I'm playing with a couple of panels, a controller and a couple of car batteries. All gerry rigged up with bits of whatever wire I have and as heavy as I have. Just want to learn and play atm before going on to bigger and more expensive things.

Each panel does about 8.5A nominal at around 30V and I have them wired in parallel to keep the voltage at minimum and the amps higher.

As this is just playing around with low voltage stuff, I'm just using the wire I have which is AC mains type with earth which I am not using. As it happens it's 2.5MM.

What I'm unsure of and hope someone can fill me in without getting too precise or others having a typical electrical argument, is which rating on a cable matters, amps or watts? I know the correlation with voltage but I seem to recall it's not linear when applied to DC over AC type wiring.

The electrical cable I'm using is rated at 16A. Not sure if this is at 240 or 440 but lets say it's 240. That gives me a total wattage of 3840W.

Now on my 24V fool around solar system, what will that wire carry?

Is it 16A @24V or any volts up to 16A, OR is it a total of 3840W at any voltage which means I could put 160A @ 24V giving me the 3840W limitation.

Pretty sure that's not right so what is the principal or law here ( in simple terms, A or W?)

I seem to recall there is some non linearity in the way this works and without getting into all the formulas and technicals, what's the story?

Is my cable limited to 16A at any voltage giving me a total 16 amps or am I able to pump through any volt/amp combination up to the 3840W?

If it's a 3rd situation, could someone please explain that as simply as possibly how I pick up a piece of wire ( most likely going to be household type) and know what I can put through it for my playing around.

Other question is what should my min voltage on these standard lead acid batteries be.

I know they are not designed to take much discharge so what can I safely discharge them to Volt wise to avoid damage? I know I can't take a lot off them as the are not deep cycle types but wondering what do I set the load cut off voltage to in order to be able to use them without shortening their life.

I understand the amount I can draw off them with regards to the total capacity is very low but for my tiddlywink purposes, this is irrelevant.

All I want to know what's the limit I set on my controller cut-off on the load to keep the batteries safe?