Mower not charging the battery?

Discussion in 'Mechanic and Repair' started by tsh1773, Feb 8, 2008.

  1. tsh1773

    tsh1773 LawnSite Senior Member
    Messages: 319

    I have a 2004 Scag with a 19HP Kawasaki. First of all, how can I tell if the alternator is working? If it's not where it is found on the engine? The original battery died about a month ago. I assumed it was due to the cold weather. I purchased a new one. It worked fine for about 3 weeks. The it had to jumped off again and again. I took the new battery, had it checked, and it tested good. They replaced it anyway. I haven't tried the new battery yet, as I just got it replaced late last night. Any ideas?
  2. lucforce

    lucforce LawnSite Member
    Messages: 223

    You do not have an alternator. You have a stator, a few rotating magnets, and a regulation device.

    First, you need to purchase a voltmeter.
  3. mason dude

    mason dude LawnSite Member
    Messages: 74

    I had this same problem on a new hustler with a 25kaw, bought new battery, 3 weeks later,I'm jumpin it again. the dealer told me I wasnt running the engine at a high enough rpm to recharge the battery, it was during the drought last year and to save fuel and noise on thin grass I was running about 3/4 throttle, I still pull back on the throttle occasionally but not all day, the test we ran at the dealer was clamp meter to the battery and watch it as the engine is idling and at half and full throttle, even at 80% throttle the juice coming off the engine wasnt enough to recharge the battery, you may want to run this test on your machine, I am unsure of the specs but it is something like it needs 16 volts to recharge a 12 volt battery and at 75-80% throttle was only putting out 10.5 or 11 ,,, this situation will affect your machine more if you have a lot of small lawns,which would mean a lot of starts/discharging.. someone suggested I put a battery maintainer on the mower and plug it in every other night if I just cant stand to run full throttle all the time, I may do just that this year if we have another slow growth period as I hate to run wide open in small areas, sorry this went long

    SILVERSTREAK INC LawnSite Senior Member
    Messages: 295

    well there should be a fuse for the charging circuit, check that first

    coming off the wiring harness on the motor, with it running there should be one wire putting out like 36 volts or is it just 12? ground your voltmeter and test each prong it should be the red one, these motors are externally regulated i believe (meaning your volt regulator which stops charging when the batt is full is somewhere under the control panel or mounted on the chassis the regulator takes the 36 volts and turns it so about 14 for charging, then shuts off power to the batt when it reads the batt is full) if youre getting no power then the stator is bad

    but the fuses go often so check that out first
  5. topsites

    topsites LawnSite Fanatic
    Messages: 21,653

    Yeah we had one like that, after much tribulation that particular mower simply went on the slow trickle charger every single night.

    Not the best solution, but something to keep in mind just in case.

    SILVERSTREAK INC LawnSite Senior Member
    Messages: 295

    the wiring harness adapter going to the mower might be different than my exmark so poke around and see what you can find

    looks like it does have a regulator on the side of the motor, it has the two white wires coming to it, i guess you could check both sides there and see if youre getting any power on either side with the motor running. id disconnect the wiring harness from the motor till youre finished the test to make sure youre getting a good reading

    if you have power on one side and not the other you can figure it out, it would either be the stator or your regulator, if there is power to both sides coming out then it must be a loose or blown connection somewhere on the mower

    if you figure it out to be one of these probs i have that 19hp kawi fc-601v in the pics for sale, the top seal is bad and dosent have bushings so the motor is trash, but if you need a stator or regulator let me know what you have in mind for price ill take 50 bucks for both plus like 5 shipping (the regulator is prolly around 67 new and the stator is prolly something like 70-100?) oh and sometimes magnets like to fall off the flywheel too and will take out the stator, ill throw that in the deal too if thats your prob (you gotta pay shipping though)

    Picture 112.jpg

    Picture 110.jpg
  7. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Messages: 956

    Your alternator consists of the stator and rotor. The rotor magnets are under the flywheel and the stator consists of many turns of wire surrounding it.

    You most likely have a regulator/rectifier mounted on the engine with 3 wires going to it. 2 wires (probably the same color (yellow?) are from the alternator and the 3rd wire goes to the battery/electrical system.
    The 2 wires from the alternator should produce at least 28 volts AC.
    The 3rd wire should produce in the range of 14 volts DC.
    Disconnect the regulator and check the AC voltage on the appropriate wires with 1 test lead on each wire (AC function on meter) to check the alternator.
    Use the DC scale on your meter to check the DC voltage from the 3rd wire to ground to check the regulator if the alternator checks out OK..
  8. tsh1773

    tsh1773 LawnSite Senior Member
    Messages: 319

    I do have a voltmeter. The battery registered 12.53 volts before I installed it. The mower started right up. I immediately connected the volt meter to the batter and the voltage dropped down to 12.42 and gradually started going up. I'll check around some more. Thanks for the input so far.
  9. GravelyNut

    GravelyNut LawnSite Bronze Member
    Messages: 1,594

    Easiest way to figure a charging voltage for a lead acid battery is that the final charge voltage should be 1.125 times the nominal battery voltage. 6 = 6.75, 12 = 13.5, 24 = 27, 32 = 36, 36 = 40.5, 64 = 72

    At times the voltage will exceed that when first charging the battery if everything is normal such that 6 = 7, 12 = 14, 24 = 28, 32 = 37.5, 36 = 42, 64 = 75.
  10. corey4671

    corey4671 LawnSite Silver Member
    Messages: 2,931

    YES. My Everride did this. It was so bad that I would be mowing and the blades would stop and then the motor sould just die. Check that fuse. A new battery is just a band aid.

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