Alternator charging for 1983 27 Hunter

[Keith Fawcett]

I have a 1983 Hunter 27. I was wondering what the charging setup was for the engine mounted alternator. I usually start and motor with both batteries. When the battery switch is in this position am I charging both batteries ? If I start and motor on "1" battery am I just charging number "1" battery? As always I appreciate the help and love my Hunter. She is a fine and noble girl !Keith Fawcett

 

[David Foster]

Battery Switch

It would help to describe the batteries. A deep cycle battery is designed to support starting. The standard wiring would be 1. The "house" battery is usually 2.The switch probably has 4 positions - 1, 2, Both, and Off. The idea is to set it to 1 to start the engine. Once started, set it to "Both" to charge both batteries. When on the hook, or otherwise using power for lights, instruments, and radio, set the switch to 2 to avoid running down your starter battery.With a boat as old as ours, you should check _all_ the wiring, both to ensure things are really wired as you expect, and for any problems with insulation, connection corrosion, and simply wrong connections. No telling what has happened over 20+ years!By the way, Lady Lillie is wired for two batteries, but only has one. Because our "house" load is so small, we can run cabin lights overnight and still have plenty of reserve to start in the morning. We like the simplicity, and we do have sails as a reserve power source!DavidLady Lillie

 

[R. Young]

Yes

If you have a simple system where the 2 batteries go to a 2 way/both type of battery switch then yes, when on both, both are charging. When on 1, only 1 is charging. Buy yourself a digital voltmeter ($25 & up) and you can easily check this out yourself. The battery being charged will show a voltage somewhere > 13 or 14 volts while the non charged battery will be in the 12 volt range. A digital voltmeter is the best/simplest way to know the status of your batteries. You can determine the state of charging, approx. current battery status etc. R. YoungHunter 37Destiny

 

[Brian]

don't switch while running

You run a risk of blowing your alternator diode if you switch from 1 to both. It's easiest to just put it on both to start the engine so they both get charged.Just remember, it takes more then an idle to charge your battery and it's really bad on a diesel engine to run in idle for hours. If you do run your engine in neutral to charge your batteries, it is suggested by Yanmar to take your boat out and run at hull speed for at least 2 hours, once a month to heat the engine properly and burn off any glazing that can occur in the cylineder walls.Always best to be safe

 

[Terry]

Hi Keith, both batteries on our H28 were of...

the deep cycle marine grade flavor. They seemed to work just fine for starting and house use. One tip I learned early on when coming aboard to use the boat was to routinely switch to battery one on odd days and battery two on even days. This routine helped to ensure balanced battery use and that you always had a fully charged battery on standby. Terry