Faulty tachometer and solar

[sheyes]

The tachometer on my Beta 28 died the death and was replaced by another one from Beta. Unfortunately, despite many attempts my local engineer has been unable to calibrate the new one which continues to give random readings which bear no relation to the engine revs. One suggestion that Beta have made is that this may be due to having solar panels on the boat.

Has anyone else experienced such a problem and if so have you been able to solve things, I surely don’t have to choose between solar and a functioning tachometer

 

[PaulRainbow]

The tachometer on my Beta 28 died the death and was replaced by another one from Beta. Unfortunately, despite many attempts my local engineer has been unable to calibrate the new one which continues to give random readings which bear no relation to the engine revs. One suggestion that Beta have made is that this may be due to having solar panels on the boat.

Has anyone else experienced such a problem and if so have you been able to solve things, I surely don’t have to choose between solar and a functioning tachometer

Load of rubbish !!

 

[Refueler]

I'm with Paul there ...

Just trying to understand how Solar could affect the Tacho ?

Tacho's are basically .... 1. optical based on flywheel / crankshaft rotation - usually portable hand .... 2. Mechanical drive - usually cable .... 3. Magnetic sensor on alternator case detecting stator rotation .... 4. Wired to alternator for pulse count.

Where would Solar come in ?? Is there another format ?

 

[sheyes]

I suspect you are right and I would never have connected the two either but since the suggestion has been made I thought it worth checking whether anybody had actually suffered the problem.

 

[VicS]

I suspect you are right and I would never have connected the two either but since the suggestion has been made I thought it worth checking whether anybody had actually suffered the problem.

It'll be easy to test Beta's suggestion. Does the "interference" disappear after dark or if you cover the solar panels?

 

[Supertramp]

My Beta has the tachometer wire connected to the alternator, and reads when the engine and alternator rotates. Standard Beta wiring. Check your tacho is wired up as per the Beta wiring diagram and check connections.

Solar will not affect it - it might stop your alternator giving charging voltage, but that will not affect the tacho operation unless you have different wiring to the Beta manual.

 

[snowbird30ds]

It's dead easy to check, disconnect solar and calibrate tacho and see what happens.
On my volvos if charger has been plugged in overnight and sun is bright tachos mess about the next day, since I've changed to led warning lights the charge light always flicker when tacos play up.
I have 2 engines with an old driftgate splitter, I think it's the splitter cutting the field windings as the batteries are well cooked, no field coil volts equals no alternator output equals no tacho signal.

 

[William_H]

It is conceivable that solar charge can discourage the alternator from charging (via alternator regulator reducing field current to reduce charge) however highly unlikely it will reduce alternator charge so much that it will not provide the AC from coils that drives the tacho. More likely is that alternator has bad brush to slip ring connection which will deprive the alternator of field current so no charge and no ac to tacho. Intermittent connection of brushes is typical causing tacho to go crazy. Suggest remove alternator and get tested or remove the panel at the back which holds brushes and exposes slip rings replace brushes and clean rings. ol'will
PS of course the solar charging can mask the fact that alternator is bad.

 

[Mistroma]

Perhaps you could ask them to explain the theory behind the suggestion.

Does it relate to voltage regulation and high voltage?
Is it rapid fluctuation due to PWM controller?
Perhaps it's phase related?

I favour the last one.

But surely that's not solar if it depends on whether the moon is waxing or waning.

Def. Lunar see.

 

[Refueler]

Regardlessas of what you want after diagnostics .... surely the way forward to determine cause - is to try Beta's idea ... disconnect solar / controller from system ... see if calibration can be done then ... if not - then its alternator / tacho problem Will H suggests.

I know its not same setup - but having gone through the process of comparing proprietary vs add on Tacho .... I am now of a mind to never look at another proprietary setup.
The sensor that straps to alternator case feeds to a standard pulse tacho ... just works ... no alternator wires to play with ... simple and cheap as chips ..

Just commenting.