Best method of Over-Wintering Leisure Batteries?

[AlastairH]

Could someone with Moho electrical knowledge please advise me the best way to over-winter my leisure batteries without removing them please?

I am lucky enough to be able to store our Moho in a shed with an EHU but it is not exactly convenient to check it too often. In the past, I simply left the Moho hooked up and left the Sargent electrical unit to do the business in the belief that it was a battery maintainer rather than just a charger. Following the replacement of my batteries, my dealer has advised that it is not a good idea to leave the batteries on charge as this will eventually evaporate the contents of the lead-acid batteries. In fact the two batteries that were taken out were almost dry (little wonder they were not holding charge).

My attempted solution was to put the Moho on an EHU but to place the connection on a timer for an hour every day, thinking this would be enough to keep the batteries charged. This didn't seem to be long enough so I increased it to 1.5 hours per day. Even this does not appear to be enough as the batteries were down to 12.3v after a little over a week.

Monitoring the acid level in the batteries is also a problem. The caps are very tight and my attempts to use a coin and a pair of pliers was abandoned when the first plug I went to remove began to crumble.

Nothing is left switched on in the Moho other than the alarm. Advice will be gratefully received.

 

[StillGoing]

Most lead-acid leisure batteries are sealed. Are you sure your battery can be topped up? Which battery is it?

 

[AlastairH]

2 X Banner 110Ah leisure batteries as recommended by my dealer.

 

[TinaLes]

I leave our van on hook at home switched on permanently, The batteries are the original 80AH Exide Gels and are sealed units, no topping up required, and The CBE charger & Solar Panel keeps them topped up on float.

If & when needed. I will replace with lithium's, or another set of Gels, but I wouldn't even consider the old lead acid types that needed topping up regularly, did enough of that years ago on boats.
They Exide Gels are coming up to being 7 years old, and still working well, I doubt any AGM or wet unsealed lead acid batteries would have lasted this long.
LES

 

[StillGoing]

12.3V is about 70% charged. You have used 30% of 220Ah, or 66Ah, of battery in just over a week. With the charger on every day you’ve actually used much more than that.

That seems like a lot.

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[TinaLes]

I think a Clamp Meter put over the positive lead from the batteries might be the best way of telling how much current is being drawn when everything apparent is turned off. I cant imagine an alarm, tracker or even a radio head unit would run the batteries down that quickly in a week.
Good luck to the OP, more investigation is needed as to what is drawing current whilst van is laid up.
Check out my example link below, there are so many Clamp meters available, most are very affordable.
LES
Amazon product ASIN B08FD9Q1Q5

 

[IRHP]

Batteries with no load should stay charged for months. Disconnect and leave them. Charge every 6 weeks or so

 

[Gromett]

Lead acid batteries self discharge at around 3-5% per month.
disconnect negative lead after you have fully charged them and I would guess you could leave them for 3 months easily.

My personal choice though would be to connect a CTEK MXS 5.0 charger and let it do the long term maintenance task. This will not boil off the battery.

 

[StillGoing]

You said your charger is on for 1-1.5 hours a day. If your charger is about 15A, your batteries are getting 15Ah - 22Ah a day and you’re saying they are still losing charge. Something is very wrong if that is what is happening.

You need to investigate what is taking power from your batteries. As TinaLes says, a clamp meter is needed to track down the problem.

Once you’ve sorted out what’s happening, a battery maintainer (like the one Gromett suggested) would be better than using the motorhome charger for an hour a day.

 

[Old Gibber]

When I had a caravan, I used to isolate the battery, and charge it up once around Christmas. By that time the voltage had only dropped slightly. The batteries lasted for many years.

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[tonka]

If the Sargent unit is anything like the past one on my Autotrail they seem to have a small drain even with everything off.
Mine was 0.2 amps and Sargent said it was normal. Add that up over time and it can soon drain a battery.

The charger on a timer seems a good way to go.

 

[autorouter]

This problem is a very common one, and a solution is available if you want. You need to get a proper multi-stage intelligent charger. It will constantly monitor the state of the battery, and feed it whatever charge is appropriate. Such a charger can be left connected indefinitely.

For example, a Victron BlueSmart 15A charger has three basic charging stages. Bulk charging outputs the full charge current, to charge the battery until the voltage rises to the absorption voltage of about 14.5V. When it reaches this voltage, it stays at the same voltage until the amps falls to a predetermined low value. Then it switches to float charging at about 13.5V. It can stay in float charge mode for some time, for weeks if necessary. It has a storage mode too, so if there's no activity for a long time it switches off for a week or two, then back on to ensure it's kept fully charged.

 

[royandsharont]

Adria say that regardless of charge level the van and hab batteries should be charged once a month for 2 days to ensure the charge cycles are met and the life if the batteries are prolonged

 

[AlastairH]

Thank you very much for all your contributions. They are very much appreciated and food for thought.

 

[PhilandMena]

The Sargent 3 stage intelligent charger (PX 300) can be left on indefinitely as it will go onto float mode and little to no fluid will be lost during this stage.
I have done this since owning my motorhome without any issues.
As an aside. Banner lead acid batteties are in my experience poor performing leisure batteties. Mine only lasted for 3 years.

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[PhilandMena]

Sargent charger.

 

[bladerunner]

I've left my MHs permanently hooked up to EHU at home for past 13 years, motorbikes trickle charged permanently past 25 years.
Use both as often as possible throughout year (at least monthly)
Never a problem with batteries.