Leisure battery danger level

AGM is though just one of the Lead Acid battery technologies, and yes, one of those less damaged that some by a low dropping to a low state of charge.

I discovered soon after getting into caravanning a couple of years ago the leisure battery quickly went flat when in storage. A bit of messing about with a multi meter and discovered the control box at the entrance to the van was permanently live, something to do with it being ready to receive signals from a remote.

Pull the fuse for the battery out and it stops the drain.

Not always practical if you have a tracker / alarm, as the back up batteries on our old Bailey only operated for a few days and needed to top up from the Leisure battery. However, even with that drain I only needed to swap the battery over every 6 / 8 weeks, by which time it had discharged to 12.5 / 12.4 volts. What do you mean by quickly went flat? I would have thought the drain from a panel on standby for a remote input would have been minimal.

A tip that I have mentioned before, is that we are lucky enough to store the caravan at home so always have it 'hooked up'. The power is on a timer, (unless overridden) and so the battery gets a two hour top up on a daily basis. I've done this for a few years without any apparent problem and always have a battery charged at about 12.8 volts.

1. Get solar panel(s) - as much as will fit.

2. Swap to Lithium battery

3. Say goodbye to electrical energy problems.

Bit expensive if normally on EHU though. Particularly for a caravaner who has no cab battery to worry about. We’ve got the solar bit of your list on our MH and they proved invaluable during lockdown, as our van is kept in storage.

All the Autosleepers motorhomes that we have been looking at now have Lithium batteries as standard. Perhaps this is the future.

Couldn't tell you the make of our caravan battery but we purchased a new caravan last year and a new battery was obtained at the same time. Unfortunately due to covid and lockdowns we only managed to use it for just over two weeks before putting it into storage hoping to use it again before the winter set in. Unfortunately we had another lockdown and were unable to get to our storage area except to drain the water out and to be honest forgot to remove the battery. The result was that when we eventually managed to get back to the caravan the battery was well and truly flat and I mean flat. The battery was removed and taken home where I have several smart chargers and two old analogue ones. At first the smart chargers would do absolutely nothing as with there being no voltage there was no reference for the smart chargers to pick up so it was put on an old 4amp analogue one which immediately fired up and left on charge for 24hrs before being switched over one of the smart chargers but this again would not fire up so it was put back on in parallel with the analogue one and left for three days before removing the older charger and leaving it to the smart one for a further two weeks. By this time the battery green fully charged indicator was back. We, tbh, have only had the caravan out once since then but we have a mover and have had no problems with it and even though that was six weeks ago the voltage indicator still showed 12.7v when we checked it this week so hopefully we have managed to save it.

Whilst not to be recommended, I have managed to recover a couple of E-Bike batteries that had gone completely flat. So much so that, again, the charger wouldn't recognise the battery. I managed to fool it into accepting the charge by connecting the charger to the  output terminals to put enough into the battery to enable it to charge normally. Moral to these tales - check your voltage periodically. 

My battery must be around 10 years old by now. My battery analyser suggests it has 90% capacity still - Only needed for the mover and for short stops, otherwise EHU and my caravan has a fixed 13.8v SMPSU.

In my opinion, at 10v a battery has suffered serious damage, but if it has not been left too long at that voltage, most of the capacity will be recoverable if put on charge quickly.

I certainly would be worried if I let any battery fall below 12.0 or even 12.3v.

In the past, I have left batteries year round on 13.8v via ECU at home in my drive and batteries have been dead after a couple of years of that treatment. Instead, now I disconnect the battery and reconnect every couple of months for 24 hours or so. After and before a trip, they get connected for 48 hours. Very occasionally,  I put the battery on one of my Smart chargers.