Winter battery use question.

[Bill in AZ]

Originally Posted by Ray Cover

Thanks for the input everyone. I talked to a friend of mine who is an electrical engineer and is really into alternative energies. After talking with him, and doing a bit more research, here is what I have decided to do.

I have an area on the tongue behind my propane tank cover for a platform the is 16" wide and 48" long. The platform will be made with an angle iron frame and an expanded steel "floor". On this platform I can fit 3 deep cycle marine batteries and a good size pwm charge controller. Two covers will be made out of FG or kydex thermal-plastic to cover this platform to keep it all out of the weather. One cover will be vented for summer use and the other will be insulated for winter use.

I will add a solar panel set up for daytime use and a small wind generator like they use on sailboats for night time use. I will get a charge controller large enough to handle having both "plugged in" at the same time.

I am also planning to get some of the 1/4" fan fold foam board insulation at the HDWR store and laminating heavy duty white tarp to each side of it and make underpinning skirting out of it that snaps on all the way around the camper.

This system should be redundant enough that I shouldn't have to use the gas generator very often if at all. Within the next few months I am going to be full-timing it in this camper so it will be worth the investment.

Again, Thanks for the input folks.

Ray

I experimented with a home brew wind generator on the salt flats in Nevada because they get REAL wind there, and pretty consistently. It consisted of a fan kit, a mast, and an automotive alternator. I had (I thought) a pretty sturdy galvanized mast (weighed a ton), but the winds got so high one night, the mast had a nice curve to it the next morning! If I were to do it again, I'd buy a ready made one, as they have automatic overspeed braking and some feather in high winds. Also, those suckers can pump out 400+ watts in a high wind...that's a lot of solar panels, and in the dark!

[blodn1]

And magnet power might be another option:

[David Tilston]

Troll face! Not many people use that logo.

[Timber Wolf]

Originally Posted by stevebaz

You may consider using a propane only Catylitic heater by day while your awake and use the furnace at night while your sleeping. That would drop your battery power consumption by 60 % or so.

That sounds like a good plan. And it would also mean having backup or redundant heating systems. I would hate to cut a nice trip short because something zonked out on me. I would still have a good detector though as I might fall asleep with the catalytic running.

[EcoHeliGuy]

First off head over to Trojan battery website and have a look at some graphs. They show the effects of cold vs hot temps. ( even if your not using Trojans this is valuable information)

Second you need to charge the batteries at a higher voltage in the cold, if your charger isn't temperature compensated your loosing capacity fast.

A 12v battery that needs to be charged at 14.6 volts but only receives 14.4 volts will never get 100% capacity. You way think oh .2 volts that's a small 2% capacity loss no big deal. But a dead battery isn't 0volts, its at 12volts. So .2volts really equals 8% and when a deep cycle should only be depleted 20-25% for long term health. You've already started off 30-40% loss on you batteries true capacity.

Now we all know a Battery is a massive dense object. If you insulated the battery box with ridged foam during an outting (painted black for winter). You could enjoy a few extra degs of held in warmth over night. The battery even produces a bit of heat during charging.

[Night Sailor]

Batteries will not freeze if the are holding a charge. The best way to keep them warm is to charge them. Solar panels work better in the cold. The ideal solution for you is to add a bunch of fix solar panels to your roof and a good MPPT controller. Sized properly you will not need a generator.

Larger and better batteries will help. These should be sized to match your charging capability.

You should have a battery monitor so you know what is going in and what is coming out. I recommend Victron as they are the best and least expensive. This will show your usage and based on that you can make intelligent decisions about battery capacity and charging capability balanced against your usage.

Another consideration is camper insulation. Your big electrical draw is your furnace. Find the cold spots and insulate them. On my Bigfoot I found gaps at the beveled corners and filled them with spray foam.



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