Battery charging isolator vs combiner

[Kirk Martin]

I have a 1999 36 mds and just changed to a combiner to charge both house and starter battery banks while on shore power and running. Now I have sporadic "engine maint" light coming on. I have it configured with alternator connected to house bank with combiner to starter batt. Removed the old isolator. This should allow both banks to charge when running and on shore power.

Has anyone had this issue? Solution?
Also does anyone know what sensors are on the "engine maint" light?

[twinboat]

Do you get the light at times that the house bank is low ?

If the voltage is low, the combiner may be delayed in combining to the start battery. ( I see this on mine )

It needs to bring the house batteries up to 13.5 volts before closing the contacts.

With the delay the start battery may stay low and cause a light.

It may, also, not be related to the charging system at all.

[Kirk Martin]

It happens when both banks are fully charged. When disconnect the combiner and reconnect the isolator no "engine maint" lights. Once it turns on the only way to turn off is the shut down the engine. When restarting it may/may not come on.

[twinboat]

Have you tried moving the alt output to the start battery.

Could you be overcharging and having the combiner opening due to high voltage.

If your alternator has a sense wire that goes to the chassis battery it may make odd things happen.

Find out if it has a start battery supplied, 12 volt hot wire, to the regulator. If it does, just use a jumper on the alt from it too the output wire post.

With no diode isolator, you don't need a separate sense wire.

[Kirk Martin]

Yes have tried both batteries moving sense wire with the alt output connection. It is strange in that yesterday drove 150 miles with no "engine maint" light.

Thinking of just removing the bulb in the "engine maint" and driving as there are separate warning lights for all major issues. Does anyone know what other sensors are connected to the "engine maint" warning light? The manual says this is a minor warning light.

[Kirk Martin]

Thank you for your thoughts Twinboat. I think I am going to go with ignoring the "engine maint" light and see if I ID any other issues.

[tiredvet]

Kirk I had an issue with the engine maintenance light coming off and on and that led to a few other problems.I felt like a gerbil on a cage wheel, once I changed out my ground fuse all was well.The fuse is located in the maintenance bay(pass rear).You can not tell that it has blown just by looking at it.I think it is a 300 amp fuse.Napa has them for about $7.00. I carry a spare now.The way mine fractured the ohm meter would show that the fuse was OK and then other times that it was faulty.