leisure battery not charging

[bongosfr]

my leisure battery is not charging for some reason? i measured the voltage across it and it read 8.5 volts, left the vehicle running for a good hour and the voltaged rose by 0.5 v? was thinking it might be the switching relay? any ideas please?

[g8dhe]

There should be two fuses, first one close to the SB in the lead to charging relay, the second close to the LB again in the lead from the relay, check both of them and make sure the contacts are clean. Do you know which type of charging system is used either Voltage Sensitive Relay (they often have an LED to show operation on them) or standard relay operated from the Ignition key circuits ?
If its the former then the relay won't operate until there are some rev's and the voltage across the SB has risen to at least 13.8-14 volts, with an Ignition switched type then it will charge all the time the Ignition is ON and not in Starter position, however without some rev's to get the alternator voltage up you won't get much charging taking place.