Discussion:
Crown 20MT Battery & Charger & the Crown PM Guy

So I had the Crown PM guy come out last week and check out my 20MT. I bought new batteries and switched over to a "Smart Charger" instead of the onboard charger. The PM guy said I bought the wrong batteries and that I am using the wrong charger. I'm not an idiot, but maybe I did miss something.. I bought 4ea 6v batteries with the same dimension as the batteries I took out. The slight difference is that the new batteries are 130ah and the old ones were 100ah.

As far as the onboard charger, I told the PM that the charger NEVER turns off. Thus will definitely kill the batteries over a period of time. So I tool a voltage test on the batteries before I plugged in the charger. I got 12.7v resting. I plugged in the charger and 10 minutes later tested the voltage and it was 13.7v. I left the charger plugged in overnight (12 hours) and when I came in this morning I did a test and got 16.37v (charger still plugged in). I unplugged the charger and let it sit for an hour and tested again getting 13.3v.

My smart charger goes through 7 stages of charge and I believe that it is better than roasting the batteries at 16.37v without shutting off. <-- What am I missing?

Furthermore, I told the PM guy that I do not get anything from the "Rabbit" speed switch. He did some basic voltage tests and stated that "I am only getting 12v through the switch and I should be getting 24v". Lol, I know better.. The motor runs on 12v in turtle speed and when the switch is activated to rabbit speed there is 24v applied to the motor (ONLY TO THE MOTOR). 24v does not travel through the control handle.

So my question is about the onboard charger mainly. Should I stick with it or use my smart charger? The rabbit speed and such is a whole other topic and the lift works fine for what I need. Rabbit speed would just be a luxury at this point.

Thanks in advance.
  • Posted 24 Apr 2018 03:11
  • Discussion started by Crash
  • California, United States
Showing items 1 - 15 of 21 results.
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??
  • Posted 23 Feb 2021 06:40
  • Reply by HyundaiChCH
  • New Zealand, New Zealand
I have a manual with schematics. Give your email and I'll send them to you.
  • Posted 18 Feb 2021 01:24
  • Reply by Old_Fred
  • West Yorkshire, United Kingdom
I saw your response and was wondering if you have wiring schematics for a MT20 or know where to get them?
  • Posted 5 Dec 2020 02:17
  • Reply by james_Wiese
  • Alabama, United States
James Wiese
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.
  • Posted 26 Oct 2018 22:52
  • Reply by MRFS
  • South Australia, Australia
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
  • Posted 25 Jun 2018 11:37
  • Reply by armando_g
  • California, United States
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
  • Posted 24 Jun 2018 04:18
  • Modified 24 Jun 2018 04:26 by poster
  • Reply by justinm
  • New York, United States
New York, New York its a heluva town..you know that The Bronx is up..and I'm Brooklyn down
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.
  • Posted 23 Jun 2018 02:32
  • Reply by Service_T
  • Kansas, United States
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.
  • Posted 11 May 2018 01:04
  • Modified 11 May 2018 01:11 by poster
  • Reply by richard_y
  • Singapore, Singapore
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!
  • Posted 10 May 2018 01:06
  • Reply by Crash
  • California, United States
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.
  • Posted 9 May 2018 20:53
  • Reply by triumphrider
  • Texas, United States
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.
  • Posted 9 May 2018 10:14
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.
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.
  • Posted 9 May 2018 09:59
  • Reply by Crash
  • California, United States
Ok, so I located the 4 twist grip switches and all four of them click at the appropriate time when twisting the grip so I am assuming they all work?
  • Posted 9 May 2018 09:54
  • Reply by Crash
  • California, United States
There are at least 10 possibilities that the Crown M series do not have 3rd speed. All the 5 contactors must be activated. The first 2 contactors from the right are for directional. 3rd contactor is for 2nd speed and the last 2 contactors on the left is for 3rd speed. Try this way, open up the door, bypass the door switch, put the handle in operating position and then push in the 4th contactor by hand. Remember not to operate the speed handle (twist grip). The 5th contactor will then pull in. In other words, this will make the 4 batteries to be in series and thus have 24 volts. That is why, there is no lift function when unit is in 3rd speed. Hope this help
  • Posted 27 Apr 2018 00:34
  • Reply by richard_y
  • Singapore, Singapore
That voltage is very low.
Might need to replace the Rabbit Switch.

Before you dig deeper into the Rabbit Switch, you have to take a close look at the 4 small switches that click when you rotate the Twist Grip.
They might be arranged in groups of 2, or they might be all next to each other.

These switches enable the travel function to work.

For now, ignore the Rabbit switch, and focus on those 4 small switches.
There is a chance that the 3rd speed switch can't close.
There is a small screw directly above the Red or White colored button of each switch.
If you carefully turn the screw clockwise, of the 3rd Speed Switch, then you'll be able to hear that switch click when you rotate the Twist Grip either full Forward or full Reverse.

Please be sure to have the Drive Tire above the floor.
  • Posted 26 Apr 2018 10:40
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.

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