Leisure batteries for dummies

Campervanningwithkid · Jul 14, 2026

I know there is a lot of info on batteries, but I need it in a simple explanation!

I’ve recently replaced my leisure batteries, they were the original ones for my 2017 Ocean.
We went away at the end of June, and since we have been back the fridge has inadvertently been left on. - it was still on when I went out today. However I then noticed on the panel that the battery was flashing as if it was totally discharged - fridge was still on at this point.
I do have a solar panel, which I assume is working - I’ve attached some screenshots of the last few days.
I need someone to explain in very simplistic terms - more simple the better! As I’ve looked and read a bit about the batteries and I’m still not sure how to know when all is ok, and when is not.
So - have I ruined my new batteries? When I turned the fridge off and went back battery on the panel said 90% - assume it can’t go from empty to 90% in mins so maybe one is a mistake?
How do I know if they are in good health?
Is my solar panel working?
What do I need to do to keep them maintained?

As I say simple is best for me with this

Thanks

Perfectos · Jul 14, 2026

Your solar panels have been supporting the fridge usage.

I doubt you have ruined your LBs , look at the max & min Voltage per day !

The batteries are getting discharged, but then getting a full charge whilst on solar.

When your fridge has been off for a day , the solar (app) read out will no doubt show "float" which means the LBs are fully charged an in maintenance mode. (Float or absorption)

Edit the consumption 10Wh is the load from your fridge

Your solar panels have been doing exactly what they should do :cheers

Perfectos · Jul 14, 2026

Use this chart to confirm battery health - as you can see your LBs have not gone below 50% , before being topped back up to full by the solar

I hope this helps reassure you

egena · Jul 24, 2026

Hey - I hope this may help you also;

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Its great you replaced your leisure batteries! This reply assumes you swapped them for the original AGM lead batteries.
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I also use solar to keep the batteries topped up and I have found that when solar is strong, it makes the camping console battery symbol flash.

Firstly, I think this is because the camping console wasn't designed to monitor solar power coming in so it just thinks there is a fault and flashes the battery symbol.

Secondly, because the camping console cannot measure your solar power coming in, the percentage you see on the camping console no longer reflects the actual power remaining in your batteries.

Instead, its a calculation based on how much power you've been using. It watches power LEAVING your batteries. Solar never makes it go back up again, only when you start the engine (the console can detect that!) or plug into mains power (it can detect that too!) will the percentage climb. This means you could have fully solar charged batteries but the camping console still says "17%" or something like that.

Its great you've got your Victron monitor so you can see the power going in - its a great stand-in for the camping consoles limitations. What was mentioned by Perfectos in the above posts was Voltage. Any battery in the world reports how full it is by measuring its voltage - the fuller the battery, the higher the voltage it produces. Your Victron monitor app shows the voltage of your batteries (highest and lowest) and, from your screenshots, the batteries got down to 12.05-ish volts which meant they were at about 50% capacity before the solar charged them back up again (the "highest" shown in your app being 12.95-ish volts). This indicates your batteries are fine.

The summary is, its the limitation of the camping console when solar panels are fitted - its unable to measure your remaining available power accurately.

You can, by the way, reset the percentage shown by holding down the back-arrow button for 5 seconds. Personally, Ive learned to ignore the percentage shown on the camping console altogether Instead, I would gently recommend changing the display on the camping console to "Battery" using its menu. This will then show the voltage of your batteries at all times so you can know how much charge you have based on that (use the graph above from Perfectos).
It may seem a little overwhelming at first, but it truly isn't. If the voltage drops to 12.05 volts, you're down to 50% battery charge. Its quick and easy to look at and is a true indicator of battery health.

:::A GENTLE WARNING:::
Lead acid batteries, including the AGM batteries installed by VW for the living space, really do not like going below 50%. I won't bore you with the details but the internals of the battery slowly accumulate irreversible damage when being charged below 50% capacity. To get the best out of them, try your best to keep them above 12.05 volts - the solar will definitely help, but only in peak summer. Mains power or engine use (watch out for your Diesel Particulate Filter (DPF) if running the engine on idle for long periods!) will work well.

:::FUTURE ADVICE:::
I would absolutely recommend replacing both batteries for a single 100Ah LifePo4 (lithium!) battery, as and when you feel the time comes.

- They charge faster so you only need to run your engine for a much shorter time (great for DPF management!)
- They only experience damage if charged below 10% (so you get to use virtually the whole battery capacity, not just half of it like Lead Acid)
- They're much lighter (so better on your Miles Per Gallon)
- You can buy one for the same price as 2 x lead acid batteries (one will provide more battery capacity too!)
- They can be recharged 3000-5000 times (Lead Acid AGM are around 500-800 charging cycles) so they last a very long time
- They are designed as direct drop-in replacements for retrofitting. (Its great to also make extra enhancements to your charging modules built into your campervan but its truly optional these days)
- Your Victron will also get a small change in its menu for the battery type its charging - thats it!

Something to think about for 5 years time, anyway