Victron lead acid battery failure under guarantee

Really interested to follow this thread as I'm weighing up whether to stick with lead acid or move to lithium for my tiny house setup.

We had a similar situation with a set of lead acid batteries running through a Victron MultiPlus — two of the four cells started dropping voltage after about four years, well within what I'd consider a reasonable lifespan. The question is always whether it's the batteries themselves or something upstream causing premature failure.

A few things worth checking if you're in a similar boat:

• Absorption and float voltage settings — are they correctly configured for your specific battery chemistry in the Victron interface?
• Temperature compensation — lead acid is notoriously sensitive to cold, and UK winters don't help
• Equalisation cycles — are you running these regularly enough?

I ended up replacing with Fogstar lithium drop-ins eventually, but I know that's not always practical cost-wise, especially if the rest of your Victron kit is sized around lead acid capacity.

On the guarantee side — did you buy direct or through a UK dealer? My understanding is Victron warranties on batteries are handled through the reseller, which can make things complicated. Has anyone here actually pursued a warranty claim successfully in the UK?

Would be useful to know what charge controller you're running alongside it too — a poorly configured MPPT can absolutely cook lead acid cells over time without you realising until the damage is done.

Trevor1975 | 847 posts | ⚡ Off-Grid since 2019

@CarolThomas79 worth knowing that lead acid and lithium failures under warranty can be quite different beasts to deal with. With lead acid, manufacturers often scrutinise your charge/discharge records closely - any over-discharge events and they'll use that to wriggle out of a claim.

For a tiny house setup specifically, I'd lean lithium nowadays purely because the usable capacity is so much better - you're genuinely using 80-90% rather than the 50% you're limited to with lead acid to protect longevity. Means fewer cycles overall which keeps warranty claims less likely in the first place.

What's your approximate daily consumption? That'd help work out whether the lithium premium actually makes financial sense for your situation. The maths has shifted considerably in the last couple of years as lithium prices have dropped.

DownsCruiser | 312 posts | 🔋 Off-Grid since 2021

Ran lead acid in my motorhome for two years before switching to Fogstar Drift lithium last spring. Night and day difference honestly. Lead acid warranty claims are a nightmare — manufacturers always find a reason to wriggle out of it (partial discharge records, temperature logs, etc).

For a tiny house setup @CarolThomas79 the maths just works out better long-term with lithium. Higher upfront cost but you're not replacing them every 3-4 years and the usable capacity is actually what it says on the tin.

Only caveat — make sure your Victron MPPT is configured properly for lithium. Caught a few people out on here running wrong charge profiles.

LazySocket | 1,204 posts | ⚡ Off-Grid since 2018

@CarolThomas79 for a tiny house setup the maths really does favour lithium long-term. Lead acid's usable capacity is roughly 50% of rated, whereas with LiFePO4 (I run Fogstar Drift cells) you're accessing 80-90% reliably. That fundamentally changes your bank sizing calculations.

The warranty angle matters too — lead acid failure modes are notoriously difficult to attribute to manufacturing defects versus user error (undercharging, sulphation, etc.), which gives manufacturers wiggle room to void claims. Victron's BMV monitoring at least gives you logged data to fight back with.

Tiny houses typically have predictable, consistent loads which is actually ideal for lithium cycle life — you're not hammering the chemistry with irregular demands like a motorhome does.

What's your approximate daily consumption figure? That would help frame whether a used Fogstar or new Renogy LiFePO4 bank makes more sense financially.

NicolaTaylor72 | 23 posts | 🏠 Off-Grid since 2023

@CarolThomas79 I'm in almost exactly the same position — tiny house, seriously considering the switch. One thing I keep coming back to is whether the upfront cost of lithium (looking at Fogstar Drift cells mainly) is actually justified when you factor in the longer cycle life.

Has anyone here got concrete numbers on how long their lead acid bank actually lasted in a tiny house context specifically? I keep seeing "5-7 years" quoted but I wonder if that's under ideal conditions rather than real-world use with irregular charging patterns.

Also curious whether anyone has successfully made a warranty claim on Victron lead acid batteries — what documentation did you need and how straightforward was the process? That feels quite relevant to the OP's situation.