Exide Orbital resting battery voltage?

[lwg]

What should the "resting" voltage of a 12v battery be? I have an Exide Orbital that is just about 2 years old that I'm starting to suspect is having problems. The resting voltage is just about 12.24v, this is after the truck has sit for about 18 hours, hence resting. I have checked all my additional electrical additions for battery drain and none seems to be occurring. 12.24v seems to be a bit low to me.

Here's what has recently brought to my attention a potential electrical/battery problem. I have the new ARB fridge and I can't seem to leave it running in my truck for much over a day before either the battery protection kicks in (depending on what level its set at) or the battery has lost too much juice to start the truck. In fact, when the ARB is set to MD (Medium) level once it reaches this level and shuts off the fridge, the truck still doesn't quite have enough voltage to start the truck. As a precaution I can set the ARB protection to high, however the fridge will usually shut off leaving everything to start warming up inside of it. Heck the starting voltage required for a fridge set at "High" is 12.6v, I can't even start the fridge now without changing the settings or starting the truck.

As a precaution I have recently replaced/upgraded the alternator from 130a to a 150a unit. I figured it's probably the original and will likely fail soon anyways, so I know that's fine as well.

I have really given all of this some thought. I used to have the old ARB fridge and it would easily run 2 days without a problem, the new fridge is spec'd to pull less power hence it should run for 2 days as well.

Really starting to wonder if my Exide Orbital has enough reserve capacity at 2 years of life to be useful to me?

Thoughts?

 

[Northern Explorer]

This is what my Xpower owner's guide says.

You can measure ............. approximate state of charge with a voltmeter. .............. Make your measurements when the battery has not been charged or discharged for "several hours". For a deep-cycle battery at 77 degrees fahrenheit, use the following table:

12.7 to 13 volts = 100%
12.5 to 12.6 volts = 80%
12.3 to 12.4 volts = 60%
12.1 to 12.2 volts = 40%
11.9 to 12.0 volts = 20%

 

[lwg]

It occurred to me this afternoon that I should pull the negative cable off of the truck as well just to ensure there's no power drain. Then take the measurements as you mentioned.

Actually your tables in another post is what got me thinking about this. Thanks!

edit:
12.37v after about 4 hours of sitting, negative cable disconnected. I'll check it again in the morning.