Fully charged voltage

Dwiegel

what should the voltage indicator read when I have a full charge ? Thanks

ScottG

Welcome @Dweigel. Most regular lead acid batteries will settle in at 12.6-12.8V depending upon their age and condition. This assumes the surface charge has been given time to dissipate, and there are no loads n the battery. It also assume the T@B is not plugged into shore power; if it is your monitor will be indicating the voltage output of the converter, not the battery.

This is just general info. YMMV depending on what you have for a T@B and battery.

pthomas745

A big battery FAQ for reference: https://www.solar-electric.com/learning-center/batteries-and-charging/deep-cycle-battery-faq.html

Photomom

ScottG said:

Welcome @Dweigel. Most regular lead acid batteries will settle in at 12.6-12.8V depending upon their age and condition. This assumes the surface charge has been given time to dissipate, and there are no loads n the battery. It also assume the T@B is not plugged into shore power; if it is your monitor will be indicating the voltage output of the converter, not the battery.

This is just general info. YMMV depending on what you have for a T@B and battery.

If there is a load (like refrigerator, water pump, etc.) the voltage readout will be less. For example my battery might read 12.6 but will drop to 11.6 when the water pump is on. You will see a higher voltage, maybe 13.4 when the battery is being charged and for a short time after.

so the answer is, it depends.

Awca12a

For the Harris AGM batteries in our trailer, the spec sheet says they are fully charged at 12.65 volts and fully discharged at 11.8 volts.  To get an accurate voltage reading, you must disconnect the trailer from shore power, or you will see a voltage of between 13 and 14 volts which means the battery is being charged.  Once removed from charging, the batteries must rest & cool down before attempting to measure voltage.  It is like waiting to see how much fluid is in a measuring cup while holding it unsteadily in the air and filling it.  Electricity is created through a chemical process within the battery and after “filling” it, it needs time to settle and rebalance itself.  That also why you put the glass measuring cup down after filling, so you can see exactly how much liquid you have.

klenger

If you really want to know the battery state of charge at any time, consider installing a battery monitor system, which will show battery capacity in Amp-Hours from full or % of charge in real time.  

From my experience, attempting to determine the battery state of charge from the battery voltage is like trying to determine how much gas you have in your tow vehicle by measuring how fast it can go when you push down on the gas.  This method kind of works until it doesn't.

TerryV6

Will shore power fully charge a battery over time?  I also have a genius trickle charger I use in the winter and leave on.  Currently using shore power and monitoring charge once in a while...