Continued Overcharging Problems - AC5 Alternator

[alan_fincher]

This has already been directed at the forum guru on such matters, and who was kind enough to send us replacement parts, and give us much advice. I'm Ppsting this in case anybody else sees it first and can offer suggestions.

 

We thought we had fixed our problem, but having set off again, we sadly discover we have not.

 

Original problem was AC5R severely overcharging at at least 15.5v. It then had both its own internal regulator and a separate Kestrel alternator controller, and we were not convinced the Kestrel was working, or that it might not be part of the problem.

 

The regulator on the back of the AC5R has now been replaced, and all relevant wiring to the Kestrel removed. I am fully confident that can not power on and override the AC5s own regulator.

 

My son David and I remade some of the cables that had unnecessary joins in, just as a precaution, and we now have about the simplest set up you could imagine. Three connections to alternator only, being the main positive and negative, plus the one to the warning light, (which comes on and off when expected to).

 

Initial tests yesterday showed a maximum charge voltage of 14.1v, which seemed OK, given the battery voltages were well up due to the previous overcharging.

 

However getting going today the inverter shut down on over-voltage, and I measured a very excessive 16.5v of charge voltage at the battery bank.

 

So now with the regulator replaced, the Kestrel removed, and very simple set up, can any body please suggest what we look at next. The only one component actually not required to make it work is a basic in-line ammeter in the positive feed to the batteries.

 

It seems the alternator itself must be going over voltage, despite the new regulator. I can't find any bad connections, and, even if there were, can't quite see how they would give this symptom.

 

I'm out of ideas! Can anybody else do better, please?

[MtB]

Have you calibrated or checked for accuracy whatever it is you are using to measure that 16.5v?

Edited May 28, 2016 by Mike the Boilerman

[alan_fincher]

  On 28/05/2016 at 21:13, Mike the Boilerman said:

Have you calibrated or checked for accuracy whatever it is you are using to measure that 16.5v?

 

Yes, I am confident in the meter, and it read a very sensible voltage yesterday.

 

There is a basic in circuit analog meter as well, and that ia going hard against the end stop at 16v indicated.

 

The Heart Interface inverter is also shutting itself down on an excess voltage fault.

 

We are also poaching eggs on top of the battery bank

 

(Only the lest of these statements isn't true, by the way!).

[Tony Brooks]

If it is a 9 diode machine have you checked the three small field/Aux. diodes?

 

Is there any way the regultor is measuring the charging voltage from a point external to the machine, If so can you get your meter onto rthat point tos ee what the regualtor is "seeing"?

 

However I expect SirN has already coverd this.

[Sir Nibble]

On the case.

I suspect a short to earth on the rotor under centrifugal stress. Not hugely difficult to deal with but quite daunting if you aren't completely comfortable with machines like this. There are two wires passing from the rotor winding through a groove in the shaft under the bearing and slip ring to solder on at the very end. It is easy to damage the insulation on assembly and start it slowly breaking down. One of the few things I put a megger on.

[Guest User]

I expect it's already been considered, but are the batteries themselves in good order?

 

LCx

[Sir Nibble]

  On 29/05/2016 at 07:21, Lady Cassandra said:

I expect it's already been considered, but are the batteries themselves in good order?

 

LCx

Not any more.

Edited May 29, 2016 by Sir Nibble

[alan_fincher]

Thanks Sir N &Tony!

 

Just to further add to communication problems, Yahoo mail is deciding it doesn't really want to let me see my mails without a fight this morning () but I have just finally opened about same time as Sir N has reposted here.

 

I'm feeling fairly out of my depth here, if I'm honest, and am certainly not equipped to get pulley off, or with a megger!

 

I have not done any investigation of the alternator itself Tony, because it was assumed to be a regulator (or external controller) fault, and swapping to Sir N's replacement reg appeared to fix.

 

No idea how many diodes, or how to access anything like that. Not in the engine room at the moment, but I don't remember much being visible without dismantling.

 

Sir N's explanation sounds very plausible to me, because it appears to work, until you run the speed up. It may well be that the fault he suggests doesn't kick in at lower revs, but that centrifugal forces cause the short when things are spun faster.

 

I think I'm tempted to just try limping back to home mooring with it all disconnected, thereby taking urgency out of fixing it.Need to survive for about 3 days with no charging if I do that.

 

I'm increasingly thinking the alternator should be replaced with a different type, but suspect mountings will not match. Someone lent me one supossed to be from an HR engine, and absolutely nothing lines up with the bracket or pulleys that I have!

  On 29/05/2016 at 07:27, Sir Nibble said:

Not any more.

 

Well they have a (high!) voltage on them that I have not seen in a long while.

 

One further complication is that a key part of the hans start mechanism on the HA did not come with the boat, so at the point I don't have batteries to start the Lister, we can't continue.

[Sir Nibble]

I am on leave from work and willing to come and look.

[alan_fincher]

  On 29/05/2016 at 07:50, Sir Nibble said:

I am on leave from work and willing to come and look.

 

I have sent you an email

 

Alan

[Sir Nibble]

  On 29/05/2016 at 07:52, alan_fincher said:

 

I have sent you an email

 

Alan

And I have replied. This is fun isn't it.

For the benefit of the forum, Alan is not surprisingly reluctant to have me drive to Hertfordshire, I on the other hand quite fancy the trip!?

[alan_fincher]

  On 29/05/2016 at 08:03, Sir Nibble said:

And I have replied. This is fun isn't it.

For the benefit of the forum, Alan is not surprisingly reluctant to have me drive to Hertfordshire, I on the other hand quite fancy the trip!

 

Alan has accepted, and you now have another email.

 

Please bring old clothes or overalls.

 

Engine room not particularly salubrious!

[Alan de Enfield]

  On 29/05/2016 at 07:40, alan_fincher said:

 

 

I think I'm tempted to just try limping back to home mooring with it all disconnected, thereby taking urgency out of fixing it.Need to survive for about 3 days with no charging if I do that.

 

 

Would a 'cheapo' generator (£60 from 'Machine Mart' type of thing) not be able to keep your battery topped up to give you 'starting power' each morning until you got back-to-base ?