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Dead Battery

Discussion in 'Mechanic and Repair' started by newblade, Dec 18, 2005.

  1. newblade

    newblade LawnSite Member
    Posts: 162

    I have an Exmark and the mower runs great and charges the battery I guess as long as the blades aren't on. It has -12.36 volts when the blades are on............any ideas? It keeps a positive number until you turn them on.

    CLARK LAWN LawnSite Silver Member
    Posts: 2,526

    short in the wire to the clutch or in the clutch itself
  3. DEEJ

    DEEJ LawnSite Member
    Posts: 230

    12.36 volts is not near high enough to charge the battery. A fully charged lead acid battery will read 12.6 volts. When charging, it should read about 13.5V to 14.5V (with a good battery in the circuit). You are drawing more current than the charging circuit can handle - so one of three things is wrong:

    1. The load from the clutch circuit is higher than it should be due to a bad part or a short. In general though, the electric clutches are power hungry beasts, so don't be too quick to replace the clutch.

    2. The charging circuit is weak and can't handle the additional load of the clutch circuit.

    3. The last possibility is a weak battery that doesn't present the right resistance or charge capacity to the charging circuit.

    The negative number you mentioned does not mean -12.36V is at the battery. The negative is a red herring. Battery voltage does not reverse. If so -12.36 volts is actually 25 volts lower than where you started at +12.6V - not possible. The battery is simply giving out more than it is taking in from the charging circuit. It can only do this for so long before it dies.

    If I had to guess from what you have told us, I would say the charging circuit needs some repairs, or possibly a bad battery.

    You could test the clutch circuit by hooking it to a known good power source, like a charged car battery, and measure the current draw. Compare this number against the clutch manufacturer's specs. If it is in the same ballpark, the clutch is not your problem.

  4. viper00085

    viper00085 LawnSite Member
    from NC/VA
    Posts: 237

    you need to check your clutch resistance. hook up the multi meter leads to the 2 wires coming out of the clutch and set the scale to ohms. it should be between 2.5-3.8 resistance. if the resistance is to low, is will create a major draw on the charging system. but as was said up above, you need to have 13.8-14.4 coming out of the purple wire on your kohler regulator/rectifier going to the units wire harness to properly charge the system up. Good Luck
  5. fixer67

    fixer67 LawnSite Silver Member
    Posts: 2,100

    The way you have that writen it reads 12.36 volts BELOW zero. From what you have said here I say first thing is to get the meter leads hooked up right.

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