Camper Battery Setup

[pfuller Lurker Find all posts View Profile Close pfuller]

Ive recently built a small camper and bought a 2008 Prado VX 120 Series D4D Diesel to do some weekenders and a few future longer term trips.

I plan on putting a 120ah AGM battery in the van, and running an Older 40L Engel Fridge (5amp), some LED lights, water pump and car stereo off it.

From the research i've done, the below is the most cost effective setup to achieve 100% charged batteries with a decent lifespan:

*Install a booster diode to accomodate for the low voltage output of the alternator.
*Solenoid next to the crank battery.
*Run 6 B&S wire to rear of vehicle to 12-pin plug.
*Run 6 B&S wire through the camper to battery.
*Connect Engel Fridge straight to van battery.
*Install a 20A mppt solar regulator next to the van battery.
*Stick repositional/removable solar panel/s on the roof of the van.

The theory is, With the above setup i can get bulk charge into the battery plus run the fridge from the alternator while driving. The solar panels running concurrently can add to the bulk charge plus kick in at absorbtion and float stages to bring it up to 100% and maintain it. The solar regulator can also maintain the battery when the van is unused at home (outside) or a 7-stage 240v if stored undercover.


Questions:

1.\ Can the solar regulator be hooked directly to the van battery, as well as the direct alternator feed? Any protections needed?
2.\ Can the fridge be run straight off the battery effectively, while charging the van battery from the alternator feed?
3.\ Will the heavy pins (35amp) of a 12 pin plug be sufficient to handle the load from the alternator?
4.\ Should i go with one big solar panel, or a number of smaller panels?
5.\ What sort of cost-effective isolator should i get that will protect both batteries? Is a VSR really needed or can a simple solenoid be used?

Any other suggestions on tweaks to this setup welcomed.

Cheers,

Pete

[Fred63 Advanced Member Find all posts View Profile Close Fred63]

get your self a DC/DC charger for the Van, one that has solar option.
While camped you run off solar
While driving you run off the car.
Use 50A Anderson plug between van and car.
one portable solar panel >120W should do the trick.

very quick simple set up

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

Ive recently built a small camper and bought a 2008 Prado VX 120 Series D4D Diesel to do some weekenders and a few future longer term trips.

1.\ Can the solar regulator be hooked directly to the van battery, as well as the direct alternator feed? Any protections needed?
2.\ Can the fridge be run straight off the battery effectively, while charging the van battery from the alternator feed?
3.\ Will the heavy pins (35amp) of a 12 pin plug be sufficient to handle the load from the alternator?
4.\ Should i go with one big solar panel, or a number of smaller panels?
5.\ What sort of cost-effective isolator should i get that will protect both batteries? Is a VSR really needed or can a simple solenoid be used?

Pete

As suggested above a DC/DC with solar is definitely an option but you miss out on the benefit of the booster diode.

1 & 2 I run a similar set-up, except that my fridge doesn't connect to the alternator and solar reg simultaneously. Connecting the battery to the alternator and solar reg simultaneously will confuse both the alternator and the solar reg as they try to adapt the voltage to suit the perceived battery voltage. Not sure what the result of this will be.
3. It's not the pins but the cables running to the load that is the problem. You definitely want a dedicated heavy gauge cable with dedicated circuit breaker.
4. I use two match panels but the tech has improved heaps and I would just use one provided that it is not too big. Mine are permanently mounted on the roof of my camper.
5. VSR or solenoid linked to ignition, VSR is probably simpler. Not sure if you need one with DC/DC so that may be an advantage.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Your proposed setup will work fine, if you have a little electrical knowledge then you could use a relay instead of a VSR, keep in mind though that some VSR are two way, so if the car is connected to the camper you can also charge the car battery off the solar panel.

For redundancy I would stick to individual Solar/charger/car setups rather than put all youreggs in one basket, a good quality stand mppt charger will be more efficient than an all in one unit.

To get the best out of the mppt get a 12V out unit that can handle 24V or house panels. I would go for a 240W at least of solar, 120W will probably meet you needs with bright sunshine but as soon as it gets overcast you'll have problems.

If your like most you'll try to camp in the shade so portable panels with long leads are handy,
mount the controller near the battery.

You can use the heavy pins in the newer plugs but you'll have to common over a few pins. Personally I would go for an Anderson plug for the simply reason if you somehow damagethe plug, ie forget to plug it in and drag it, it a fairly easy job to replace it rather than rewire the trailer connector in the field.

[pfuller Lurker Find all posts View Profile Close pfuller]

Thanks for all the replies.

So many more questions:

* If i use a simple ignition-triggered solenoid as an isolator between crank and van battery, i believe the danger is that if the van battery is dead flat, that a current rush to the van battery could flatten the crank battery. Is this true/likely? If so, is there another supply instead of the ignition to trigger the solenoid? e.g. one that will guarantee the alternator is charging before it triggers the solenoid? (I know that a VSR is a solution to this (but an extra expense - i'm thinking bang for buck here).

* Using 6 B&S wire (rated about 100amp) for the run to the back of the car, what fuse/circuit breaker should i use? I have an ANL 100amp fuse in the shed, is this too heavy to position between crank battery and isolator? I read this 100amp fuse will only blow at around 120amp for an extended period, so is it too heavy? Some suggest an auto-reset circuit breaker, but wont this just mask any problems and be hard to diagnose?

* To separate the solar and alternator feeds, could a change over relay be used, that will use the solar feed to the van battery by default, and then switch to the alternator feed when active? Would a 60amp changeover relay be fine?

* Should i just buy a Ctek D250S + smart pass which will probably meet all my requirements (but leave me a few hundred out of pocket)? By the sounds of it, it can use alternator charging, then switch to DC-DC charging and also switch in a solar feed. (Any downsides i'm missing - except for the price?)

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Firstly, no the cranking battery will not be flattened, your only talking a few seconds until the car starts, it would take a considerable amount of time for the cranker to loose any real charge into the aux.

Secondly the van battery should not be "flat", you shouldn't discharge the van battery below 50% SOC if you want it to last any length of time.

You don't need to separate the solar, just leave the controller connected to the van battery all the time.