Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  

Gurus needed - ammeter showing discharge

Recommended Posts


So I was cutting the grass yesterday and noticed the ammeter reading about -10amps (discharging). That was at engine speed used for mowing.

Disengaged the PTO and dropped the throttle back to idle. Ammeter climbs almost to 0.

Did more testing, and here's what it's doing:

1. Shows about -10amps running 3/4 or more throttle.

2. Shows almost 0 at idle

3. At about 3/4 throttle, if I turn on the front and rear lights, the ammeter climbs back to about 0.

4. If I turn the lights off again, the ammeter goes down to about -10amps.

I pulled the battery and cleaned all the terminals as well as those on the ammeter.

Started back up, same symptoms. Grabbed the voltmeter, at idle it's about 12.2volts, at 3/4 throttle it's about 13.5 volts.

I'm stumped. If the battery were really discharging, I don't see how turning the lights on would decrease that, if anything it should make it a lot worse.

I wonder if it's ignition-related instead of charging system related? Would a bad coil do this (something is making the discharge worse as engine speed increases).

Thanks in advance for your help all.

Share this post

Link to post
Share on other sites

No, the wires are not switched. This just became an issue Friday when mowing, and I hadn't taken the wires off the ammeter since the previous mowing day when the problem did not exist!

Share this post

Link to post
Share on other sites

My experience on cars says bad voltage regulator but the last one I bought was 120.00 plus so I'd do as much as I could before blowing your load on that little thing!

Share this post

Link to post
Share on other sites

Turn on the key and then the lights (motor not running) and see which way the ammeter needle moves. If it moves to the right (+) the flow through the ammeter is backwards, or the ammeter is messed up internally.

You didn't accidentally drive your tractor through a reverse polarity vortex sm00

Share this post

Link to post
Share on other sites

Scott,Your voltmeter check says that the generator is charging properly. I would either reverse the two wires on the ammeter or just remove the ammeter and hook the wires together. I do not have ammeters or voltmeters on any of my tractors. That way there is no gauge to distract me when mowing. I work on the charging system only when the battery will not stay charged.Here is a picture of the dash on my 713S:



Share this post

Link to post
Share on other sites
quote:Originally posted by BLT

Belt drive generator?

id="quote">No, it's a Kohler K341. I am going to go over all the wiring and look for a short. Still can't understand why it would discharge more at HIGHER revs though. I know for absolute that the ammeter wires are NOT reversed because I removed and replaced them one at a time to clean them.I have a new and known good rectifier/regulator and will swap that.I am leaning to a short though somewhere... I remember that on the last mow it almost cut out a couple of times when, and only when, I was moving the hydro control lever with the tractor on a downhill spot. Maybe there is something grounding out.

Share this post

Link to post
Share on other sites

I drove A-C's for years, WD, WD45, D17, D19, 190xt, ammeters all. Never understood the ammeter, never consulted it. As long as it starts and the battery is at 12 volts, that's all that matters.... I guess.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Who's Online (See full list)

    • ParkerBarker
    • RustyZipper
    • Talntedmrgreen
  • Today's Birthdays

    1. Carchief
      (57 years old)
    2. Geoff
      (56 years old)
    3. mohrds
      (51 years old)
  • Recent Status Updates

    • SonOfCreepfeed


      Thinkin' about this old girl.

      · 2 replies
    • Dean McFadden

      Dean McFadden

      Good morning peeps! I’m always searching for helpful information with my AC collection. Hope to find out new information and pass on my own experience in restoration. Here are some pics of my babies. I’m still looking for front rims for the 410 so yesterday I put the 310 wheels on took it for a drive. Working pretty good but still needs some carb work. Gotta get the 310 running next. Have a great day!😁

      · 1 reply
  • Adverts