'15 AF 811 Battery charging voltage

Jack Spratt wrote:
When plugged in to shore power my batteries come up to about 13.0
volts. I was expecting a little more, 13.4? or so.
Was this overly optimistic?

This bears some further investigation.

How LONG had it been connected to external power when you took that meaurement ?

My first guess is that the batteries aren't charging fully, either because of the charger or the health of the batteries themselves.

Fully charged batteries should read around 12.8 to 13.1 volts after several hours disconnected from loads or chargers.

Under heavy current draw, seeing battery voltage dip to 12V is not unusual, but when the short duration draw is done, the voltage should climb back to near what it was before the drain in a few minutes.

A lead acid battery that reads 11.9V after sitting for several hours disconnected is near total discharge.

I was measuring across the battery poles with a voltmeter.

Have not checked the water level

But will check tomorrow along with the voltage while plugged in.

When plugged into shore power you should see about 13.6 @ the battery terminals.

Have you checked the water levels recently & or used a hydrometer to test each cell ?

Where and with what are you measuring it?