Readings Taken at Charge Controller

[mustangcats]

I have the Renogy Wanderer PWM 30 amp charge controller. There are 4 screws on the front that I guess can be used to take various measurements. The two attaching the wires from the solar panel show the voltage coming into the controller. When I take a reading from the terminals leading from the controller to the battery, is that the voltage going to the battery or is it showing the voltage of the battery (or a little of both)? What other useful readings can be taken using a multimeter? The manual has no information.

[John61CT]

All devices on a circuit "negotiate to result in one voltage.

Unless a long run and too thin wire causes voltage drop.

Measure at the batt posts to make adjustments.

[absolutsnwbrdr]

The voltage at the BATT terminals on the charge controller is what is being delivered to the battery, but will not necessarily indicate battery state of charge. So that voltage will be an indication that your charge controller is trying to do its thing, and that's about it.

To get a good idea of battery state of charge, the battery needs to be at rest (no applied voltage, or voltage draw, from any sources) for a period of time (a few hours). After its resting for a while, you can take a voltage measurement at the battery terminals and that will tell you about how full the battery is, but not how much power it has. To do that, you need a power meter measuring wattage and amperage going into the battery. And to know how much power is left in the battery, you would need another power meter to measure the output of the battery. It can get pretty complicated if you want to be super technical.

[John61CT]

Voltage is a very inaccurate measure of State of Charge best of times. 24 hours is minimum, sometimes 72+ rest is needed.

Except for 100%, easily determined via mfg specs for trailing amps at Absorb voltage.

[mustangcats]

Regarding the Renogy charge controller: This is in the manual regarding the equalization phase that the charge controller performs every 28 days.
Equalization:
Is carried out every 28 days of the month.
It is intentional overcharging of
the battery for a controlled period of time.

WARNING:
Once equalization is active in the battery charging, it will not exit this
stage unless there is adequate charging current from the solar panel. There should
be NO load on the batteries when in equalization charging stage.

The warning statement makes no sense to me. There is always a potential load on the battery at any given time...and I have no way of knowing when it will enter the equalization phase. Any experts out there care to comment?

[John61CT]

Never allow any charge source to automate maintenance protocols.

If that feature can't be disabled, buy another unit.

Only equalize manually, and ideally from shore power with a user-adjustable charger or power supply. You will be watching and adjusting volts and amps to follow the batt mfg's specs for the procedure.

You don't need a high-amp charger for the equalization protocol, since the first step is to get to 100% Full first at Absorb voltage, and by then (by definition) the bank's accepting only very low current rates.

[NorthEGPhoto]

i'm a little late to the party, but I have dealt with renogy support before when I was investigating expanding my Parents' solar installation. They have pretty good tech support if you email them, might be worth a try.