Car battery solar chargers - Again!

[Wittsend]

All you can do is power it up and measure the output with a meter.


 

[John]

All you can do is power it up and measure the output with a meter.


 

I expect I would need to do this in bright sunlight,..... it may be some time before I feedback from wet Wales

[Beowulf]

Mine arrived today and seems to be working. The only drawback is having such a short lead from the panel to the usb socket, so cannot really be used outside, unless you can somehow waterproof the connector.

With production costs its about how short can they get away with, and for us, how long is long-enough? but there's no doubt they`ve been stingy. I wrote them saying I was very disappointed about the length of the leads and they offered me a £4 refund, how could I refuse

[2 Du]

Just to stick my nose in here, I have to say that the amount of power from solar PV is very much determined by the amount of insolation available. To that extent any "fixed panel" can only get its' "max" for a very short period of the day when the sun is as perpendicular to the panel as possible.
Not very long in reality.
Having lived of-grid now for over half my life I can attest to the benefit of pointing your panel as directly to the sun as possible. For me that meant building a trackable array that allows me to maximise the amount of time the array is pointed at the sun.

Anything that improves the amount of sun hitting your panel directly is worth it - even if it means you have to get up and move it. But at least angle it towards the point where you get the most direct light in a day.

Not being able to track is why most people over egg the number of panels on their house or van in order to get something useful.

Hope that helps???

[John]

^^^ as said you need to get as much direct sun as you can but if you opt for a fixed panel on your Land Rover flat on the roof must be the best location, as pictured on Panda

OT....I wonder how well these work under a clear glass sunroof on a modern car

[richardhula]

Maximum power point tracking (mppt) controllers help as well although only viable for larger arrays. There is a loaded voltage on any PV panel that gives the maximum power transfer. This is typically around 18 volts for a nominal 12 volt panel. The mppt controller varies the load according to light conditions to maintain this voltage from panel then outputs the required DC voltage.

[simonbav]

My battery was up to 12.5v today after a week on the 60w charger above, from 11.7v, shaded by a hazel tree a couple of metres away. That'll do for me.

[Daisythelandie]

I've had one like the OP refers to for years and it certainly keeps the battery up to scratch over long periods, the Landrover never fails to start even after its winter slumber.


Dave.