Hi there, I know this is an old post but did you ever get the charger problem sorted out. I have a M20 that needs a new charger. I cant find them. You mentioned that you purchased a smart charger. What charger did you buy? I would appreciate any advice.

Suggest that you read the instructions for the new battery carefully again, whether it is really the wrong buy

Hi OLD FRED any chance of getting a copy of that schematic please.
it would be very appreciated thanks

Check the main battery cables, I had one which had no 3rd speed after the blue battery plugs had been replaced, the Tech had swapped the wires around. All other functions worked perfectly. Can the program in the charger bee changed??? is it set for a Lithium Battery??

I have a manual with schematics. Give your email and I'll send them to you.

I saw your response and was wondering if you have wiring schematics for a MT20 or know where to get them?

Have you solved this problem? Just about everything on the stacker needs to be working for 3rd speed to operate. All batteries and connects, key sw, door, sw, brake sw, SAS sw, mast sw, rabbit sw, interlock sw, etc. Voltage drop across the hole system is a big problem. I normally run a new feed to the B and C contactor coils. I also use a relay. The first thing I do is replace the interlock switch with a change over relay. Much cheaper than an interlock switch, it never needs adjusting and it also overcomes the voltage drop because it takes a lot less voltage to energize a relay than it does to energize a contactor coil.

this trucks work in 6 to 19 volts the resistor is locate in the back the batteries were tthe solenids you need the 12 volts charger 40 amp charge and charge it 2 hrs and use it the the motor waste to much
amp is why the batteries no last longer only 6 monts until dies one at time

That's not true Service T. This truck is 12v until 3rd speed. Then it's 24v to the drive motor like the OP said. Tricky lil trucks sometimes. Interesting way of doing it.

Remember that it's set up that two 12v batteries (two 6v batteries in series = a 12v battery) are in parralel. In high speed 24v goes to the drive motor but the rest of the machine is stil only 12v.

I'm looking at a schematic. Here's what should happen:

-1st speed (F or R) - only the F or R switch closes which pulls in the appropriate contactor. Motor current is forced through a resistor causing the motor to spin slowly.
-2nd speed (A contactor) - F or R switch is closed along with the A switch which then pulls in the A contactor. This bypasses the 1st speed resistor allowing thw full 12v to the motor.
-3rd speed (B and C contactor) the B switch is actuated in the handle pulling in the B contactor. The C switch is located on and actuated by the B contactor.
There should be a little actuating arm on the moveable tips of the B contactor that presses in the C switch actuating the C contractor. Sometimes you need to adjust it (bend it in a bit) so it actuates the C switch properly. IIRC, its just a little hook looking metal piece screwed onto the movable tips of the B contactor.
At this point the B contactor removes the negative side of the parralel circuit from one of the 12v battery sets and sets up half of the series circuit. The C contactor provides the second half of the series 24v drive circuit and isolates the drive motor circuit from the rest of the machine which is now still using 12v but from only one battery set.

Whew.

Here's a quick test. When the B contactor pulls in, can you raise the mast? That little switch on the B contactor has two circuits in it. One to actuate the C contactor and the other disrupts the lift switch circuit as mentioned before. If you can raise the mast with the throttle at full speed, something is wrong with that switch or its wiring.

Tracing wires and cables in these can be a pain since everything gets bundled up and ran behind the contactor panel.

I had a customer who had 5 of these. Got to know them pretty well. One of the major dealers was literally across the street. Right before I took over the account they shopped one for this same issue, couldn't fix it and charged something like 2500 for the failed attempt. Needless to say the customer dropped said dealership for service lol.

If you want a copy of the schematic, email me. My email is in my profile. It's 2 pdf pages. Simple on paper compared to the spaghetti you're looking at. Lol

Crown 20MT are 12 volt trucks. It has 4 6 volt batteries. But uses 2 for the lift and 2 for the drive. 2 12 volt systems.

OK it seems the micro switch on top of the 4th contactor is working. Work this way around. Open up the door and bypass door switch. Jack up the wheel (door), making sure the wheel does not touch the floor. Then try to operate the twist grip to go into speed sequence. As you mentioned, there is 1st and 2nd speed, that means either the 1st or 2nd contactor will close followed by the 3rd contactor. When you go into the 3rd speed, make sure the 4th and 5th contactors close too. If not then there is no power supply to the 4th contactor. You can also measure the brown wire on the terminal board situated at the door side and should have about 12vdc. This brown wire supply positive to the 4th contactor coil. As such you should be looking at the mast switch and the rabbit switch. Charger output is 12vdc and 10 amps.

Triumphrider, I am not sure how the PM guy is at least trying to solve the problem, I believe that he is wrong about 24v should be running through the switch, that I bought the wrong batteries, and that I am using the wrong charger. The fact that the charger "NEVER SHUTS OFF" kinda bothers me more than a little. I am not quite sure where the guy is getting the idea that 24v would ever run through the switches. At any rate the skill level of the PM guy is the least of my concerns. I am going to continue troubleshooting with the help of you guys here and ultimately find the cause of the problem.

Thanks in advance!

Crown trucks have a higher current load running through the switches than most other mfgrs. I am not saying it is a bad idea but over time the resistance across the switches can increase due to carbon buildup across the tips. check your micro switches for resistance. I have found any more than a ohm or two can cause all kinds of problems. You should be reading close to 0 ohms direct across the switch. The 20 MT is a very good unit for what it was designed for. Sounds like the pm guy is at least trying to solve the problem.

When you can hear those switches clicking, that means the Actuator Screws are adjusted well enough to enable the switches to Close and Open.

You found that the voltage decreases, from 12 volts to less than 9 volts, when the switches are closed.

That much of a voltage drop tells me that there is high resistance between Common and Normally Open, when the switch is held closed.

I suggest replacing all 4 of the Directional Switches, plus the Brake Switch and the Door Switch.
If you buy these parts from Crown Lift Trucks, my guess is that each switch cost approximately $12.

The next potential problem is that you might have a problem that you can't diagnose, until new switches are installed.
Replacing switches is relatively cheap and effective.
If you can do this yourself.
Another service call means more money, and the Tech that shows up might not truly understand how to deal with this problem.
Take lots of photos of the parts we have been discussing, before you begin to disassemble anything.

And yes, when the #4 contactor is pushed in the #5 contactor engages.

As a side note, when I measured voltage at the 4 switches in the handle it was 12.6v at rest and then drops to about 8.6v when the handle is twisted and the wheel is moving. All batteries are just 2 months old and fully charged btw.