How to set up Powerline 100Ah wet leisure batteries with Victron MPPT 100/20 charger

Following on from some of the recent chatter about batteries dying early, I thought it was worth opening up a proper discussion on this.

I've been running a pair of Powerline 100Ah wet leisure batteries for about 18 months now, paired with a Victron MPPT 100/20, and I'm still figuring out whether I've got the charge profile dialled in correctly.

The main thing I keep second-guessing is the absorption and float voltages. Wet lead-acid needs a decent absorption voltage — I've been running at 14.4V absorption and 13.2V float — but some folks swear you need to push it higher with leisure batteries to get a proper full charge, otherwise you get sulphation creeping in over time.

A few questions for anyone who's gone down this route:

• Are you running the battery preset on the Victron or custom settings? I've been using custom but not confident I've optimised it.
• How long are your absorption phases lasting day-to-day? Mine varies wildly depending on the solar input obviously.
• Anyone using the equalization function periodically? I've read conflicting things about whether it's actually worth it for these batteries.

The reason I'm asking is that I had a set of AGMs fail embarrassingly early last year — almost certainly poor charging — and I don't want to repeat that mistake with these wet cells. Getting the settings right from the start seems crucial.

Would be good to hear from people running similar setups, especially off-grid where you're fully dependent on the solar rather than topping up from the mains regularly. What's your experience been?

Good shout @Nessa73. Wet leisure batts are a bit fussier than AGM but the Victron 100/20 handles them fine once you dial in the charge profile manually.

Key settings to check in VictronConnect:

• Absorption voltage: 14.4–14.8V
• Float: 13.5V
• Equalization: worth doing monthly if your batts support it — check the Powerline spec sheet

The default profile on mine was slightly off for wet cells when I first set it up at the cabin. Five minutes in VictronConnect sorted it.

Also worth making sure your battery temp is factored in — if your static or hut gets cold overnight, temp compensation matters more than people realise. Victron's Smart Battery Sense is decent for that.

@LochChild is right that the 100/20 handles them fine — the key settings people consistently get wrong are the absorption voltage and float voltage for wet/flooded cells.

For a 12V flooded leisure battery you want:

• Absorption: 14.4–14.7V (I run mine at 14.6V)
• Float: 13.5V (not 13.8V — that's AGM territory)
• Absorption time: 2–3 hours minimum

Also critically — set the battery type to "Flooded" in VictronConnect rather than leaving it on the default AGM preset. Sounds obvious but I've seen folk skip this and wonder why their plates are sulphating within a year.

Wet cells also benefit from an equalisation charge every month or so (around 15.5V for 2 hours), which the Victron supports. Worth checking electrolyte levels beforehand obviously — don't equalise a low-water battery unless you enjoy fireworks.

Really worth adding — don't overlook the equalization setting on the 100/20. Wet cells actually benefit from a periodic equalisation charge (maybe once a month), which you can enable in the Victron Connect app. Keeps the cells balanced and knocks back sulphation.

Also check your temperature compensation if you're in a boat or motorhome — wet batteries lose capacity faster in the cold and the voltage curve shifts. Victron's smart shunt paired with a temp sensor sorts this automatically.

Running a similar setup on my static and the difference after properly configuring equalization was noticeable — batteries have lasted considerably longer than my previous pair ever did.