Ohms law v/i=r in the case of a battery how much current is in the battery dictates how much voltage it can produce, and how much resistance (current drawn) will have an effect on that voltage too. 

A fully charged battery would normally be 13.5vdc 12v could mean that the battery is discharged and requires charging. It could also mean that the battery is no good ( There is a reason they are supplied partially charged). The battery is supplied to the distributor with a charge but not fully charged. While its sitting on the shelf it will over time discharge, but it takes a while and its not good for the battery. We as a company have a high turn over of batteries, so we never have a discharged battery on any of our van stock, or in our stores they dont sit around long enough to.

The manufacturers recommended life span of a battery is 4 years, but because a battery is a consumable it entirely depends on how much it has been used as to how quick it becomes past its best. I am not talking about how many power cuts either, mains is never a constant and you get spikes and dips, so how clean the mains electricity is that is supplied to your alarm effects the life and condition of battery.

  

Simplistically ? Otherwise you need discharge rates in the equation 

6 minutes ago, al-yeti said:

Simplistically ? Otherwise you need discharge rates in the equation 

It was a basic explanation I was going for, something that even you would understand ;-)

What you on about? Lol

I will remove the old battery from the panel that is reading 13.60 volts and leave it off over night to see what it discharges to .

 

very odd that a battery that is 5 years old is reading 13.60 volts ?

 

When i get a another new battery i see what the reading that comes to me as   .

A fully charged battery would normally be 13.5vdc 12v could mean that the battery is discharged and requires charging ?

 

old battery is reading 13.60 volts ...............so why change it ?  that my question   

voltage of a battery doesn't mean its ok. You either need to out some load on it to test its capacity. The reason its reading so high is because its just come off charge

Ok. Thanks for that information.

 

When i get a replacement new one i will see what voltage it comes supplied to me at then i leave it on the panel and leave the system in engineer mode for a few days for it to charge up then take another reading. As well as taking a reading off my old one which should have discharged slightly.   Thanks

5 hours ago, karl taylor said:

Ok. Thanks for that information.

 

When i get a replacement new one i will see what voltage it comes supplied to me at then i leave it on the panel and leave the system in engineer mode for a few days for it to charge up then take another reading. As well as taking a reading off my old one which should have discharged slightly.   Thanks

To discharge it you need to put a load on it, leave the battery connected and diss the mains this will discharge the battery slowly, a good battery should keep the system working between 8 and 12 hours depending on the current drawn. The less time it lasts the poorer the battery