Ohmmeter

12.7 volts. 120 watt panel.

Charge current will be dependent on the solar panel and state of charge of he battery.

If the battery is showing 12.7V it would appear the panel is providing very little charge as you have monitored. Was the panel in bright sunshine?

You indicate you have wired the panel in parallel but write 120W panel, do you have two 60W panels?

What are the specs of the panels?

Don't have the panel specs on me as I'm at work but it is a 12V, 120W folding panel so I assume it is 2 x 60W. And yes, it was in full sun when tested.
I'm thinking the charge rate had been cut right back by the regulator as the battery was nearly still at full charge.

I don't think that would be the case, most regulators will go revert to float charging around around 13.5V, 12.6V is way below a float setting, sounds more like it is not charging.

No, the analogue meter is permanently hard wired, in-line inside the car. The panels are 12V, 120W (total). The test meter was a digital multimeter.

Thanks Racey. Panels are 12V and are 120W in total. Battery was at 12.7V and ammeter doesn't show discharge.

Sorry RMD. My thread heading should have said 'Ammeter' and you have deduced the rest of thread correctly. Now that I have the time I will tell you what happened more thoroughly.
My ammeter is hard wired, in-line in the wiring inside the car adjacent the auxiliary battery and regulator. My intention was to use the ammeter as an indicator for the optimum positioning the solar panel. I had driven for 2.5 hours and the battery was fully charged at 12.9V but I used about 2 hours setting up camp and waiting for the sun to move around the ridge line. By then the battery was down to 12.7 (fridge running) and I thought the panel would have been putting some sort of a big charge into the battery and therefore the analogue meter showing some sort of charge - but it wasn't. My friends and I concluded it was because the 20A analogue meter was not sensitive enough to register a meagre charge. So we hooked up a hand-held Arlec digital multimeter, set it at the correct scale and found it showed about 1.8amps. Because none of us are electronics experts we assumed that the panel was faulty and should have been putting in 12amps. Now, if I'm understanding everyone correctly, it appears the battery was nearly fully charged and so the regulator had correspondingly cut the charge rate back to 1.8amps. What I don't u/s is why it read only 1.8amps, when we had disconnected the charge lead and stuck the probes of the multimeter into the contacts of the Anderson plug. I'm sorry, electronics is something I know little about. But thanks for helping.

Deejay
If you disconnected the anderson plug which is the lead from the solar panel and connected a digital ammeter across those terminals, you would read the dead short current the panel was able to supply in that degree of sunlight. That wouldn't really tell you much at all. If the digital ammeter has a 10amp fuse and the panel can top that, it will blow the fuse doing that. Then you don't measure anything.

In full sun the dead short current will be near the panel spec bit it still relies on the voltage and current from the panel for the regulator to handle. I have similar on my vehicle and the ampmeter is between the regulator and the battery in the positive line. It is only a PWM regulator and it makes the meter jump as it switches on and off when near/at full charge. A MPPT reg will most likely be a smooth reading as it is switching at a high Hz speed.

Even if the battery was near fully charged, you should have read at least whatever amps the fridge draws while it was running.
If you had used the battery for 2 hrs, then the controller should have pumped some decent amps....at least 5+.....even if only for a short time until the battery went back into float....and when it was in float, the voltage should have been mid or high 13's.

Thanks very much Allan (and everyone else). I'll follow your instructions this weekend if we have sunlight and see what measurements I get.
Did I read you were tackling the Simpson? How did the trip go? We went across solo, the weekend of the Birdsville Races. We had an easy go of it and nothing untoward happened.

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Nah Deejay, the Simpson is not in my current sights. I now only view it as a shortcut to the Western Deserts and even then use the southern route (Rig Rd etc) provided the Warburton Crossing is open.

OK Allan, I'm pretty sure I followed your instructions correctly. I put the probes of the multimeter into the Anderson plug on the end of the lead from the solar panel. It read 11.23 volts. The thing that Jeepster recommended read 11.27 volts and zero amps. I then hooked up the multimeter and changed jacks and scale and it read 10.4mA. You said it should be 6 or 7 amps so something isn't right. It's over my head so I've packed it all into the car and I'll go and see the solar mob in Caboolture tomorrow. Thanks for trying to help though. Deejay.

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Deejay,

If the panel open-circuit voltage is only 11.23v instead of about 20v then it does not look too good for the panel. Nor would it charge a nom.12v battery. I am not surprised that it can only deliver 10.4mA. Best to put it into the hands of the supplier.

Just be sure that you have the panel connections correct. Use the diagram below to check. And it could be also worth checking that both panels terminal markings of Pos & Neg are correct by disconnecting the wiring and place a voltmeter across the terminals in sunshine.

Thanks Allan.
First question. Despite the information I was given in my posting of a few weeks back, does it really matter which way the panel is wired - series or parallel? What would YOU advise? If you reckon 'series' then I'll swap it back.

Second point. I have attempted to wire the panels in parallel, (only because the guy at Springers said that is how all other panels are wired) and looking at your sketch I may have c*cked up.
I took the red wire from each panel and the red wire of the lead going back to the car, twisted all 3 together and clamped them inside one of those 'cap' shaped things that have a pinching screw in the side. I did the same for the 3 black leads. Have I got this wrong?

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Deejay,

There are merits for either series or parallel wiring, but given the specs of your panels, I would wire them in parallel.

Your description of wiring (all reds joined together etc.) is correct for parallel operation. Do your panels have terminals on the back or just red & black wires coming out from inside the panels?

It still may be a good idea to totally disconnect each panel and then test each one for open-circuit voltage and short circuit current as before. At such time you can observe if each red wire is truly positive..... the manufacturer could have got it wrong. You will not need strong sunlight to check the polarity.

Thanks Jeepster. Funnily enough, since putting up the post I went to Jaycar and this is what they sold me. I'm going out now to learn how to use it and have a play with Allan's instructions.