Hello, l want to check the output of my generator to see if the guage is indeed correct and no power is being pumped back to the battery, BUT l dont know how to do that !!!.
When l turn the lights on to either dim or high beam the guage moves to the discharge portion ok, but when l start the car , and then turn the lights on it still moves to the same position on the discharge part of the guage, l would have thought that it may have only moved, say 1/2 way , showing a charge against the draw.
Can anyone describe what l need to look at to check.
Car is a 26 Tudor, still 6 volts , with a 12volt12 amp hr deep cycle battery for the stop and turn signals (LED)

Thanks in advance for your input.

Cheers David

Quick way to see if it's charging with a digital meter is to connect it across the battery after the car has been driven for a while. With the engine still at a high idle, the voltage across the battery should be about 6.9V with all the lights off. If the voltage is still around 6 or a bit below, then it isn't charging.
Your ammeter would appear to be working. It should show a charge at high idle speed with all lights off. If not, the cutout or generator is faulty. You can touch a piece of wire across the cutout terminals with the engine running and see if there's charge current. If there is then the cutout is faulty.

David
If the 6 volt battery is being charged and the ammeter is not showing any charging current with the lamps off your Model T may have a very common wiring fault. If the yellow wire from the generator is not on the "Gen" side of the ammeter and connected to the "Bat" side of the ammeter the battery will continue to be charged but you will not see any of the charging current on the ammeter.
To verify if this wiring is correct. With the engine NOT running quickly ground the wire to the cutout (if you are suing a FunProjects Voltage Regulator remove it BEFORE doing this)and have someone watch the ammeter looking and tell you if the ammeter shows a major discharge. If not the generator to ammeter wiring is wrong.
Ron the Coilman

Some stuff is better done with the analog-needle type voltohm meters.If the voltage varies a bit while the engine is running and the generator is chargeing,the needle will swing between the low and high point,but the dang digital meter will sit there and flash numbers at you like it is confused,which in reality it is.

You should be able to check the battery with no load,car not running,and get a good reading.Crank the car,and check the voltage again.should be a bit higher.
On a more modern car with 12 volts and alternator,you should read 12.5 or6 with the car not running,then 13.6 or a tad higher once the car is cranked up and running.

I am sorry to have to disagree with most but I will say again that one cannot make any meaningful measurements with a digital type meter when the engine is running - period. It is not a case of the readings being off a bit - it is rather a case of the meter giving total gibberish for you to use. If you then try to make sense out of this nonsense, you will be further mislead and can come to most any conclusion you want to. I find it is difficult to resolve electrical issues with a fleet of well meaning technicians all helping. Pick one of us and work offline or you may be in pursuit of that elusive wild goose for awhile. If you start pulling and tugging on things you may in fact accidentally fix the problem for awhile only to have it return at a less than opportune time.

You can try the AC volts scale on a digital voltmeter with engine running.

Harbor Fright has $3 DVMs, but have only 200 volt scale for AC, so not precise enough for 6.9 vdc. You need one with 20 or 30 volt AC scale.

rdr

Thirty bucks or so will get a good analog VOM at Radio Shack. That's about the price of a tank of gas these days.

Simpson 260 and Tripplett 630 analog multimeters go unsold for $9.99 on eBay all of the time. These are great quality meters that still have a lot of life in them.

Check it out.

Be_Zero_Be

Fooling around whith digital meters on old cars with solid core spark plug wires is usually a TOTAL waste of time.
Turn the lights one with engine stopped. Does it read about 8 amps dicharge? If so I'd say the amp meter is working. Now sart the engine, if it shows anything at all on the + or charge side the generator is working. 10 amps is good. If it shows anything on the charge side at speed with the lights on... leave it alone.

Ralph Ricks:

You ARE kidding aren't you.

It depends some on the meter, which is why I suggested to TRY it (with your meter). After all, they all convert AC to DC internally for the display.

rdr

That is not the problem. Of what use is it to perform a test if you can't depend on the results? Do you really think something meaningful can be done by measuring the battery voltage using the AC scale of a DVM?

Thank you for your comments, l have worked thru what l could, l now have a pos charge shown on the needle, when running at mid range, will try it tonight with the lights on, if only l could get rid of the miss that easily !!!

When driving tonight, l see that my charge rate was with the lights on are now running at just below the zero say neg 2 , so l am guessing that l am just about covering the discharge from the lights, but should it be charging just over the zero or more ??
Dip beam generally when stationary discharges at about neg 7 , high beam about neg 8 or 9.
This would mean that over the period of say 2 hours or so , l am going to end up with a flat battery aren't l, l'm not sure ??
Cheers David

I think a group one battery in a T has about 160 amp hours storage? That means that if your losing 2 amps, you have 80 hours before it's completely dead. A rule of thumb with Rv'rs is use only 1/2 the rated capacity before recharging - so if you want to be safe, only drive 40 hours each night after the sun goes down.

If your running on mag at night, the worst case would be dim or no lights by the time you get home. The car will still run even after the battery is dead. Carry a flashlight or unplug the right headlight if your worried about it.

Sorry, you might want to unplug the left headlight - whatever side is closest to the curb. You don't get hit head on.

OK thanks Tim, l'll take that as on the long nights of 40 hours of darkness l may be in trouble, but if l am only limited to 9 hours of night driving, ( cant ever see me doing that ) l'll be right, those figures l submitted , is that showing a normal generator activity, or should l be looking at the cutout as mentioned by John H , by the way after a 15 minute drive the battery showed 6.62 volts.
Cheers David

Best way to use a digital voltmeter on a Model T.

Ron the Coilman

The ONLY way to go if you use lights often is to set the generator up to 20 amps (with lights off) and put a Fun Projects voltage cutout with a built-in regulator on top in place of the cut-out.
They really work. I put two on last week, one on a '35 Ford and one on a '36.
When you start the engine they charge 20 amps for a few seconds and then drop down to about 5 or so. When you turn the lights on they keep a little on the plus side when the engine is at a fast idle or more.

OK thanks, do they look like the original cut out ?
Cheers David

http://www.funprojects.com/products/5055r.cfm
They look the same, but works better - saves the battery from overcharging & the generator from destruction due to uncontrolled output, should a cutout fail.

David,
The generator can be adjusted to be set up for the typical driving you do. If you drive short distances you will want a higher charge rate, if you drive long distances you will want a lower charge rate, if you drive with the lights on all the time you will also want a higher charge rate. If you almost never drive with the lights on a slight discharge is probably right for you. The Ford Service Manual describes how to do this by moving the 3rd brush, it is not hard, having the Ford S shaped wrench helps, but adjusting an old generator risks damage to the insulation on the brush holder, and overtightening the third brush holder nut will damage the insulation.

After 30 years of suffering with the Ford cutout, I have upgraded to the Fun Projects Voltage Regulator (VR) and highly recommend it. Now the generator is only charging when it needs to so some horse power is saved, the battery is never overcharged, and I no longer have to re-adjust the cutout to suit my type of driving. The down side of the VR is that I cant keep air in my right front tire and my drivers door is starting to sag and squeek, neither problem existed prior to adding the VR so it must be related. I had a previous thread about My T getting excessive dust and my seat springs receiving a local radio station because of the VR, but I am not going to cover that ground again. Just be advised about the tire and door befor you convert. Oh, and a VR will not cure a sick generator or fix incorrectly wired vehicles. Be sure you have the heavey gage wire from your generator to the ammeter and from the ammeter to the battery or your charge rates will be affected.

Jeff:

Sorry about the door/VR issues. I do have a fix for the front tire air issue. The problem is that your tires are rejecting modern air. Get some really old tires that still have old air in them and hook up a transfer hose of some sort and move the old air into your tires and the problem will be solved. Alas I don't have an easy solution worked out yet for the sagging door issue and it may in fact not be related to the VR at all but now sure at this point since your case seems to be certainly "cause and effect" pointing to the VR as the beginning item. Others mileage may vary.