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Inverter doesn't work with engine running

I've just replaced my 3000w modified sine inverter with a 5000w pure sine. Brilliant, it runs my PS3 and espresso machine, which is why I bought it. I thought all was well. But, I took the boat out today for the first time since fitting it and as soon as I turned the engine on, the inverter threw up a fault light and stopped working. Turn the engine off again and it's works perfectly. What's going on? How does it even know my engine is running when its drawing power from my batteries (5 x 110a all new). The 3000w ran perfectly. Thank you.

Asked by: Carl Young  | 3.00pm, Sunday 22 September

WW says:

It sounds as if your inverter is shutting down due to over voltage when your batteries are being charged by the alternator. This might be an actual problem in that the batteries are being charged at too high a voltage, or something else causing the inverter to trip, due to perceived high voltage.
Assuming that your inverter is wired directly to the battery bank with hefty cables and a 500A fuse; it is worth checking that all the connections including the inter-battery links, are tight since the inverter could draw in excess of 400A.
The link cables between the batteries should be as big as the ones to the inverter to spread the load evenly between the batteries.
If the inverter cables are connected at the same point as the alternator, move them to the other end of the battery bank. This will stop the inverter seeing the highest charge voltage, especially important if you have an intelligent charge controller.
If after doing all of the above there is still a problem, check the voltage across the inverter connections; if when you start the engine the voltage rises to above 14.5V, you have a problem with the alternator or charge controller. If not, the inverter is faulty and tripping at too low a voltage.

Rupert Smedley  | 5.22PM, Sunday 22 September

Readers say:

I've got a victron monitor which says that the voltage going in is 14.84. So, a bit over the 14.5. Is that enough to tip it over?
What can I so to reduce the voltage?
The engine is a year old Beta 38 wit 120 hours on it and under guarantee.
Thanks for your comprehensive answer by the way.

Carl Young  | 5.07PM, Wednesday 25 September

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