Hi

I put a new engine battery in our Hymer campervan last March - its built on a 2002 Fiat Ducato 2.0 JTD. Everything was ok at the start but recently the campervan has been a little sluggish to start. It was nothing of any significance and I put it down to listening to CDs on the stereo when parked up and occasionally using a DC-AC converter in the cigarette-lighter to charge batteries.

I drove about 170km last Friday evening, I only moved a few hundred yards on Saturday, and then on Sunday the engine wouldn't turn over and had to be jump-started off a friend's car. I drove back home (another 170 km, no stops) and when I was parked up I turned off the engine and tried turning it back on again - again it wouldn't start.

I reckoned the problem was with the alternator, so I put the battery on charge yesterday. With the engine turned off I get a 12.4V reading with a multimeter, and this goes up to 13.3V with the engine running. This shows that the alternator is doing something, but does anyone have any idea whether this is sufficient? I just listened to CDs on the stereo on the journey back on Sunday. Alternatively, any suggestions as to what might be draining the battery?

Thanks in advance


kieran

I had a similar problem which turned out to be the starter motor drawing too much current. You need to check for a fault that may be drawing current even though everything is switched off. Your meter reading should drop after switching off to almost zero, if not; one of your relays may by still on. If you Google aa1car.com library there is a section there that covers battery faults and how to do the tests.
Hope this helps.

12.4v on a rested battery indicates 50% charge
13.3v is low output for an alternator battery can never be fully charged at that voltage.
Check for a current draw with the ignition off.

Charge your battery fully, at least 24 hours on a home charger, some will take 48 hours or more. Then get your battery tested. You can't accurately test a flat battery, but it is possible you have a dead cell. Test leak off as mentioned by pcspike. A maximum of 100mA is acceptable, most modern vehicles drop to 20mA or less. Test the alternator output, there will be little difference between idle and revs, but you should get at least 14.2V, anything up to 14.6V is ok. Recheck under load, eg fan on high speed, lights on high beam, it should still reach 14V or more, though will drop initially after turning loads on. Increase revs to about 1000-1200 for this test.
If you have a sealed calcium type battery, it will not accept a full charge from an alternator if it has been partially flattened. It will need recharging on a calcium charger for 24 hrs plus. It is a good idea to have a dual battery system in a motorhome, keeping all the accessories isolated from the starting battery, running them on the house battery. The alternator will charge the two batteries in parallel.
What size is your DC-AC converter, and what batteries are you charging with it? The o/e power socket wiring (cig liter) is only suitable for up to 8 amps continuous. Depending on the type, inverters are power hungry. For every 100W output they will draw 8 - 9 amps off your battery.