H Charging Problem

I took my 41H out for a hayride last night. The tractor seemed off. I noticed a large discharge on the ammeter with the lights on. A few minutes ago I checked the voltage with the engine off (Its a 6V positive ground system). The reading was 4V. I fired up the tractor, went to intermediate power and took a reading of 12V.

Does this seem a bit too high?

Art

Yes that is excessive. 7.2 is normal. Do you have a digital meter, or one with a needle? A digital gauge, unless it is pretty expensive, will take random samples and may not read a steady average voltage on these old systems. 4 volts is way low at the battery, I would not expect it to start. If the H has a regulator, and a 3 position light switch, the regulator may be failing. The following is from John T a GURU contributor:

Its been a while since I posted my entire Troubleshooting Procedure for non charging, so here it is.
TROUBLESHOOTING CHARGING SYSTEMS

ARE YOU SURE THE AMMETER IS WIRED CORRECT AND WORKS????? If you turn the lights or ignition on (if coil ignition not a mag) when she?s not running, the ammeter should swing over to the - discharge direction, does yours??? Are BOTH the ammeter terminals reading hot battery voltage?? They MUST !!!!!!! There?s but one wire on the ammeters Supply (from battery/starter) terminal while its other Load terminal wires to the BAT terminal on a Cutout relay or VR PLUS wires to feed loads like lights or ignition, unless where a 4 terminal VR is used where lights n ignition are fed from the LOAD terminal on the VR.

To Polarize the Generator, first temporarily dead ground the Gens Field post to case/frame, then momentarily flash jump a wire from the Cutout Relay or VR"s "BAT" terminal over to its GEN (or ARM) terminal and you ought to get a small spark. Same things accomplished by momentarily flash jumping a hot wire (BAT terminal on Cutout Relay or VR or starter post etc) direct to the Gens ARM post to get the spark.

TROUBLESHOOTING A CHARGING PROBLEM IN CLASS A DELCO TYPE SYSTEMS

1) For a good working Gen to get to and charge the battery, it has to have a path usually from the Gens ARM post,,,,,,,,,,to and through the Cutout Relay (between its GEN and BAT terminals, regardless if on a VR or Relay),,,,,,,,,up to the Load (NOT to battery) side of the Ammeter,,,,,,,,,to and through the Ammeter,,,,,,,,,,from BAT side of Ammeter to ungrounded battery terminal, often via the starter lug post. Is yours wired that way or equivalent ??? The ammeter should read hot battery voltage on BOTH terminals, does yours??? Even if an ammeter were stuck (but still continuous) as RPM increases the battery voltage should rise from 12.6 to near 14 volts and/or the lights glow brighter (half that on 6 volt systems). Have you tried that in case the ammeter isn?t working right?????

2) If the above is so, the BAT terminal on the VR or Cutout Relay MUST ALWAYS READ HOT BATTERY VOLTAGE. Does yours??? If not, the Gen cant get to and charge the battery.

3) The Gen to VR (if it has one) wiring is as follows:

BAT on VR to ammeters load (NOT battery) side

ARM (or GEN) on VR to Gens Armature post.

FLD on VR to Gens Field post.

(L) Load (if you have a 4 wire VR) up to BAT supply input terminal on switch to feed loads like lights and ignition.

WIRING ON CUTOUT RELAYS: They wire BAT side to ammeters Load terminal,,,,,,GEN side to gens Armature post. On cutout relay systems, the Gens Field post is wired to the light switch where it gets a dead ground for high charge or a resistive ground for low charge. Therefore, there must be a good connection from the Gens Field post up to the switch PLUS the switch is good and it?s well grounded !!!!!!!!

4. THE GEN AND VR OR CUTOUT RELAY MUST BE WELL GROUNDED AND THE BELT GOOD N TIGHT. If any doubt, run a ground wire from the grounded battery post or clean solid frame member direct to the Gen and see what happens????????????????????????????

NOW, if the Gen and VR are grounded,,,,,all is wired correct,,,,,,,,BAT terminal on VR or Cutout Relay is HOT,,,,,,,,Belt is tight,,,,,,,,,Ammeter is good n continuous n works but she wont charge, have you had the batteries tested lately????? Is there electrolyte above all the plates and no cells have a gray or milky appearance?????? A bad battery may not accept a charge you know!!!!!!!! If the battery checks okay, proceed below to see if its a Gen or VR problem (AFTER you have insured the wiring per the above)

TO DETERMINE IF ITS A GEN OR VR OR CUTOUT RELAY PROBLEM

5. a) VOLTAGE REGULATOR SYSTEM: With the tractor running, temporarily ground the Gens Field post to case. If she charges then but NOT otherwise, the VR may be bad, or a wires missing from VR"s Field post to the Field terminal on the VR, or the VR isn?t well grounded.

b) IF IT?S A CUTOUT RELAY SYSTEM and she charges only if you dead ground the Field but NOT otherwise, its either a bad switch or the switch isn?t well grounded or else the wires bad or open from the Gens Field post up to the switch. INSURE THAT GOOD SWITCH GROUND AND WIRING

6. If she still don?t charge, leave the Field grounded and jump a wire across from the VR or Cutout Relays BAT terminal over to its GEN terminal (jump by passes the cutout relay) and see if she charges. If then but not otherwise, a VR"s cutout relay isn?t working correct (maybe points burned/carboned) or a Cutout Relays NOT working or not wired correct.

7. With the 2 steps above, you have basically by passed the VR or Cutout relays functions, so if she still don?t charge, you"re left with a bad battery or wiring or the Gen itself.

8. MOTOR TEST. You can Motor test the Gen. If its grounded and you remove the belt and apply hot battery voltage direct to its ARM Post and have the Field Post dead grounded to frame, it should motor n run well (Armature n Brushes and Commutator likely okay). Then, if you next remove the Fields ground and it speeds up some, the Fields probably good. If it passes both those tests, it should charge, and if not, it may be a wiring or battery or grounding problem. The hot battery voltage may be taken off the VR"s BAT terminal or the starter post or the battery itself for this test.

9. Typical Gen problems may be the brushes are worn down or the hold down spring assemblies are stuck/corroded/dirty and arent pushing the brushes tight down against the commutator. Check those things out. Worse may be bad fields or armature etc. Air and WD 40 etc can clean and free them, the hold downs must be free n snap and hold the brushes DOWN TIGHT and they cant be worn down too low.

SUMMARY: Check the wiring,,,,,the grounds,,,,,,insure BAT on VR or Relay is hot,,,,,,,check battery (maybe load tested and Specific Gravity checked),,,,,,,,,good tight belt,,,,,,,insure ammeter is continuous (BOTH sides HOT),,,,,,see if battery voltage rises above 12.6 (half that for 6 volt system) and/or light glow brighter,,,,,,,,,do the Field and cutout relay VR by pass checks,,,,,,,,insure the Gens brushes arent worn down and the hold down springs are free n clean and push the brushes down tight,,,,,,,,,,,check the connections,,,,,,,,,try the Gen Motor Test to see if its good.

You may just have a bad battery or bad ground or connection if the Gen and VR or relay are okay. Good Luck n God Bless, let us all know.

John T Nordhoff in Indiana, retired electrical engineer who usually lurks over on the Mother Deere pages instead of over here on the "dark side" lol

I used a needle ammeter, grounded the generator (but not with the engine running), and generally did most of what John suggests. I'll go back out to the barn in a few days and run through the rest of his troubleshooting routine

Check the fluid level in the battery. A dry battery will blow up when it is over charged at a high rate.
SDE

"The reading was 4V. I fired up the tractor, went to intermediate power and took a reading of 12V. "

WOW was that the battery voltage???????? A battery would have to be in a terrible state of discharge and/or there's a huge discharge to get down to 4 volts???????????

LIKEWISE, it would take a bad battery and/or voltage regulator problem PLUS a darn good generator to raise a 6 volt battery up to 12 volts.

If that's the voltage at the genny and NOT the battery its more believeable.

You can have the batterys Specific Gravity and voltage and a load test for free at most shops ID DO THAT FIRST.

Next I would insure BOTH the battery and Voltage Regulator (or cutout relay and light switch if its a cutout system) are well grounded.

After that Professor Jim was kind enough to post my Troubleshooting Procedure. Check wiring and grounds and especially have the battery tested as described above, BECAUSE THOSE VOLTAGE READINGS ON THE BATTERY DONT MAKE SENSE

John T

I am really questioning your readings, doubt a 4V battery would even crank the engine over.

I can see you are very knowledgeable about this system. I have a related question maybe I can horn in with? I have a early 1940 "H" with the "Mag" ignition and the "cutout & 3-position light switch" which seems to work fine. We use a 12 volt battery to start the tractor and I noticed the generator shows a positive charge sometimes (maybe all the time-The belt is loose) Could the 6 volt generator with the cutout be adjusted to maintain charging the 12 volt battery??

I have a new belt to put on but don't want to ruin the generator by expecting it to do something it can't do. I do know the lights work fine on the lower light switch setting and most likely will blow on the high setting. Just wondering what I can expect to pull out of that generator??Cleddy

EXACTLY, WE AGREE a battery that actually measured 4 volts is SHOT and no way could crank an engine. Likewise, it takes one heck of an outstanding generator to take a 6 volt battery up to 12 volts YEAH RIGHT. He must be reading at the Generator and its NOT connected up to the battery via a closed cutout relay.

John T

I would agree on the high generator output indicating it is not connected to load, that would also explain discharge while running.

Open cutout relay?

I have a Farmall B with a mag & can use a 6 or 12 volt battery without changing anything. No lights on it. It has a diode instead of a cut out.

Just so everyone is clear:

yes, the ammeter is really reading 4V static (I'm an aeronautical engineer, so although electricity is not my forte, I do know how to set up and read a gauge)

yes, the gauge is also reading 12V at intermediate throttle

yes, the engine cranks easily (compression readings last night [warmed up engine] #1 - 78 psi, #2 - 100 psi, #3 - 92 psi, #4 - 90 psi)

The readings were taken with the probes touching the battery cables, not the battery posts

First a couple of observations:

Ammeters read amps, voltmeters read volts, no way an ammeter can read 4 volts
I do not see what compression has to do with this, but your #1 is pretty low.

So,

Can we start over?

I will drop the sarcasm.

Measure the voltage across the battery:

When off
When cranking
When running

A 6V battery should be above 6V static, then drop a little below 6V at cranking, then about 7-8 volts charging.

Great idea!

I agree with your assessment about the relative voltage ranges. I will hopefully be able to check the voltages as you suggest tomorrow

You are also correct about the ammeter comment - I am using a multi-meter set to read voltage, with the scale set to 25V max

The compression readings were added to the conversation based on the voltage being too low to crank. The compression is low on one cylinder - I need to make a decision about rebuilding the engine

4V is still too low to crank the engine over, no matter what the compression is. At 5V the battery is depleted of all usable energy.

If you hit the starter and the engine cranked over your battery is much healthier than 4V.

You said you were touching the battery cables, not the posts. Most likely the cable ends are corroded and you are not getting a good contact.

Without malice!!! An Amp meter reads current flow in amps. A volt meter reads electron "pressure" in Volts. An H has a amp gauge as standard equipment in the electrical panel. An intermittent connection at the battery post to terminal can act like your readings. the current of starting can temporarily weld a small segment of the post to the terminal letting it start. then when running it can fail and become a high resistance letting the chatrging system "loose on the world". Clean things up and check it again. Your performance issue may be un related, or it could be that the 12v you saw at the battery was overheating the coil when on your ride. Jim

John/David,

Here's where things stand:

took the generator and voltage regulator into the old-time garage down the street. They told me:

a) the generator was missing an internal ground and
b) as shown in the pics, I had the 'F' terminal on the regulator coupled to the terminal on the generator next to the F terminal
c) they hooked up the A terminal on the underside of the VR to the post (I couldn't find the A stamp on the generator casing - the F was clear as day)
d) they made a jumper for me (I misplaced the attaching screw) to go from the F on the generator to the F on the VR

So, before I fire the tractor up, is the setup shown here correct? The L and Batt wires go the light box and battery as I would expect. The wire from the loom that is sharing the F terminal with the jumper appears to emerge up near the starter switch.

Art