LA ammeter shows no charge.

46chief

Member
I have restored a 1942 LA and is complete except the ammeter will not show charge. It will show discharge when I turn the light on but will not show charge. I have the downloaded diagram for the wireing and have wired it exactly. The gen is rebuilt and charges 7.5 v0lts but not on the ammeter. I have checked all wires and terminals several times and the shop that rebuilt the gen came and tried to help me to no avail. This is a three brush wired with a light switch. We have bypassed the switch and tried it that way and I even replaced the ammeter. Still nothing. HELP if you have any suggestions.
 
The diagram you are using may have the charging current bypassing the ammeter. So in order to show the charging current you will have miswire it according to the diagram and get over that part.

Some people like it the way you have it and others would really like to see the charging current. So diagrams do exist in both flavors of preference. I can't help without wire color guide and your diagram or links/directions to same, but it's as simple as moving one wire from one side of the ammeter to the other. And it would be the charging wire from the generator. I sure hope that's enough to have you try it like that and it works. Otherwise diagram and wire colors please.
 
My diagram was from OHIO.VOYAGER.NET and I have already tried switching the wires on the ammeter. This diagram showed all black wires except from the field on the gen to the resistor on the switch and it is white.
 
I just got my computer back out of the repair shop today and I don't have the printer scanner re-installed yet
 
Hi the heaver ga (no 8 on my diagram) wire from the cut-out connects to the - post of the ammeter then a heaver ga wire connect to the + post of the ammeter and to the starter switch post the lighter ga wire connects the light switch to the generator "F" field post. the light switch has to be grounded to the tractor frame/hood
If the battery is fully charged abd the light switch is in the low charge position you may not see much needle deflection on the ammeter but if it is switch to high charge the needle will move up noticeably if you suppect the switch isn't working you can try a jumper from the generator "F" field post to the engine this will full field the generator same as pulling the light switch out to high charge
GB in MN
 
Not enough good help, if you meant my.ohio.voyager.net instead you did not include the person's name from where the diagram originates which means I can't find the diagram with those directions.

Too bad about the lack of color to help us with, but it is what it is. How many wires do you have at the ammeter on each side? The wire that needs moved currently is at the ammeter post that shares the connection to the starter post and from there on to the battery. A better way to state that is one side of the ammeter should only have one single wire on it and it is going to the starter post. Move all others to the other ammeter post.
 
If indeed the gennys output is getting to and charging the battery when running at fast RPM the battery voltage should rise to at least 6.5 and more volts IS IT ????????????

If not insure its wired so the gennys output (via ARM on Genny to cutout relays GEN/ARM terminal then its BAT terminal then to ammeters LOAD side) is flowing thru the series ammeter then to the battery often where the big cable attaches to the starter switch or solenoid.

To register charging the ammeters SUPPLY terminal wires to the battery often at the big cable on starter while its other LOAD terminal wires to the BAT terminal on a cutout relay. If its not wired that way the ammeter doesn't see charging current.

You can run my Charging Troubleshooting Procedure to determine cause of non charging but when running if you dead ground the gennys FLD post that by passes the low high charge light switch function and should make it charge to the max.

Insure ammeter is in the series circuit from BAT on cutout relay to ammeters LOAD side then ammeters SUPPLY side which gets to the battery

If battery voltage isn't rising and its wired right try dead grounding the gennys FLD post.

Did you POLARIZE the genny prior to start up?? Id try that to be sure a genny shop may have the genny polarized for NEG ground while your tractor was originally POS ground..........

Run my Troubleshooting Procedure and post back findings or questions

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=jd&th=458743

John T
John Ts Charging Troubleshooting
 
I always run a eight volt battery on six volt systems. Have done that for years. Today I am going to use a jumper and make sure the switch is grounded because of the new paint it might not be.
 
I ran a jumper wire this morning to ground the switch to the frame with no change. It is wired like this. The No. 2 & 3 wire goes to the lights and switch. No. 4 wire goes from switch to ammeter with fuse. There is no No. 5. No. 6 is the battery ground strap. No.7 is from gen field to resistor on switch. No.8 is from cut out to ammeter and hooks to the same terminal as No.4 . No. 9 is from gen to cut out on other side. No. 10 is from starter to ammeter on its other side and that is exactly how I have it wired. It will show discharge with the lights on running or not but that ammeter will not show a charge and that is the second ammeter. I even went so far as to take the gen off and back to the rebuild shop. It charged great and by moving the third brush it was capable of putting just over 8 volts.
 
Well its time to step back and think about this in your 1st post you said the generator is putting out 7.5 volts and in the last post you said you have a 8 volt battery here's your prob;em 7.5 volts can not charge a fully charged 8 volt battery it needs 8.5 or 9 volts to over come the 8 volt battery.
GB in MN
 
I agree, you need to crank regulator up to 9.5 volts to charge 8 volt battery, it will never show a charge at 7.5 volts.
 
I know what you are saying and I thought the same way so I borrowed a six volt battery from a friend and tried that but there was no change.
 
I have ran a eight volt battery on a 9n ford for years with no problem. It i9s not enough over to burn anything but really helps them start and I have never had to replace or rebuild the gen or starter.
 

<image src="http://forums.yesterdaystractors.com/photos/mvphoto5276.jpg"/>

Wiring diagram is actually from <a href="http://vintagetractors.com/" target="_blank">Vintage Tractors</a> about midway down the page. The power of google is pretty awesome. There are part numbers there which I have loped off in the above depiction of their page for maximum clarity.

Have you tried to apply a jumper across your cutout relay 8 to 9? If the cutout relay is defective it will never show a charge. I suspect the cutout relay cuts out real good but does nothing else very well. Might be a bad ground at the relay due to fresh paint? And generator frames also need a good ground too.
 
OKAY only now we know you're trying to charge an 8 volt battery and 7.5 volts is never gonna get the job done, you need at least 9 volts to charge a battery that's 4 x 2.1 = 8.4 volts. You don't have a voltage regulator you can adjust and you may or may not have an adjustable third brush genny, but if you do set the third adjustable brush as close as permitted to the fixed non grounded brush beside it and see what happens

John T
 
John I have already tried using a six volt that I borrowed from a friend because I was thinking possible the same thing but it didn't change a thing.
 
You are so full of it.

You post on here with a problem, give partial information, then a solution is found, then argue about the reasoning.

Keep on believing 7.5 volts will charge a 8V battery.
 
David, John posted the very diagram that I used and one of my post tells exactly how I wired it and it matches the diagram. My printer scanner is not operative right now because I just got my computer from the repair shop yesterday and have spent all my time on this tractor and have not got the scanner re-installed yet.
 
Thanks anyway guys but I have to shut her down for a while and get to town. I have tried everything and can't imagine what it can be but I guess I will figure it out sooner or later. It's starting to get cold so I am going nowhere with the tractor anyway. Thanks
 
Chief,

Again, sorry about my vent.

Did you measure the voltage at the battery off, then running at fast idle?
 

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