8N battery not charging after engine warms up

I have a 1949 8N running a 6-volt system with a front mount distributor. The tractor has started without problem and has run well for the year that I’ve owned it. Earlier this month I was using the tractor with a shredder when it quit running in the pasture and wouldn’t start. I checked fuel flow, no problem. I checked the plugs, no spark. I towed it to the barn.

In the barn, I dissembled the electrical components and discovered that the battery was connected NEGATIVE to ground and the resistor block had been bypassed. Some of the wiring was frayed, the plug wires were brittle and the distributor cap alignment pin was sheared off.

I completely rewired the tractor and installed new points, condenser, rotor, distributor cap, plugs and plug wires. I installed a new OEM resistor block and replaced the old voltage regulator with a new after market one and polarized it for POSITIVE ground.

The first time I tried to start the tractor it turned over slowly, clicked and then nothing. The battery read a charge of 6.28 volts. I jumped the battery and it started right up but the dash mounted amp meter occulted wildly between + and – and after a couple of minutes settled at 0. I put a meter on the battery and it read 7.80 volts indicating that it was getting a charge. After the engine warmed up the voltage across the battery dropped to 5.60 volts, and less, with the amp meter still sitting at 0. The amp meter does read a negative when the key is first turned on.

Bottom line; I CAN NOT start the tractor without jumping the battery. After that it runs fine but when the engine warms up the battery quits being charged and voltage across the battery reads anywhere from 5.60 volts to 4.50 volts.

What would cause this problem?

po boy........ya re-wired yer tractor and now it won't charge yer 6-volt battery. Do you see enny relationship there??? The 8N uses a 3-terminal squarecan voltage regulator under the oil pressure gauge. There are 2 side-by-side terminal labeled ARM and BATT. Wanna guess Which one connects to the genny? Yer description of wildly swinging ammeter and discharged battery implies ya wired it WRONG. There are 3-wires connected to the genny and corresponding terminals on the squarecan voltage regulator. FLD (field) connects to the insulated terminal on side of genny. There is a 2nd terminal on side of genny which is GND (ground), it connects to enny mounting screw on the squarecan voltage regulator. Once you've correctly re-wired yer squarecan voltage regulator, you need to "polarize" the voltage regulator and genny to yer 6-volt battery polarity. Just "arc-spark" the side-by-side ARM and BATT terminals together, engine OFF. Simple, eh? Me? I use a broad blade stubby screwdriver, but you kenn use bailin' warr iff'n you want. As an aside, there are subtle advantages to positive ground, but surprizingly enuff, yer genny will put out negative volts iff'n polarized that way. (which depends upon how the battery is connected and regulator polarized) Cupple of other notes about yer squarecan voltage regulator. They originally came mounted on rubber baby buggy insulators 'cuz there wasn't alotta confidence in the mechanical ruggedness of the voltage regulator bouncin' out across the ground. Modern replacement squarecan voltage regulator do NOT need the rubber baby buggy insulators. So ditch'em, iff'n you gott'em and the extra mounting plate.

Cupple of other notes: The ammeter is a 20% accurate device, it really justs indicates whether yer genny is chargin' or not. Generally reads about +3 amps charge during normal operation. The weird 4-nipple squarecan ignition coil needs the MANDATORY infamous ballast resistor. Without it yer squarecan coil will MELT and loose all its sparkies. 3rd note: the points (0.015") are designed to be replaced on the kitchen table. Just un-snapple yer capple and remove the 2-bolts and walk. The 2-bolt scheme means you can NOT re-install outta time. ALWAYS remember to "polish" the INVISIBLE corrosion from between the points. Me? I stick the corner of $1-bill between the points and pull. You kenn use heavy BROWN paper grocery sack or cardboard from paper match book.

Changin' sparkies is always a good thing to do, recommend AutoLite 437's gapped 0.025". Don't throw yer FLOODED sparkies away, just clean'n'dry 'em, one-atta-time in HOT runnin' engine, and save'em fer the NEXT time. (and there will be a next time) Fer ears used to the whirrrr of their BelchFire-V8, the slow rumpa-rumpa of yer 6-volt starter is disconcerting. Surprizingly enuff, yer starter motor don't care positive (+) or negative (-) ground, it will always turn the correct direction. One final note on starter motor; it works quite well with 12-volts applied to the copper "L" bracket fer faster starting of FLOODED engine. It should be intuitively obvious, do NOT jump 12-volts to yer 6-volt battery. .........Dell, yer self-appointed sparkie-meister

work yet?

Rechecked all wiring this morning and wiring is correct. Plugs gapped to 0.025” and points to 0.015”. Timing set with meter so continuity collapses just as breaker starts to open.

Charged the battery overnight to 6.25 volts. When I press starter, the engine attempts to turn over then NOTHING, not even a clicking. Tractor jump starts with the aid of a battery charger and runs smooth through the RPM range. Again, battery will charge for about 3 to 4 minutes then the charge across the battery terminals will begin to drop into the mid to low 5 volt range.

This morning while I cranked the engine I heard a clicking sound form the voltage regulator. Could be the new VR is defective. I’ll replace it with the one I took out and see if that makes a difference. I plan to take the battery to the local parts store and have it tested.

At this point it’s all trial and error.

po boy........you complain......battery will charge for about 3 to 4 minutes then the charge across the battery terminals will begin to drop into the mid to low 5 volt range......guess what? yer genny ain't re-chargin' the drain of the starter motor. It should take about 15-mins to replace the starter motor drain. When the battery volts drops to 5-volt range, guess what?? DEAD BATTERY and no start. As fer the clickin' sound, thats semi-normal. Relays do make noise. You never hear them in yer BelchFire-V8 'cuz the hood is closed. Remember, unlike 12-volt alternators, 6-volt gennys don't charge at idle. Yer hand throttle hassta bee about 1/3 up. As advised, some of the new square can voltage regulators kenn be BAD rite outta the box. New or used, always good plan to re-polarize yer square can regulator. You kenn "re-polarized" as many times as it takes to feel warm'n'fuzzy ...er... charged.......electrical Dell