Phoenix 12/375 blown fuse?

Had a similar scare with my setup in the shepherd's hut last month, so this feels timely.

Was doing some rewiring to tidy up the 12V distribution panel and somehow managed to momentarily reverse the connections on my Victron Phoenix 12/375 before I caught the mistake. Classic brain fog moment. The unit went completely silent — no green LED, nothing on the display, absolutely dead.

Before assuming the worst I went through the basics:

• Checked the ANL fuse on the positive cable from the battery — that was fine
• Checked the inline blade fuse on the remote panel cable — also fine
• Then I noticed the small internal fuse on the PCB itself

Cracked the casing open (out of warranty anyway) and sure enough, there was a blown SMD fuse on the board near the input terminals. Replaced it with a matching value from a spare fuse kit I had lying around and the unit came straight back to life. Happy days.

Worth noting: the Phoenix 12/375 does have some built-in reverse polarity protection but it's not infallible — if the surge is significant enough it'll sacrifice a fuse rather than the whole unit, which is actually sensible design.

Anyone else had this happen? A few questions for the thread:

1. Did yours come back after a fuse swap or was there deeper damage?
2. Is there a Victron-approved internal fuse spec anywhere in the documentation? I couldn't find it in the manual and just matched visually.
3. Would a proper fused Anderson connector on the input prevent this kind of thing in future, or is that overkill for a 375W unit?

Keen to hear what others have done.

@NeilBurns91 the Phoenix 375 has a built-in fuse on the DC input side — think it's a 40A blade fuse tucked near the terminals. Worth checking that first before assuming the unit's cooked.

Reversed polarity even for a split second can take that out without damaging the inverter itself. Had something similar happen with my Victron setup after a daft moment with a multimeter probe.

Pull the fuse, test it with a multimeter (continuity check), replace if blown. Fuses are pennies from any auto parts shop or Amazon.

If the fuse is fine and it's still dead, check the remote on/off pins — sometimes those get shorted during rewiring and the unit just won't wake up.

@JimKelly is right about the blade fuse — worth checking that first before assuming the worst.

One thing I'm curious about though: did the unit throw any fault LED codes when you reconnected it correctly? My understanding is the Phoenix range has some protection circuitry that might just need a reset rather than a fuse swap.

Also, what gauge cable were you running to the distribution panel? Wondering if an undersized cable caused excess resistance that contributed to the issue when polarity reversed, or whether it was a straight short.

Has anyone actually replaced that internal fuse on a 375 themselves, or does it typically need to go back to a Victron dealer? Seems like a straightforward job but I don't want to void anything if it's still under warranty.

@NeilBurns91 had this exact scenario with my garden office setup — reversed polarity for a split second during a tidy-up and the blade fuse took the hit rather than anything more serious. Swapped it out with a replacement from a local motor factors (same spec, don't go uprating it) and the unit came back to life no problem.

One thing worth checking alongside the fuse — inspect the DC input terminals themselves for any scorching or discolouration. Even a brief reversal can leave residue that'll cause resistance issues down the line. Give them a clean with some contact cleaner before reconnecting.

If the fuse is intact and it's still dead, Victron's warranty/support process is actually fairly straightforward — worth logging it with your supplier before assuming board-level damage.

@NeilBurns91 worth grabbing a multimeter and probing the DC input terminals before you do anything else — if you're getting battery voltage there but nothing on the output, that 40A blade fuse is almost certainly your culprit.

One thing nobody's mentioned yet: Victron's protection circuitry on the Phoenix range is actually pretty decent against brief reverse polarity events. Good chance the fuse took the hit and nothing else is damaged.

Replaced one on my own Phoenix 12/500 last year — Halfords or any decent car parts place will have the blade fuses. Cheap fix if you're lucky. 🤞

If the fuse is fine and you're still getting no output, then it's worth downloading the VictronConnect app and checking if there's a fault code logged — assuming you've got Bluetooth on yours.