Alternator output

[Bob Nash]

I checked the output of my alternator (Mando 55 amp--about 2 1/2 seasons old) with my digital multimeter and got a reading of 14.5 volts. Should I be concerned about that high a voltage? I have deep cycle flooded batteries.

[Don Moyer]

Bob,

It's my understanding (from West Marine's literature and other sources) that the alternator industry designs its regulator output to 14.2 volts, due to this being the desired maximum charging rate for gel batteries.

I wouldn't worry at all about 14.5 volts with deep cycle flooded batteries. I'm not sure where you're reading 12.5 volts, but you might try connecting the meter directly across the battery terminals. I usually notice a .25 voltage drop at my batteries, compared to the reading I get directly at the alternator output terminal.

Don

[Bob Nash]

Thanks, Don

I'll check it ocassionally next season. I've gotten readings of 14.5 at the baterries and at the alternator. Having replaced the previous Prestolite alternator because of a faulty voltage regulator that was putting out more than 16 volts, I'm a bit wary.

[msauntry]

Old post, but if anyone is researching for problems and comes across it, here's some further info.

It seems different types of batteries prefer a different charge voltage. The Balmar ARS4 or 5 instructions list what their external regulators can be set to for each type of battery. Flooded lead-acid batteries, were recommended to charge at 14.7 volts, as I recall. I rarely see over 14.2 from my Mando 55 alternator, though I'd like to see more since I do have wetlead batts.