Camper Trailer Battery Management?

[AK7 Senior Member Find all posts View Profile Close AK7]

My parents bought a used camper-trailer and want to be able to charge two batteries off the car, as well as solar and maybe 240V mains. Their 150 Prado currently has an isolator with cables (I think) 6B&S to an Anderson plug at the rear for the trailer, which essentially goes directly to the batteries in the camper. They say it charges the batteries when they do long drives. My biggest query is how safe this is... Pretty sure it's a bad idea to charge three batteries off the Prado's alternator. I know it's certainly not an efficient way of charging, but what are the risks? I'm led to believe that this setup could be made safer, more effective and probably easier to manage with a DC-DC charger in the camper. I was thinking that if the big battery's max charge rate was over 25Ah, a good option might be the Redarc BCDC1225?

The camper currently has:

• ~100Ah lead acid battery (waiting confirmation on brand/model) plus
• 85Ah Fullriver AGM (30A max charge rate)
• SCA 240V to 12V/10A battery charger (via a 240V 15A plug on the side of the trailer)
• Volt & Amp Meters (ABR-Sidewinder)
• Tons of 12V accessory outlets around the trailer - very handy!

As for solar, they already have portable low-current solar panels that they use for their little 35Ah Waeco batteries. The solar panels use alligator clips to connect to those batteries. I was thinking maybe sacrifice a 12V accessory sockets on either side of the camper to use as DC input to the BCDC unit (identifying them with red traffolyte labels stating "Solar Input Only") and then change the alligator clips on the solar panels to 12V accessory plugs (and use a fly lead for charging the Waeco batteries - 12V accessory to alligator clip). Or would it be possible to just put an Anderson plug on the solar panels and connect them to the Anderson plug on the trailer (where the car connects to the trailer)? Woulde definitely be easier.

I want to be able to write a note that they can present to an auto electrician and say "this is basically what we want - do it".

Hoping LeighW and drivesafe cast their eyes over this thread, although I know Derek will be cringing at my lack of correct terminology! Hope he can see past that and offer his expert opinion

[Guest Close Guest]

There shouldn't be any issues charging 3 batteries off the alternator. You will need to replace the cabling throughout to 6B&S as the typical 6mm cable is not adequate.

Is there a regulator in the solar panels? If so it can be connected to the battery. If not, you'll need to connect it via a DC-DC charger.

Depending on the wire gauge of the accessory sockets, it might not be enough to connect a charger through it. Easiest would be through the Anderson plug at the front of the trailer as you mentioned.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Charging 3 batteries off the alternator is not a problem, I have been doing it for years.

I also have 6mm2 wiring to my camper battery. I read all the time how this wont work, but it seems to have worked for me foe the last ten years

Cheers Andrew

[AK7 Senior Member Find all posts View Profile Close AK7]

Sorry - I meant 6B&S. I'll correct that in the OP. It's shit how different industries in Australia rely on different standards for the same bloody cable...

Yes, the solar panels have a cheapo yum-cha regulator. I just remember reading something Leigh said about not trying to charge three batteries off the Prado 150 alternator... Will try and track it down. I'm guessing it's probably related to voltage drop resulting from inadequate cable gauge for length it runs and current it carries, relative to what the batteries should be getting in order to fully charge.

Wire gauge (and terminations) to each socket is more than sufficient for 12V 10A load. The solar panels also supply well under that amount of current.

[AussieAndy Find all posts View Profile Close AussieAndy]

I was talking about this very thing about 3 weeks ago in regards to a new install in a friends camper. Was told if money isn't an issues, and you want the best these are very hard to look past.
http://www.redarc.com.au/products/product/themanager30/
I have no direct experience with these, but if they are like any other redarc product it will be great quality.

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

I was talking about this very thing about 3 weeks ago in regards to a new install in a friends camper. Was told if money isn't an issues, and you want the best these are very hard to look past.
http://www.redarc.com.au/products/product/themanager30/
I have no direct experience with these, but if they are like any other redarc product it will be great quality.

yep this is the way to go if $ allow
best of all worlds 240 V mains, 12 V from car or solar in one unit.

Next setup I would go this way.

[AK7 Senior Member Find all posts View Profile Close AK7]

Was told if money isn't an issues, and you want the best these are very hard to look past.
http://www.redarc.com.au/products/product/themanager30/

At $2,000, it's a tad steep just to charge two batteries in a camper. Aside from 240V input and a display with a comprehensive range of information, I'm struggling to see what benefits it has over the BCDC1225. As mentioned, they already have a 240V charger.

[AussieAndy Find all posts View Profile Close AussieAndy]

At $2,000, it's a tad steep just to charge two batteries in a camper. Aside from 240V input and a display with a comprehensive range of information, I'm struggling to see what benefits it has over the BCDC1225. As mentioned, they already have a 240V charger.

Damn straight it's expensive, but it is the ducks guts apparently!

It also can charge from solar and other power source at once, automatically switches between them dependant on power supply to the unit rather than being told where to draw its source from like the bcdc series chargers. So it can use all useable power from the solar system, then draw what else is needed from the vehicle, thus taking some load (however small) off the alternator/vehicle. It also has a better battery condition monitoring system than the bcdc series chargers, so should charge the batteries better (once again small but a difference none the less).

Not saying I could justify it, but it is out there and supposedly a great system.

Now back to the real world, because it has two batteries wired in parrallel the max charge rates can be added together, thus a BCDC1240 could be used. I would change the ends on the solar panels to Anderson plugs and yes they can just be plugged in to where the vehicle is plugged in, just remember to not set it up to plug them in when the vehicle is still plugged in without a relay isolating one from the other. The BCDC just uses a change over relay to switch between vehicle power supply and solar power supply, it is the same input to the actual unit.

So, if they are happy with the current 240V charge system, install a BCDC1240 to charge both from the vehicle and solar using the same Anderson plug.

[AK7 Senior Member Find all posts View Profile Close AK7]

From what I've been reading, if they're getting 13.2V or higher from the car's Anderson plug, all they'd need to do with the current setup is slap a relay in to isolate the camper's Anderson plug when the 240V charger gets turned on. The idea with that is that there's no backfeed if they have the solar panels or car connected at a powered site. No need for a BCDC either if that's the case.

As for the BMS, the BCDC1225 also has solar input, but switches to solar via an external changeover relay. I suspect ultimately the BMS1230 would use the same method internally, though for a $2000 unit, you'd expect it to analyse the solar current before switching. Regardless, the end result is the same. As you say - back to the real world I reckon that two grand would be better spent on other stuff. Camping gear, car mods, etc...

I think I'd prefer to stick with the lower output BCDC, rather than using one matched to the combined max charge rate of the two batteries. At least that way if one battery fails, the charger isn't too powerful for the remaining battery.

[Redsand Junior Member Find all posts View Profile Close Redsand]

On my hard floor camper I have a 80w solar panel mounted on top which can be removed easily, as I drive it charges the camper battery.
I have it mounted so it can stay fixed to the underside of the floor when the camper is erected. I don't bother taking it off if I'm only staying one night.
The panel is connected to the solar controller / battery in the camper via a Anderson plug.

I also have a second battery is in the rear of the Prado where the fridge is mounted, this battery is charged by the alternator via a isolator.
If I'm in one spot for a few days I can connect the camper and second Prado battery to the solar panel and charge both.
Good not having to worry about running the car to keep the batteries charged.

The solar panel also charges the batteries to a higher percentage than just relying on the alternator.

If I'm not taking the camper I can mount the solar panel on top of the Prado and swap the solar controller from the camper into the Prado to charge the Prado's second battery.

I find this setup good as it gives some flexibility

[AK7 Senior Member Find all posts View Profile Close AK7]

Thanks for the input Red I'm looking into solar panels for my own setup too. My folks already have portable solar panels that they pack into the camper (or into the car if they ditch the camper) and swear by them. They can move them according to where the sunlight is best. Quick and easy. Just need to remember to clean them