Blowning fuses with a 15Amp battery charger

Hi
I continue to blow fuses and need some help troubleshooting. I have a sail boat with a typical battery and charging system.
A house bank of lead acid and an AGM starter battery, an alternator for each. I have a 15A Victron charger between the house bank and the starter battery to keep it topped off when on shore power or at anchor. I have 2’ of 10 AWG wire with a 30amp fuse in line between the house bank and the Victron. When I start the engine this fuse blows, otherwise it is good, ie when connected to shore power and engine is off.

The odd thing is that the Victron charger replaced a Magnum charger. The only thing that has changed in the set up is the AGM and the Victron.

i have the settings to, AGM profile and regular alternator and have rechecked my wiring connections.

Any and all advise is very much welcome.

Which model of charger, assuming a DC to DC is what you mean.

i posted the wrong specs on the original post. its a 30A not a 15A.

VICTRON ORION-TR SMART 12/12-30 30A (360W) ISOLATED DC-DC CHARGER OR POWER SUPPLY

No wonder it is blowing, the manual recommends a 60A fuse. The unit will output 30A and input more than that. For 2ft it also recommends 10mm2 cable (8awg) but it is right on the change between 10 and 8 awg.

See Section 4.2 of the manual.

Voltage rating (Input or output) External battery protection Fuse 0.5m 1m
12V 60A 6mm2 10mm2

www.victronenergy.com/media/pg/Orion-Tr_Smart_DC-DC_Charger_-_Isolated/en/installation.html

ah, great thanks