Would you say that applies to all leisure batteries ?
I believe so. If you don't then sulphation slowly starts to take over, reducing the battery's capacity, which it will do anyway, just a little quicker. As the Americans say, batteries wear out.
My last 110 amp leisure battery was 6 years old when I had to replace it.
For the work we did it would support my Shurflo pump with my daily work load. When my lad was out with me he mainly used his backpack as he prefers working with it rather than the hose reel.
As soon as I added my diesel heater the battery was flat at midday. It had no capacity left. So what I thought was still a good working battery as it did the job actually wasn't. Had I continued using it without the diesel heater it would have lasted another year possibly?
The batteries you use are a class 3 battery. I personally wouldn't look at buying one as their charging cycles are low. The specs don't give it a CCA rating, but they say it can be used with a motor mover. I'm a little confused as the class rating and motor mover application conflict.
https://www.norwichcamping.co.uk/shop/product/monbat-xl-110-lb-leisure-battery-1996/
The NCC rating on this battery isn't good. NCC have the battery they tested as a XLM110LB so I don't know if this is the same battery NCC tested or not. But the Norwich Camping website does say it's an NCC Class C battery.
https://www.thencc.org.uk/Our_Schemes/ncc_verified_leisure_battery_scheme.aspx
It gives a capacity of 98 amps and a Life Cycles 50% DoD of only 70. However, if you are getting good service from them in your application then there is no reason for you not to continue using them.
If you look at the duty cycles on class B batteries you will see that they are up in the 220's + for a similar price tag.
So did the marketing dept. of Monbat drop the "M" for a reason? Why did the manufacturers give the battery NCC tested a 110 figure model number on the label when the battery capacity was only 98 amps? Was that to mislead me into thinking something different without doing anything illegal? The first thing that went through my mind was that this battery was a 110 amp, exactly what the Norwich Camping website said it was.
An example of being mislead was an advert produced by Ford South Africa about 30 years ago. Trust me, it was a brilliant 'manipulation' of the facts.
Ford had a Madza 3 based hot hatch in the 1.6 engine class. It was in competition with Opel and several others in the same class all promoting their 0 - 100km acceleration times. Ford was the slowest of the class. It wasn't marginal, it was a difference of a couple of seconds. So Ford's advert didn't give a time. It was 0 to 100km "in one deep breath." Wow, that was quick. And it worked; they sold plenty of that model. How long is one deep breath? Absolutely brilliant but very misleading.
BTW. This is my opinion of the battery and the way I see it from the "facts" I see.
If you are running a diesel heater you need 2x 110amp batteries.
Supplying 2 batteries is a good way suppliers can use to cover more bases. It's a bigger power bank with double the reserve. It also reduces the load on each battery. If I was a supplier, I would tend to do that as well.
However, I have 1 x 105amp battery which is powering the diesel heater as well as 2 Shurflo pumps. This is new territory for me. I have a good quality combination battery that also has starter battery characteristics. The diesel heater draws around 18 amps on start up for a couple of minutes and once fired up draws between 3 to 8 amps depending on where it is in the heat cycle.
The trouble with diesel heaters is that tend to cycle on and off which makes them very power hungry. That diesel heater draws 0.5 of an amp hour from the leisure battery from starting to reaching full internal temperature.
I have modified my 2 man system by adding a third heat exchanger. Using a 12v digital temperature controller, I'm able to regulate the internal heating circuit between 78 and 83 degrees C which keeps the heater working all the time. The extra heat is bled back into the van's tank in the form of hot water. Another Shurflo pump is activated when the water in the internal water circuit reaches 83 degrees, It draws cold water from the tank, pumps it through that third heat exchanger and back to the tank. That pump is switched off when the water in the internal hot water circuit drops to 78 degrees C. The diesel heater is on idle (very low heat output mode) between those temperature parameters.
So far this year on our round, the most current I have drawn from the leisure battery is 22 amps deficit in a day. As the charger is plugged in every day when I get home, that battery is fully recharged every night.
This battery is a year old now. I don't know how it will continue to perform in the future. As I have said many times before; a combination leisure and starter is neither a perfect starter battery nor a perfect leisure battery. So I don't expect it to last as long as my previous leisure battery did. But it's an experiment I'm closely monitoring, and we will have to see where it goes. I will be extremely happy if the battery lasts 3 years.
I have been starting the diesel heater when we arrive at our first job. I could save current being drawn from the leisure battery by switching the heater on when on route to our first customer. That way the van's alternator will 'cover' the heater's starting current.