I have an Ample Power hi output alternator, smart charger and energy monitor system; installed probably around 2000 or so. Last time I was on the boat earlier this month, I was motoring and saw the tach drop to zero. checked the belt which was fine. After anchoring, I checked the wiring to the alternator, and all seemed fine. Started the engine later and getting 80 amps, tach reading normal again.
Today got to the boat and the shore power had gone off, low battery alarm going off, batteries around 50%. Started the engine to charge the batteries and sure enough, after about 10 minutes, amps go negative and tach reads zero. Then jumps back to 80 amps charge, tach normal. Then off again. This went on for some time. Motoring out to the Bay, the tach dropped to zero and has stayed there.
Question: does this sound like the alternator is going bad? I'm going to recheck all wiring tomorrow after everything has cooled down (already burned myself). Engine has 485 hours on it, probably 350 on this alternator.
Scratching my head on this one, any suggestions will be appreciated.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
I went through similar (not identical) symptoms. Tach died (went to zero) with the engine running and was not putting out any juice. The tach going to zero is a tell tale of the alternator unless there is "no load" on full batteries but usually there is something on (fridge, instruments, lights) that will force a charge to bounce the tach up.
You may have witnessed the final "beats" before it died.
I had it rebuilt and it solved my problem.
Mine had never been rebuilt and the boat has about 750 hrs on it, but they could not give me an expected life of the alternator other than 14 years/750 hrs was "a good run."
Hope this helps.
Jack
Solstice
Hull #1598
1996 MKII/TR/FK - M35AC - 3 Blade MaxProp
Lake Texoma
www.texomasailing.org
thanks. sounds like it's off to the rebuild shop..:mad:
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
When the tach goes to zero it's usually because the alternator isn't putting out anything. But why is the big question. It could be the regulator acting up or the alternator itself. Most of the aftermarket alternator guys give a troubleshooting flow chart to test the alternator and find out if it is toast, the tests are fairly simple and done with a jumper wire and test light. Ample might have something on its website. Might save rebuilding the alternator only to find out the reg is bad.
We have a Xantrex XAR regulator, had a Hehr Aqualine on the last boat, when those regs go into float the tach dies for a minute or two (because the reg turned off the field) then comes back on with the reg holding things at float voltage. But clearly if your batteries were at 50% it wasn't going into float, or at least shouldn't have been.
just to add to the confusion..... Today I start the engine, run it up a bit above idle and it's pumping 95 amps into the batteries; let it run about an hour, way longer than it would charge yesterday. Ran fine every time I had the engine on, no problems whatever.
And; the bilge blower came on this morning too, for the first time since it quit a few months ago. Hmmm, seems like a strange coincidence. I'm starting to suspect that the ignition switch might be the culprit. If you turn the key off with the engine running, the tach drops to zero, and the alternator stops charging. Turn the key back on and the tach comes back up.
It seems really strange that the charging system would work fine today and that the blower came back to life at the exact same time.
I'm going to contact Ample Power when I get home, see what they have to say.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
[QUOTE=plaineolde;6811]
...to suspect that the ignition switch might be the culprit. If you turn the key off with the engine running, the tach drops to zero, and the alternator stops charging. Turn the key back on and the tach comes back up. [/QUOTE]
Nope, that's normal.
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)
Yes, what Stu said. Though some alternators with internal regulators are self-exciting once they are making power and turning the key off won't do that.
It sounds to me more like you've got a loose wire somewhere. One test to determine real quick if the alternator and diodes are OK is to full field it. You disconnect whatever is connected to the field terminal and in its place you put a live 12 volt + wire then start it up. If the alternator makes power, it and the diodes are fine. You only do this for absolute minimal time, like 2 or 3 seconds, just long enough to see that it is putting out power, and with no electronics active because it will put out maximum volts and amps which could be well over 16.
But it seems to me that the alternator is OK, they usually either work or they don't so the fault is probably somewhere else. I'd go over the power circuit wiring to the regulator and from the regulator to the alternator very carefully and start testing those connections for a bad one at each end. I'd check the voltage on the power in and sense lines to the regulator and all the wiring with an ohmmeter for continuity while wiggling all the joints. If they use spade connectors I'd suspect them in particular. I'm not familiar with Ample's equipment so can't offer any more detailed ideas than that. Also make sure all the primary wiring from the alternator to the batteries has no problems, no corrosion, etc.
I'm thinking the alternators OK, too. The only thing I could think of that might go intermittent in the alternator itself is the 'brushes'; as you say, diodes either work or don't.
Stu, I should have noted that, as you say, it's normal that turning off the key would cause the tach/instruments to be turned off, along with the charging circuit. What I am thinking, is that the ignition switch may have an intermittent connection that may be causing the tach and charge circuit to go in and out. I'm replacing it in a week or two when I swap out my instrument pod for one of the newer ones.
The charging/energy monitor system is very complex. I installed it myself about 10 years ago; many, many control wires and heavy gauge cables. I think I'm going to start with Ample Power to get some guidance, to help narrow down the options; the usual suspect, the exciter wire, appears to be OK. At least I know I can blame the installer for any problems :)
Thanks for all the suggestions, I appreciate them all.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
Gary, when we installed our new regulator and alternator, I had intermittent problems, like yours. What i discovered is that the ring terminals that were factory made for the regulator wires that connected to the back of the alternator ALL ended up giving up the ghost and required my replacement. And I'd thought the factory crimps were better than my own. NOT!
I really don't think Ample's gonna be able to tell you anything that we haven't already. It really sounds like a connection issue of the wiring and/or fuse holder between your alternator and your regulator, or maybe, but rarely, the key switch. There was one fuse holder that was so close to the back of the alternator from the factory wiring that i moved it way back away from the alternator.
If the alternator was dead, it wouldn't just come back on.
To repeat, intermittent problems are ALWAYS a wiring connection.
You're right, go blame the installer!:)
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)