Fuse/circuit breaker on main battery wire

[desertrat]

Hi

I'm currently trying to diagnose a starting problem with our engine and one of the things I'm not sure of is should there be a circuit breaker/fuse on the main battery wire to the engine?

I currently have a 60A circuit breaker on both the main and aux battery wires but on occasion the breaker on the main battery wire trips when I try and start the engine. I'm not sure if I need a higher rated breaker or whether this might be a problem with the starter motor?

Any thoughts or ideas welcomed.

Cheers
Rob

[C-NUMB]

I never had a fuse on the he main battery wire to the engine, but maybe someone has, don't know. I guess starter typically uses much more than 60 amps so no wonder if some issues?

I do have main circuit breakers on engine wire but typically they are rated for short bursts like 500-1000 amps, blue sea sytems is an ok brand for that purpose.

[ashbypower]

A starter motor can draw in excess of 330a therefore it is inadvisable to have an in-line circuit breaker unless it is high current rated.

[Pikey Dave]

Originally Posted by desertrat

Hi

I'm currently trying to diagnose a starting problem with our engine

Would that be an Etec 150 by any chance?

[desertrat]

Originally Posted by Pikey Dave

Would that be an Etec 150 by any chance?

Nope but close it's predecessor the ficht 150. Sounds like you may have experience of a similar problem?

[Pikey Dave]

I'll give you a better answer tomorrow, rule #1 is in force at the mo.

[Seaflyer02]

Hi,

Circuit breaker 60 amp that is your problem. Like posted earlier the starter motor draws a lot of current way in excess of 60 amp. I have the same motor and I have always gone direct to the solenoid.
When I had a problem everything was dead apart from the trim on the engine, turned out to be a broken wire in the harness to the helm.
Fantastic engine has given brilliant service.

Good luck.

[Pikey Dave]

Originally Posted by desertrat

Nope but close it's predecessor the ficht 150. Sounds like you may have experience of a similar problem?

I had a 175 ficht on my previous boat, but didn't have any problems. As the others have said, lose the breakers, both in the main starter line & the auxiliary charging line from the motor, I'm assuming you have the dual charging harness fitted. Anything that reduces the voltage to the engine when it's trying to start will screw with the EMM electronics & cause problems. Anything that can connect or dis-connect a battery to the engine whilst it's running is a charging circuit killer. Neither of your breakers are necessary & are failure points.

[desertrat]

Thanks for the replies guys, going to remove the breakers tomorrow and see how it behaves.

I have a feeling I may have a starter motor problem as well but we'll see once the breakers are out of the way. Everything is fused through the fuse box anyway so no breakers shouldn't cause any other issues.

Cheers
Rob

[desertrat]

Well breaker removed and engine started first try and every try thereafter.

However now on to the next problem, the engine is lumpy and surges at tick over and there is a misfire. Time for another thread about this

[Nightfisher]

From your list of items, I'd say the total fuse size to handle all on the main power line (AT THE BATTERY + Seven inches),depends on what you plan to run off the 12 volt socket power-amp wise? Add all the max amp draws for each item , plus anything electrical you may add later then look-up the gauge of the main power wire required from battery and add 2 gauge sizes to know the proper main wire gauge then add the total the main fuse size of what U have added-up, plus 5 Amps.

Two reasons, 1) The heavier the gauge Main wire you use the more power that will be lost during the DC Voltage trip from the battery to the main fuse panel. 2) The main fuse at the battery is there only in-case a short occurs along the route from the battery to the fuse panel. All other shorts between the fuse panel and each powered-item should they occur, will blow the small fuse in the panel.