Fuses??

[Barking Mat]

Where's @brightspark , I think he's avoiding this one.....

 

[Barking Mat]

What diameter nail or screwdriver? I've some threaded bar...

 

[Chris Snow]

When investigating odd issues like this that suggest an impedance issue the easiest way to find the problem is to measure the voltage across components when under load. Ie across the fuse. A good fuse will have a small voltage with load and none with no load. Where you find voltage you have resistance.

Obviously not wise to do this test for long if you have a stalled motor etc.

 

[Barking Mat]

Will reply tomorrow....

Beer.....

 

[Matrixx]

A fuse will be working or not. you say A 12v relay, but the fuse is a 315A/ 690VAC , the relay/contactor will work independently of the supply voltage to the motor. is the motor three phase? if so where are the other 2 fuses? the contactor will have is own control fuse.

 

[Barking Mat]

A fuse will be working or not. you say A 12v relay, but the fuse is a 315A/ 690VAC , the relay/contactor will work independently of the supply voltage to the motor. is the motor three phase? if so where are the other 2 fuses? the contactor will have is own control fuse.

all 12 volt.

 

[m_c]

It's not the best of photos, but given the main components look OK, and the construction, it's likely a dry solder joint.
Is the fuse subject to quite a lot of vibration where it's mounted?

I would have said it could have been corrosion on the holder contacts, but at that kind of current, if that was the problem, the contacts/holder would very likely be melted. That is unless it's happened to have been sat unused for quite a while, and the corrosion has built up over that period, so it's gone from working OK, to enough corrosion to stop things working, without the period in between where it was likely to melt things.

 

[Barking Mat]

Well, the boat came out yesterday. Even bypassing the fuse holder. It still didn't work.
so I think the relays contacts are toast.

we'll see.

 

[Matrixx]

At 12v dc I have seen batteries with no output even with clamps on tight, but take them off and clean them and they will conduct, such low voltage can be stopped by corrosion or contamination.

 

[slim_boy_fat]

@barking mat Why not just buy a new replacement instead of faffing about in the hope that'll still be working when the boat is launched again for next season?

They're as cheap as chips and something to give you peace of mind....which is very important

https://uk.rs-online.com/web/p/cent...Va4BQBh2lbAWQEAQYASABEgJ4afD_BwE&gclsrc=aw.ds

 

[Wallace]

Chips must be expensive in the Highlands John!

Are cables good, any damage? I went out to a tail lift one night that refused to go up but had lights lit and seemed to have Voltage everywhere. I eventually found the main Positive cable had a bulge in it and was full of verdigris, just damp enough to pass Voltage but no current. It had a small nick in the insulation from a hole drilled in the chassis during installation and corroded over the years.

 

[slim_boy_fat]

Chips must be expensive in the Highlands John!

Wouldn't know really, as I make my own - that said if there were a proper chippy in the village, guess where I'd be frequenting.

Anyway, £18-19 for a part surely wouldn't even scratch the business maintenance budget and the job'd be jobbed.

 

[Barking Mat]

Thank you folks.

Fuse to be replaced with a more standard style fuse.

Contactors are my guess.

But I'm having to reorganize the entire workshop, at work.

Day 4? Tomorrow.