Running the Generator and Engine at the same time

[O'RION]

My 2018 R-27 OB has the Westerbeke generator which, when running, supplies a 6 amp charge to its starting battery (one of the house batteries). The Yamaha engine also charges the house batteries when it is running. My understanding is that there should not be more than one charging source applied to a battery at the same time. So will running both the engine and generator at the same time damage the batteries, or is there a circuit that protects this?

On my previous boat, the marine electrician who installed the generator added a switch which when in the off position disconnected the generator's charging circuit to avoid a dual charging source issue.

Thanks for any advice.

 

[captstu]

There should be no problem with adding a second alternator to the charging circuit.

NEVER run an alternator without a battery connected. The no load alternator voltage might damage the diodes in the alternator.


Stuart Bell
Ranger 25: Shearwater
(561) 352-1796

 

[BB marine]

As Stu stated there should not be an issue. If the 27 OB is wired the same as previous Rangers all battery banks are for the most part being charged together ( automatic charge relay ) So the 2 alternators are not just charging one battery. The alternators have voltage regulators built-in, to turn output off when voltages reaches the regulators set voltage peak. Normally this is between 14.3 to 14.7 volt. There is a very good chance that both Yamaha and Westerbeke alternator regulators are not set at the exact voltage shut down. When the batteries are fully charged one shuts down and the other keeps charging until it meets the set shut down voltage. At this point the alternators will cycle on and off until a changing demand is required again and repeat the cycle.In your case I would say the generator alternator will be cycling most of the time when the main engine is running.

Stu's comment on running an alternator without a load attached to it will destroy the diodes and the alternator will not have output. This is right on. On your previous boat your alternator may have had a field circuit that needed to be turned on by out side voltage and that is what he switched off to shut the alternator down. I'm not familiar with Yamaha charging circuits today but the older charging circuits used a voltage regulator/ rectifier to convert AC to DC and regulate voltage this would fail if there connection between the battery and alternator was opened.