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608KEB

520H overcharging and not turning over

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I printed the manual, thank you

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I measured the AC volts from the regulator and at 3/4 throttle its reading 37 V ac. I ran a jumper wire from the aluminum regulator to the - battery terminal with the tractor running and there was no drop on the voltage gauge ( still at 18 or more on gauge). Another problem has started too. I had to shut the tractor off because while it was running the starter engaged. I could hear it grinding or trying to engage and shut it off fast. what do I look at next?

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Start another thread in the ENGINES section so you get the most eyes on your new (most likely) mechanical issue. You may need to pull the starter and dry lube the "bendix" assy. If the starter is re-engaging as the engine is running, we would then have another electrical issue. If the small blue wire going to the starter motor suddenly gets 12 volts on it and engages the bendix, then that would be an electrical issue, possibly a bad ignition switch. I would address the starter issue before continuing on with the overcharge issue.

 

Your AC from the stator is good. Recheck the DC VOLTS DIRECTLY ACROSS THE BATTERY TERMINALS with the engine off and then again with the engine running 3/4 throttle

 

Ignore the tractor voltmeter for the moment and see what the multimeter reads at the battery terminals at 3/4 throttle.

Edited by Save Old Iron
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Not running the battery read 12.86V. Running at 3/4 throttle battery read 14.56V. The bendix engaged when I hit the warning lights wiring harness underneath the dash. I have started it 8-10 times since and shook those wires a little and it has not happened again. :eusa-think: So what's next.

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You either need a new tractor voltmeter or a new multimeter as the tractor voltmeter is also connected across the battery terminals. I'm guessing the tractor voltmeter is faulty. Make the same voltage measurement on your car / truck battery to confirm your multimeter is working.

 

12.6 volts w/ engine off and 14.6 volts running is a properly functioning charge system.

 

If your on tractor voltmeter is reading 3 volts higher than it should, it will need to be replaced (or ignored).

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Concerning the starter re-engaging, there appears to be an issue with the wiring harness. Visually inspect the harness near the ignition switch. Somehow, the starter BLUE wire is being powered on at the wrong time.

 

Flexing the harness repositioned either the wiring or the connections in the starter circuit. Inspect the TAN wiring at the back of the ignition switch and along its run thru the wiring harness down to the safety relays.

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O.K. I will take the volt meter off and put it on another 520 and see if it does the same thing. I'll test the meter tomorrow on my truck and let you know if it's functioning properly.

Edited by 608KEB

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also - check the on tractor voltmeter reading without the engine running. The reading should be close to the 12.8 volts seen by your multimeter. If it reads 14 -15 volts, then the pointer is off in the mechanics of the gauge.

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Good idea! I'll check it out. My curiosity got to me. I turned the key to the on position. The battery had a charger on it. Battery read 13.5 volts. The volt meter gauge was at 16.5 volts.

Edited by 608KEB

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Is the voltmeter a Toro labelled gauge? I thought they only go to 16 volts?

 

If the gauge is worth saving, and is functional but just out of calibration, "recalibration" of the gauge is possible by adding common resistors in line with the gauge's sense terminal..

 

 

finalwiringconnects.jpg

 

 

10ohmparallelwrap.jpg

 

 

The resistor steals power from the gauge mechanism, making it read a lower value. I did had an older thread on RS about doing the recal but darned if I can find it now.

 

I was successful in recalibrating the meter reading to agree with the 14 volts produced by the RR unit. From that cal point, the gauge was no more than 1/4 volt off at the 15 volt "overcharge" point and the 10 volt "battery dead" meter indication. 

 

 

torovoltmeter04.jpg

Edited by Save Old Iron
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What I don't get is how the calibration gets off. I've put about 30 hours on the 520H and it seemed to be accurate. As far as the voltage reading. I took the gauge out. This morning, I also tested the VAC on the 520H at 3/4 throttle. It read 35.9 I also tested my truck. Not running it was 12.3 volts. running, it was 14.8 volts. I did not test the VAC on the truck, because the alternator was hard to get at.

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Edited by 608KEB
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I'll test my multimeter and the voltmeter I took off on another 520H.

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No need to do any VAC tests on your truck! Totally unnecessary.

 

The Toro gauge is out of wack.

 

Never had one that far off, but it might be worth the effort to recalibrate. Do you still have access to a Radio Shack in your area?

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Yes, there is a Radio Shack nearby.I got a chance to test the other two 520's the same result on the multimeter. 12.4 V not running and 14.6 V running off the battery. The VAC was the same too. It was about 37 VAC of the regulator on both tractors.At least I know its charging correctly.I will inspect the tan wire. When I get some time in regards to the starter engaging.

Edited by 608KEB

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Your VAC is fine, No need to troubleshoot that aspect any further.

 

The RR unit converts AC from the stator to pulsating DC to charge the battery. The RR "chops off" half the VAC.In your case, 38 VAC gets cut into just the positive half of 38 VAC or 19 VDC pulsating DC. Bottom line, if your VAC was too low, you would never have enough VAC to be chopped in half to create and regulate to 14.5 VDC.

 

The RR allows the 19 VDC pulses to pass into battery until the RR senses VDC at the battery to be at the set point - or around 14.5 VDC. When the battery VDC reaches the set point of the RR - the charging pulses are stopped.

 

 

tiedBplusandActerminal.jpg

 

 

 

codrr005a_tn_zps3c58bd13.jpg

 

scrconductioncycle3.jpg

 

 

codrr014a_tn_zps4e4497a2.jpg

 

 

codrrterminalsconnected_tn_zps28a89ca6.j

 

 

codrr008a_tn_zps3ff5ac03.jpg

Edited by Save Old Iron
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I've learned a lot from this.

Edited by 608KEB

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Quick calculations show we may need to put between 20 - 30 ohms of resistance in series with the voltmeter gauge leads.

Essentially we are asking the added resistor to drop approximately 3 volts outside the meter. The meter indication SHOULD drop by 3 volts and be in agreement with actual battery voltage.

 

I'm not sure what Radio Shack carries anymore as far as resistors. I have all the values you may need and can send them to you in the post. PM me with your address if you would like to pursue the recalibration of the gauge.

 

It might be worth a shot. I have never seen one that far off. The gauge may be damaged and ultimately may need to be replaced.

Edited by Save Old Iron
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I did a short capture of the stator pulses and the charge pulses coming from the RR unit I repaired.

 

The upper 'scope trace (orange) shows the stator AC into the regulator. The lower trace (white) indicates the battery voltage and the charge pulses the regulator "lets thru" to charge the battery.

 

In the first 40+ seconds, few pulses are seen in the lower trace as the battery is fully charged. At 43 seconds, I placed a drain on the battery and the lower trace fills up with charge pulses. As the battery charges back to 14 volts, the pulses become fewer in number until they virtually disappear when the battery voltage reaches full charge.

 

In this case, I have re-calibrated the RR unit for summer use by lowering the set point to 13.8 volts instead of the previous 14.5 v set point. My theory is the battery will last longer when not subjected to aggressive charging in hot weather. I usually have 2 - 3 hour seat time per cutting session and 13.8 volts to the battery is plenty to maintain proper charge in the summer. In the winter, I will switch over to 15.5 volts to compensate for the shorter use sessions in colder weather.

 

Enjoy

 

 

 

Edited by Save Old Iron
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I picked up 1/2 watt 10 and 15 OHM resistors. I tried several combinations of the resistors. No luck. The voltage reading dropped a little with the resistors but not much. It didn't matter if I used 1 or 5 resistors. I'll pick up a voltage regulator. Thanks for your input!!

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My question at this point is if you wired the resistors in a "parallel" configuration as I had shown in my previous post. If you duplicated my resistor configuration, this would be incorrect for your particular needs. In effort to recalibrate my gauge, I needed only a small drop in voltage to correct the gauge reading. Two 10 ohms resistors wired in parallel resulted in 5 ohms in series with the gauge (last diagram below).

 

Your requirement would be for 20 to 30 ohms of resistance in SERIES with the meter.

 

If you wire one of the SERIES combinations diagrammed below, we should get you in the ballpark.

 

Once again, your RR unit appears to be working properly. The 14.5 volts on the battery at 3/4 engine speed shows this to be true.The measurement made with the multimeter at the battery terminals confirms this.

 

It is the voltmeter gauge that appears to be the issue.

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Edited by Save Old Iron

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I will wire it in series. I'll let you know the result. If this works, I saved $68.00 for a new voltage meter.

Edited by 608KEB

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2 15 ohm resistors wired in series got the volt meter to 14.6 when testing it directly off the battery. I installed it and the resistors look like they burned and got hot. The reading is over 16 volts. What next?

post-5623-0-47710000-1428959808_thumb.jp

Edited by 608KEB

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Interesting. I looked at the hi-res image you included. I see what looks like the series resistors wired to the black (ground) lead. Can you confirm if this is so?

 

If the mod was put in the ground circuit, the resistors were carrying both the voltmeter current and the gauge light current, which would certainly overload the resistors and turn them brown. The mod should be placed in PINK ?? wire wire going to the voltmeter.

 

I'll draw out a pic for you to reference in the morning.

Edited by Save Old Iron

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The gauge I recal'd was on a 416 w only one wire going to the voltmeter. Let me check on a 520 to see if there is anything special about the wiring to the gauge. I know they daisy-chain a few connections for power off the pink wire.

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