Battery Going Dead...Wiring?

[8N_John]

Attached is a group of pics that shows the wiring in my 1952 8N (12V conversion). Every couple days, the battery will go dead. The battery has been replaced...that's not the problem. I fried the wiring a couple weeks ago when I pinched a wire in the oil filter cap....a lot of the wiring burned up. I replaced the wiring, diode, and ignition. I'm thinking the problem now could be:

-Bad ammeter (maybe it got fried?)
-Wiring is not correct
-Bad battery cables...I'm getting new ones now
-Diode problems

Does anyone know why this may be happening? Another note- when I hooked up the new battery, the (-) terminal sparked as I was putting the cable on it- someone mentioned that this could mean there is a current running through the system even though the ignition wasn't turned on?

 

[theonlybull]

could be a bad altenator, or it could be wired so the current to the feild coils aren't shut off with the key.

 

[Soundguy]

Get your voltmeter and check to see if you are leaving p1 powered. Other things may be that you have the ignition resistor grounded somewhere.. or even a short in your key switch, or a pinched / abraided wire. I doubt a leak across a dirty battery would do it in a couple days.. but for the heck of it.. clean it up.

If it sparks when you hook up the cables.. something is drawing power. Disconnect one wire at a time till you can hook it up with no sparks.

Soundguy

 

[jinman]

</font><font color="blue" class="small">( Get your voltmeter and check to see if you are leaving p1 powered. Other things may be that you have the ignition resistor grounded somewhere.. or even a short in your key switch, or a pinched / abraided wire. I doubt a leak across a dirty battery would do it in a couple days.. but for the heck of it.. clean it up.

If it sparks when you hook up the cables.. something is drawing power. Disconnect one wire at a time till you can hook it up with no sparks.

Soundguy )</font>

Good points, Chris. I've even seen one diagram where a lamp is installed in series with P1 so you can tell when the ignition is on. I also agree with you about the bleed across a dirty battery. That would take one or two weeks to pull a fully charged battery down. It most certainly would not drain the battery overnight.

I guess this is a silly question, but I wonder if John has had the tractor running since he replaced the battery and did a rewire. If you turn off the ignition and the tractor keeps running, there is a miswire. The battery may be bleeding off thru closed contact points and the ballast resistor or internal resistor in the coil. If the ballast resistor or coil is warm/hot, that could be the source of the drainage. /forums/images/graemlins/confused.gif

 

[stevenf]

8n john
I am an absolute Newbie to Tractors Dad owned an old ford on our last ranch and my Kubota M9000 is not delivered yet and I don't really know how familiar you are to electrical systems So Please don't find this insulting but Dad's old Ford was a +Positive ground Tractor you didn't perhaps wire to the the wrong side as this would not only creat a spark but as soon as you lit it off it would do bad things to the rest of the electical system as well.
PLEASE Understand I know nothing about an 8N but it might be worth checking if your not already laughing at me.

 

[Soundguy]

He's added an alternator.. so that pretty much guarantees a neg grnd system ( yes.. there are both 6v, and positive ground.. and completely isolated ground alternators out there.. etc. ). He's also most likely using a delco 10si or variant.. etc.

Like Jinman said.. could be a powered field. Not sure if his diode inline with p1 could be shorted? ( this would keep the tractor running .. and drain the battery when tractor off, depending on wireing.. )

A lamp could be inserted inline with the battery cable.. low wattage would be good.. this will then light if current is flowing.. he could unhook a wire at a time till the current flow is isolated..

Soundguy

 

[8N_John]

Thanks for the info, but I'm not exactly sure what P1 refers to and exactly how to check using a voltmeter. I'm sure it's not hard to use once I figure it out. My first step is to buy one tomorrow.

 

[RHP]

I'm afraid I can't offer any solutions for you John, but there is also another board where you may find some if the wealth of knowledge here can't help. Here is a link to a board I used to visit a lot while I had my 8n (for 18 years). Great advice from 8n folks.

8n's are great machines, but it was truly a step up in luxury when I got my TC 35D that was 50 years newer! /forums/images/graemlins/cool.gif

Good luck, there aren't any problems with 8n's that can't be wupped. /forums/images/graemlins/wink.gif

 

[Soundguy]

(By the way.. I'm one of those guys from ytmag...)

On a gm 10-s1 alternator ( and other variants).. you can basically get a 3 wire alternator, or a 1 wire alternator, depending on the internal voltage regulator that was installed in it.

P1 and P2 are the two spade terminals on the side of the alternator case. On the 1 wire jobs, you only connect the big battery output stud to your battery.. the alternator will self excite when it reaches a high enough rpm. ( some need up to 1800 rpm, though pulley size makes a huge difference).. once excited, it will charge down even at a low rpm like 600.

On the 3 wire jobs.. you use p1 and p2. P2 is the remote voltage sense, and is basically an annoiance on a tractor. What p2 is used for is to make up for charge voltage dropped between the alternator output, and the battery terminal. The vr looks at the potential at the alternator output and compairs it to the potential on p2 which is hooked up at the battery.. it then can correct for a voltage drop. On a tractor with a very basic and rudimentary electrical system ( ford N series! ) the p2 is jusst looped right down to the big charge stud.
P1 is the external excite line that controls field coil excitation. It needs a momentary jolt of power to power the field up. once powered up, the field will sustain itself, however, the p1 line is then energized at that point, and if wired up wrong can do one of 2 things.. either make it difficult/impossible to turn your tractor off if you use the standard 2 position ignition switch.. or it can let the battery discharge thru p1 while the tractor is off, as it is just setting there powering the field.

For that reason, there are a few ways to isolate p1.. a 3 position key switch that has an ACCY tab works.. or the gm idiot light' scheme works.. though there is some quiescent current draw.. but if you run the tractor once a week it won't be noticed. Another option is a diode installed in the line to p1.. If correctly installed.. it allows power to excite the firld.. but not bleed back tot he tractor. lastly, A momentary switch can be used between the battery and p1.. hitting it energizes the field..yet isolates it as soon as the button lets up.

When using the vom.. just measure between the part and ground..

Soundguy

 

[dieseldoc]

john,the first thing i would do is buy a cheap 12v test light(around 10 bucks at any auto parts store)then disconnect the ground cable from the battery,hook the wire lead on the test light to the ground post on the battery then touch the probe end to the ground cable,if the test light lights up you have a current draw on the system,while the test light is still connected start disconnecting powered systems one at a time until the light goes out,the first thing i would disconnect is the power cable on the alternator,good luck