Hi all, we go away next week so a couple of days ago I hooked the caravan up to the electrics, I noticed that I had forgot to turn off the supply to the motor mover. I could hear a buzzing in the caravan which I located to the charger, thinking its having to work harder as the battery was probably flat. This morning I could hear a faint alarm, traced it to the co2 alarm in the caravan, there was a smell like cauliflower inside, checked the battery and it was gurgling and was warm, so I disconnected it. Its voltage was only 11.4v, now I believe the onboard charger isnt designed to charge flat batteries, so my question is, is the battery goosed or might it come back if charged? It been on about 20mins and is showing 12.3v now.
Your battery is fubar - the CO alarm going off is a sign it's been overcharged, which happens when one or more of the 6 internal cells fails, evidenced by the 11.4v.
A good smart charger, like the CTEK, might be able to resurrect the battery if it's badly sulphated but a caravan charger won't.
As well is two words!
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Remember, if you buy something you bought it, not brought it.
A voltage of 11.4 volts is below normal 'fully discharged' level (should be no lower than 11.9-12v unloaded), and into damagingly discharged/dead battery figures, rather confirmed by the 'gurgling' which is excessive gassing of electrolyte, warm is a relative term, there's very slightly warm which is normal on charge, and 'warm' and beyond which is not so good!
TBH, a new battery is likely called for. You may resurrect your old one to a degree, but with almost certainty it'll be with much compromised capacity, which with motor movers is not good at all, it'll likely leave you stranded part way on your MM journey, MMs detect battery voltage and will shut down if too low under load!
Many MMs (certainly Powrtouch) have a sleep function if you forget to turn off the power supply, whereby they shut down automatically after circa 20 mins of inactivity and only draw a very minimal current, that is so low it's generally not enough to have an impact on a healthy leisure battery for many weeks, even months. So your battery may have been on it's last innings anyway.
Usable life of a leisure battery is anything from maybe 18 months, to 7-8 years if lucky (I had 7 years out of mine, still OK and functional, but showing first signs of end of life, and they die fairly quickly at that point!), 3-4 years life is commonplace. It all depends on the quality of the battery in first place and how well it's looked after, as in NEVER letting it over discharge, and/or never leaving in a discharged state for long periods.
None of us like spending money unnecessarily, but a truly dead leisure battery has consequences beyond just inconvenience of no 12v power! They can gas excessively and even explode on charge. Many battery suppliers will do a free 'heath check' for you if you take it into a store. BTW, your battery box should be sealed from the habitation area of your van and ONLY venting to outside, so your CO2 alarm should not really be picking up fumes if properly sealed!
Whilst it's true that battery boxes should be sealed from the interior of the caravan, to prevent the gassing fumes getting inside, I have heard of several failing batteries which set off the CO alarm, alerting the owners to an issue.
NB - they are CO alarms, not CO2 which is the relatively harmless gas we all breath out.
Realised the battery was purchased when we bought this caravan in August 2019 think I need a new one thanks for all your help and advice much appreciated ??
Quote: Originally posted by cliffbrown on 31/8/2026
Realised the battery was purchased when we bought this caravan in August 2019 think I need a new one thanks for all your help and advice much appreciated ??
Glad to be of help. If it's any consolation, you have done well, and had your moneys worth out of a 7-8 year old battery! Nothing to justifiably complain about on that score.
As well is two words!
How does a sage know everything about everything? or does he? or does he just think he does?
Remember, if you buy something you bought it, not brought it.
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Topic: Leisure battery advice please
via mobile 31/8/2026 at 11:04am
