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Curious alternator problem...


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39 minutes ago, Mike the Boilerman said:

 

Thanks. As I thought. So the relay is truly redundant isn't it!

I can’t see any purpose for it other than to save the indicator lamp’s current flowing through the ignition switch. Unless that relay has other terminals doing something else?

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26 minutes ago, WotEver said:

I can’t see any purpose for it other than to save the indicator lamp’s current flowing through the ignition switch. Unless that relay has other terminals doing something else?

 

Nope. The relay has no other function AFAICS. 

 

Anyway I've disconnected the short lead connecting the relay coil to the warning lamp, and connected the D+ lead directly to the warning lamp so the energising current is supplied directly through the ignition switch and warning lamp in series. All works correctly now. 

 

The really puzzling bit is how it ever worked correctly when the previous engine was installed. 

 

Thanks for all the help everyone. 

 

 

 

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It looks as if it was a redundant split charge relay that someone did not understand so did not remove it when the split charging as altered/removed. That is the only reason I can think of for a rely in that place in that circuit. The best solution for energising a second alternator is with a relay as Brian implied but not in series with the warning lamp. In that case the lamp is in series with the relay contacts.

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1 hour ago, Tony Brooks said:

It looks as if it was a redundant split charge relay that someone did not understand so did not remove it when the split charging as altered/removed. That is the only reason I can think of for a rely in that place in that circuit. The best solution for energising a second alternator is with a relay as Brian implied but not in series with the warning lamp. In that case the lamp is in series with the relay contacts.

 

Thanks Tony. This boat has never had twin alternators, but may have had split charging from one alternator a couple of engines ago but I can't remember.

 

 

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There is however one further wire which might provide a clue. I left it off the previous wiring diagram as it did not seem relevant. I've added it on now, below. 

 

I have yet to find out where it goes, it disappears into the wall behind.

 

 

570E1767-FFEC-4AD0-99F0-9E999845BFE6.jpeg

Edited by Mike the Boilerman
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13 hours ago, Mike the Boilerman said:

The really puzzling bit is how it ever worked correctly when the previous engine was installed.

Even more left field but wiring altered by an electrician who didn't understand alternators and thought the "Ignition" light should be on permanently to indicate, err "the ignition is on"?

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16 minutes ago, 1st ade said:

Even more left field but wiring altered by an electrician who didn't understand alternators and thought the "Ignition" light should be on permanently to indicate, err "the ignition is on"?

 

Well it all worked correctly when initially installed (WITH relay!) in about 2015 so must have been wired appropriately at the time even though the relay appears redundant.

 

It only changed when the current alternator was installed. I'll ask the installer if any changes were made to the connections to the wiring of the redundant the relay, even though it looks as though there was none.

 

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15 minutes ago, Mike the Boilerman said:

I'll ask the installer if any changes were made to the connections to the wiring of the redundant the relay

Or replaced the relay. I'm given to understand there are multiple variations with the pins in a different order

 

(although I can't actually see any combination of the four relay connections which make sense...)

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42 minutes ago, Mike the Boilerman said:

 

 

There is however one further wire which might provide a clue. I left it off the previous wiring diagram as it did not seem relevant. I've added it on now, below. 

 

I have yet to find out where it goes, it disappears into the wall behind.

 

 

570E1767-FFEC-4AD0-99F0-9E999845BFE6.jpeg

Anything which needs a switched ignition feed - stop solenoid; oil pressure or other instruments.

 

Or a previous bodge to stop high current loads being turned on if the ignition isn't

 

(Off topic slightly - On Magpie Patrick's previous boat [Ripple] I wired a relay to stop the bilge pump running automatically if the ignition was ON. The assumption was, if the engine was running you could run the bilge pump manually if there was a problem and the relay stopped the bilge pump automatically emptying the oily bilge into Saul Marina as you reversed off the pontoon...).

 

I imagine the current owners of Ripple may have been through a similar "what the F*** is this" while working through the electrics.

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1 hour ago, 1st ade said:

Anything which needs a switched ignition feed - stop solenoid; oil pressure or other instruments.

 

Or a previous bodge to stop high current loads being turned on if the ignition isn't

 

(Off topic slightly - On Magpie Patrick's previous boat [Ripple] I wired a relay to stop the bilge pump running automatically if the ignition was ON. The assumption was, if the engine was running you could run the bilge pump manually if there was a problem and the relay stopped the bilge pump automatically emptying the oily bilge into Saul Marina as you reversed off the pontoon...).

 

I imagine the current owners of Ripple may have been through a similar "what the F*** is this" while working through the electrics.

 

Thanks for the ideas. This is an old boat with a vintage engine and very little in the way of electrics.  Bilge pump? Overcomplicating things. I was surprised to see ANY relays let alone four, given how basic the boat is, electrical appliance-wise. Water pump, nav lights (which dont work) tunnel lamp, shower waste pump. Thats about it...

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6 hours ago, Mike the Boilerman said:

 

Well it all worked correctly when initially installed (WITH relay!) in about 2015 so must have been wired appropriately at the time even though the relay appears redundant.

 

It only changed when the current alternator was installed. I'll ask the installer if any changes were made to the connections to the wiring of the redundant the relay, even though it looks as though there was none.

 

So all that has changed since 2015, is the recent alternator.  If no wiring changes have been made, then Sirnibs offer seems to be the best bet, for the truth.  Could you send him both alternators, the fault might be with the first?

 

Bod

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1 hour ago, Bod said:

So all that has changed since 2015, is the recent alternator.  If no wiring changes have been made, then Sirnibs offer seems to be the best bet, for the truth.  Could you send him both alternators, the fault might be with the first?

 

Bod

The wiring must have changed. The warning lamp could never have worked correctly wired as it is. It used to work correctly, ergo it must have changed. 

  • Greenie 1
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