I have one of these on the 25 touring. My question is: how can I tell if it's charging? The magnetism appears to be ok an it does spin but not sure if there is output Needle on gauge moves imperceptibly and when lights are on needle jumps to the minus side of zero.
Is it self-exciting or is there something I need to do to have if excite? It's a Becker Delco-remy unit
When the alternator is charging, the ammeter will read "charge" when the engine is running at speed. So if when you turn on the lights the meter reads discharge, the alternator is bust....
You can test more accurately with a digital voltmeter, when being charged it will read over 6.33 volts, but you MUST measure to an accuracy of 0.01 volts.
Tony is correct about the ammeter readings, IF AND ONLY IF the alternator is wired through the ammeter. Sometimes you find that the wiring has been changed so that the alternator (or generator) is direct to the battery, and the ammeter doesn't know it's there.
If that is the case, it may be merrily charging the battery correctly, and you just can't see it on the ammeter.
As Tony suggests, your best bet is a voltmeter directly on the battery posts. Measuring the battery voltage at rest, and with the engine just started and then after running a while, and when the lights are turned on, will tell you worlds about the alternator's operation.
What you should see is 6.3 volts at rest (nothing on or running). Then after starting (with the starter), the voltage should jump up to maybe 8 or even 10 volts as the juice used to spin the engine is replaced, and gradually taper back to maybe 6.5 volts. Then when the lights are turned on (engine running above idle), the voltage at the battery should stay essentially the same. That means the alternator is producing as much juice as the lights are using.
In many commercial areas, especially marine areas, ammeters are passe' and voltmeters are found on the dash. They just give a better idea of what's going on, if you know how to read them.
Actually the set voltage of the alt should be 7.2V +/- a few tenths. It should not exceed this.
A digital VOM will become an exercise in futility.
Use an analogue meter. Also if the car has been setting a while restart and increase the speed well above an idle and see if it will turn on. You can force it to turn on and I will address that if you PM me.
It means nothing and I don't subscribe to this test but if a screw driver is attracted to the back bearing it indicates the field is being driven, nothing more.
I suspect it is a 10SI and you can actually test the diodes with pretty good accuracy with a VOM while it's in the car. That's another story tho.'
I think the battery is slowly dying. It had 6.13 on it before starting and after starting it leveled st 6.20
Here is a quick way to tell if an alternator is charging:
When the engine is running, bring the tip of a screwdriver close to the rear bearing. If it is magnetic, the alternator is charging.
Works on my Mopar muscle cars, anyway....
Mr Vanderburgs Alternator has been repaired for Free ! No additional cost , By Myself and returned to him, ANOTHER Correction that needed made from a incorrectly made alternator from L.D. Becker Auto Electric of NORWALK OHIO shop ran now sadly by Larry Becker Jr. who has no skill set to properly manufacture these units, so Buyer beware and be aware that Macs antique parts continues to sell these improperly made alternators. I would strongly suggest spreading the word that these units have continual problems and are not being taken care of by the Norwalk shop, other vendors of these units are available or Generator repair can be made by the MANY very professional rebuilders on this forum., I of course continue to honor my fathers history by happily correcting these mistakes , contact me if any problems arise with your alternators already purchased Thank You
I should be receiving it tomorrow. I want to thank Daryl for explaining the problem as to why it was not functioning correctly and taking the time to fix it for me. I cannot wait to get back on the road.
Here is a quick way to tell if an alternator is charging:
With the engine running, place the blade of a screwdriver near the rear bearing of the alternator. If the blade is attracted to the bearing (the back of the alternator is magnetic), the alternator is charging.
Note that if the alternator is like mine (a "one-wire" alternator), you will have to rev the engine up above the alternator's "cut-in" speed after you start it to get the alternator to start charging. Once the alternator "cuts-in", it will continue to charge even at lower engine speeds.
One other suggestion - paint the alternator black so that it's not so obvious
Why hasn't anyone recommended this: get a Fun Projects voltmeter! It fits perfectly where your ammeter is. I only have a speedster, but my voltmeter runs through a switch so I can turn it on or off as I choose. It even looks like an ammeter.
Super clean and nice and very accurate.
Mark S., do you know what make (brand) that your alternator is? It doesn't look like a Delco to me, but I could be wrong.
It came with the car when I bought it, according to the receipts the previous owner gave me he bought it from Mac's back in 2007, part number T5119A6.
That part number would be invalid now. Part numbers now begin with a 16
The alternator he has appears to have a 4 pin connector on the side. It looks like the one I have, a Delco CS 130, but I cannot be sure from the angle of the picture.
Here's a link to it on the Mac's page:
Here's a closeup view of the back of my alternator, it only has one wire going to it, the yellow and black wire that would normally attach to the generator cutout.
It is a CS alternator. Can't tell if it's a 130. The 130 designation is 130MM stator diameter. The 85 amp CS's were smaller and hard to find, CS121.
They are nice alternators will very good output at low speed. In an original OME version 70 amps at idle or slightly above idle.
They quickly becoming obsolete, that was fast.
No, it's not like the one I have.
unless that pin connector was removed
These are all Larry Becker Sr alternator kits yes It is a cs 121 Delco alternator, yes they are a 1 wire system , some have the regulator port covered , some do not , at one time he left the port open for 6 volt applications and used a plug / epoxy for the 12 volt version, I myself stamped 6 Volt and 12 Volt by the B+ Terminal to simplify which unit it was, Those pin connectors in the regulator are unused for the Model T application
Marks alternator was an early version of Larry Sr's Model T and is using a 10 si regulator configuration, as the 6 Volt CS Regulators were unavailable at that time, there are extensive wiring modifications inside to make this work properly and function at the lower rpm
Thanks for the info, Daryl. All I can say is that it has worked great for me so far, no worries.
Can you elaborate in detail on the internal modifications?
Ron the Coilman
Would the internal modifications really matter since it was Larry Sr.'s early version ????? The present 6 volt Daryl Becker alternator works as it should with no problems whatsoever. ,,,,, mine has been serving since 2010, no problems.
with an on/off switch
I just installed the alternator back on the T.
Daryl and I discussed it at length. I had gotten one in 2009 that stopped working and Larry Becker Sr replaced it. It would appear that it was not prepared correctly to run with my set-up.
It seems to be charging correctly now. I'm going to put the car away after dark so I can see the lights. Last time I drove the car in the dark it looked like two matches in front of the car. lol
Thank you Daryl. I appreciate the help.