Windlass Circuit Battery Fuse?

Nigelb

Nigelb

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If the windlass circuit has a breaker within 150cm of the battery, do I still need fuse protection at the battery?

Also the Lofrans website for a 12v Tigres recommends a 100A breaker but the data sheet for the windlass has a load of 160Amps?

If I use the Blue Sea Circuit Wizard (App) it calculates a breaker or fuse rating of 175-200A?

Getting very confused!

Batt 820 Amps MCA
Voltage 12v
Load 160 Amps
Duration <1min
Wire 50mm2
Single Run
Outside Engine Bay
 
Nigelb said:
If the windlass circuit has a breaker within 150cm of the battery, do I still need fuse protection at the battery?

Also the Lofrans website for a 12v Tigres recommends a 100A breaker but the data sheet for the windlass has a load of 160Amps?

If I use the Blue Sea Circuit Wizard (App) it calculates a breaker or fuse rating of 175-200A?

Getting very confused!

Batt 820 Amps MCA
Voltage 12v
Load 160 Amps
Duration <1min
Wire 50mm2
Single Run
Outside Engine Bay
Click to expand...

If you have a windlass breaker 150mm from the battery that is your protection. Why do you need anything else?
 
For 1.5m of cable I would say yes, but a lot depends upon the way the cable is run and the chances of it getting damaged. Hopefully the cable can easily take the current as the fuse is meant to protect the cable.
 
Ruffles said:
Plenty of boats out there with no battery fuse at all. Plenty of cars for that matter!

But if it's a new install I guess it's not a bad idea. I'd question the rating though. I'd go for a 300A fuse for reliability. It's protecting the cable not the windlass.

These seem really neat...
Click to expand...

In many cases you would be correct, but not in the case of a windlass.

Most, if not all, windlass installations use cable substantially overrated for the windlass motor, to counter voltage drop. If you fitted a thermal breaker (don't use a fuse for a windlass) rated for the cable you could overload the motor and burn it out.

Edit ; if the breaker is left in place, a battery fuse would only be protecting the cable up to the breaker. The cube fuse is indeed a neat solution in this case.
 
Last edited:
Nigelb said:
If the windlass circuit has a breaker within 150cm of the battery, do I still need fuse protection at the battery?
Click to expand...

The cable between the battery and the breaker is unprotected. If you are 100% happy that the cable cannot chafe/short etc, you might decide it's OK. If you do decide to protect it you will only be protecting the cable as far as the breaker and you don't want a fuse blowing if you overload the windlass, you want the breaker to trip. So, the fuse should be a higher rating than the breaker, by a good margin.

Also the Lofrans website for a 12v Tigres recommends a 100A breaker but the data sheet for the windlass has a load of 160Amps?
Click to expand...


The recommended breaker should be fine, it will withstand currents greater than 100a for short periods.
 
Nigelb said:
Also the Lofrans website for a 12v Tigres recommends a 100A breaker but the data sheet for the windlass has a load of 160Amps?
Click to expand...

Pretty sure I've the same windlass, 12v. With a 100a breaker, which will trip occasionally if you flip between up and down before the motor has slowed to a stop. Which isn't a nice thing to do anyway, it just happened once or twice when not paying enough attention.
 
Thanks Paul,

Based upon your feedback, I Understand that the battery fuse (if fitted) should be ANL 175 Amp.

The existing 100Amp breaker should be sufficient, however you specifically mention ‘thermal’ breaker, my current installation is a traditional single toggle breaker, no thermal functionality as far as I can see. Do I need to upgrade the breaker to a more modern thermal specification?

Thanks for the advice
 
Nigelb said:
Thanks Paul,

Based upon your feedback, I Understand that the battery fuse (if fitted) should be ANL 175 Amp.

The existing 100Amp breaker should be sufficient, however you specifically mention ‘thermal’ breaker, my current installation is a traditional single toggle breaker, no thermal functionality as far as I can see. Do I need to upgrade the breaker to a more modern thermal specification?

Thanks for the advice
Click to expand...

Use a fuse close to the cabling rating, this ensures the cable is protected, whilst minimising the chances of blowing the fuse, rather than tripping the breaker.

If the existing breaker is working OK, don't worry about it. There's a good chance it's thermal anyway, but don't lose any sleep over it if it works.
 
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