10si Alternator indicator light necessary?

Howdy, all.
Is the resistor (or lamp) in series with the wire to P1 necessary? If you just run 12v straight to P1 (from the ignition switch) and then use a short jumper between BATT and P2 will it charge? I'm installing one on my tractor and don't see much use for the indicator lamp (during the day when it's in use I probably won't see it light up if there's a problem.) At the same time I don't want to omit anything that's necessary for proper charging. My apologies if this has been asked a zillion times already-- I really did search before asking.

Thanks in advance,
Darren

As long as you wire it to avoid the problem John mentions, you do not need any resistor or light or diode. The #1 spade terminal needs to have 12v+ when the tractor is running and isolated from everything when it is not. On my diesel tractor I do this with a NO oil pressure switch that actuates at 5 psig in the line between battery + and the #1 terminal. On my gas tractor (magneto ignition) I use a DPDT 2 pos toggle switch to 1) ground the mag in the off position and also isolate that lead to the alternator and 2) take the mag off ground and also supply 12v+ to that #1 terminal in the on position. Works great. I take it you have a conventional battery ignition system so I don't know if your ignition switch is capable of being wired to avoid the problem John mentions. While a diode would prevent any feedback from the alternator via that lead, I don't really see how a resistor or a light would. The idiot lights in automobiles usually have 12v+ on both sides of their contacts - hence no light during normal operation. When the alternator fails, that #1 terminal goes to ground in the alternator and the light lights up.

You are correct in just jumping the #2 spade terminal directly to the alternator main output stud.

Rod

The idiot light DOES eliminate feedback, not 100%, but to a value of current too low to power the ignition system, therefore allowing the engine to be shut off with a simple ignition switch, with no "accessory" terminal needed.

The #2 terminal was originally designed to be connected as near to the (+) battery post as possible, to more accurately sense actual battery voltage.Link

http://www.madelectrical.com/electricaltech/onewire-threewire2.shtml>Link