I am no expert but have gained a little knowledge on Batteries of late.. Modern AGM batteries differ from old style wet lead acid batteries in both their ability to hold charge, their normal terminal voltages, expected lifespan, and of course costs. An AGM battery thus may best be charged using a charger designed for that specific type of battery, given the different voltage /charging expectations..?
Apparently a replacement battery for a P car can cost circa £500 to be fitted and coded to the vehicle... Coding is a must on the P car given the advanced battery monitoring and charge regulation systems. ALSO in the case of a P car it is advised NEVER to connect a charger across the battery terminals, there is a remote earthing/neg point to be used along with the battery +/positive for such situations.
Apparently if a charger or jump start kit is connected directly to across the battery there is a chance of damage to the battery monitoring systems... I have no idea if Morgan use any such system. My old +8 does not..(-:
The life expectancy of an AGM can be from 6-15 years... if treated well, i,e. not allowed to go flat or be overcharged on a regular basis..?
I guess much depends on your use of the vehicle and how much time it spends being laid-up and whether it is on a CTEK or not. My AGM was too flat to start my car after sitting for 8 days not connected to a charger, the car having had a run of a couple of hundred miles which would have left it in a fully charged state prior to being garaged..! It now is permanently connected to a CTEK charger/conditioner specifically designed for use on an AGM battery
I suspect if connected to a CTEK permanently when not in daily use, an AGM battery can soldier on for many a year, though only when left off charge for a period of time will you be likely to find out whether or not your battery has lost a degree of capacity to hold enough of a charge to fire up the engine when you need it to..! Thinking a weekend stay at a hotel, or left in an airport car park.
Apparently in a P car a new battery is expected to still fire up the engine after 6-8 weeks off charge... I think much of that capacity is down to the level of sophistication in the battery monitoring system whereby the system apparently can go into a sleep mode, and further to that a deep sleep mode after a further period of time to reduce the load on the battery from all the many and varied systems..
Hope I have not muddied the water..
