"new" 2008 EZgo ST 2+2

[JohnnieB]

Here is a list of commonly used Golf Cart batteries: (Sorted by highest AH rated batteries at top, then by brand name if AH is same.)
You want to get the highest Amp-Hour rating you can afford.
Prices vary by location, so shop around and include shipping for price comparisons.
I got my 245AH Exide batteries through a Tractor Supply store.

[lobster]

We wound up purchasing brand new (Feb 13) T-105's through the dealer, he knocked $20 off the price and without shipping it was easier and faster than ordering online.

The cart was performing normally, but exhibited the SAME behavior again, speed sensor (1 - 3). Can I disconnect the sensor completely or would that actually force it into limp mode? The dealer told me they checked all the wiring and focused specifically on the sensor but couldn't duplicate the problem.

Edit: Dealer said he charged the new batteries also, so today I went out and checked charge, 37.3 volts, that would be about 24 hours after charging. Sounds ok to me.

[JohnnieB]

Originally Posted by lobster

We wound up purchasing brand new (Feb 13) T-105's through the dealer, he knocked $20 off the price and without shipping it was easier and faster than ordering online.

The cart was performing normally, but exhibited the SAME behavior again, speed sensor (1 - 3). Can I disconnect the sensor completely or would that actually force it into limp mode? The dealer told me they checked all the wiring and focused specifically on the sensor but couldn't duplicate the problem.

Edit: Dealer said he charged the new batteries also, so today I went out and checked charge, 37.3 volts, that would be about 24 hours after charging. Sounds ok to me.

That sounds terrible to me. Those batteries are only at 75% SoC and if they had been fully charge 24 hours earlier, the voltage would have been above the 100% SoC level on the charts because the charts are for mature batteries. Here is a copy of the State of Charge (SoC) vs voltage chart ffrom the Trojan Battery User Guide and a chart extrapolating those voltages to the voltages used in various sized battery pack typically used in carts.

New batteries ought to be fully charged prior to use, no matter what the vendor says.
Then they have to be broken in properly to otain their maximum stoirage capacity.
Here is how to do it: http://www.cartsunlimited.net/Batter...n_Methods.html
While on the website, read everything with the word "Battery" in title. Tons of good info.

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The speed sensor has to be connected ot the PDS controller goes into the limb home mode.

[lobster]

I'm sorry, but I did not mention I did drive the cart for several short trips and then a long trip around the campground. It was that point that I measured voltage, not prior.

It was during the driving around (was going to discharge them to 75% and then charge again) that the cart did the same thing it did before and I had to limp home.

[JohnnieB]

Keep the controller on Diagnostic mode while using it.
When cart goes into a limp-home mode, there ought to be a beep code when it happens.
If it is the speed sensor failure code (1-3), either the magnet disk, sensor, wires between controller and motor, the connections, or the controller is bad.

If it is the controller that is bad, replace it with a DCX400PDS, which doesn't use the speed sensor.

[lobster]

Originally Posted by JohnnieB

Keep the controller on Diagnostic mode while using it.
When cart goes into a limp-home mode, there ought to be a beep code when it happens.
If it is the speed sensor failure code (1-3), either the magnet disk, sensor, wires between controller and motor, the connections, or the controller is bad.

If it is the controller that is bad, replace it with a DCX400PDS, which doesn't use the speed sensor.

This is what I told the dealer 1-3 code, they said they could not replicate the issue with the cart off the ground, they checked all the connections, drove it around for a while, wiggled the wires to get it to exhibit the behavior, and they could not replicate the issue.

I did not want to start replacing parts indiscriminately, isn't there a way to test the speed sensor itself or controller? (If there is, then this dealer should have done it is my thought)

[JohnnieB]

If you or the dealer has an oscilloscope, check the pulse train on the white wire. (The sensor puts out 8 pluses per motor revolution.)

Other than that, it is replace parts until something fixes it.

The magnet disk probably isn't defective, but it could be slipping on motor shaft if the screw that holds it in place isn't tight.

The sensor is an electronic gadget that does fail, but tends to fail completely rather than intermittently

The controller is also an electronic gadget, but sometimes a heat related problem may cause intermittent operation of some of the subsystems.

The wires/plugs between speed sensor on motor and controller may have dirty contacts, which can cause intermittent operation under certain conditions.

Personally, I'd make darn sure the contacts in J5 are clean and tight.
Then I'd replace the speed sensor.
Then the controller.

OR:
Most likely, I'd just replace the PDS controller with an aftermarket one that doesn't use a speed sensor to limit motor to 4,400 in freedom mode, so the cart could go faster than 18MPH on stock height tires.

[yurtle]

Is there a way to check the magnet sensor without an oscilloscope? I'm assuming it's an inductor, so it should give off pulsed DC, which could be read as AC, correct? My WaveTek DMM can measure frequency, so if you knew how many magnetic poles there are, couldn't you just measure the frequency and determine RPM? Just asking because he may have a neighbor that could count the frequency without a scope.

Just thinking crazy now, but if it's in the audible range, you might could hook it up to a 1/8" jack and record it with Windows Media Recorder, then play it back and fairly accurately measure the frequency.

None of this helps if it's intermittent.

[JohnnieB]

You're right yurtle, frequency counting might also work and some DMMs have frequency or tachometer functions.

However, since the sensor has three wires rather than two, I suspect it is a Hall Effect device rather than an inductor.

The output is a series of spikes that is 8 time the motor shaft RPM, so it would be in the audible range with the motor spinning from about 5 RPM (40Hz) to about 2,000 RPM (16kHz).

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The speed senor won't be needed after I get my DCX controller installed so I'm kicking around the idea of using it as a signal source for a tachometer, but the idea is in the early vaporware stage.

[lobster]

How difficult is it to replace the speed sensor? As far as the dealer said there is one bolt and an o-ring plus wiring it to the controller.