Troubleshooting charging system issue - dual alts

[BlackAdder]

Greetings CF'ers,

I have a Valeo CH8 alternator and the stock Volvo alternator on my Volvo D2-55B engine. Both alternators have a whole swack of wires on the back of them. Recently I noticed that the positive power cable had come off the Valeo alternator. Upon closer investigation someone had used the wrong size lug (too big) and just tried to crimp the snot out of it to hold the cable. Of course, with time and vibration the cable fell out. I purchased the correct sized 8AWG lug and crimped properly and reinstalled. Now getting to my problem....

I'm only getting about 6 Amps charging when the engine is running and I don't know what's wrong. The boat is French and came with a battery monitor made by Thira Electronique. I can't find an English manual for it and I don't know whether or not to trust what it's showing me but it shows me the house bank voltage, current going in/out of the batteries through the shunt, and how many Ah's I'm down. So yeah, when the engine is running at night and the wind and solar aren't pumping anything in, the engine alone is giving me 6 Amps (all power consumers off). In the day my solar was pumping out 6 Amps as well and the battery monitor was showing a combined whopping 13 Amps! The Valeo alternator is rated at 14V, 60A. I know enough not to expect anywhere near rated output but 6A vs 60A is a bit much, and what about the other alternator's output?

Some more information to ponder. When I put my volt meter to both alternators I was measuring 12.75V and 12.88V. This is when the battery bank was down a lot. Later I came back and measured again when the bank was up a bit and I was measuring 12.95V on both. Still, doesn't this seem low? Then I have this clamp on meter that measures current, although I know the unit is broken so the readings it provides aren't accurate, but when I clamped it on the stock alternator it showed current but on the Valeo it read 0A which leads me to believe the Valeo is not putting out anything. Could it or it's voltage regulator been damaged when the cable fell off?

Any idea how to troubleshoot this?

Any assistance would be greatly appreciated. I'm a beginner cruiser that's been hit with a bunch of problems at the same time and I'm trying to dig myself out of these issues and CF has proven to be a great resource. I truly appreciate everyone's help.

[smac999]

is this at idle or high RPM? alternators don't do much at idle.

[BlackAdder]

Wow smac! Good job on not overlooking the obvious. I never thought of that. Yes, that was at idle. But how can I charge the batteries at anchor, because when I put the throttle down the prop engages automatically?

[DeepFrz]

But how can I charge the batteries at anchor, because when I put the throttle down the prop engages automatically?

Well then, you have another problem.

[StuM]

Originally Posted by BlackAdder

Wow smac! Good job on not overlooking the obvious. I never thought of that. Yes, that was at idle. But how can I charge the batteries at anchor, because when I put the throttle down the prop engages automatically?

Surely, you have a neutral of some sort on your throttle?

Possibly a big round button on the side which you hold in, or a way to pull the lever out before moving it forward?

[StuM]

According to the owner's manual here:
http://www.nostressyachting.com/wp-c...at-Manual-.pdf

It's a small red button on the side of the morse lever that you need to hold in.

[BlackAdder]

Oh boy, don't I feel silly now guys. You must think I'm a real newbie.

OK, I've had this boat for a year and a half and I never thought to find out what the red button does. Morse control, huh. Thanks StuM! And the manual will be an interesting read. I see that's more of a charter manual. I've been trying to find an actual Beneteau manual online but no luck. Especially something with wiring diagrams. Is that too much to hope for?

OK, tomorrow I will try out 1500 RPM and we'll see how many Amps I see on the monitor. Any guesses though as to what I should expect. I see the Valeo is rated at 60A @ 14V and I don't know what the stock alternator puts out.

[Sailmonkey]

If the wire came off of the alternator when running you've more than likely fried the diodes in the alternator. The only fix is to replace the diodes.

As far as alternators not working at idle......they will, certainly not 100% output but my 80 amp alt will out put 55-65 amps at idle when the regulator goes full field. A small increase in speed ramps output rapidly too.


Sent from my iPhone using Cruisers Sailing Forum

[BlackAdder]

Thanks Sailmonkey, I had read that before in another post somewhere here on CF that disconnecting a wire while an alt is running will damage the diodes so you just confirmed that may be the case. Also, as I mentioned in my first post I have a clamp on Amp meter, which although being uncalibrated, showed 0 Amps on the Valeo alternator (the one which had lost the wire) so I'm pretty sure it's not putting out anything.

I will do some research on how to tackle the diode situation.

Also, last night I did a test and used the button on the morse control to increase revs to 1500 RPM and indeed my power output increased to 36A! But as Sailmonkey confirmed for me I believe that is far too little for my dual alternator setup. 60A would be a dream Sailmonkey! I think that should be achievable in my case, no? The 36A is probably the stock alternator alone.

The troubleshooting continues, but we're making some progress guys!! Thanks so much for your help.

On another note, I would like to take this opportunity to give StuM some praise for being the "Amp-Hour Nazi". I've been a long time lurker on CF (probably about 2 years) and only recently started posting. I think you're doing a good work in clearing up the confusion and helping people understand correct terminology and unit usage. It will increase understanding in the long run and that is a good thing. Keep it up!