Baker Electric Forklift Weird Problem

I've got a Baker electric forklift B-70CE with some annoying electrical problem. If I raise the forks while driving forward or back the forklift stops. The forks continue to raise and the hydraulics continue to work fine but it won't go forward or backwards. Turning the key off and on again has no effect. So far the only thing that will make it drive again is to unplug the battery and plug it back in. Then everything works normally again. Very annoying as I'm used to adjusting the forks up or down a little as I drive up to a load. Now I have to stop first, adjust the forks up a little, then go again which I suppose isn't that big a pain but I keep forgetting that I have to stop first before raising the forks. Other forklifts I own have never had this problem (feature?).

One other weirdness. Just sitting everything is quiet of course. When I put the drive lever forward or reverse I can hear the steering pump start, which makes sense because it thinks you are getting ready to drive. But I also hear the steering pump start if I touch the brake pedal. Not really a problem just doesn't seem correct.

Anyone have either of these problems? Source for a schematic? I've pulled the floor boards up and looked around for shorted or loose wires with no luck.

Alan

adh2000 said:

Anyone have either of these problems? Source for a schematic? I've pulled the floor boards up and looked around for shorted or loose wires with no luck.

Alan

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"floor boards" ? I have a Baker 4000 lb electric, probably about 1988 vintage, and all my contactors and such are in the counterweight area behind the seat...just lift the rear deck lid and look in.

I've never had that exact problem with mine but it did stop running once and I ended up bypassing the "timer" contactor that would shut it down after a certain idle time. Only difference in then and now is I have to make darn sure I've turned the key off when thru with it or it will be "on" until the next time I use it, whereas before it would shut down the system on it's own. Problem was it was shutting system down even when I didn't want it to.

Milacron said:

"floor boards" ? I have a Baker 4000 lb electric, probably about 1988 vintage, and all my contactors and such are in the counterweight area behind the seat...just lift the rear deck lid and look in.

Click to expand...

Thanks for the one response. What are these things super rare or something? I'm having trouble finding reading material and don't have much experience with electric forklifts. Anyway there are a bunch of wires and connectors which looked suspect under the floor plate and I initially thought I was on to something because everytime I unplugged and replugged one of them the problem went away. However if I understand correctly the machine has some sort of electronic sequencer that wants everything in neutral before it will start driving. I believe there is a short in the brake wire microswitch someplace causing the sequencer to think the brake is on. If I put the drive lever back in neutral, make sure the brake pedal is up, turn the ignition off, then turn the ignition back on that usually fixes the problem. If that doesn't work unplugging the battery will "clear the stack and reset the sequencer" as it was explained to me by a forklift tech. Anyway he may have been right because so far everytime that has worked. Still a total pain, but at least I don't get stranded. I suspect the brake pedal microswitch because when I step on the brake with the machine at rest and in neutral the steering motor starts. That can't be right. Anyway on to the next problem. The battery has a date of 6/13/00 and was low on water. I added 4 gallons and charged it up. Seemed to go OK. I used it for about an hour on Saturday and everything seems to be fine other than the problems already mentioned plus it really doesn't seem to have much drive power. I can lift heavy items, but it has trouble driving up even the driveway approach. Works fine on flat concrete. As you press on the accelerator is it supposed to have multiple gears or something? Is there a low gear? What is the theory of how the thing is supposed to be? I can't believe it should be this wimpy. Maybe one drive SCR is blown or something. How can I check any of this? After an hour of use the battery measures 36V. Its a 36V battery, I thought it was supposed to measure something like 38 or 39V when fully charged.

Alan

Measure the vooltage under load

Fully charged battery in float charge (trickle) will be 2.25 volts per cell * 18 cells or 40.5 volts.

Put a good volt meter on the battery and measure the voltage while going uphill.

Horsepower is all about WATTS, the resistance of the motor is fixed, watts is voltage * amps, amps is voltage / resistance so the variable here is the voltage on the battery .

The lift motor is likely "free running", it is pumping fluid through an open valve back to the tank when you touch the handle, as you pull the handle it closes this pathway and forces the fluid into the lift cylinder.

The drive motor is direct via gearing to the drive wheel and needs all of the torque that it can get.

Usually a switching power supply is what feeds the power to the motor, increasing the pulse width to increase the torque, if the voltage drops these pulses drop off greatly and torque suffers greatly.
Yours is old and was dry so the surface area of the plates may not be in very good condition and the voltage is likely dropping under load.

Most lift trucks have safety devices built into their controllers that will limit actions on low voltage.

If your voltage drops to below 34 or so it could be causing this. A dead battery is when the voltage per cell drops to 1.75 VDC ot 31.5 VDC total, if you are getting anywhere near this with little time from the charge then the battery is toast.

Re lack of power, my guess is you have a bad battery cell. Check specific gravity and you may find one cell way different from the others.