Measuring amps from solar

With the multi meter you should put it in series in the output line between the controller and the battery.

Hail The Bantam. When you explain it like that even fellas like me can understand it. I would dearly love to know as much as some of you guys have forgotten, which would make me much smarter than I am now. Cheers.

Hmm. Thanks. I do have a switch in the positive lead from the panel. Maybe that's faulty, although I have checked continuity.
The fact that I can read VOC at spec, suggests leads, terminals, etc are OK. It's just the ellusive Amps. :)

I installed the switch naively thinking I could address the warning on the panel that says, do not connect panel with load connected, or something similar. But the switch doesn't address that because the load is there whether the switch is there or not. But why is the warning there anyway?

More checks tomorrow.

John

The answers above are mostly too detailed and confusing.

To measure the output from a solar panel do this:

Disconnect both leads of the panel from any controller, battery or any other van wiring.
Take your multimeter, set at a suitable voltage range and measure what's coming out at the two wires, making sure your panel receives sunlight of course.
With a digital multi meter it does not matter which meter lead goes to which wire, the meter just displays a negative reading if its reverse connected.
There should be between 18 & 21 volts for a 12V nominal panel, depending on how many cells the panel has.

Next, and this might worry some people, it is quite OK to short circuit a single solar panel by itself (its not connected to anything else). The max current (Amps) that can flow is what's shown on the label under short circuit current.
Just set the multimeter to the 10A DC range, assuming the panel has less than 10A sc rating. Connect the meter probes to each wire of the panel, this is the same as short circuiting the panel BTW, and measure the short circuit current.
It should be close to the spec on the label but is dependent on the amount of sunlight. If it shows a healthy Amp reading the panel is fine and you can eliminate it from the cause of your problem.

^^^^^^^^
What he said.

Allan, I think I have eliminated the possibility of a blown fuse, as I mentioned earlier, I checked the current from a mains battery charger that I had charging another battery, and I could read 5 Amps OK. So I conclude the MM is working OK.
Back out to do some more tests.

John,
I think you have missed my point.
I know you read 5 Amps on the charger earlier but since then you have applied the meter to a circuit of unknown current. It is possible that this current exceeded the meter fuse rating and has blown the fuse.
I suggest checking it again on Current Range in the charger circuit to verify that the meter is still working or you will be chasing your tail.
It is correct electrical practice to re-verify your instruments if the measurement is not what was expected. Believe me, I and many others have been caught by assuming that all was right with the instruments.

True cruiser. That is why when testing it is important to have the circuit or equipment operating or in the same mode as when the condition of interest is present.

JohnG

I will not profess to be well conversed in all the various regulators and other devices on the market and many people out there will have much more experience than me with other systems, but generally if you pay $24 for a regulator it will not be much "chop" - you pretty much get what you pay for.

I have been using and am a fan of the D250Sdual from ctek which as far as I know is an MPPT regulator and lets you have one device (around $250) to control battery charging from both alternator and solar (max 20Amp into the battery which is generally enough for most configurations).

That may give you an option to explore depending on what your requirements are.

If you want to add mains charging into the design that complicates it a little more as I have found (smart) mains chargers do not like being connected to the battery without first disconnecting the ctek and while I have not blown my D250Sdual up I don't know what it's tolerance is to do such a thing - although ctek do have a mains charger designed for this purpose but at a cost. There are ways around this that can be automated or manual.

I am sure others out there will correct anything here that I may be wrong about or not thought of.

Ken