Perkins intermittent starting problem

[Tamar]

Presumably the 12.8v you measured was with the battery at rest and ,measured across its terminals.

Can you check what the voltage reads while cranking (a) across the battery terminals and (b) across the starter motor terminals?

Just tried it across the battery, with the engine cranking and starting as normal it read 12.4V but when it struggled it went down to 10.5 volts. I didn't get chance to read it across the starter motor.

 

[billskip]

Ok a very simple test could be ...when its struggling keep it struggling for about 3 seconds and then off...something should have got hot..immediately feel all the terminals and see if one is hot.
The amps taking the battery down with the starter stalling is going to generate heat somewhere.
I presume you have tried a replacement battery or feel sure it's not the battery?

 

[Tamar]

Ok a very simple test could be ...when its struggling keep it struggling for about 3 seconds and then off...something should have got hot..immediately feel all the terminals and see if one is hot.
The amps taking the battery down with the starter stalling is going to generate heat somewhere.
I presume you have tried a replacement battery or feel sure it's not the battery?

Thanks I will try later. As to the battery, the engine spins over as if the battery is fully charged when it's behaving. Could it be a dud?

 

[Portofino]

It’s a dud not holding its charge .Ideally when off the charger should be nearer 14 v certainly above 13 v .
Drooping to 10.5 v after a few secs spinning the starter tells me that .= new batt .

 

[Tamar]

It’s a dud not holding its charge .Ideally when off the charger should be nearer 14 v certainly above 13 v .
Drooping to 10.5 v after a few secs spinning the starter tells me that .= new batt .

12.8v is fully charged when resting, which both batteries show. Maybe a cell is breaking down when under load. These were new batteries three years ago.

 

[billskip]

Thanks I will try later. As to the battery, the engine spins over as if the battery is fully charged when it's behaving. Could it be a dud?

Let's put it this way...I have experienced problems like this, and it was the battery although all indications seemed to say battery ok.
Stalling under cranking can also be caused by problems with the engine, but let's not go there at this stage.

 

[Tamar]

Let's put it this way...I have experienced problems like this, and it was the battery although all indications seemed to say battery ok.
Stalling under cranking can also be caused by problems with the engine, but let's not go there at this stage.

Yes let's keep it simple

 

[Tamar]

It started this from cold as soon as I turned the key. Then struggled on the second start about an hour later after a long run. I think I'll try a new battery before I take stuff apart

 

[Croftie]

12.8v is fully charged when resting, which both batteries show. Maybe a cell is breaking down when under load. These were new batteries three years ago.

You say both batteries. Both for starter or 1 starter 1 domestic? If the latter have you tried linking them in parallel, even just a good jump lead +ve >> +ve

 

[Seastoke]

No

Can you

No

Does it struggle when cold sometimes.

 

[Tamar]

You say both batteries. Both for starter or 1 starter 1 domestic? If the latter have you tried linking them in parallel, even just a good jump lead +ve >> +ve

Yes. They are both in parallel at the moment.

 

[Portofino]

Put a voltmeter on the starter batts with the engine running .If the alternator is working it should read 14 v .

How ever if you are setting off from shore + charger the batts artificially as high as it’s gonna get which isn’t that high ( you say 12.4v ) So goosed anyhow .
Just check the alternator actually works as well .
Otherwise a few deep dischargers on the new replacement and this will be goosed PDQ .

 

[Tamar]

Can you
Does it struggle when cold sometimes.

Occasionally, but mostly just jumps into life

 

[Tamar]

Put a voltmeter on the starter batts with the engine running .If the alternator is working it should read 14 v .

How ever if you are setting off from shore + charger the batts artificially as high as it’s gonna get which isn’t that high ( you say 12.4v ) So goosed anyhow .
Just check the alternator actually works as well .
Otherwise a few deep dischargers on the new replacement and this will be goosed PDQ .

All works as it should

 

[Croftie]

Engine size, Battery size. xx Ah xxxCCA

 

[tillergirl]

Years back I suffered intermittent battery readings, performance and connection. It was all down to a worn battery switch. Note the left wiper; it was burnt and when cleaned was worn. The other 'side' similar shew that the terminal was worn (and offset). New battery switch solved the problem. I now do not use a both - 2 -1 switch.

Worth looking. The wear looked minimal but was sufficient to fail. I hope it is as simple for you as it turned out for me - except I had cleaned and remade every single connection in the whole system first!

P1040421 by Roger Gaspar, on Flickr

P1040422 by Roger Gaspar, on Flickr

 

[Tamar]

Years back I suffered intermittent battery readings, performance and connection. It was all down to a worn battery switch. Note the left wiper; it was burnt and when cleaned was worn. The other 'side' similar shew that the terminal was worn (and offset). New battery switch solved the problem. I now do not use a both - 2 -1 switch.

Worth looking. The wear looked minimal but was sufficient to fail. I hope it is as simple for you as it turned out for me - except I had cleaned and remade every single connection in the whole system first!

P1040421 by Roger Gaspar, on Flickr

P1040422 by Roger Gaspar, on Flickr

Thanks one more thing to check ☺i seem to remember a previous boat of mine that had this problem. I put a VCR? Diode in which cured it