Parallel two solar controllers??

[thomm225]

Originally Posted by goboatingnow

Not really. Estimating panel current by measuring voltage is quite a crude approximation as the transfer function is not linear and panel surface temp has major impacts.

Sure it's crude if you are used to having all the data, but if you don't, you can still troubleshoot/maintain your system just by knowing it.

(If you do need or want more data, switch out your PWM's for Victron MPPT Controllers and you get tons more data right on your phone or laptop)

You don't need to know your panel current normally though.

By knowing your system, I mean what it normally reads at any given moment with the indicators you have

Like in the morning after running a fan and depth finder all night while at anchor, my battery voltage on my monitor shows just in the Dead area or just above which means the batteries are at a voltage of 11.8-12.1 volts. This with my old setup of two 90 ah 12 volt batteries in parallel.

If my inverter alarm goes off before daylight, I know I have a problem or the batteries were not fully charged before dark.

And there are many other indicators I use.

Like when sailing with autopilot on, VHF, depth, etc on a good Sunny Day battery voltage stays around 13 volts. If for some reason it's way lower, I know there's a problem. (which is usually that a connection needs to be reseated)

Since I installed my 6 volt golf cart batteries though, morning voltage is up near 30-40% on my Battery Power Monitor which means it's close to 12.4 volts that is before the Sun is up. So ......much better than before.

I have sailed under autopilot in the early am with 11.8 volts on the batteries but the autopilot ran a bit slow (but still worked)

[skipmac]

Originally Posted by noelex 77

A clamp on multimeter is very helpful (make sure it can read DC current) for these types of measurements.

Not only can you easily read the total output of your solar array, without the influence of the load, it can also be used to check the performance of each panel individually, as well as myriad of other electrical troubleshooting jobs. The clamp feature enables all these measurements without disconnecting any of the wiring or disturbing the circuit.

They are not expensive and really a must have tool for a modern electrically sophisticated cruising boat.

If you are reliant on solar power, it is even worth putting in an ammeter to permanently display the input from your panels.

Our Pico battery monitor has a page where it will display the individual output from the output from all three of our panels together with net current entering or leaving the battery. While this battery monitor is expensive there are a myriad of inexpensive ammeters available that will provide the same information for a small cost.

Another alternative is one of the many solar charge controller than will display the current in. The popular Victron units will do this via Bluetooth.

Old clamp current meter died. New one is on the list. If I recall, checking AC current does require separating the hot and neutral wire which is a problem if they are in a 2 or 3 conductor cable.

Monitoring current from each panel, total current produced vs current in or out of the batteries, etc would be nice to have at my fingertips but would require a good bit of change in the wiring, a lot of additional connections and such. I can accomplish all that with just a bit more trouble by switching off loads or disconnecting panels and looking at the change on the existing battery monitor.