Jayco 2005 poptop has a battery installed under a bed, and are looking at folding portable solar blanket connected via anderson plug on drawbar to charge when 240 mains power not available
Would I need a controller/ regulator of any kind or does Jayco have some sort of management system ? I have no idea how this works but charges fine on power and while driving.
Thanks
-- Edited by Chrisrich on Sunday 23rd of January 2022 01:18:12 PM
Blankets are useless, you would be lucky to get 50% of their watts out of them, even the really expensive ones, as it is pretty hard to position correctly in the direction of the sun. But sometimes weight and availability of space for the other aluminium framed panels means you don't have a choice. I only use a 80 Watt portable aluminuim framed panel due to the weight of the bigger ones, and I religiously get 4 plus amps an hour out of it, and that's enough for my system, as before I had an 105ah battery and only ever used 8 amps a nite. Now will be going to an 40 ah, so it will work even better because my draw will be no more then 4 amps per night. You will need a regulator with it as well as an diode, so you don't get battery power being pushed back into the panels if you leave them out overnite. Their is another reason for the diode, but cannot remember what it is.
-- Edited by Bicyclecamper on Sunday 23rd of January 2022 04:36:05 PM
Will add that you need to keep air flow over the front & back of any panel. It will perform better the cooler it is. So you need to knock up a structure to keep the panels pointing to the sun & good air flow.
If a manufacturer suggest that the blanket is putting out more than 130 watts per actual square metre of cell, not overall blanket, they are using a rubber ruler, sky hooks, mirror ball & smoke. They are inefficient. Walk away.
I have 120 watt setup that puts out 7.8 amps & output from a Victron MPPT 100/20 controller is typically 9 amps & up to 11.3 amps under perfect conditions.
You would be better off with an 80 watt hard panel with quality controller at the battery, not on the panel, than a 250 watt blanket.
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After using Projecta 120W folding solar panels for 10 years on our extensive travels we decided that we'd had enough of lugging their heavy weight around. We bought a 200W folding solar blanket from Kings. It charges our 110ahr caravan battery in half the time it took the Projecta panels. It also has a USB port on the controller to charge mobile phones etc. in no time. We've had it for 2 years & basically it kicks a*se.
if you have no solar at the moment then yes you will need a solar controller. The kings blanket comes with one with Andersen style plugs and it should be fitted as close to the battery as possible.
You need to keep wire resistance to a minimum. Wire resistance is the total length of both + & - so if your cable is 2m it is actually 4m.
Wire resistance from the solar panel to the controller is not as critical, but it is simply a waste of energy if the cable is too thin for the length.
The wire between the controller & battery should not have too much resistance, for the controller's calculations for the state of your battery, will be out of wack & won't charge correctly.
So you have 2 options, make the cable short or increase the wire diameter. Better still, both!
So let's say for arguments sake that your controller is producing 10 amps & you have 4m ( + & - ) of wire.
16awg wire 0.536 voltage drop which is too much, which is probably what the panel comes with.
I would get at least 10awg wire which has a voltage drop of 0.134
But if you need to add an extension lead to reach the sun the wire resistance goes up. No point having 2% of the panel in shade as it will produce nothing.
Quite frankly 6m would be the minimum practical length to reach sun for a greater number of situations. It's still not much. Trees cast shadows a long way.
So 12m ( + & - ) of 6awg wire then the voltage drop will be 0.158 volts.
You could use the 2m cable where possible & plug in the 6m extension when needed.
Then your voltage drop is 0.134 + 0.158 = 0.292 not ideal but bearable.
You could modify your jumper leads to use them as well. Make all your equipment multi purpose. Another 3 metres reach is very handy.
__________________
Procrastination, mankind's greatest labour saving device!
50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
think of power loss in the same way a long garden hose resists the flow of water.
Long hose = less pressure.
Long wires = less voltage.
Now whilst a 1 volt drop doesn't sound like much, if the controller at the panel and is chucking out the required 14.4 volts to charge your batteries, this could over a long wire of say 5 meters, become 13.4 volts with a 1 volt drop and that means you wont get your batteries charged properly.
So leave the panels without a controller at the panel end chucking out perhaps 18 volts and even with that one volt drop to 17 volts, your controller placed at the battery end can still regulate that to 14.4 for a proper charge.
