BSC 12/5 always on?

Been running a Victron Blue Smart IP65 12/25 on my narrowboat for about 18 months now, left permanently connected to shore power when I'm moored up. Short answer: yes, it's fine to leave it always on.

The Blue Smart range uses proper absorption/float/storage charge cycles — once the bank is full it drops to a maintenance float and just trickles in what's lost to self-discharge. It's not hammering your battery continuously.

That said, a few caveats worth mentioning:

• Battery chemistry matters. If you've got AGM or gel, the float voltage is different to flooded lead-acid. Make sure the profile is set correctly in the app, otherwise you can cause issues long-term.
• Lithium is a different story entirely. If you're running LiFePO4 (Fogstar Drift or similar), most folk disable the storage mode or use a BMS with a dedicated Victron Li profile. Leaving a charger on li with the wrong profile isn't ideal.
• The 5A model is quite modest — on a decent-sized bank it'll basically never do harm just sitting there in float. More of a concern with higher-output units.

On my boat I've got a 200Ah Fogstar li bank and the Victron just lives on the Li preset. Shore power goes in, BMS handles the cutoff when full, charger idles. No drama in 18 months.

What size bank are you working with and what chemistry? Makes a difference to the advice here.

@OakSpirit good to know you've had no issues with the 12/25.

Worth adding — Victron's absorption/float cycle means the battery isn't being constantly hammered. Once it hits float it's basically just a trickle. The IP65 range is also pretty solid on thermal management so it won't cook itself sitting there.

One thing to watch on a narrowboat specifically: if you're on shore power with long cable runs, make sure your input voltage isn't drooping too much under load. The Blue Smart will compensate to a point but persistent low input can cause it to work harder than needed.

I run a similar always-on setup in my garden office with a Victron Smart IP43 — been on 24/7 for two years, no drama. Just keep the firmware updated via VictronConnect and you're sorted.

@OakSpirit eighteen months permanently connected and still going — that's practically a marriage by Victron standards. Mine's been on continuous float duty for coming up on three years now as part of my emergency backup setup, and the only drama has been me panicking every six months convinced something must be wrong because nothing has gone wrong.

The Blue Smart IP65 really is bor

Interesting thread — I've got a similar question but for a motorhome context rather than a narrowboat.

When you say "always on," does that include when you're away from the vehicle for extended periods — weeks rather than days?

I'm running a Fogstar Drift 100Ah LiFePO4 and wondering whether the Victron charger's storage mode actually kicks in properly if the battery is already sitting at say 90%+ when I disconnect from shore power and walk away.

Does the charger recognise that state and drop back accordingly, or does it just keep pushing absorption cycles unnecessarily?

Also — @OakSpirit — are you on AGM or lithium? Suspect the answer might differ depending on battery chemistry, particularly around what voltage the float settles at.

@AZY_Marine "practically a marriage by Victron standards" — took me a moment, then I snorted tea out my nose, cheers for that.

@BevJackson64 motorhome context is essentially the same deal. Victron's absorption/float cycle doesn't care whether you're moored on the Cam or parked on a

@BrianBrown the real question is whether Victron's absorption stage lasts longer than most marriages — spoiler: it does, and it's equally exhausting to sit through.

Worth noting for @BevJackson64 that motorhome context is essentially identical electrically — the Blue Smart IP65 will just float your bank once it's full, drawing barely anything from shore. Pedant hat on: do double-check your shore power hook-up lead is rated for continuous use rather than occasional, some of the cheaper ones aren't happy about it long-term. Fogstar or a decent 16A blue CEE connector setup sorted mine on the van conversion without drama.

@FETFan 😂 can confirm my Victron's been more committed than most relationships I've known

On the actual question though — yes, leaving it always on is genuinely fine. Mine's been permanently hooked up in the van for two years solid, no drama. The float stage keeps the battery topped off without overcharging, that's literally what it's designed for.

@BevJackson64 motorhome context is basically identical — if you're on hook-up at a site, just leave it running. Victron's battery management is clever enough to do the right thing. I've got a Fogstar Drift lithium and the two play nicely together once you've set the correct battery profile.

Only thing worth checking is your ventilation if it's in a tight space — they do get slightly warm.

On the actual question though — does anyone know if the BSC 12/5 specifically has the same storage/float behaviour as the IP65 range? I'm looking at one for my motorhome where it'd be permanently wired in, and I want to confirm it drops to a proper float rather than cycling through absorption repeatedly. The Victron docs are a bit vague on the smaller units. @OakSpirit your 18-month experience sounds promising — have you ever monitored the actual charge curve on yours, perhaps via a shunt or the VictronConnect app?