We have a C500-55 that we use, but don't own. The owner had it serviced as it wasn't holding a charge. The service center installed a new alternator. Owner said it was all set but whenever we go to use it we need to use a battery charger on "start" mode to start the forklift. We installed a new battery as the original was 5 years old. Still not starting without at least a trickle charge on it. Troubleshooting it now, as we should have before, we only get nominal battery voltage of 12.55V at the battery when forklift is running and 12.48V at alternator. Before I blame the new alternator, what else can I check? Anyone have a wiring diagram for this model they could share?
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Update on what we found
It appears that the replacement voltage regulator that we were supplied was not the correct unit. I received quotes from multiple forklift part distributors and they all said the replacement voltage regulator was part # CL336290. I purchased 2 of these and they each burned out after running for 10-15 seconds. I went to a generator rebuild company who was familiar with these alternators with external voltage regulators. The alternator tested good so they crossed the CL336290 to a Delco D635. They purchased two for testing and also burned them both up. They bought a third and wired it differently than our forklift. They wired it to a typical GM external voltage regulator and it worked. We made a wiring change in our forklift and it worked. Now I know the wiring in our forklift didn't change, so I continued to research why we had to make that change and that's when I determined that it must be the voltage regulator.
After cleaning off the surface rust of the original voltage regulator I found that it was a GM 1119507/Delco D632 but the replacements being sold for this forklift are equivalent to GM 1119515/Delco D635. I found many listings that show the CL336290 as being equivalent to many different part numbers including D632 & D635.
Since we spent so much time resolving this charging issue, we have decided to not try a D632 back to the original wiring, but I figured I would post this update for anyone in the future.
More issues...arrggghh.
So the forklift had been charging for months, then we started having problems again. We cleaned up all of the connections and that seemed to get things back to charging. Then a few weeks ago, not charging again. We had to charge the battery to get it started. While running, battery voltage is ~12.5V with the voltage regulator connected or not.
We replaced the voltage regulator this morning. I had my Fluke multimeter connected to the battery when I started it. Battery was at ~12.5V, forklift started, battery voltage climbed to 13.8V (yeah!), then after a few seconds it started climbing all the way to 15.5V sometimes coming down to 15V but wouldn't come back down so I turned it off. Could this be anything other than a bad voltage regulator?
The battery holds a charge when charged with a 2A charger for 12 hours, and the charger only goes up to about 13.8V so I don't think it's a bad battery.
That's awesome! Nice quick fix. Yeah, if there is no light then its hooked up to a resistor in the circuit. Finding diagram for these machines is like finding lost treasure. I joined this forum a few days back because I couldn't find any help online. The forum warns not to share that type of material before you post.
Yes, I agree you will need a new belt for it. However in the mean time try belt dressing to make it go away for a short while if it really gets to you.
No problem!
I was doing some more voltage & resistance checks, this time with the seat(hood) up. Some test with the engine running. When I turned off the engine, I noticed the fan would spin a few revolutions, but the alternator belt would stop. I pushed down on the alternator belt and it was so loose I could push it down at least 1.5". I tightened up the belt and now I get 13.5V when running! Apparently the belt was never tightened and it was slipping. Now when I turn off the engine there is a chirp from the belt trying to slip on the fan pulley, but that's a minor annoyance to have a working alternator. Maybe time for a new belt as when the alternator was changed, they kept the old belt on.
As a side note, there is not idiot light, no lights at all, on this forklift. It would be nice to have a wiring diagram for future us, if anyone has one.
Thank you PRAUTO
I see a few possibilities:
1. RPM is too low - check the tension on the belt, maybe its slipping.
2. Usually these machines have a 2 PIN alternator. PIN 1 is for the idiot light and PIN 2 is the voltage sensor. The voltage sensor wire is just battery positive and the idiot light provides enough resistance to become battery positive once running. Perhaps the idiot light/resistor is faulty Without that giving the alternator it's initial magnetism, it wont work correctly. Now every alternator varies, so trace the wires before you do anything as this applies to what I worked on.
3. Parasitic drain and/or resistance somewhere in the circuit causing voltage drop. Its draining the battery and its unable to recharge after the initial crank. That's why even with a new battery you have to trickle charge it. You'll need to do a voltage drop test along the wires. Check the battery lead first.
4. The new alternator really is a faulty.
Good luck
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