Parasitic Discharge?

[Google it Research]

Hello, I'm running 2x 120 watt solar panels on a jeep trailer. The panels are wired through the charge controller to my battery. I've noticed that in mid-sun my voltmeter reads between 14.4-14.7 volts. By the evening my voltmeter reads 13.1 and at late-night/early morning the voltmeter reads 12.3v. Now, my question is do I have a parasitic leak or is the higher voltage reading due to the fact the panels are charging? I've mounted a battery disconnect to the negative terminal which I use to disconnect all electronics (floodlights, trailer lights, inverters). The only thing connected to the battery full time is my solar panels by-way of charge controller.

Thanks for your input-

 

[unseenone]

As the temperature & charge level varies the conductivity and charging voltage. As you get charged, and float, power might be used and power might drop, but I suspect it's the temperatures. If you've got a temperature sensors somewhere the charging voltage is going to vary based on temperature and battery charge state.

I noticed something similar yesterday when it was 111F. You might try, under multiple circumstances to measure the voltage at the battery and at the end run of your wiring to ensure they are the same, or close.

A multimeter is your friend.

 

[Google it Research]

Thanks, I'll follow your advice with the multimeter. I'm most worried that I have a leak, but it sounds lie the voltage fluctuations may be due to the panels charging. Please correct me if I'm wrong.

 

[unseenone]

I think you're probably ok, but test with a multimeter and see what you find. I am making the assumption it's the temp, and it sounds ok.

 

[Sardog1]

Have you tried penicillin for your parasitic discharge?

Sorry, couldn't resist!

 

[Joe917]

Disconnect your solar then disconnect the battery neg cable, put your multimeter set to amps in between the battery neg and the battery cable neg. Is there a reading? milliamps are OK amps are not.
If you are reading amps start pulling fuses until the reading drops, this is the circuit drawing power (parasitic draw). Find out why and correct it.
Hope this helps.

 

[Martyn]

I think what you are seeing is a full charge rate at you battery from the solar panels vs. a rested rate.

Solar controllers will charge your battery to what ever voltage the battery was at when you first connected it. In your case it looks like you first connected the controller right after it had been charged to 13.1 volts. The controller then assumes 13.1 volts is 100% charged and will try to charge the battery back up to this point.

If the solar is disconnected, or you go into partial sunlight, or it's dark, the battery will reach it's rested state, 12.3 volts, which is on the low end of normal, a new battery will have a voltage of 12.6 or 12.5 at rest. Load testing the battery would tell you if it was on the way out or not.

 

[Joe917]

A solar controller charges to the voltages it is programmed for. It has no memory of its first battery voltage.
Checking battery state of charge with a volt meter can be very misleading. It takes time for the charge to penetrate/dissipate into/out from the battery plates. Having a charge or draw on the battery will also give a false value. A battery must rest at least 4 hours and be disconnected for the voltage to have any accuracy. This is why volt meters are a poor tool for everyday state of charge measurements.
Specific gravity of the electrolyte is the most accurate test.
An amp hr meter connected to a shunt is the easiest most accurate tool for battery state of charge.

 

[Google it Research]

I think what you are seeing is a full charge rate at you battery from the solar panels vs. a rested rate.

Solar controllers will charge your battery to what ever voltage the battery was at when you first connected it. In your case it looks like you first connected the controller right after it had been charged to 13.1 volts. The controller then assumes 13.1 volts is 100% charged and will try to charge the battery back up to this point.

If the solar is disconnected, or you go into partial sunlight, or it's dark, the battery will reach it's rested state, 12.3 volts, which is on the low end of normal, a new battery will have a voltage of 12.6 or 12.5 at rest. Load testing the battery would tell you if it was on the way out or not.

A solar controller charges to the voltages it is programmed for. It has no memory of its first battery voltage.
Checking battery state of charge with a volt meter can be very misleading. It takes time for the charge to penetrate/dissipate into/out from the battery plates. Having a charge or draw on the battery will also give a false value. A battery must rest at least 4 hours and be disconnected for the voltage to have any accuracy. This is why volt meters are a poor tool for everyday state of charge measurements.
Specific gravity of the electrolyte is the most accurate test.
An amp hr meter connected to a shunt is the easiest most accurate tool for battery state of charge.

Thank you! This was exactly what I was looking for.