Hey I have an older 300 motor that is our pump motor for a very large sprinkler. It runs on natural gas and is wired into a front panel that has numerous gauges having to do with the pump and it also has a tattletale installed (tattletale is an automatic shutdown device). It hadn't run for a while but I pulled it out, started right up with a good battery but the alternator wiring was mostly non existent and it was a bad alternator. We bought a new re-manufactured alternator and a new voltage regulator. I have been working for the last 3 days trying to get it to charge and it is very frustrating. I finally got it to charge this morning but it started with 14.8 volts then dropped slowly to 14.2 and when I came back later it read 12.8 at the battery while running. My wiring is kind of random and strange, so I'm guessing thats my problem. It also seems to draw on the battery pretty strongly when its off. I was wondering if anybody has any advice on how to wire a charging system in with no idiot light, just an ammeter, and no ignition switch.

 

You're readings are good except for the 12.8 running.
Somewhere you have an on/off switch, maybe not an ignition switch per say, tied into that tattletale setup. Is it just a timer with autostart too?

See if this helps


At the risk of being flamed, for this application, I would just convert (pretty simple to mount) a GM 10si alternator from the 70s. Dirt cheap and for less than 20 bucks you can get rebuild kit that includes a 1 wire internal regulator kit in it. Wiring doesn't get any easier. Just hook up the battery hot wire. Available up to 63 amps and very durable.

 

Yeah, the reasons I gave the readings is because they seemed to be dropping pretty quickly. In the course of a minute it had creeped from 14.8 to 14.2 and after 10 minutes or so it was at 12.8.
As far as an on/off switch goes, there is a start/run switch and a kill switch but the start/run switch is just so the high vacuum pressure while priming doesn't cause the tattletale to go off, it just stops it from making a circuit, telling the tattletale to go off.
I was thinking I could wire into that except that switch is not hot, so if my thinking is right, that wouldn't work for an ignition wire.

And that sounds great and simple.. except I just had the ranch I work for spend almost $100 for the alt and regulator so its a little late for that now.