1. Andrew Lenton
    May 30, 2019 @ 15:31

    H I do not agree with “Once they reach the 12volt mark they are flat and you should not use it anymore as damage will occur”

    A fully charged 12 Volt Leisure battery, will very quickly fall to 12.5V or less in a hour or so of moderate use, at 10.5V it would be considered fully flat. All Leisure batteries like to be kept close to full charged, once charged their shelf life is very long when new. I would say you need to start thinking about recharging at 11.5V. A 200 Watt solar panel will allow you to wild camp all summer, providing you have an MPPT charger, or at least a PWM charger. A DC current clamp meter is the best way to find out where the power is draining away.


    • Paul Fabrizio
      May 30, 2019 @ 21:24

      A while back I would agree with your figures but generally 12 volts or under is regarded as flat. These figures are not from me but from battery manufacturers, some retailers have the same information.
      You can run a battery much lower but there will be damage to the plates and will be very difficult for the battery to recover shortening the life of the battery.
      Of course the most manufacturers recommend a 50% depth of discharge (DoD) which is actually around 12.4 volts. Just remember these voltages are measured when the battery has no load.
      So when the battery is connected to the motorhome or campervan you sort of have to guess as the voltage will be lower under load which makes battery management even more of a challenge.
      I have tried to explain batteries a bit more in this blog post;
      Here is some info from Yuasa Batteries


  2. Andrew Lenton
    May 30, 2019 @ 22:46

    Hmm ???? it sounds like to me the manufactures do not want to admit the fact the full deep cycle batteries only have 50 to100 cycles. So at 30% discharge they want you to recharge so to extend the life.

    They should then reduce the advitised AMP Hour capacity as 32Ah not 110AH.

    My background is submarine lead acid cells we only came up to recharge when we had to




    • Paul Fabrizio
      May 30, 2019 @ 23:24

      I think you have hit the nail on the head. The sweet spot for wet batteries seems to be about the 30% mark to get the number of cycles advertised.
      The only batteries that seem to get round this are the lithiums which can be discharged 80% for thousands of cycles. They are about a grand to buy so you have to use your batteries seriously to get your moneys worth.


  3. Carol
    November 23, 2019 @ 08:35

    Are my leisure batteries(2) dead /need replacing. It’s winter .. I have no electric hook up. But 2solar panels. I am stationary waiting for other work to be done on my Motorhome and in the wait..I am living on board Last night I charged the battery by running the engine .. after about 15mins it reached 12.8 on my interior digital readout..after switching everything I could off ie heating, lights, at 2.30am I still had 12.2 in the readout.. but by 6.45am it was down to 10.8
    I have charged it again by running the engine and am back to 12.7
    I will be able to get EHU tonight..
    How do I know if I should replace them or not?
    Thank you in advance


  4. Sian
    June 15, 2020 @ 11:23

    Hi Paul,

    I’ve recently installed a new battery and VSR to my camper and have noticed it hasn’t been charging. In fact on some drives the leisure battery power seems to drop significantly. Could it be that the starter battery is drawing power from the leisure battery? I thought power could only flow the other way through the split chargers? And if I’m right could it be a faulty split charger do you think? My starter battery did recently go flat so I recharged it with a battery charger. So the leisure battery is in a better state than the starter battery. But as I said I thought that power could only be drawn into the leisure battery not the other way around.
    Any help would be greatly appreciated.



    • Paul Fabrizio
      June 26, 2020 @ 10:12

      Hi Sian
      You might have a faulty split charger. The first place to check is the actual batteries. I would fully charge the batteries. Test the batteries with a battery tester which puts then under load (they are about £30) to make sure they are in good shape. Disconnect each of the batteries in turn and see if there is any power drain. So, just have the leisure battery connected but not the starter battery, leave for a few days and vice versa. Test the voltage at each stage of both batteries.
      This will let you see if the batteries are holding a charge and if there is something pulling down the power.
      You may want to check that your leisure battery is actually getting a charge when the engine is running, the voltage should be over 14V when the alternator is charging.
      I had a really poor battery in our motorhome. It took a while to find the problem but the faulty battery was pulling the power from the good ones. All was well with the multimeter and each battery looked fully charged. When a load was put on the battery it was a different story – the duff battery would just die but would show a healthy voltage of about 13.4V.
      It can be time-consuming finding faults in the van. One of the things that killed one of our batteries was the inverter, if you have one make sure it’s off.
      Hope this helps a bit


  5. Andrew Lenton
    June 27, 2020 @ 17:01

    Paul’s advice is sound, I cannot fault it. if you have a clamp meter, and you join two batteries together that are fully charged there should be no or little equalising current, this was not the case with Apollo 13, they had shut down all power, as their fuel cells in the command module utility’s module had loss all its oxygen; The crew need 20 Amps max to bring up the guidance computer, but the batteries in the command module could not supply this for the time required, the answer, was to connect the LEM batteries in parallel before they discarded it, this gave them enough power to bring up the computer before they let it go! So you are not alone with battery issues!!


    Andrew Lenton


    • Paul Fabrizio
      June 29, 2020 @ 21:57

      Your van sounds exciting Andrew, look after those LEM batteries!
      (Loved that film, by the way)


  6. Caleb Pottebaum
    October 22, 2020 @ 05:37

    To be honest your article is informative . I search many site to know about The main causes of battery drain is a faulty leisure battery. but I didn’t get the information I needed.
    I saw your site and I read it. I got some new information from here. It is beneficial for many more like me.
    Thanks for share your kind information.


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