Energy Management

[SailbadTheSinner]

I recently acquired a Hunter 42 Passage Centre Cockpit. While it's not the biggest yacht I've owned, it is the most complex! I have what I believe to be an almost complete "Owner's Handbook". However, I am having trouble with understanding and operating the energy management. I have an AirBreeze wind generator, large solar panels, an 8kva Kohler and, of course, the Yanmar main engine's alternator all providing charge. There's a Heart Interface Freedom Model 20 and an Ample Power Energy Montitor/Controller. There's more flashing lights than Luna Park/Coney Island! Is there anyone out there with a similar system? There's two rotary battery switches on the Hunter panel opposite the chart table/behind the aft cabin door. What position should these be in under the various circumstances? Batteries off - both off. OK. Engine or genset start - both on? Charging - both on? Or Starter on "On", House on 1, 2 or "ALL"?

 

[Flying Colours]

G'day Sinner,
Engine can be left in ÖN Position and Battery can be left in ALL.

 

[SailbadTheSinner]

Thanks for that, Flying Colours. However, I assume that you're referring to the situation when the engine and/or the gen-set is ON. If I left the switches as you say (Engine/Gen-set Start Battery ON and House Battery ALLl), I would run the chance of running down both batteries wouldn't I? I turn the Start Battery OFF the moment either the engine or gen-set is stopped to save it in as fully-charged state as I can. I am worried that leaving it ON and house batteries in ALL will flatten everything. Am I wrong?

 

[Bill Roosa]

It depends on wither you have a battery isolator or not. If you have one you don't need to turn the engine switch OFF in any case.

 

[SailbadTheSinner]

Thank you, Bill. I assume the Battery Isolator Switches you refer to are the Perko rotary switches as shown in the attached photograph.

 

[JWC]

Marine electrics made simple at this link will give you much of the info for your individual solution.https://www.smashwords.com/dashboard

 

[Rich Wallace]

Sorry to be late in getting in on this but some clarification is needed. First, a battery isolator is a dedicated piece of electrical equipment that isolates each battery from the others. The one on my P42 has five terminals top to bottom. Bat 1, Alt 1, Bat 2, Alt 2, and Bat 3. The alternator from the main engine and the alternator on the generator (12v, not the 110 AC one) are attached to the Alt studs. The batteries are each attached it their own stud Bat studs. Either alternator will feed all the batteries but none of the batteries can discharge through isolator to the other batteries.
The second piece of information you need is that the 1/2/All switch is intended to only control which battery is feeding the inverter. However, I found that the actual installation had all kinds of connections to the output stud on the rotary switch so it was not just controlling the power to the inverter.
With that said, I run the rotary switch on ALL, and leave the Start rotary switch ON all the time. If I did not have the isolator, I would then shut the Start switch OFF when I was not starting the engines.
One other comment, the battery isolator lowers the output voltage by approximately 3/4 of a volt. If the alternator is putting out 14.5 volts (typical) the actual charging voltage to the batteries is only 13.75 which is barely enough to really keep them fully charged. As always, you give something to get something.

 

[SailbadTheSinner]

Rich,

Many thanks for that. I have a marine electrician coming to check out the whole system on Wednesday. I hope to have a better understanding of it after that. In the meantime, I prepared a "flow chart" which, I hope, is an accurate representation but the electrician can put me straight - or others can - if I'm not right.

Cheers,