We have a 2000 35' Open with 370HP Cummins. Everything was fine until a week ago when I started the engines the port gage (engine bank) showed 11V and starboard gage (house bank) read 11.5V (this .5 deviation is normal only about 1.5V low) I took a reading directly from both banks and the both read 12.5V (engines running).I decided to take it out for a short run and after a short period of time the voltage increased to normal readings on the gages. Today I started the port engine and reading on the gage was normal, when I started the starboard engine both gages went to the previous low reading of 11V and 11.5. I once again took it out for about 2 hours (constantly monitoring the status of the batteries) and this time it did not return to normal. With the engines still running at the dock, I once again checked the banks and they both were 12.45V. It seems strange to me that both alternators would give me trouble at the same time. Is there a voltage regulator that works both engines. Any suggestions, advice, or comments would be appreciated.
There is a voltage regulator for the alternators. I have a 2000 Tiara 3500 and the regulators is located on the forward bulkhead right at the day hatch to the engine room. What is the reading on the batteries with boat running at about 1200 RPM? Should be in the 13.8-14.2 range. Check the voltage read ins downstairs as well on the panel gauge and verify they match either the batteries or the gauges on the helm. There are some relays that will affect the voltage readings at the helm station.
The Voltage does not change with RPM, stays at 12.5V. the gage on the panel reads close to 12.5, I haven't checked the leads to the gage to verify that reading, but I will. As I mentioned in my first post the voltage was ok when I started the port engine and it dropped when I hit the starter of the starboard. When I shut down I shut down the starboard engine first anticipating the voltage may increase. That did not happen.
I will assume at this point the air heaters, switch behind the steering wheel is off. If on, they take a lot of power so that may be the problem. If you find the regulator and have a manual to troubleshoot then you can determine the problem, i.e. alternators, regulators, wiring issues etc. Bascially there are 2 regulators stacked on top of each other, made for Tiara but quite easy to troubleshoot if you have a DMM and manual. I have it if you need it and the people at Charles Industries (maker of the regulator) are great to work with and very very helpful.
Well I believe the problem has been solved. with my limited knowledge will try to explain what fixed the problem. I am not an electrician, I know just enough to get me into a lot of trouble, that is why I leave it to the professionals. First we checked the regulators as suggested and found them to be ok. We then called the Charles regulator technician and the only thing he suggested was that it may be the battery heat sensors, we then disconnected the two sensors and nothing changed. We then started to check the alternators on the starboard engine and found that when we moved the wire to the field terminal the voltage went to 13.6V and ran fine (I have owned the boat for 2 years and have never had over 12.4V). We then changed the Port engine over and the voltage went to 13.6V. After a short period of time the alternator on the port engine began to smoke, we shut it down and took the alternator for repair (stator). Put it back on and now it puts out 14.2V. I have run both engines about an hour and everything seems to be ok. We plan to have trip this weekend if anything changes I will let you know. Thanks for all your help.
John
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