Alternator/tach issues

[cardude01]

I've been having some problems with my tach lately. It usually works for about 20 minutes then falls to 0. If I stop the engine and restart it will work for awhile then fall back to 0. I have tightened the connections on the back of the alternator, taken apart the two connector harnesses and inspected and they seem clean.

Today I changed my Racor fuel filter and when I tried to start the engine it ran and then died. I restarted and it ran then died. Third time it ran and stayed running. On the third time I noticed the charge light on the Yanmar panel was glowing bright red. I checked the charge at the back of the alternator and got 12.85-12.9V at 1500 RPM so it doesn't seem to be charging.

Now the tach will only work for a few seconds-- actually just started the engine again and the tach doesn't work at all.

I did notice today when I started the engine I inadvertently left the battery charger switch on before I caught it. Is that a clue?

The alternator is a Balmar and it is set up with a Balmar Digital Duo Charge and a Balmar Max Charge MC-612 regulator. All this stuff was factory installed. I have not messed with anything.

 

[jleonard]

After the tach falls to 0 does it go back up to the original rpm again if you leave the engine running?

I ask because my Balmar falls to 0 after approx. 45 minutes of running (if the batteries are fully charged at the dock) but after a few minutes of 0 it climbs back again.

 

[cardude01]

After the tach falls to 0 does it go back up to the original rpm again if you leave the engine running?

I ask because my Balmar falls to 0 after approx. 45 minutes of running (if the batteries are fully charged at the dock) but after a few minutes of 0 it climbs back again.

No. It stays at zero. If I shut the engine down and restart sometimes it starts working again.

 

[fryedaze]

Is it possible that the Balmar regulator is turning off excitation due to another charge source that is higher than the Balmar setting. Maybe check the 612 digital indicator when you start and then see what it does when the tach goes away. If you have alternator or battery temp on the balmar regulator they could be shutting it off if the temps are high.

 

[cardude01]

Is it possible that the Balmar regulator is turning off excitation due to another charge source that is higher than the Balmar setting. Maybe check the 612 digital indicator when you start and then see what it does when the tach goes away. If you have alternator or battery temp on the balmar regulator they could be shutting it off if the temps are high.

Maybe that's what happened when I started it with the AC battery charger on accidently? The Balmar regulator sensed that and shut off the alternator?

 

[cardude01]

...

 

[cardude01]

Update. Went to eat some crawfish, came back and disconnected the wiring harness going to the engine and tried it-- same thing.

Turned off all the DC power to the boat and disconnected and reconnected all the connectors to the Balmar reg and duo charge thing. Started it up. 14.5V at the alternator. Tach works.

Bad connection at the regulator I guess??

?

 

[Arctic Traveller]

I have the same setup but the opposite problem. When I first start up, the tach won't go above idle, but once it warms up, the tach finally catches up. In my case, the belt is slipping, so the tach runs slowly until the belt warms up. In your case, I would measure the output voltage of the alternator when the tach is working and then again when it quits. If it drops, but your battery voltage is such that they still require charging it could be the regulator, the temp sensor or the alternator. You could temporarally disconnect the sensor to see if the charging / tach returns. My Balmar alternator runs crazy hot (270+degs) when in bulk charge and I'm just waiting for it to quit before I replace it with a different brand. When they run hot, they cook the diodes and windings, so the sensor cuts back on the charge rate, but in your case it may be completely turning off the excitation voltage due to a malfunction.

 

[cardude01]

Buttoned everything up and decided to start it one more time to check. Light on and not charging but the tach is working. WTH!


Charge light flickers like it wants to go out, dims a bit, then back on bright.

?????

(Belt is tight)



Probed around the Balmar regulator doing a test I found on the net. Unplugged the main connector, plugged it back in. Now it's charging again. Tach still working.

From what I've gathered on the net, others with this Balmar regulator setup are having tach issues as well.
Guess I need to call Balmar.

 

[cardude01]

I have the same setup but the opposite problem. When I first start up, the tach won't go above idle, but once it warms up, the tach finally catches up. In my case, the belt is slipping, so the tach runs slowly until the belt warms up. In your case, I would measure the output voltage of the alternator when the tach is working and then again when it quits. If it drops, but your battery voltage is such that they still require charging it could be the regulator, the temp sensor or the alternator. You could temporarally disconnect the sensor to see if the charging / tach returns. My Balmar alternator runs crazy hot (270+degs) when in bulk charge and I'm just waiting for it to quit before I replace it with a different brand. When they run hot, they cook the diodes and windings, so the sensor cuts back on the charge rate, but in your case it may be completely turning off the excitation voltage due to a malfunction.

Interesting. My issue does sound similar. Thanks for the heads up.

 

[cardude01]

Update

On my cruise from Rockport to Kemah I continued to have some interesting tach/charging issues.

The tach would start off working for a few minutes, then quit. If I unplugged wires to the regulator and back in the tach would work correctly for awhile, then quit after a few minutes.

Batteries are AGM and only one year old.

On the trip the Balmar Smart gauge panel would constantly generate a high voltage error code. Showed 14.5 volts and over for much of the morning, then would drop down to a normal charging level of 13.5-14V. The charge rate remained erratic for the entire 3 day trip however-- jumping from 12v to 14.4v and all around in between. I don't remember having such an erratic charge rate before. Sometimes the charge light on the Yanmar panel would flow for a few seconds when the charge rate would drop low.

Any ideas on what I should check? Is my tach issue related to the erratic charge rate? Is my regulator going bad?

The regulator is a Balmar MC 614.

Connections at alternator are tight. Belt is tight.

 

[av8r]

If you have a separate battery charger that is being powered either by a running generator or an auto-transfer inverter while the main is running it can produce the symptoms you see. This would be easy to check by unplugging the charger. It can happen because the regulator sees the output of the battery charger as a fully-charged battery and doesn't bring the alternator online, which can mean no tach reading.

 

[cardude01]

I do have a Charles charger that runs off shore power but it wasn't running when this was happening.

I did accidentally start the boat with the Charles charger on at the beginning of the trip however. Could that have screwed things up?

 

[mgdavis]

Be careful with this issue. On our first ride on our boat, before we purchased it, the alternator belt was squealing a bit after engine start. It stopped after a minute, but shortly thereafter it was noticed that the tachometer was not indicating. We later realized that the belt had catastrophically failed, removing power from both the alternator and water pump. The engine overheated and had to be shutdown so that the belt could be replaced and the cooling system refilled. We were equiped to handle the repair, and it happened when we were in a safe spot, but it could have gone from inconvenient to dangerous easily.

I have the same setup but the opposite problem. When I first start up, the tach won't go above idle, but once it warms up, the tach finally catches up. In my case, the belt is slipping, so the tach runs slowly until the belt warms up. In your case, I would measure the output voltage of the alternator when the tach is working and then again when it quits. If it drops, but your battery voltage is such that they still require charging it could be the regulator, the temp sensor or the alternator. You could temporarally disconnect the sensor to see if the charging / tach returns. My Balmar alternator runs crazy hot (270+degs) when in bulk charge and I'm just waiting for it to quit before I replace it with a different brand. When they run hot, they cook the diodes and windings, so the sensor cuts back on the charge rate, but in your case it may be completely turning off the excitation voltage due to a malfunction.