Charging problem......

urednecku

Member
I got this Kawasaki Mule that I inherited from my late Daddy, I think it's a '91 model. Had very little trouble with it, heck it still has the original tires on it!
Started a while back having battery troubles, & a volt meter at the battery terminals showed a drop in voltage as the engine sped up. Took it to a local small engine repair, they said they thought it was the stater, but wanted to keep it for a few days to go all thru it to make sure. (Long story short, attitude of the owner, I'll never -willingly- give or send him any more business.)
I just got finished putting a new stater in it & got it started up. When it's at an idle, my volt meter would read ~13.2v, but at full throttle only ~12.2. Idling & riding it around for probably 10 or 15 minutes it did charge the battery up enough to start it back up, but what gives?
ANYBODY got any ideas on what to check?
Thanks!!
 

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SpudHauler

Active member
Site Supporter
Here are some things you can check.

Loose ground straps, if any, can cause problems. Hopefully the ground strap from the battery is attached to the engine and that is not a problem. Ground connections are often over looked and are very important. If the circuit is not complete, battery to load (positive wire) and load back to battery (ground wire) no circuit will work properly.

Normal charging is;
12 - 12.4 volts, no load, is a good sign your battery is good.
key on and that will drop slightly.
idle should produce 12.5+ volts.
over 3,000 rpm usually gives the max 14+ volts or at least 13.5+ volts.

Alternator usually has 3 wires that should show the same voltage output when engine is running with the alternator wire unplugged. Touch volt meter to each wire and ground to get voltage. Not sure what this unit will be but 15 AC volts per wire is common.

Then test each of the three wires to each other with engine off and see if you get continuity, usually 5 ohms or less. Looking for shorts internally. Then test each to
ground looking for shorts to ground.

Try a known good battery to be sure the battery does not have a bad cell. I had one that would not produce over 13 volts. One year old battery with bad cell was the issue, charging system was fine.

Only other piece is the regulator / rectifier that the 3 alternator wires plug into. Impossible to test. If all else fails this could be the issue.

Looked for a online service manual but not to be found.

So I'm just guessing.

Had issues with not starting equipment that turned out to be a simple dirty blade fuse.

Old machine so check all connections.

Oh, reg/rec don't work well if they don't get a good 12 volt feed, so make sure the power wire to the reg/rec is good when the key is on. Sometimes dirty key switch reduces voltage. Test wire to power reg/rec will eliminate that fault if that is the case.

Mule will run on a full charged battery without charging system working or unplugged. So testing with engine running and alternator unplugged will not hurt anything other than the battery will eventually go dead.

Manual would be nice to have.

Good luck.
 
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SpudHauler

Active member
Site Supporter
OOPS;

Just remembered that is AC voltage out of the alternator not DC.

Make sure to change you meter for that test.

Otherwise everything else is DC because that is what the rectifier does, converts all the 15 AC volts to DC.
 

Peanut

Well-known member
SUPER Site Supporter
one thing to think of is the engine needs power to keep it running so at full throttle the engine is using more power than just idoling my old jd gator was somewhat the same way.i eventually installed a second battery along with a toyota alternator after that I had all the power I needed plus some.i had the stock system separated by a battery disconnect switch if the stock battery ever started to go down I would flip the switch and give it a quick charge. getting back to your problem I think it should be fine unless you drop below the 12volts also is it a stock battery? if you or your dad ever installed a battery that has more cca then you need to get the battery that is made for the mule.i tried going with a larger battery on my gator before I went the double battery rout and I ran into problems . the stock system is only designed to charge a stock battery so if you put a larger battery that will put a strain on the system and eventually have a fuse meltdown.when I say larger battery I don't meen size wise I meen more cca. try looking up what battery is recommended for the mule and see what you have installed in it.
 

urednecku

Member
Thanks, Peanut! Wound up being the regulator, but also needed a new battery. I've been using the battery called for in the books. Didn't know about a bigger battery killing the system, thanks.
 

SpudHauler

Active member
Site Supporter
Hi Peanut,
Had not ever heard that about CCA (cold crank amperage) having any effect on the charging system.

All batteries are typically 12 volt, of course some are 6 volts or 24 volts, but in most of our vehicles it's 12 volts.

The capacity is measured in CCA which I understood as how much it can output when called on for such things as starting, which is the biggest load of any vehicles electrical system.

It still only charges at 14.5 volts max and any good charging system will handle that. A bigger or higher CCA battery should still charge the same, I believe it's more a case of a small weak battery discharges quicker or can not hold a charge and then over loads the charging system.

Case in point a 12 volt battery with one weak cell would not charge over 13 volts and we thought the alternator was bad. Tried another battery and wham we had 14.5 volts. Looked at the old battery and noticed sulfation in one cell. Nothing wrong with any thing in the charging system.

I think the Mule could charge a small motorcycle battery or a huge bus size battery with no problem. BUT the motorcycle battery would only start the Mule a few times before loosing it power, while the bus battery with it's large output capacity could run the starter all day or at least until the starter burnt out.

By the way, that was a great looking rack you built. NICE JOB!!!
 
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