D4 alternator overcharging??

[ozzie]

I think I may have a charging problem on my starboard engine, not sure whether it's an alternator or battery issue. Twice now we have been out and on either the outward or return journey the voltmeter keeps rising from it's usual 14.4v and going into the red showing just over 15v for a few seconds before dropping back. It continues to do this for the entire journey. I have run the engines up to the max 1500 revs on the berth, and all seems ok. I have taken all the terminals off the back of the alternator and cleaned them, and have cleaned all the battery terminals. Am I looking at a new alternator, or, as has been mentioned, a battery problem? Any advice gratefully received!!

 

[julians]

It could be the battery, can you swap over the port and starboard batteries easily and see if the high voltage follows the battery?

 

[halcyon]

Am I looking at a new alternator, or, as has been mentioned, a battery problem? Any advice gratefully received!!

Is the alternator machine or battery sensed ?.

Brian

 

[ozzie]

I have 6 batteries in 3 banks - 2 starters, 2 domestic and 2 bow thrusters. I have checked them all with a multimeter and they are all showing good voltages.Presumably I would need to swap all the batteries over to see if the issue changes sides?

 

[julians]

I have 6 batteries in 3 banks - 2 starters, 2 domestic and 2 bow thrusters. I have checked them all with a multimeter and they are all showing good voltages.Presumably I would need to swap all the batteries over to see if the issue changes sides?

Might be easier to swap alternators over in that case?

Did you check the battery voltages after they had been resting for a few hours and also each battery isolated /disconnected from any other battery?

 

[VicS]

I think I may have a charging problem on my starboard engine, not sure whether it's an alternator or battery issue. Twice now we have been out and on either the outward or return journey the voltmeter keeps rising from it's usual 14.4v and going into the red showing just over 15v for a few seconds before dropping back. It continues to do this for the entire journey. I have run the engines up to the max 1500 revs on the berth, and all seems ok. I have taken all the terminals off the back of the alternator and cleaned them, and have cleaned all the battery terminals. Am I looking at a new alternator, or, as has been mentioned, a battery problem? Any advice gratefully received!!

If the alternator is battery sensed check the sensing.

If this and all other connections are good I would suspect an intermittent regulator fault. When I had a similar problem with a car ( no voltmeter but the ammeter went full scale for short periods ) I simply changed the regulator ... problem solved.

You don't have any added fancy regulators or other gizmos that could be the cause presumably ?

 

[ozzie]

I have just run both engines up to 1500rpm and the stb voltmeter was fluctuating within the 14v range, port staying spot on, no movement. Swapped the domestic batteries, still the same. Swapped the starter batteries and the port then fluctuated, so it appears to be a battery problem rather than alternator! She is starting perfectly, so the question is, will I do any damage to the other batteries if I run like this?

 

[DavidJ]

You have identified the problem, just replace the battery. The problem won’t go away.

 

[Assassin]

If the alternator is battery sensed check the sensing.

If this and all other connections are good I would suspect an intermittent regulator fault. When I had a similar problem with a car ( no voltmeter but the ammeter went full scale for short periods ) I simply changed the regulator ... problem solved.

You don't have any added fancy regulators or other gizmos that could be the cause presumably ?

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