large battery banks

[hinoranger]

It's been awhile since I discussed my project- a camper on the chassis of a fairly large commercial truck, so I may have to back up at some point to explain my rationale for this idea- but, other than size and weight- any thoughts as to the drawbacks of using a large bank- say, 6 or so- of deep cycle batteries instead of a larger on-board generator?

Right now, I have a Honda 1000i. For the same money, I probably would have been better off with the less-refined, noiser, and heavier Coleman model (2 or 2.5k, I think) but it's what I'm stuck with now. It has an 8a 12v output, so I woudn't mind running it 4 hrs a day or more if I could be charging a battery bank instead of just say, a radio, a few lightbulbs and
the occasional power tool.

Having a good sized battery bank might make a small windmill worth the expese and storage space.

thoughts, anyone?

[Scott Brady]

That is what EarthRoamer does, and I am impressed. They generate ~30+ amps of solar power and run a around 300 ah of battery power. No generator

The Honda 1000 is a great little generator and would be a perfect compliment to that type of system.

IMHO, you are on the right track!

[Jonathan Hanson]

Hinoranger, your idea to go battery power is a good one, but I would certainly try to avoid running a gas generator for half the day to charge them!

If I were you I'd forget the wind generator idea and go with photovoltaic panels. Wind generators of a size you could transport are very low in output at anything below a real blow. PV panels are totally reliable and have no moving parts. With 300 or 400 watts of PV power, plus engine generator charging while on the road, you should be in good shape. You'll need a charge controller for the panels to avoid overcharging and reverse current flow through the panels at night.

If you're going to install a battery bank, multiple six-volt batteries wired in series are generally more efficient than 12-volt batteries. At our house (which is off the grid), we use 12 Trojan T105 six-volt batteries wired for 12 volts, and a 2500-watt inverter. With around 1,000 watts of PV panels we have plenty of power; I run our backup generator maybe twice a year. You wouldn't need nearly that for even a big camper.

We also have a 600 (theoretical) watt wind generator, and while it's nice to generate power at night and on cloudy days, it really only augments the panels slightly. with a normal breeze it puts out maybe 75 watts at 12 volts.

[PCRover]

I agree with the idea of using batteries and photovoltaic panels. With a large truck you should have plenty of room on the roof for mulitple panels. The sizing of the bateries and panels will depend on your load and there are a lot of "system power calclators" out there to help you determine proper sizing of the system.

[hinoranger]

thanks for the feedback.

One "problem" I have is that my truck is actually sprung to carry a lot more weight (somewhere around 13,000 pounds) than I'll ever need to, unless I add a jaccuzi or start a really large coin collection. I bought the truck for commercial purposes and needed the capacity at the time. Also, the most powerful motor was only available in the heaviest chassis, so that was a consideration, too.
Ideally, it would be nice to trade the box I'm building onto a lighter vehicle, but you know how hard it can be to actually get any equity out of a vehicle by trading down. Also, 4wd versions of this truck do exist in other markets and it might be somewhat feasable to retrofit the front drive axle.
Someone in Wyoming claims to be doing exactly that with a very similar truck, a Mitsubishi.
-so the good thing about that is that an extra 500 lbs of ballast wouldn't hurt much.

Havn't done any homework here at all, but I have around 100 sq. feet of roof area available, or maybe a little more if I really need it. Can someone throw out some ballpark figures as to how much output for what kind of cost I'd be looking at?

[hinoranger]

here's a the only pic I could find easily (new HINOs have a conventional cab).
Mine has the same cab but an 18' van box in front of a 5' flatbed and is the 33,000 lb GVW.

http://cgi.ebay.com/ebaymotors/Flatb...QQcmdZViewItem

and here's the guy who's doing somthing similar with a Mitsubishi.
http://www.ruf-inc.com/aatrec.htm

I'm sure that's going to be out of my price range for awhile.

[Jonathan Hanson]

Mitsubishi 110-watt panels are 25 by 56 inches and list for about $680 each in my current catalog. Sharp 175-watt panels are 32 by 62 inches and run $1,000 each. Weight is 25 and 37 pounds, respectively. You wouldn't need nearly all your 100 square feet to get enough charge capacity. Just enough money!

[haven]

One idea I've been thinking about is an awning made of a fabric base plus a flexible thin film solar panel. Here's a web page illustrating the idea

http://www.powerfilmsolar.com/produc...bles/index.htm
http://www.powerfilmsolar.com/produc...ents/index.htm

If you're deploying a tent or awning in camp, it may as well contribute some solar power. This would only supplement a roof-mounted system, since you'd need to recharge your batteries while driving during the day.

For more conventional rigid panels, Sharp, Kyocera and BP all make 170 watt panels with 25 year warranty.

Chip Haven

[Scott Brady]

Chip,

Your idea is a great one, and Iowa Thin Film already does similar with their military line.

Regarding the while driving comment. No issue there, as the alternator charges the batteries while driving.

Oh, and I use the Power Film panels and love them. I just need to buy more as I am a gadget freak and need more power

[hinoranger]

"You wouldn't need nearly all your 100 square feet to get enough charge capacity. Just enough money!"

verrry funny...

maybe if I plant soybeans on my roof, I'll have my own portable source of biodiesel, too.

Seriously, I'm going to do what I can with solar but for the cost of two solar panels I can buy enough fuel to run my Honda year and have enough left over to buy a new generator when I wear this one out!

I'll think about it, though.