kt 17 charging voltage

[rwilson 128]

I have a c175 with a series 1 kt17. last time i was plowing snow around half throttle the lights kept getting dimmer. It wasnt charging. I replaced the voltage regulator and it is now charging 17.01 to 17.05 vdc idleing and 17.84 to 17.88 vdc at full throtle. that is tested at the batery. Is that too much? what could be wrong?

[TT-(Moderator) 1,129]

What is the AC output at the stator leads? (disconnected from the R/R & engine at wide open throttle)

Is the R/R grounded properly? If it's questionable, run a dedicated ground wire between it and the battery negative terminal - at least for a test.

[rwilson 128]

I'll check it out tomorrow.

[Wheel-N-It 2,967]

I keep a ground jumper between the regulator and negative side of the battery on my KT-17 series 2.

[Save Old Iron 1,564]

You're in good hands so far.

As a time saving step, I will say if the charge voltage is TOO HIGH, you can assume the AC output from the stator is OK. Considering the RR unit chops half the AC voltage away to convert to DC, you can assume you have at least 35 volts AC from the stator and the stator is OK.

35 / 2 = 17.5 which is what you are seeing from the RR unit. And then there are some small losses in the RR unit so I believe you will find the AC voltage at or above 36 VAC.

[meadowfield 2,545]

Those voltages are too high though, 13.8 -14.4 is the sweet spot, for 30 mins on a non sealed battery you are safe at 15v. I wouldn't want to be running that high for too long....

Sounds like r/r is regulating and working, but set too high. Either the ground to the PCB is poor or the Zener reference diode (if fitted with one) is shot.

Mark

[rwilson 128]

thanks for all the input. I'm going to check the AC voltage in a bit and will let everyone know what the magic number is. I dont mind it at 17 volts. My headlights are nice and bright!!

[TT-(Moderator) 1,129]

Hey Rich.....

Reminder: Make sure the terminals are clean on the R/R & connector, along with the ignition switch and amp gauge terminals and connectors.

The resistance from corrosion can fool the R/R into thinking the battery voltage is lower than it actually is.

[rwilson 128]

ok i'll make sure its clean.

i'm heading out in a few minuits to check it out.

[rwilson 128]

ok got good ground. took the plug off the RR and found one bad wire end. fixed that checked the voltage out of the stater and got 24ish. cleaned all my plug ins and now its charging 14.4 to 14.6 at the batery. so I guess i found and fixed my problem.

[TT-(Moderator) 1,129]

now its charging 14.4 to 14.6 at the batery.

Perfect! :handgestures-thumbup:

[Save Old Iron 1,564]

checked the voltage out of the stater and got 24ish

When you measure the stator output, measure on the AC volts scale of the multimeter with the meter leads attached directly across the AC terminals of the RR unit or if the stator leads are off the RR unit, place one meter lead on each stator lead. When measuring the stator output, DO NOT MEASURE TO GROUND - THE MULTIMETER LEADS GO DIRECTLY TO THE STATOR WIRES.

I believe in your case, the AC voltage would be about double what you measured and would have been over 40 volts AC. And that's a good thing

If you told someone your stator output was 24 volts, and they assumed you had the meter hooked up properly, they would have advised you the stator was defective.