Rogue alternator

[snowleopard]

I recently fitted an exchange alternator. After about 15 hours use, the output voltage went up to 15.5v which cooked the battery. Has anyone come across this problem? What is the likely cause? And can I retrieve a battery that has lost a lot of fluid through overcharging? I don't know how long the overcharging was going on - maybe an hour or two.

 

[snowleopard]

A curious factor is that I have an Adverc external regulator. The first thing I did was to unplug it which should bring the internal regulator back on line but it made no difference.

 

[snowleopard]

Adverc is battery sensed so check that connection. If the original is battery sensed check that.

The alternator without the Adverc is a bog-standard machine sensed setup.

 

[snowleopard]

Being only recently fitted take it back. Dont mention the Aardvark or they'll try to wriggle out of fixing or replacing it.

Or if thats not an option get it tested by an automobile electrician.

No point in trying to cover up the Adverc - they soldered on the control lead for me!

 

[boatmike]

No point in trying to cover up the Adverc - they soldered on the control lead for me!

Snowie.... It depends on where you are measuring the 15.5 volts and what your set up is. If you have fairly undersized wiring (and many installations do) on the charging side and perhaps a diode splitter as well, and the Adverc is wired to sense the voltage at the battery, it is going to increase the alternator voltage to compensate. If the battery is down on charge the adverc will probably try to pump up to 14.2 volts into the battery. That would mean 1.3 volts drop on the way there. If so the alternator is OK. Of course you need to very regularly check the electrolyte level in your batteries with a setup like this and it can very quickly need topping up. You may not have damaged your battery but as Vic says, top it up and put it on charge again checking the voltage at the batteries rather than the alternator. When my batteries are deeply discharged (I have a sterling but basically the same thing) on boost charge my engine panel voltmeter can show 15.5 volts but the maximum I have seen on my battery monitor is 14.5 volts very briefly at about 30 amps. Then after about 20 minutes it drops to 14.2 and 10 amps. I have never had a problem with this but check my electrolyte after every longish trip and usually need to top up a little... Of course if you are measuring at the battery itself disregard all this and have a word with your supplier. Before doing this however disconnect the sensing wire from your Adverc and try again. It might be the adverc rather than the alternator.
Edit (Doh) I just read your post again and you have already disconnected it but the rest is still valid....

 

[Piddy]

I suffered this earlier in the season when 2 of my oldest batteries got cooked. At the time I measured them (when charging) at 15.2v with a multimeter and was concerned that either the alternator regulator was duff or the external Sterling regulator was misbehaving.
The alternator is about 18months old and is a bog standard 70A and the Sterling unit has been fitted for about 11yrs, As the batteries were quite a few years old I decided to renew them anyway and take my spare alternator and a spare Sterling unit I have, ready to fit once I could see what was going on.

Once the new batteries were fitted, the voltage level returned to normal (about 14.7v when charged and motoring).
I can only put this high voltage problem down to a low electrolyte level allowing the batteries to cook - when I tested them with my new hydrometer, all I could get out of them (or at least a number of the cells) was a thick gooey gel-like liquid, bearing in mind they are lead acid - proving my regular checks of the level aren't/wern't regular enough!

I have now done nearly 100 hours of motoring in the course of this season and at no time whenever I have checked the voltage level, it has been what I expect.

Cheers

 

[boatmike]

I suffered this earlier in the season when 2 of my oldest batteries got cooked. At the time I measured them (when charging) at 15.2v with a multimeter and was concerned that either the alternator regulator was duff or the external Sterling regulator was misbehaving.
The alternator is about 18months old and is a bog standard 70A and the Sterling unit has been fitted for about 11yrs, As the batteries were quite a few years old I decided to renew them anyway and take my spare alternator and a spare Sterling unit I have, ready to fit once I could see what was going on.

Once the new batteries were fitted, the voltage level returned to normal (about 14.7v when charged and motoring).
I can only put this high voltage problem down to a low electrolyte level allowing the batteries to cook - when I tested them with my new hydrometer, all I could get out of them (or at least a number of the cells) was a thick gooey gel-like liquid, bearing in mind they are lead acid - proving my regular checks of the level aren't/wern't regular enough!

I have now done nearly 100 hours of motoring in the course of this season and at no time whenever I have checked the voltage level, it has been what I expect.

Cheers

That's also a good point. If the batteries were duff in the first place a battery sensed system will show a raised voltage. Might be the batteries not the alternator....

 

[michael_w]

Didn't the green light on the Adverc go on, showing an over voltage condition?

 

[boatmike]

Vic there is not need for all that red lettering and exclamation marks. Frankly it sounds like you are going hyper and are frustrated with all the lesser mortals on here that are only trying to be helpful. I also acknowledged that I overlooked the fact that he had disconnected it in my edit.
Point1. IF this is a machine sensed alternator you may be correct. These days battery sensing is far more common though and the assumption that it is machine sensed may not be correct.
Point2. Tired batteries could be causing the problem and it's worth checking everything before assuming the alternator is boogered. This may be a case of confusing symptom with cause.
Point3. IF it's battery sensed the voltage drop in the system MAY be a contributary cause.
It's worth considering ALL possible causes before coming to the conclusion that it is a duff alternator that's all...

 

[snowleopard]

Didn't the green light on the Adverc go on, showing an over voltage condition?

Yes, that's what alerted me to the problem. The sequence of events was:

1. spot the green flashing Adverc over-charge light
2. check the Link10 for voltage across the house batteries - 15.5v
3. unplug the Adverc controller - still 15.5v
4. Stop Starboard engine - still 15.5v
5. stop port engine, restart starboard - back to 14v
6. remove alternator belt from port engine, bridge port splitting diode
7. restart port engine, 14v again.

BTW, the following day the starboard engine lost a prop blade so I had to swap the alternators to give me one engine capable of both propulsion and charging. An interesting discovery is that a twin-engine Adverc doesn't work unless the control wires are connected to both alternators. Haven't figured out why yet.

I was reminded of the old saying - cruising is doing repairs in beautiful surroundings. In this case the Cove at St Agnes. See every detail of the bottom in 4m of water - but I still couldn't find the missing blade!

I forgot to mention a dreadful chemical stench from the engine compartment, probably burned insulation but nothing visible.

 

[boatmike]

Yes, that's what alerted me to the problem. The sequence of events was:

1. spot the green flashing Adverc over-charge light
2. check the Link10 for voltage across the house batteries - 15.5v
3. unplug the Adverc controller - still 15.5v
4. Stop Starboard engine - still 15.5v
5. stop port engine, restart starboard - back to 14v
6. remove alternator belt from port engine, bridge port splitting diode
7. restart port engine, 14v again.

BTW, the following day the starboard engine lost a prop blade so I had to swap the alternators to give me one engine capable of both propulsion and charging. An interesting discovery is that a twin-engine Adverc doesn't work unless the control wires are connected to both alternators. Haven't figured out why yet.

I was reminded of the old saying - cruising is doing repairs in beautiful surroundings. In this case the Cove at St Agnes. See every detail of the bottom in 4m of water - but I still couldn't find the missing blade!

Now you have said all that I agree it must by definition be a duff alternator. Ignore everything else..... unless of course you have a high resistance somewhere on that side causing it. You have eliminated the diode splitter but are all other connections OK? And where are you measuring the voltage? At the battery itself or at the alternator. If both are the same it is DEFINITELY the alternator. Now't else to check!

 

[iangrant]

beware the foul stench

if it's a bad eggs foul stench then extinguish everything and vent the compartment, yer batteries have been gassing.

if its like burnt haddock then it's electrical insulation/components melted

 

[Heckler]

Yes, that's what alerted me to the problem. The sequence of events was:

1. spot the green flashing Adverc over-charge light
2. check the Link10 for voltage across the house batteries - 15.5v
3. unplug the Adverc controller - still 15.5v
4. Stop Starboard engine - still 15.5v
5. stop port engine, restart starboard - back to 14v
6. remove alternator belt from port engine, bridge port splitting diode
7. restart port engine, 14v again.

BTW, the following day the starboard engine lost a prop blade so I had to swap the alternators to give me one engine capable of both propulsion and charging. An interesting discovery is that a twin-engine Adverc doesn't work unless the control wires are connected to both alternators. Haven't figured out why yet.

I was reminded of the old saying - cruising is doing repairs in beautiful surroundings. In this case the Cove at St Agnes. See every detail of the bottom in 4m of water - but I still couldn't find the missing blade!

I forgot to mention a dreadful chemical stench from the engine compartment, probably burned insulation but nothing visible.

For what its worth, I had the same message thru the flashing lights on my new Sterling, I phoned up and spoke to Charles, "its a bad negative connection somewhere" says he. No small talk!
So i went back to the boat and cleaned up every connection thru the battery system and vaselined them. its been as good as gold since.
Stu

 

[snowleopard]

The problem solved

I just got back from the repair shop. The internal regulator had failed so he fitted a new one. I think the guy was a bit surprised because the first thing that happened when he put it on the test rig was that it blew the bulb!