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Compass Marine How To | all galleries >> Welcome To >> Alternators & Voltage Sensing - Why It's Important > Regulator Volt Sense To Battery - Positive Only
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Regulator Volt Sense To Battery - Positive Only

In this illustration I have run the regulators dedicated positive voltage sense wire direct to the house bank. As we can see the regulator is now compensating by 0.29V. This is the voltage drop in the alternator outputs positive wire. The regulator is now producing 14.69 volts, across B+ & B- in order to get what it thinks is 14.4V across the voltage sensing circuit.

Because we have not completed the voltage sensing circuit, and the negative wire is still connected to the back of the alternator, we have not compensated for all the voltage drop, only half of it.

I know, I know "Balmar says to connect regulator negative to the alternator."

What they actually say is this:

"In most applications, this wire can be connected directly to the alternatorís ground terminal post."

For a cruising sailboat they are giving you very general information in this regard. The key word in that sentence is "most". Heck most boats in this country are power boats who run engines long enough for incorrect voltage sensing to not matter as much. If you own a trawler or power boat you probably fall into this "most applications" scenario. However if you want to run your engine for a maximum of 1 hour per day, and get the absolute most from your charging system in that time, then you really don't qualify for the "most applications" discount....

If you pick up the phone, call Balmar, and talk to Dale or Eldon they will confirm exactly what I have just shown you here. It simply needs further clarification in the manual for those who want the utmost in performance..

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