Need Help with “A tach issue” - The title that keeps on giving…

Noah · February 15, 2024, 08:41:42 AM

I run my engine frequently with shore power plugged in using glow plugs. I have also never had an issue with glow plugs failure nor with my tach not registering when batteries are at 100% SOC. Don't believe I live a "charmed life", either. Anyone else have issues with your tach not registering when batteries are full?

tvorgitch · February 15, 2024, 05:27:14 PM

I too have started my engine while on shore power and I've never had the tach not work when my batteries are fully charged. I find it hard to believe the 5 amps from my charger would make any difference to the glow plugs.

What would cause the tach to not function if the batteries are fully charged?

Stu Jackson · February 16, 2024, 11:36:24 AM

Quote from: tvorgitch on February 15, 2024, 05:27:14 PMWhat would cause the tach to not function if the batteries are fully charged?

Please read reply #9 on page 1 of this thread.

Noah · February 16, 2024, 02:14:50 PM

I believe Stu is referring to reply #8. However, i don't see that issue in my world. I run my engine all the time with shore power on and battery charger on and batteries at 100% SOC using a Balmer 614 external regulator, Leece 95A alternator and my TACH WORKS FINE. Been doing it this way for YEARS as my boat stays plugged in and charging until I disconnect it to go sailing. Just did again it today. Tach starts registering when the motor fires up. Maybe my regulator settings are different than Stu's?? I also have battery sense and temp feeds and Balmer battery SmartGauge monitor. Also, I have not had any glow plug issues, either. I have the glow plug solenoid modification installed.

Stu Jackson · February 17, 2024, 10:50:52 AM

External regulators usually start up in the bulk mode. That means the target voltage is always higher than the battery voltage, therefore the alternator is being directed by the regulator to output current. Hence, the tach will work.

Noah · February 18, 2024, 08:14:15 AM

To those folks who's tachs don't work when their shore power charger is on:
I did some consulting with an electrical engineer to further delve into why I DO NOT have an issue with my tach while running my engine when on shore power. His response was "It is a common problem for alternators to reduce their output when the batteries appear charged to such a high level that the amplitude of the pulses from the stator winding of the alternator becomes too low to drive the tach. However, many external regulators, such as the Balmar contain a dedicated terminal that you can use that provides an amplified version of the pulses from the alternator to reliably drive the tach. Balmar has a doc on their site."
So possibly, Stu (?) may not have hooked his tach to that special terminal. And others, who have internal regulators, may not have this capability. Bottomline is, there is a way for those with most external regulators to solve this issue, so their tach works regardless of being on shore power or not (or on solar for that matter).

Ron Hill · February 18, 2024, 01:32:49 PM

Guys : Have a Balmar alternator and external regulator. Have never started the engine while shore power is ON. Just believed it was not good to have two charging sources ON at the same time.
Noahs' post indicates that the smart regulator and alternator take that into account - have NEVER had a problem!!

A thought

Gulfsailor · February 19, 2024, 01:11:46 AM

Tested everything and determined tach was bad. New one on the way from Catalina Direct. More news to follow.

Stu Jackson · February 19, 2024, 10:52:49 AM

Quote from: Noah on February 18, 2024, 08:14:15 AM>>>>>>>>>>>
So possibly, Stu (?) may not have hooked his tach to that special terminal.
>>>>>>>>>>>>>

Just to clarify, I've not had this problem (I have an MC-612 properly wired). I was only answering someone else's question about why their tachs could be not operating with full batteries, which have been a recurring question on the internet for decades. I agree with Jeremy's answer to you, although I think "...when the batteries appear charged to such a low level..." he actually meant high level.

Gulfsailor, glad to hear you figured your issue out, thx for letting us know.

Noah · February 19, 2024, 11:16:35 AM

THX STU—. I made the edit from "Low" to "high".

Gulfsailor · February 23, 2024, 06:06:41 PM

Well fellas....I received a new tach and connected it with jumper wires with alligator clips and it did not work. I removed the alternator and took it to a local shop that rebuilds starters and alternators where they bench tested it and viola! My alternator was bad! He sold me an identical, brand new one for $249 out the door.

Bet my tach works when I install the new alternator!

Gulfsailor · February 25, 2024, 01:54:25 PM

Well,well, well.....

Today I installed the new alternator and all is well. Tach working again, system charging and birds seagulls singing, "sail her, sail her"!

A note for future travelers down this rabbit hole: If your tach suddenly stops working, check your alternator!

Thanks for all of the input here everyone!

KWKloeber · March 03, 2024, 02:27:33 PM

QuoteA note for future travelers down this rabbit hole: If your tach suddenly stops working, check your alternator!

I've said it several times before and will again. First thing is to put an AC multimeter on both the Alternator tach ("AC") terminal and on the Tach input (S terminal.) Most diesel alternators need like 7 volts AC to drive the tach.

They probably rebuilt your Alt for $30 in parts.

BTW, if you install a new Tach and want to, you can advance the hourmeter to match the engine hours.