Battery Won't Charge

[femsailor]

My battery does not charge while the engine is running, but charges fine while in port. do i set to regulator or rheostat?
thanks for any help or advice.

[djmarchand]

Measure the alternator output votage (the red wire on the back of the alternator is + and any ground for -) while the engine is running and not hooked up to shore power. You should read 13 or more volts at cruisng rpm. If not the alternator is not putting out. Diodes could be blown or whatever.

[femsailor]

thank you for the info, but do i turn the switch to rheostat or regulator and how far should i turn the dial?

[cabo_sailor]

It might also be as simple as the reference voltage line has come loose. Unless it's reading the battery voltage, the regulator won't send any juice.

Rich

[femsailor]

thank you, but do i turn the switch to regulator or rheostat and how far do i turn the dial?

[cabo_sailor]

Originally Posted by femsailor

thank you, but do i turn the switch to regulator or rheostat and how far do i turn the dial?

I'm not clear. What switch are you referring to that is either "regulator" or "rheostat"?

Rich

[Artif]

Are you sure you have a Rheostat? If you do then the rheostat may control the output of your alternator, but you have to be very careful about overcharging and monitor your battery voltage.
Or you may have a regulated output for constant running (regulator position) and a rheostat position for fast charging (see above cautions), an odd system.

Can you post some pictures of the switches and engine /alternator to help diagnose your system better.

[Marqus]

Originally Posted by femsailor

thank you, but do i turn the switch to regulator or rheostat and how far do i turn the dial?

I would set it on "Regulator" and then measure the output voltage as suggested by Djmarchan. That would be the 'default' mode for an alternator to charge an SLA battery (like it does in a car), and if that does not work, there could be something wrong with the alternator or the regulator.

If that works well, then I would move on to check the Rheostat option (the rheostat would probably be a fairly large disc-shaped item with a central shaft; the disc probably over 2.5" in diameter; it should be rated at least 50watts to handle a 4amp field current; preferably higher). As you turn the rheostat shaft, the output voltage of the alternator (measured at the same output stud) should vary accordingly. Try to keep the output voltage under 15volt as you turn the dial. Be careful not to over-charge the battery with this option.

[skipmac]

Originally Posted by femsailor

thank you, but do i turn the switch to regulator or rheostat and how far do i turn the dial?

You really need to clarify what switch you're referring to. Most systems do not have this switch. Do you have an externally regulated alternator or a custom charging system? If you have no clue what I'm asking then can you describe the switch, what brand it is, any details at all?

I am guessing from the labels on the switch that rheostat is a setting that allows you to set the charging voltage by adjusting the voltage to the field terminal on the alternator.

Skip

[femsailor]

thanks everyone for all the advice. i am printing it out and showing it to a mechanic this afternoon. i'm pretty much clueless - just love to sail! amy in mdr, ca