Boat won't start.

[WotEver]

am I right in thinking that Laurie is using his domestic battery for starting?

 

mystery is not quite solved until we get the answer.

No.

 

The explanation as supplied makes no sense therefore all we need the know is that it was, unsurprisingly, a dirty connection that now appears to be clean.

 

Tony

[Bill]

If I'm reading the explanation correctly (and I may well not be), both the starter battery negative and the domestic negatives are connected together as per normal. However the final connection before being connected to the hull (not sure if that is next to the starter or domestic battery) was a bit high resistance which dropped the voltage getting to the started via the solenoid to approx 4V. Hence when jumping the +ve domestics to the starter battery it made bugger all difference.

[WotEver]

If I'm reading the explanation correctly (and I may well not be), both the starter battery negative and the domestic negatives are connected together as per normal. However the final connection before being connected to the hull (not sure if that is next to the starter or domestic battery) was a bit high resistance which dropped the voltage getting to the started via the solenoid to approx 4V. Hence when jumping the +ve domestics to the starter battery it made bugger all difference.

Yup.

[Murflynn]

makes good sense.

 

dunno why the OP and his mate couldn't say so.

[Guest]

A teacher where I used to work had a lovely old Honda car. She was late to work one morning as her car wouldn't start. She had taken it to three garages over a short period of time, none of whom could cure it. Our caretaker whacked the battery terminals with a spade, and it was fine afterwards, right up until the time when she traded it in. One mechanic/geezer had wanted to do something close to the back axle?

[Murflynn]

A teacher where I used to work had a lovely old Honda car. She was late to work one morning as her car wouldn't start. She had taken it to three garages over a short period of time, none of whom could cure it. Our caretaker whacked the battery terminals with a spade, and it was fine afterwards, right up until the time when she traded it in. One mechanic/geezer had wanted to do something close to the back axle?

what? p*ss on it?

[Guest]

what? p*ss on it?

Might as well have done! I suspect he was taking the pi55 to the tune of a few hundred quid.

[Tony Brooks]

No.

 

The explanation as supplied makes no sense therefore all we need the know is that it was, unsurprisingly, a dirty connection that now appears to be clean.

 

Tony

 

Well that is my reading of it, especially as I had warned about the possibility that the engine earth may be via the domestic bank and thus a not so bright idea. I note this was ignored.

 

 

If I'm reading the explanation correctly (and I may well not be), both the starter battery negative and the domestic negatives are connected together as per normal. However the final connection before being connected to the hull (not sure if that is next to the starter or domestic battery) was a bit high resistance which dropped the voltage getting to the started via the solenoid to approx 4V. Hence when jumping the +ve domestics to the starter battery it made bugger all difference.

 

I agree that that is what it sounds like but if so cleaning the domestic battery terminals shoudl not have done anythingt o the electrical path through the negative link cables UNLESS it was twisted on the stud and that cleaned it.

 

As we still have no real test figures I fear we may not have heard the last of this OR Murflynn is right and he is starting from his domestic bank.

 

We wait to see what happens.

 

 

 

 

[dmr]

Hi Dave,

 

Now thanks to all on this forum and Kevin for giving up his Bank Holiday Monday, we hope to set sail towards the Maccy canal on Friday. We will be going via Penkridge etc. so in theory we should meet Is Goliath about? We'd love to meet up with you all again and tell tales of daring during the BCN 24 hour challenge.

 

I have sent you a PM detailing our current and future drinking and boating exploits.

 

...............Dave

[16csvt]

There does not seem to be any appetite to 'play the game' . I had hoped to create a tail to the thread which would have consisted of the combined wisdom of the many interested bodies, which may well have been of use to a less electrically savy person in the future.

Never mind.

To the chase.

Laurries problem was a corroded crimp connector. Not one of the little 'squash it on yourself with pliers' type, a proper 25 sq mm to M6 / M8 lug.

To be fair, it didn't look that bad from a distance. Once diagnosed, on dissasembly there was hardly anything to be seen, a tiny bit of brown between the hole and the threaded stud, and a slight coat of white powder. Rubbed it off with a green kitchen scouring pad.

It was in the 0V return from the block back to the neg battery straps. The other two proper lug ends on the battery post adaptor were a tad oily, but were making to the post adaptor. The crimp from the 0V return was up at +6V or so, while still sandwiched in the stack, but only when trying to pass start current. That is why he only saw +4 or so when turning the key.

 

I would have half expected white, blue or perhaps green powdery corrosion on a battery connection. Can't be sure where the brown came from, but the header tank is almost directly above the joint There did not however, seem to have been a flood of brown oily water onto the cables. That would have suggested another , greater, problem.

I do not recall a strap to the hull. It is almost as if the installer was trying to achieve an insulated return arrangement while using a chassis return starter.

Unless of course it used to be insulated return and the starter has been changed at some time in the dim and distant past for a chassis return one.

 

Laurries account of the events is fairly accurate from a laymans perception, but the events were technically slightly different.

All voltages measured w.r.t. Start battery neg post,

Start batt +ve Well up, 12 /13V ish.

Work the starter, only drops perhaps 0.5v.

Starter solenoid input. Same as observed at the Batt +ve

The retun came from deep down under the engine rear end, via a red key isolator, backto the negative straps on the batteries. Difficult to get at.

Jump lead from a convenient thick bare metal point on the top of the engine back to the negative batt straps just to check / confirm it was a return issue.

Engine started very nicely.

Stop engine. Remove jump lead.

Work way along return path, dab on the point to be tested and work the starter.

Anything more than perhaps 0.25, 0.5V means I hadn't got to the fault yet. Getting typically 6V or so all the way along the path.

All the way to the crimp back at the neg straps. Adjacent crimps at 0V wrt start batt neg post.

Strip clean reassemble. Starts grand. Cup of tea, prove it again (Sod's law detect and prevent).

The End.

 

Mike, your confusion probably derives from the fact the engine return presents itself onto the post connected to Domestic1, but tis of little effective consequence as all the negs are strapped together with good cable and proper ends.

 

 

 

Regards to all

 

16csvt

[Paul C]

Do you have one of those hydraulic crimpers? A 25mm2 cable on an M8 (or M6) ring terminal is best done with the hydraulic crimped style, and heatshrink. I've heard that there's 2 versions of terminal, one with a hole and one without - the ones without are better for boats because they don't allow moisture in, thus corrosion is slowed/prevented.

[Murflynn]

......................... we can relax, guys

[16csvt]

Didn't need to remake the joint, just gave the external tarnish a scrub.

I used to have access to a set of non hydro lever action BICC crimpers. but sadly no more.

Dependant on which way retirement takes me, I might invest in a cheap and cheerful hydro tool with assorted dies, but not yet.

 

Regards

 

16csvt

[Laurie Booth]

 

 

Can't be sure where the brown came from, but the header tank is almost directly above the joint There did not however, seem to have been a flood of brown oily water onto the cables. That would have suggested another , greater, problem.

 

 

 

A few years ago all my water pipe work feeding the engine was sabotaged, with all the joints being loosened. This led to two brake downs during one of the BCN 24 hour challenges (never got to the finish line), with water spraying all over the engine and steam shooting up at me from the engine.

Edited September 1, 2016 by Laurie.Booth

[Tony Brooks]

 

snip

 

Mike, your confusion probably derives from the fact the engine return presents itself onto the post connected to Domestic1, but tis of little effective consequence as all the negs are strapped together with good cable and proper ends.

 

 

 

I am going to take issue with the last bit on three grounds.

 

First every extra joint in a system causes volt drop, especially on high current systems like starters so in marginal cases extra joints may just be the thing that sops the engine starting.

 

Second, the fact that this is decidedly non-standard makes faulty finding, especially remotely, difficult.

 

Thirdly, each joint introduces extra potential unreliability as shown in this thread.

 

I agree that most of the time such a layout will work and show little, if any, difference to a system with the hull/engine "earth" run direct from the engine battery but it is still not best practice.

 

Anyway, thanks for sorting him.