Charging the house batteries

[Mock Tender]

Looking for a simple method to charge the camper house batteries while driving.

We just got off a boat that I had set up to charge the 930 AH of house batteries through either 6 x 140 watt solar panels (could get up to 55 amps per hour at high sun (tropical) or 150 amps per hour charge from generator via two chargers or maintain batteries charge while motoring with the excess from stock alternators.

Since we will be predominately in the northern latitudes, the two smaller solar panels I have will not be enough and I would rather not use a generator except when absolutely necessary.

So has anyone used successfully any other numerous options out their for charging the house batteries once the truck batteries are full?

Mark

 

[pugslyyy]

I have a second alternator for my house batteries, completely separate from the truck system.

http://shop.advanceautoparts.com/p/toughone-alternator-remanufactured-120-amps-p7814-4.3/3100324-P

It's a near a universal size as you can get - cheap and easily replaceable.

I have a heavy duty Blue Sea 1, 2, 1+2, Off switch that allows me to bridge the house/start batteries in emergencies (failure of a bank or an alternator)

 

[702krawler]

I charge off the alternator running a 7-pin connector. It works great for me, but my trailer only has ~120 AH battery in it, and my tow vehicle even less. You'd probably have to do a lot of driving to fill 930 AH, but then again, it probably never gets close to empty.

I have a solar charger, but haven't used it since going to a 7-pin connector. I'm never in one spot long enough for it to be needed.

 

[DiploStrat]

If you look in the 12v forum, you will find this subject done to death by many, including me.

I charge a 600AH AGM battery bank off of my truck alternators using properly sized wire (100+mm2) and an intelligent relay. Been working well for over a year.

 

[702krawler]

DiploStrat, what is the purpose of the relay?

 

[dlh62c]

Are your house batteries and the vehicle's battery the same type?

Yandina LTD has a battery combiner that should work if their not.

Instruction pages can be found here.

 

[Mock Tender]

702krawler-I am only going to have about 350 to 400 amp hours on the FG- the 930 was on the boat.

Pugslyyy- how hard was it to mount the extra alternator on the FG? What size belt did you need to go to? Also, how are you controlling charge amps and over charge?

Mark

 

[702krawler]

Mark, my apologies. I misunderstood you initially. I assumed you were towing a trailer when I heard "camper". I would imagine there is probably a way to hook the house batteries up to your tow wiring (which will only be active when the ignition us on, assuming the Fuso has such wiring). Then, if you don't get the performance you need, I'd look into additional alternators and/or solar charging.

Really will come down to how much driving you do each day, and of course what your daily draw down is.

 

[702krawler]

And now that I've had my coffee, DiploStrat's comment about a relay makes sense, since that is what the tow wiring uses to cut power to the trailer when the vehicle ignition is off.

 

[dwh]

So has anyone used successfully any other numerous options out their for charging the house batteries once the truck batteries are full?

Unless you do something to run it down, the truck battery is pretty much always full. An intelligent relay is just a computer controlled solenoid (split-charge relay) that will wait until the truck battery reaches a certain voltage (recharged after starting) and then ties in the house battery to charge it off the stock alternator.

That works quite well for a lot of people. I can't see needing a second alternator except under certain circumstances - if one alternator just isn't big enough, or if the chassis accessory loads are pretty high and consume too much of the stock alternator's output.

 

[pugslyyy]

702krawler-I am only going to have about 350 to 400 amp hours on the FG- the 930 was on the boat.

Pugslyyy- how hard was it to mount the extra alternator on the FG? What size belt did you need to go to? Also, how are you controlling charge amps and over charge?

Mark

I have a Balmar MC-612 multi-stage regulator with temperature compensation - it is programmed to charge the AGM batteries appropriately. I have 840AH of AGM batteries (over $2000) and for me having a completely separate system that charges them exactly the way they like makes the most sense.

Nice thing about the Fuso is there is plenty of room to bolt extra stuff on to the engine.

 

[calicamper]

I guess it depends on how much power consumption you have and how often you need to charge vs solar power catching up or falling behind etc. I have a sailboat and the money I invested in the power system is considerable but not having power on the water can be a pretty big issue in some cases. Pending the cost for the truck set up I would probably consider just a cheap little suitcase sized generator if I really needed to charge the house often. Those little generators these days are cheap and really quiet granted you would need to haul it though.

Run time vs charge load we talking charge while on the road driving or say charging while idling in the camp spot? The typical alternators on autos are pretty low output so the idling while sitting in the camp spot probably won't work too well vs a drive to the next location. So either going bigger primary or adding a second unit on a stand alone house system seems like the most likely approach.

 

[LeishaShannon]

We installed a 130A (@24v) alternator from www.rapidpower.com.au to supplement the 1200W of solar on the roof and 400W of portable solar. We didn't want to carry a generator and the sun doesn't always shine.
As we're using rather picky Lithium batteries the alternator has a pot on it to adjust the voltage set point and an external switch so the battery management system can shut down the alternator when the batteries are full. I also have the ability to switch off the alternator from the cab when we're approaching big hills as the drain on the engine is noticeable when the alternator is pushing 3.5kw into the batteries.

 

[DiploStrat]

Beaten to Death

This site is about the deepest that I have found on the challenges of charging two sets of batteries: http://www.smartgauge.co.uk/facts.html

You want to combine the batteries whenever there is a charge to either. Typically, this means engine alternator to the starter battery and shore or solar to the camper battery.

You want to separate the batteries whenever the discharge rate of either exceeds the recharge rate of either. This is especially important if you use a starter battery and a deep cycle battery, as you should.

The rest is details of execution, important, but details none the less.

You can read about what I did on my website.

 

[Mock Tender]

Thank you one and all- lots to read.

I like the alternator idea the best- except when we sit somewhere for long. Then the generator seems to make sense. But, even more so than a boat, space is more limited.

Mark