Advice on a charge controller please :)

[blackburn mark]

Anyway, like m_c I'm not sure what you're trying to achieve here? Taking 12V dc from the van (battery, alternator?) through the controller into what... some batteries? If so why? Oh are you charging the van battery with solar to offset the power drawn from the engine via the alternator?

I'm converting an extra long wheelbase sprinter van into a camper... I'm now at the point where I'm ready to add two 125ah batteries and wire it all up before i add to much of the interior that it becomes difficult to run wires up and down the length
i'm looking to fit a 250w panel on the roof so i'm not drawing current from the alternator all the time (wasting diesel) and i don't want to be reliant on running it just to charge the batteries, iv also the option of adding a wind gen if the need arises.

sooo... if the shit hits the fan at work and we all get laid off ill park up on the west coast of Scotland put a wind genny up and run my cnc once a week for my beans on toast :)

[Jonathan]

If you're doing this purely for financial reasons, then it's a rather long winded way to earn money given that it will take at least 5 years for the electricity saved to pay for the panel if you get it at a good price. Have you worked out how overall how much energy each appliance requires and thus how long you can run the CNC router for using the remaining energy? Electricity from diesel should be cheaper than from using solar panels.

For beans on toast you want a solar oven

It's annoying that you have to use 12v not 24v, since apart from the efficiency you're limiting yourself to more expensive solar panels.

[blackburn mark]

its not for financial reasons... its my little pipe dream to help me keep my chin up if i end up on the scrap heap
i like the idea of the old travelling knife sharpener :)
this charge controller will take 38v open circuit, i'm sure that's pretty typical for a cheap 250w panel

my cnc draws 130W 150W typically... it would draw a shitload much more if i leathered it but i took measurements on a typical run... my desktop will draw more than that when its rendering HD files
im pretty sure i could run for six hours before i got to 50% then sit in the dark until the sun comes up lol

[Jonathan]

Hmm fair enough...

this charge controller will take 38v open circuit, i'm sure that's pretty typical for a cheap 250w panel

But does it accept 38V with a 12V battery on the output, or just with a 24V battery? Looks like you've got this one, but the listing isn't helpful:

800W Wind Solar Hybrid Mppt Controller (600W Wind + 300W Solar) 12V/24V Auto | eBay

It looks like at least some support having a lower voltage battery, but I'd want to be sure before connecting it up...

[Lee Roberts]

sooo... if the shit hits the fan at work and we all get laid off ill park up on the west coast of Scotland put a wind genny up and run my cnc once a week for my beans on toast :)

lol