amps or voltsI'm wondering

[jake]

I'm wondering which about my alternator on my 78 cat. she has the petter one lung diesel which run great but I'm want to find out what the alternator should be putting out .I understand while running atlow rpm she should be putting out some where around 12.9 -14 volt to recharge her battiers.{ correct ???? } but what about amps? the alternator has no I.D. on it other than Lucas and I think it maybe a rebuilt unit but it doesn't have any indication about how many amps it is putting out. how can I test it ? multimeter? and how important are the amps ? are 35 amps better or worst than 95 amps? maybe I will be like BOB never run the motor. p.s.I know who BOB is he sails back to the bay . go BOB!!!!!

 

[larry w.]

amp it

Jake; amp output is a function of RPM and battery capacity and to a lesser extent, so is voltage. The higher the RPM, the higher the output. Get a copy of Calders "Boat Owners Maintenance Manual" it's the bible and will explain everything. West Marine catalogs have good tech write-ups, too, but they don't go into that much detail.

 

[Paul]

Amp and volts

Jake,You are correct in saying that alternator output should be between 12.8-14. In order for your alt to charge your batteries it's output voltage must be greater than that of the battery. I would say at least 13 volts. To ensure your alt is charging make sure you engine rpm is set high enough for your alt voltage to be in the 13-14 volt range. (Usually 1500-2000 RPM will give you this) You can check this with a standard volt meter.Amps are how much current your alt pushes. The greater amperage your alternator is the faster it will charge your battery. If you have a 50 Amp alternator and a 100 Amp battery that currently has zero charge it will take approx 2 hours to bring that battery to a 100% charge.There is only one way I know of to check current output of you alt. That is with a Ammeter. Some multimeters have this function but be careful. They usually are only capable of checking 10 amps or less. trying to test a circuit of higher amperage will fry your meter. Make sure you have a meter capable of handling the current. General alternators that are not considered "high output" usually produce between 40-80 apms. There is no real way to tell unless you check it with a meter. The size of the alt will give you some idea as to whether you are closer to the higher or lower end of the spectrum.For more info on how to use an ammeter just Google for Ammeter.Hope this helps!