Location of diodes in the Alternator Restart system?

[wslade2]

Also, be sure to check the ground. Will have to have a good ground to make a complete circuit especially if it’s low amps. I expect the negative side of the battery box to be secured to a ground somewhere. Also attention to the ground for the engine (which becomes the ground for the alternator).

[Rick Erwin]

Originally Posted by wslade2

Also, be sure to check the ground. Will have to have a good ground to make a complete circuit especially if it’s low amps. I expect the negative side of the battery box to be secured to a ground somewhere. Also attention to the ground for the engine (which becomes the ground for the alternator).

Will do, thanks again.

[Rick Erwin]

So, today I tried to do an amperage test to see what the current draw is when the dry cell batteries are supplying power to one alternator. I know I'm not proficient in the use of a multimeter ... I had no success. I even resorted to YouTube to see how to measure an amperage load, and I followed those instructions, but to no avail. I'll attempt that again tomorrow.

I checked the grounding circuit and there was no resistance at all between the ring terminal on the negative battery cable and the airframe anywhere I measured it, even at the alternators.

Tomorrow is another day...

Rick

[wslade2]

Ammeter should be hooked in “series”. one probe of the meter hooked to one end of wire and other probe hooked to the other end. Just think of it like cutting the wire and putting the meter in the line, like two leads of a light socket. If you’re able to select, start high on the amperage and work down. I don’t buy very expensive meters and most of those have a 10 amp capacity. It’ll say on the meter. They usually use a fuse and if apply too much current they’ll blow the fuse and end reading zero. If zero reading, check fuse in meter in case it’s blown. You should get some kind of reading. If not back to testing every connection and solder joint

[Rick Erwin]

Originally Posted by wslade2

Ammeter should be hooked in “series”. one probe of the meter hooked to one end of wire and other probe hooked to the other end. Just think of it like cutting the wire and putting the meter in the line, like two leads of a light socket. If you’re able to select, start high on the amperage and work down. I don’t buy very expensive meters and most of those have a 10 amp capacity. It’ll say on the meter. They usually use a fuse and if apply too much current they’ll blow the fuse and end reading zero. If zero reading, check fuse in meter in case it’s blown. You should get some kind of reading. If not back to testing every connection and solder joint

wslade2, thank you again. That is how I thought the multi-meter should be hooked up to read amperage. That's how I thought I'd done it successfully in the past, and YouTube verified that. What I didn't check is the fuse in the multi-meter. Perhaps I can get to that tomorrow, as I'd still like to know.

Well, today I had some level of success. After doing three different iterations of an under-load test at each junction in the restart system, (for some unknown reason), the system started showing voltage at the field terminals. I don't know why, which is frustrating, because the problem could return anytime.

The decisive test will be to run the engines and perform the Alternator Restart Test to see if the 1.75-ish volts at each alternator are enough to excite the fields and restore power to a cold electrical system.

Rick

[wslade2]

With wiring issues, sometimes you just have to keep going over it. A little detail can be the problem.

[Rick Erwin]

Today there was a measure of success.

We ran the engines and performed a pseudo test of the Alternator Restart system. It worked!

The entire system has not been reinstalled yet from the testing, so I just used dry cell batteries to excite the rear alternator and it fired off with 1.5v. Once the rear alternator restarted, the front came up as well. The next step is to reinstall the system and do another test. Since testing has shown I will have 1.75-ish volts at each alternator's field terminal when the system is installed, I'm hoping I'll be good to go.

I did see it would NOT restart with ANY load on the system though. Since an alternator's field has about a 3.5 amp load, I think it would be advisable to only try to restart one alternator, then turn on the other alternator.

There will be more testing to follow.