battery charging question

[redhead78]

Hi all, I have a ? on charging with the engine alternator. I have a beta with the optional 100 amp alternator, I have been doing a lot of motoring with my annual spring voyage downriver and wondered if the batteries are topped off will the alternator sense and stop charging the batteries, and not overcharge them? Red

 

[Maine Sail]

Hi all, I have a ? on charging with the engine alternator. I have a beta with the optional 100 amp alternator, I have been doing a lot of motoring with my annual spring voyage downriver and wondered if the batteries are topped off will the alternator sense and stop charging the batteries, and not overcharge them? Red

Red,

The batteries decide what current they will accept at a certain voltage and state of charge. When full they are taking very little current. Your alternator will not over charge them unless the voltage regulator is in the 14.6V+ range and you run it for very, very long periods of time. Most stock regulators are below 14.6V.

It is easy to measure your alternators set point. With the batteries known full measure the charging voltage at the battery terminals. 14.4V is where gassing can begin (of course temperature plays a role and it can begin earlier) but cars, trucks etc. run these same voltages for tens of thousands miles. If your alt is set to 14.6V or higher you might consider an external regulator, with a float stage, but only if you're going to continue this type of engine run times.

 

[redhead78]

Thanks Maine I have a fluke meter I can check it out this weekend. Red