We used to have a folding 300 Watt solar array which consisted of two 150W panels. The problem with the array was 'weight' it was heavy and cumbersome getting it out of the trailer or packing it away. When I made the DIY pool solar water heater I split the panels using one to power the water heater. The other remained with the trailer.
There's little point in mounting the panel permanently on the trailer as only "Mad Dogs and Englishmen go out in the Midday Sun". The trailer gets parked in the shade under a tree. Not the best place for a solar panel! I made a long (10 metre) extension lead for the panel using the old electric lawn mower cord.
I've always wondered if the wire in the cable was of sufficient size? Today I used my homemade Watt Meter to check for voltage drop. When the meter was connected directly to the panel the voltage was 21.26V
Plugging it into the other end of the cable gave a reading of 21.19V. AS volt drop of more than one Volt would be a concern.
As a second check I used the multi-meter to check the far end.
The Voltage looks OK. Although I'll need to repeat the test with the panel under load.
I know the output from the panel is 4 amps when placed in the optimum position to the sun. That is probably sufficient to power the trailer fridge and freezer. However it's not going to power them and recharge the 120Ah Lithium battery.
This raises the issue of recharging the new Lithium battery.
5 comments :
You can only measure volt drop with load attached even a piece of fuse wire (remember that stuff) would show full voltage with no load, its all down to Ohms Law
Just checked and if the cable is 1.5 mm cross section area then it will drop just over a volt at 4 amps
Yes... you are right Brian. I confess that I got lazy and didn't bother to turn on the trailer isolator switch. I'll do that today a re-run the test.
Why not just measure the voltage drop by connecting your multimeter across the ends of one conductor on the cable when under full charge? This would require venturing out in the noonday sun however.
Don,
The issue was the lid on the trailer was closed and configured to accept the new rooftop tent and the battery was disconnected inside the trailer. I was simply too lazy to remove everything to gain access to the battery in order to complete an accurate volt drop test.
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