solar panels

Hi Scoota

I would run direct to the battery via reg placed as near bat as possble
Cable size should be ok

Scoota

1. A 120W panel facing directly at the sun should produce about 7 to 8 amps. A cigarette lighter plug will probably be ok between battery and panel, but I'd strongly recommend something a bit better and much more reliable. Cig plugs are really pretty crude. I use cannon style connectors which are readily available from Jaycar, Dick Smith etc - these provide 3,4,5 or 6 pins, each rated at 6 amps. By using 4 pins (2 for each wire) I get 12 amp capacity in a simple robust click-locking fitting. The smaller Anderson plugs are probably the best choice.

One issue with batteries and panels is the question of which one gets the male plug and which one the female (socket.) Generally speaking, the female plug should be connected to the current source. Problem is, both battery and panel are sources. Since the battery is capable of delivering the highest current, the female should be fitted there. Very important - because the battery is capable of delivering very high current, a fuse MUST be fitted right at the battery to safeguard battery and wiring, and reduce the risk of fire.

2. Wire sizes are a pain. I use twin 6mm^2 cable (copper cross section of 6 square mm) for this job. Beware of "automotive" 6mm cable - it will fit through a 6mm diameter hole, but may have very little copper inside the plastic.

3. I suggest keep the regulator close to the battery. There will be unavoidable voltage losses in the cable which are quite tolerable "upstream" of the regulator, i.e. between the panel and the regulator, but best avoided between the regulator and the battery. I'd go from the panel through the 15m cable to the regulator then through a fuse to the battery.

You might be interested in our blog Electricity for Camping which covers a lot of ground, including solar options.

HTH

John

Good advice given so far and just to confirm it .

15M of 6M2 cable with 6A would give a voltage drop of 0.616V drop so if regulator is at panel to whatever your reg is set at would be less the volt drop at the batteries.
If the panels produce more amps then that would be worse so poor charging.

If the reg is at the batteries then the voltage drop from the solar to the reg becomes a lesser problem as the VOC could be 17V + so the voltage drop still gives an acceptable voltage at the regulator which possibly would be set to 14.4V depending on what batteries you have.
Ian

scoota, as Ian has also stated, the cable will be too small, will give you a Voltage drop you don't need, as I've advised you previously use larger capacity cable, but looks like you don't want to hear that because you start a new thread and ask the same question again when it's been answered previously.

1. Definately DON'T use a cig lighter plug
2. definately NOT thick enough
3. Attach the regulator near the battery

Maîneÿ . . .