Battery Charge from solar panel for automatic gate opener

[DeanKC]

The battery for my automatic gate opener is a 12-volt Duralast 24MS-DL Marine Starting Battery. It has been in service over six months and has never needed to be charged even though the gate is operated several times every day. In other words, everything about my Ghost Controls opener has been extremely satisfactory.
Today, I decided to check the state of charge since we have not seen sunshine for about a week. The battery seems just fine but the state of charge as indicated by the output voltage is what I don't understand as it is over 14 Volts. See photo.

 

[MAX-24-Dean]

When I worked in an industrial battery shop, we used hydrometers and cross referenced specific gravity charts to determine voltage and state of charge. The reason was that using a volt meter to find state of charge required us to let the batteries rest (no charge voltage being applied) for several hours for the voltage to stabilize to use the voltage cross reference chart.

2.3 volts per cell is typical for lead acid chemistry on charge, so 14.0 volts for a ball park while on charge is a normal reading.

A solar charger will still function in an overcast cloudy enviroment, just not at full capacity. So it appears in your case that the solar produces more than the demand on a consistant basis.

I have had several cloudy days in a row here in Washington state with 100% overcast, I was still able to produce approximately 4Kw total per day from an 8Kw system for three consecutive days. Usually producing 20Kw a day.

 

[DeanKC]

Thanks Max. Having always known about 2.3V, it was the chart that confused me. Had I disconnected it and delayed several hours, the chart might have been applicable.
I learned something important today. Thanks again. Dean

 

[CH4Ohio]

Looks like you were really checking the output from your solar charger at that instant. The battery could be quite weak but you'd still get a high reading if you're checking with the charger connected.

(Just like checking across your car battery while the car is running. If the alternator is good, you'll see ~14 volts. This doesn't tell you anything about the condition of the battery except that it still has continuity.)

 

[Fuddyduddy1952]

I'd cover solar panel with a cloth then measure battery, cycle the gate a few times taking surface charge off of battery seeing what voltage is.

 

[MAX-24-Dean]

I'd cover solar panel with a cloth then measure battery, cycle the gate a few times taking surface charge off of battery seeing what voltage is.

Always a good rational thinker in the crowd!

 

[DeanKC]

Looks like you were really checking the output from your solar charger at that instant. The battery could be quite weak but you'd still get a high reading if you're checking with the charger connected.

(Just like checking across your car battery while the car is running. If the alternator is good, you'll see ~14 volts. This doesn't tell you anything about the condition of the battery except that it still has continuity.)

Thanks. Will disconnect and see what happens.

 

[DeanKC]

Always a good rational thinker in the crowd!

I'd cover solar panel with a cloth then measure battery, cycle the gate a few times taking surface charge off of battery seeing what voltage is.

Thanks. Every response has been a very informative. Now I'm really interested in seeing the results.

 

[DeanKC]

Operated the gate a couple of times, then disconnected the battery. A while later I tested with the battery disconnected. SE Louisiana has not seen much sunshine for the past week or so. Today's reading should be accurate. If I am still missing something, please let me know.

 

[Fuddyduddy1952]

Battery is wet. Is that rain?
I'd use that meter on any car, truck, tractor. Check battery then start it. Voltage not running then running & charging...see how it compares.