QuestionQUESTION: Ongoing charging problem on lawn tractor. Battery won't stay charged. Dealer service has been questionable, and I want to make sure of a few things before I go back to them again.
1. With engine at full speed, I'm getting about 13 vdc across the battery terminals, compared to just a bit more than 12 vdc with engine off. That's not enough, is it? I thought I should expect 14+ vdc at full throttle.
2. I'm getting about 30 vac at speed across the battery terminals. Am I right that there should be no ac voltage present? Is that a smoking gun telling me the dealer did not replace the regulator as he said he did?
3. There is a scraping/chirping noise coming from the engine, seemingly on each revolution, more noticeable at idle. Could this be a sign of a stator out of whack and rubbing? Again, dealer said he replaced the stator, but I'm not convinced.
Thanks!
ANSWER: Using the link below, can you identify which alternator/charging system you have?
http://www4.briggsandstratton.com/miscpdfs/RNT/alternator_id_a.pdf
NOTE: You may have to scrap the wires, very lightly, to remove any paint so you can correctly identify the wire color.
There is a lot of theory regarding what is enough charging voltage. Some say 12.5 volts DC is just right and above 14 volts DC is too much. I run a voltmeter, granted it is a cheap one so probably not as accurate, on my motorcycle and it charges between 13.5 and 14.7 volts DC. No problems with the battery.
The best way to check the charging system is to measure the current. However, most meters have a 10 amp max. If your charging system produces more than 10 amps you need a DC shunt. DC shunts are really too expensive for home owners. I also find I rarely use the one I have. Bottomline, voltage is a good way to measure and gauge the performace of the charging system.
This link below covers charging system checks:
http://www4.briggsandstratton.com/miscpdfs/RNT/alternator_replacement.pdf
I recommend you dis-connect and clean the battery terminal posts and cable ends with a wirebrush before checking the charging system. I have fixed a lot of charging systems just by cleaning the connections. Also, make sure the battery is good. I've have individual bad cells cause many charging problems. Most auto parts stores can load test the battery, for free, to ensure it is properly working.
Once you know the battery is good and the connections are clean, then check the charging voltage.
As far at the clicking, I doubt it is the stator. Stators are solid mounted and the only issues I've had with stator is if the flywheel magnets come loose and damage the stator. However, this is very, very rare. Once is a while a diode will fail but again this is pretty rare. If you have a regulator, you should check the AC input and DC output voltage.
Let me know is the battery is good and if the voltage changes after you clean the connections.
Eric
---------- FOLLOW-UP ----------
QUESTION: Thanks for responding!
Battery (nearly new) seems ok. Once charged, it reads a bit over 12 volts. Connections are clean and shiny. This is a Briggs INTEK 20 hp engine. Closest wiring picture to my setup is "I" - the red wire disappears back up under the engine shroud, so I can't tell where it goes.
Questions:
1. The silver box on the left side of the engine, with the two yellow and one red wire, is the regulator, right? Originally I thought the regulator was the gizmo sitting on top of the firewall, right of the steering wheel. Could that just be a relay?
2. I am getting a charging voltage of abot one volt higher than the reading with engine off. From what you said before, can I assume that's ok?
3. Lastly, can you tell me if I should be seeing that 30 volts AC across the battery lugs at full engine speed? I've heard that there should be no AC voltage present at that point.
This thing has been to the dealer shop twice, and still I can't get an itemized list of parts they changed. They verbally said they replaced the stator and regulator, but after my experiences with them, I want to make sure.
Thanks!
Byron
4.
3.
Answer1) Yes, that is the regulator. Two yellow wires are AC.
2) One volts is a little low but at least it's something.
3) You should see AC on the yellow wires, 30 volts sounds correct.
What is the DC voltage at the regualtor, the red wire, with the engine running full speed?
Eric
