Anyone else had grief with a Sterling ProCharge Ultra on a narrowboat?

Had one of these on my old 57-footer for about three years and it was... character building, let's say.

The main drama was the temperature compensation going haywire in winter. It was reading the bank as needing far less charge than it actually did, and I ended up with chronically undercharged AGMs for a whole cruising season before I cottoned on. Sterling's support were decent enough when I rang them, but the troubleshooting process felt like being walked through a manuscript from 1987.

Eventually replaced it with a Victron MultiPlus and haven't looked back — the integration with the GX system means I can actually see what's happening rather than just hoping for the best. Bit of a different price bracket obviously, but when you're living aboard it's not really optional to have reliable kit.

That said, I know a few boaters who swear by their ProCharge Ultras and have had zero bother. Makes me wonder if there was a dodgy batch at some point, or whether installation quality makes a massive difference (mine was done by the previous owner, so who knows what compromises were made under those stern boards).

Anyone else noticed issues specifically with the temperature sensor placement? I reckon that was half my problem — it was stuck to the side of the battery rather than properly under a terminal. Small thing, potentially massive consequences.

Would be curious whether anyone's managed to get long-term happiness out of one, or if they're just a bit temperamental by nature. Drop your war stories below 👇

@Kingy oh mate, I feel this in my soul — and I'm not even on a boat, I'm in a tiny house on a static base, but I had the same temperature compensation lunacy with a Sterling unit I borrowed off a mate for emergency backup testing last winter.

The sensor placement is everything with these things. If it's anywhere near a heat source or drafty locker it'll convince itself the batteries are either lava or absolute zero and compensate accordingly, which on AGMs is genuinely exciting in the worst possible way.

Did yours have the dip switches set correctly for battery chemistry? Sterling's default profile out of the box is... optimistic, shall we say. I ended up cross-referencing the compensation curve against Victron's published figures for similar chemistries and the Sterling was applying nearly double the voltage correction per degree C.

What batteries were you running?

@Kingy the temperature compensation issue on those units is well documented and Sterling's response when you ring them is essentially "have you tried turning it off and on again" delivered with the enthusiasm of a man who'd rather be somewhere else entirely.

What nobody tells you is that the NTC sensor lead on the ProCharge Ultra is absolutely laughable in length for a narrowboat install — routing it anywhere near the battery bank without it picking up heat from the engine bay is a minor miracle of cable management. Mine ended up reading 8°C high in summer, so it was chronically undercharging my AGMs all season while I stood there wondering why my bank felt perpetually sulky.

Replaced the sensor, relocated it properly behind thermal foam away from the engine bulkhead, problem largely solved. Sterling aren't bad kit but their documentation is written by someone who's apparently never actually been on a boat.

@Kingy interesting timing on this thread — I've been half-considering one of these for my narrowboat to replace a tired Victron Blue Smart setup, so this is useful intel before I commit.

Can I ask — was yours the older firmware version or had it been updated? I've seen a few mentions on other forums suggesting Sterling pushed an update that addressed some of the temp sensor drift, but I can't find anything definitive.

Also wondering if the issue was specific to engine alternator charging or whether it affected shore power input too? On a 57-footer I'd imagine you're running both fairly regularly.

Might just stick with the Victron ecosystem given I'm already partway in, but the Sterling units are significantly cheaper and that matters when you're fitting out on a budget.

@Kingy not a narrowboat user myself — static caravan with emergency backup focus — but I've looked at the ProCharge Ultra seriously as a mains-input option for my setup and ultimately walked away from it.

The temperature sensor placement on those units seems fundamentally compromised. If the sensor isn't reading actual battery surface temperature accurately, the compensation algorithm is just applying corrections based on fiction. In winter that'll either undercharge (capacity loss you won't notice until you need it) or push voltage high enough to stress the cells.

@AGM_Pro if you're replacing something tired, I'd be looking harder at a Victron IP43 or IP67 series before committing to Sterling. The Victron ecosystem's integration with MPPT and BMV monitoring gives you actual data to work from rather than guessing whether compensation is behaving. More expensive initially, but the visibility alone has saved me from several bad decisions.

@AGM_Pro before you pull the trigger on one for narrowboat use, worth knowing the ambient temperature swings in a boat engine bay are savage compared to any land-based install. We're talking 60°C+ when the engine's been running hard, then dropping to near-freezing overnight in January.

The ProCharge Ultra's temp sensor placement becomes absolutely critical in that environment — most factory installs I've seen have it in completely the wrong spot. Mount it on the battery negative terminal, not floating around near the alternator.

Also worth checking whether your alternator has adequate field current protection before connecting. A few narrowboat owners have cooked alternators learning that lesson the expensive way.

For your use case @AGM_Pro, have you considered a Victron Orion-Tr Smart instead? Better telemetry, proper app monitoring, and the isolation is genuinely useful on a 12V boat chassis.

@AGM_Pro from a motorhome angle I've had similar temp sensor grief with chargers in confined spaces — the sensor placement matters massively. If you do go for it, keep it away from any heat sources and make sure it's not in a dead air pocket.

For what it's worth I ended up on a Victron IP43 for my shepherd's hut and haven't looked back — the Bluetooth monitoring alone is worth it. Narrowboat environment is obviously different but the principle of not fighting the charger constantly still applies.

The ProCharge Ultra isn't a bad bit of kit when it's working properly, but sounds like the margin for error on a boat is pretty slim given the damp and temperature variation.

@Kingy yeah the temp sensor placement is everything with these. Mine's a static setup so different world, but same principle — if the sensor's reading ambient instead of actual battery surface temp you're chasing ghosts all winter.

What alternator are you running alongside it? On a narrowboat the engine charging side can mask problems with the mains charger until your bank's already cooked or sulphated. Seen a few folk on here find out the hard way their AGMs were done before they realised the charger was the culprit.