Do you charge the battery seperately or only with the split charge relay? We need to bench charge our batteries every so often as we don't do enough mileage to fully charge the batteries going to and from work.
As I mentioned on a seperate thread recently, each pump uses 3.4amps per hour. So with 1 pump working say 4 hours per day, the battery will have delivered 13.6 amps. My van alternator charges my leisure battery at +- 7.5 amps. So, as we usually drive 10 minutes to and 10 minutes back from work the battery would only receive 2.5 amps, a deficient of 11.5 amps per day. In theory, my 110 amp leisure battery would need to be charged once a week to be safe. The van I use is a Citroen Relay hdi with a 150amp alternator.
You can check to make sure the split charge relay is working by using your multimeter. On the dial of the Multimeter you should have a voltage tester. Test the leisure battery voltage first and make a note of the voltage across it. Then start your van and the voltage should be higher when the engine is running, something around 13.5v or maybe a bit higher. If it isn't then the first place to check is the fuses followed by all connections. If they are OK suspect the split charge relay itself. Obviously, the battery will need to be in vehicle to do this.
I would charge your leisure battery overnight and see what the situation is. If the battery charges up and holds a charge, then you will need to supplement your van charging every few days. It's difficult to test a leisure battery these days as most of them are sealed. In the old days a battery was put on a charger with it's filler caps removed. A load was then put on the battery and you could tell the suspect cells as the water in them would start to bubble. They were also the cells that needed to be topped up with water regularily.
Nowdays if a battery won't hold a charge and its a couple of years old, best replace it anyway.
We have experienced failure of several leisure batteries over the years. You can charge them up and they will read 12.7v when fully charged, but each time they haven't the capacity and last no more than a couple of hours. Replacement was the solution.
Spruce