Trickle Charging via Solar

[boutdoors]

Hello All,
I want to trickle charge two 12 volt batteries run in parallel while we are boondocking. I plan on running the overhead fan (sometimes all day), a few lights and heater at night.

1. What kind of solar wattage should I be looking at?
2. What is the best kind of solar? Mony or Polycrystalline?

Thanks all.

[idroba]

You need more than a "trickle charge" to do what you want. I would suggest at least 80 and up to 120 watts of panels. The polly panels are about half the size of the mono ones for the same output, and thus take up much less valuable roof space, especially on a 16' unit.

[Jim J]

The Current draw for the Fantastic fan is about 3 Amps on high speed

The current draw for the heater is 7 amps

Each light will draw about one amp = 12 W

Fan 3 amps x 8 hr = 24 amp-hrs
Furnace 7 amp x 12 hr x 25% Duty cycle = 21 Amp hr
Lights 5 amps x 4 hr = 20 amp hrs
refrigerator, water pump and Other stuff 1 amp x 24 hr = 24 amp hr

Your solar cell needs to put out about 90 amp hrs during the day or about 10 -12 amps during the winter, Less during the summer. That means you need A solar cell package that can generate 100 - 150 watts of power and a charge controller that can handle 10 amps. This is not trickle charge rate which is usually in the 1 to 2 amp range.

Recommend you look at not running the fantastic fan, using LED lights, buying a down comforter so you can turn the furnace temp down, and then recalculating your energy consumption so you can get down to a 50 - 60 watt requirement.

You should be able to get 50 watts in a couple of solar panels.

[DaveFL]

Originally Posted by boutdoors

Hello All,
I want to trickle charge two 12 volt batteries run in parallel while we are boondocking. I plan on running the overhead fan (sometimes all day), a few lights and heater at night.

1. What kind of solar wattage should I be looking at?
2. What is the best kind of solar? Mony or Polycrystalline?

Thanks all.

lights could be led = easy to do
fan is variable, some high efficiency could be easy, but high volume fans would need a large bank of batteries and more than a trickle charge solar.
heater = easier than an a/c but not going to happen with solar even with a max system and a large grouping of gc batteries.

And finally remember batteries will last longer if not depleted beyond 50 percent.

[Jim J]

In the picture posted on this site you will find a table of power consumption for various appliances in my Airstream. Sorry I omitted the microwave and the kitchen vent fan.

The measurements were taken using a Reliance controls AmWatt appliance load tester which can measure Watts and Amps for alternating current devices.

The measurements were made by placing the wattmeter between a 30 foot extension cord and my Airstream powercord and reading the Amps and the watts. A voltmeter was plugged in to a 120V receptacle in the airstream.

All the measurements were made on the AC power coming in to the Airstream. You can expect the actual wattage when running on DC to be a little lower because there will be no conversion losses.

Take note that the Airstream is consuming a little power even with nothing turned on. The incremental wattage column in the picture shows the extra power consumed by turning on the appliance.
Ac Power Consumption - A Table of AC power Consumption for various appliances commonly found in an Airstream. Photo Gallery