Testing/adjusting amperage output

[slatgrille]

To keep this topic brief, here's a quick overview. My '48 P15 stopped charging a few weeks ago...unfortunately at dusk. Had to drive home without using lights since I needed what was left of the battery to keep it running...what a trip that was! Anyway, next day I ran the revs up and pulled the battery cable to discover no charging taking place. Opened regulator cover and manually manipulated the Bat and Arm contacts and the 'ole genny couldn't keep up. 

 

Pulled genny and rebuilt it, i.e. cleaned armature and commutator, new brushes. Assembled, reinstalled and 'viola' it works! Nice crisp spark at the battery terminals...however, my amp gauge shows increasing output as engine speed increases. At high revs, it reads more than 60 amps!. I turn on the lights to create more 'draw' and that keeps it around 40 amps.

 

Is there any way to test the output regarding amperage? I've looked online and in the manuals I have, but they show bench tests with all sorts of equipment, or just voltage tests. Is there a shortcut test of the genny or regulator while in the car, or should I just 'pony up' for a new regulator? The original generator brushes were worn down to where the copper wire was showing. Previous to that the amp gauge would show a max. of 5-10 amps charge rate.

 

Craig

 

[Plymouthy Adams]

was this 60 read on the car's amp meter or by a calibrated instrument? 

[keithb7]

You can watch me test my generator output here with simple clamp meter/ Digital Multi-Meter.

You can buy the tool here:  https://www.amazon.com/UT210D-Digital-Current-Resistance-Capacitance/dp/B0753FY711/ref=sr_1_2?crid=187OIWIDDJUEX&keywords=uni-T+210D&qid=1693926590&sprefix=uni-t+210d%2Caps%2C319&sr=8-2

 

Works very well.

 

 

[Dave72dt]

If that is a 3 brush gen, the third brush is usually adjustable and can be moved to tone down the output.  If not, go through the regulator adjustment  process as outlined in the service manual.

[slatgrille]

Thanks for the replies. First, the reading is on the car's gauge, not precise test equipment. Second, it's the 2 brush type...not an adjustable 3rd brush (like my Model A Ford). I'll check out the video Keith.

 

Thank you.

 

Craig

[CarlN-NDC]

On 9/5/2023 at 11:10 AM, keithb7 said:

You can watch me test my generator output here with simple clamp meter/ Digital Multi-Meter.

You can buy the tool here:  https://www.amazon.com/UT210D-Digital-Current-Resistance-Capacitance/dp/B0753FY711/ref=sr_1_2?crid=187OIWIDDJUEX&keywords=uni-T+210D&qid=1693926590&sprefix=uni-t+210d%2Caps%2C319&sr=8-2

 

Works very well.

 

 

Hey @keithb7, I was re-watching the segment of your video where you demonstrated a few tests with your clamp-style amp meter.  I've probably watched that video alone a dozen times since you've posted it, but I always notice some additional detail every play-through!

 

You had mentioned you weren't able to get an amp reading from the battery cables while cranking over your engine.  I hope I'm not pointing out the obvious here, but could it be because the UNI-T UT210D's limit is 200A DC?

 

Just thinking about how automotive batteries are rated (Cranking Amps and Cold Cranking Amps), they are easily rated to output 3 to 4 times the UNI-T's testing range!  We know these stock 6-Volt system can draw quite a bit of amps (OHM's law) through the wires.  I know in a separate video you had stated you replaced the battery cables in your '38 Plymouth with 2/0 cables.  That got me thinking... I wonder at what size cable would you reach a limit of "diminishing returns"?  Where it doesn't matter how much bigger up in cable size you go, there would become some other limitation, outside of the battery cables, whether it be the starter itself couldn't accept any more amps or something else.

 

Obviously there are many factors at play that can cause a starter to draw more or less amps to get an engine going.  Engine temperature, ambient air temperature, overall condition of the engine (how much compression is it making), condition of the wiring harness and connections, etc.

 

It would be an interesting topic to research further to determine what size cable is the "limit".  I'd love to perform this study myself, but my '48 DeSoto is still in pieces!  Maybe someone on here has already conducted similar testing?

 

 

Carl

[Sniper]

9 hours ago, CarlN-NDC said:

Obviously there are many factors at play that can cause a starter to draw more or less amps to get an engine going.  Engine temperature, ambient air temperature, overall condition of the engine (how much compression is it making), condition of the wiring harness and connections, etc.

 

Oil viscosity too

 

9 hours ago, CarlN-NDC said:

I wonder at what size cable would you reach a limit of "diminishing returns"?

 

When you exceed the minimum size needed to carry the expected load, anything past that is gravy on the biscuit when all you need is the biscuit.  Though there is a substantial difference between short term peak loads and long term carrying capacity.  IOW, the size starter cable Keith mentions is undersized IF the expected current load was continuous, being that it's a momentary load you can get away with the size used.  Or course, wire design plays a part in it too.  Soild core, coarse strand and fine strand copper wires conduct good, better and best in that order.  You starter cables had best be fine strand and copper.

 

Also remember that most info on the web about starter current draw is talking about a 12v or higher system,  6v requires twice the amperage of a 12v system to do the same job.

[slatgrille]

Here's a follow-up. I looked up amperage testing in the manuals and on youtube. Before attempting any testing/adjustment, I changed the existing regulator w/another exactly like it that I had on the shelf. It reacts exactly the same, so I left it on and took a 20 mile trip this afternoon. The amp gauge still showed a reading between 30-60 amps depending on engine rpm. I put a load on the circuit with the headlights and heater motor on to keep the charging rate down. I started detecting a 'burning' smell about 6 miles into the trip...not overwhelming, just kind of there. I pulled over, popped the hood and smelled nothing, nor saw anything out of the ordinary, so continued on my way. At approx. the 15 mile mark, the gauge stopped showing any charge and fell back to zero instantly as well as the smell going away. I turned off the 'loads' and continued on as the car ran fine. Just before reaching my destination, I turned the lights back on and the gauge showed a discharge. Upon my 20 mile return trip, the car started up without issue and drove fine back home.

 

Before I tackle this issue Sunday morning, does anyone have experience with this similar issue regarding too much output w/a burning smell before the circuit quits working? Again, thanks for any input.

 

Craig

[Sniper]

I could be wrong and Lord knows it wouldn't be the first time but I don't think you're generators capable of a 60 amp output

[soth122003]

Looking through the posts here, I think your genny and regulator are working fine. Quick check is to start the engine and use the fast idle to set at about 2500 rpm. Use a multi-meter and check the voltage to the battery. Anything above 8 volts, check the genny and the regulator. You said you changed the regulator and still had the same problem. (probably good) Genny wasn't putting out. Cleaned and replace brushes, genny works. (again probably good)

 

What doesn't seem to be working right is the amp gage. \

9 hours ago, slatgrille said:

I started detecting a 'burning' smell about 6 miles into the trip...not overwhelming, just kind of there. I pulled over, popped the hood and smelled nothing, nor saw anything out of the ordinary, so continued on my way. At approx. the 15 mile mark, the gauge stopped showing any charge and fell back to zero instantly as well as the smell going away.

I would check the gage and wiring first. Look for any burnt or loose wires. Start from the back of the gage and inspect the wire from one end to the other. Check the gage as well. It's not often but they do go bad.

 

Joe Lee

[slatgrille]

Well, the regulator overheated and a piece of solder fell out while removing it from the car. Since that replacement 'sh*t the bed', I set adjustments on the one that came off the car that worked. Corrected the point gaps according to the manual. Put it on, started the car, revved it up and......no change. Still showed no charge, but did show a discharge when turning on lights...and yes, I did polarize it beforehand. Pulled ground cable off battery to see if was charging, and engine would quit. Next I performed the 'motoring' test, and the genny passed with flying colors. No wires are melted, nor corroded anywhere in the system. Should I just give in a buy a new regulator, or press on trying to figure this out?

[slatgrille]

Measured the voltage output from the generator while on the car. Meter only read .445, despite 'motoring'. I'll close out this topic by saying, off with the genny to be rebuilt!

 

Thanks everyone for the help.

[Bob Ritter]

On 9/5/2023 at 8:10 AM, keithb7 said:

You can watch me test my generator output here with simple clamp meter/ Digital Multi-Meter.

You can buy the tool here:  https://www.amazon.com/UT210D-Digital-Current-Resistance-Capacitance/dp/B0753FY711/ref=sr_1_2?crid=187OIWIDDJUEX&keywords=uni-T+210D&qid=1693926590&sprefix=uni-t+210d%2Caps%2C319&sr=8-2

 

Works very well.

 

 

 

On 9/18/2023 at 6:06 AM, slatgrille said:

Measured the voltage output from the generator while on the car. Meter only read .445, despite 'motoring'. I'll close out this topic by saying, off with the genny to be rebuilt!

 

Thanks everyone for the help.

Keith, what a great video, it is guys like you that make this forum so great. Thank You...

[soth122003]

Well when it rains it pours. Guess what just happened to my 48? Testing to continue tomorrow. Today was check the brushes and commutator. Cleaned them up and no change. The VR is doing nothing. The battery is on the charger now. I'll try the motoring test tomorrow and check the voltage outputs with the meter.  I'll keep you guys posted.

 

Joe Lee

[slatgrille]

Sorry to hear it happened to you too! I'm taking my generator and regulator to the rebuilder this afternoon...aren't too many of these guys around anymore. 

[soth122003]

Well the motoring test failed. So off to the shop. It hurts to much to do this myself and I don't have the proper tools to fix it right anyway. As I get older life is great and it sucks as well. I know how to do these repairs but the worn out body won't let me without a morphine drip. LOL  However getting older brought on SS checks and they increased my income 1 1/2 times more. That means money to spend on repairs instead of nursing the car with a band aid. 

 

As far as places to get this fixed, there are more than most realize. Starter/alternator shops will be around for a while yet and the difference between the starter and genny is not a whole lot. So most starter shops work on gennys as well. The only thing that sucks is the cost. Everything goes up, but man it seems like more than normal. 

 

Joe Lee

[slatgrille]

I hear you 'soth'. The rebuilder said if I needed a new armature it would cost approx. $85 just for that, even though the copper prices have gone down, whereas they were only around $35 a few years ago. Hopefully it just needs some upgraded insulated wire and the commutator turned with new brushes that he has on hand. Unless TOTAL junk, he said it shouldn't be more than $125 total.

 

Also, this guy is only 48 yo...not an 'ole timer about to retire. He learned the trade from an older employer when he was in his 20's...plus, he knows to adjust the regulator to match the specs. required. Showed me the shop and equipment plus some finished projects he did. I should have it back by Friday.

 

Craig

[soth122003]

Question for the Guru's out there. How often or at a ballpark guess does the armature fail? 

 

I pulled the genny out and dis-assembled it. The wire coming from the armature post had lost all its insulation. I put heat shrink on it and reconnected it to the brush. Doing a continuity check, the armature post had continuity to ground. disconnected the wire from the brush and no continuity to ground. The brush holders have one grounded and one insulated from ground. The wire from the armature is connected to the non grounded brush. Is this correct? 

 

When I did my continuity checks with the genny assembled, Everything was to be grounded when I hooked up the armature wire to the brush. The commutator, the brushes, The field and armature posts. So the only thing in common is the commutator/armature. I think (but am not sure) that I checked the commutator and it had continuity from one section to the other. I.E. bad armature. The only time they are in contact with each other is the momentary contact by the brush going from one to the other. Otherwise they should be isolated from each other.

 

Please correct me if I am wrong. I also admit that this genny is probably about 75+ years old. I don't know if the armature is but it is at least 40+ years old. Now I don't expect these to last forever, so I am thinking it finally gave up the ghost. 

 

Does anyone know a good source to buy just the armature aside from Ebay? Trying to find a new/rebuilt one. Any help or advice would be most appreciated.

 

Joe Lee

 

 

[Sam Buchanan]

Joe, after you get tired of messin' with the genny and regulator yank them and install an alternator, your troubles will be over.  

[soth122003]

2 hours ago, Sam Buchanan said:

Joe, after you get tired of messin' with the genny and regulator yank them and install an alternator, your troubles will be over.

I'm thinking about it. I was of a mind to contact you for the alternator number and how you mounted it as well as the cost. I know you posted it before, but I am feeling lazy and sore this morning from yesterdays adventure with the genny. Send me a DM about it please. Also, which would be better a 60 or 100 amp alternator? Also with this set up will the amp gage still work?

 

Joe Lee

Edited September 24, 2023 by soth122003

[Sam Buchanan]

60 amp is fine and the ammeter works as usual.

 

https://www.ebay.com/str/HowardEnt?_trksid=p2047675.l2563

[soth122003]

Thanks Sam. I just ordered the alternator. I saw it earlier on Ebay. The same one you sent me the link to. I will probably get the genny fixed and keep it with the car just for originality, but the alternator is a better device. I just like keeping things original. You said ditch the VR. Where did you hook the wire of the alternator to then?

 

Joe Lee

[Sam Buchanan]

Alternator comes with a schematic. Hook alternator wire to the wire on the regulator BAT terminal. Armature and field wires no longer used. Simple.

[DonaldSmith]

Check that the wire from the starter solenoid did not connect with the generator.  If it did, just ground the wire, or run a shorter wire from that solenoid post to a good ground. Ma Mopar grounded the starter relay circuit so that if the engine were running, the genny would not provide a good ground, keeping the driver from grinding the starter and flywheel. 

[soth122003]

Well I got the alternator installed, finally. Bit of a bite in the backside to get the settings just right for the universal mount. Had to grind a little on the top piece to get the 4th bolt to fit. The alternator was also a tight fit with not much room for adjustment due to the battery tray. Also the adjustment bracket that mounts to the water pump wouldn't work with the alternator. Had to remove it and install it backwards to use it. Now to adjust belt tension, have to loosen the bolt at the water pump and adjust it there.  I also put some sealant on the bolt so when I loosen it, it won't leak.

 

I finally found pics of your alternator Sam, I didn't remember the alternator being quite so tight a fit in your install, but I guess it is. I also saw you made an adjustment bracket for yours. I had thought you said you made one but couldn't quite remember until I installed mine, then the potty mouth started until I turned mine backward and all was well again.

 

Amp gage works and the meter checks at the battery were good. So with that said, I am now a happy camper. I will still get the genny fixed for the next owner (whenever that happens). Now I just need the wiring done, upholstry and a paint job and my car will be sweet. (when I win the Lotto)

 

Joe Lee