hankyc

thanks so much, that is exactly what I needed to know, I thought it would be my ignorance rather than a problem but hey I'm still learning!

So, firstly you have to excuse me for being a novice when faced with electrical problems... Getting back on the canal after being hooked up to mains power for our first winter and we managed to drain our leisure batteries by mistake for the first time. They are taking a very long time to charge so I thought we might have a charging problem. When engine is running and I measure across the battery terminals I only get a reading of 12.8, when under load from appliances it goes down and if I use more revs it goes up, so at first I thought it might be an alternator problem as I thought with the engine running I should get a steady reading around 14v. I then checked the starter battery (which is fully charged and I took readings isolated from leisure bank) and it was getting a steady 14v so I guess the alternator is OK? Is it normal to get low readings when the batteries are charging from nearly flat? Also with engine off the leisure batteries voltage drops considerably under load. Is this normal with a half charged battery or have I got dogey batteries (note they are only a year old) Or am I missing the point all together?? thanks