Alternator question again

Im becoming a pain on here with my alternator questions i apploogize for that! but...
with everyones help on here i have manage to get the delco 10DN to charge excpet it puts out 17.5 volts and i know that i need an external regulator for it..... (thanks to Bob for putting up that pic of one cause i was not sure what one i had) however i was over a freinds house last night and he gave me a like new mitchubitchi alternator 50amp out put. I thought heck ill try that one. i have no idea if it is external or internaly regulated though. it has a terminal for the battery and two unlabled prongs in the back, looks pretty modern. Anyy way i put it on and it charges good however it charges 15.2volts at an 600rpms and all the way up 1600 rpms same. I ran it for 30mins and the volts never chaged and the amp meter keep reading over 10+ amps not pegging the gauge but over the last reaading number of 10amps. The battery is brand new and the tractor uses a mag so there is no drain on the battery and i dont think that it should read 15+ volts sooo now after alllll that im not sure what to do?!! go with the delco or the mitubitchi one? and how do i wire up a regulator and what one do i get if i need one. (i know i need one for the delco and how do i wire one up?)

Sorry for being so long winded!

Thanks again for everyones help!

Andrew

You are right Andrew – your alternator output voltage is still too high!

You should see a maximum of 14.0 and 14.5 volts. Also after the engine has run a few minutes the ammeter indication should taper off to just a couple amps of charge. (If operated at higher voltages for very long it will eventually cook your battery...)

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From your description it sounds like the mitsu alternator is internally regulated. And if it is indeed internally-regulated and you have nothing connected to the alternator aux terminals, there is no “voltage sense” feedback to the regulator. This then auses the regulator think the output voltage is too low. So it boosts voltage to compensate.

You might try this (Note: Do this at your own risk – I’ve not tried it myself!):

1 – Disconnect the battery ground cable (for safety…) then any the wiring to the alternator.

2 – Take an ohmmeter and measure the resistance from each alternator aux terminal to ground. One terminal should have a very low resistance (a few ohms); the other very high resistance (many thousands of ohms).

3 – Connect a new wire between the HIGH resistance aux terminal and the alternator’s output terminal.

4 – Now reconnect the other alternator wiring and the battery ground, start it up and see what happens.

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Unfortunately I do not have a diagram for a 10DN (externally regulated) Delco alternator. However I’m sure a quick google search can turn one up….

Make sur your Volt meter is accurate. Check a fully charged 12v battery. It should read 12.6 volts if it does, then your meter is OK.
JimN

Many thanks guys!! I will check that out and let you know what happens.

Thanks again

Andrew

Andy-- take the regulator which you will be using with this alternator & put it on a flat surface with it's mounting holes [3 of them] down. Position the regulator with the 4 hook-up terminals facing you. The farthest left terminal is the field terminal, & will be connected to the field terminal on the alternator. The middle 2 terminals don't need to be connected at all. The 4th terminal is connected to the ignition switch. This is the "turn on" connection. Of course, there will be a # 9 wire from the alternator "hot" terminal to the ammeter.
Only problem is that I don't know which terminal on the alternator is the field & which is the "R" or relay terminal [which doesn't need to be connected]. I suppose you could take the alt. apart & see which terminal was which. I'd guess it would be the right-hand terminal. Look for a small "F" or "R" by the small terminals.

Brownie 450's connection in a diagram.