Had a new thought about charging

[Q]

On the idea that a solar charger will charge even on a cloudy day. Current output is miniscule without full sun. Monocrystaline and polycrystaline module output will go to near zero if even a single cell is shaded. Amorphus modules do a little better at partial shading but are less efficient and don't last as well.

Anyway, the 43 watt solar panel on my teardrop is the only way the battery gets charged. I have no charging wire from the tow vehicle and don't haul a generator. Works great in the Oregon desert.

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[TomS]

I don't think solar is a viable option for me. I prefer shaded campsites. Also, a solar system with reasonable charging capacity is much more money than I care to spend.

[Q]

Powderburn asked about adjusting an alternator to charge slower.

Alternators that use external regulators are easy to adjust. They require 3 electrical connections. One is the wire that goes to the positive terminal on the battery, it is usually labled BATT. The second is GROUND and is just a place to attach a wire to the external case of the alternator and attached to the negative battery terminal. The third is the field, and is usually labled FLD.

The field connection is internally connected to the coil of wire on the spinning rotor. Putting power to this connection makes the rotor into a spinning electromagnet. This electromagnet gets stronger and stronger as you put more and more electricity into the field connection. The stronger the electromagnet, the more charging curent is put out by the alternator (at any given speed).

To control an alternator, all you need to do is run a wire from the positive BATT terminal, through a resistor, to the FLD terminal. A quick and easy adjustable resistor can be made with a piece of nichrome wire such as a heating element out of an old dryer.

You could also build an adjustable charge controller. A schematic can be downloaded from the Home Power Magazine link.

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