetie
Peter Connan wrote:
13 Mar 2019 18:02

To my mind, you want them to go directly to the power output of the alternator (the little screw where the thick cable going to the battery is connected) or to a bus-bar (just a sort of a multi-connector with bolts/screws into a copper or brass bar) to which the cable from the alternator is mounted, with just a heavy-duty fuse in between.
My apology in advance if this is a hi-jack of this thread, but I would like to learn more about the wiring connected directly to the alternator and not the main battery in the engine bay? That is if I understand Peter correctly....

Should one do this only for charging a trailer whilst driving, or also for a second battery fitted in a vehicle? And if so for the second battery fitted, without a solenoid or switch will the second battery still drain the main battery when the vehicle is stationary and the engine not running?

Re: Xplorer / GRX offgrid setup

Posted: 14 Mar 2019 09:38
by IR_Eddie
I checked the manual and it does not say anything about solar but mentions that the system can be charged from the towing vehicle if fitted with a charging system. I noted that the van is fitted with a Hercules 20 power pack. Any inputs or advise on these systems? I see the unit is basically just a battery charger combined DB board and not an inverter - this is a bit disappointing.
Does anyone know if this system is solar ready (I know I need an inline regulator but the sales man said I need to also ensure the system is solar ready so that I don't damage it)

It seems the ice and coffee machines is out then when we go off grid:( - wife not gonna be happy.

Re: Xplorer / GRX offgrid setup

Posted: 14 Mar 2019 16:53
by Peter Connan
From the little bit of google searching I did, it seems like the Hercules 200 is not a very capable system. Basically just a 220V charger. No 12V charger or charge controller and no built-in solar capability.

In an off-grid situation, this will not ever get a deep-cycle (or lead crystal) battery fully charged.

Also, I don't think it has the ability to protect the car's battery either.

Honestly, throw that away too, and replace it with something like an HCdP Power Panel.

Leon, to answer your question, every piece of wire has losses. If you take the power right from the source, you lose just a little bit less...
But taking it from the main battery probably doesn't lose much.

If the second battery is connected directly to either the main battery or the alternator, then it will have the ability to drain the main battery.
There should be some type of charger or charge controller before the second battery. A solenoid-based system can do this, but in terms of keeping a second battery well charged, it is just a bout the worst possible option. It will work fairly well if the second battery is a crank battery, but if it's a deep-cycle or lead-crystal, it will fail dismally.


Re: Xplorer / GRX offgrid setup

Posted: 16 Mar 2019 14:35
by biggles
Hello IR_Eddie (we chatted on 4x4community)

I have the same system as IR_Eddie (Patrol with dual on board and an Explorer)

The Hercules 200 in my van. It charges the battery on board while driving... not very well but the alternator is not going to run 2 fridges and charge 3 batteries very effectively. The alternator just keeps everything going.

I have 180W panels on a MPPT solar controller that I plug into the caravan Brad Harrison plug at the towbar and is more than effective charging the caravan battery. Most days I will switch the panels around 2pm to charge the batteries in the patrol.

So nothing wrong with the Hercules 200. It will also charge the batteries when plugged into the mains... it has a trickle function as i will leave the caravan plugged in for extended periods and the battery stays charged.

As for a panel for when driving... I am considering plastering a flexible panel to the caravan roof. particularly when touring you may not be spending a lot of time driving or camping and then you run low on battery power. It will keep the battery topped up when spending the day doing something away from a camp.