96 series 1206 controller

[JohnnieB]

Originally Posted by Timberwolflt

The solenoid is clicking

I followed some of Scotty’s diagnostics and it seemed to check out... except he said the B+ to M- throttle sensor test should go from 0 V to pack voltage but the resistor/diode(?) across the large solenoid terminals holds it just below pack voltage but the throttle did increase it to full pack V

The reed switch is bypassed but it’s hot

The MOPSFETs that control the amps that are passed to the motor are located between B- and M-. When they are turned off (no throttle signal turning them on), they are the only electrical open in the entire high current series loop, so they drop the battery pack's entire voltage.

Measuring from M- to B+ is measuring across 13 cables with 26 connections, 5 sets of electrical contacts, the motor's armature windings, the motor's stator windings and the motor's brushes, plus six batteries, so there somewhere in the neighborhood of 53 possible opens vs a single known one.

Both measurements are valuable troubleshooting tools, but have different uses.


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True, the precharge resistor keeps the B+ terminal at just below pack voltage, but that is when the negative test lead is on B-. With the negative test lead on M-, there should not be any voltage measured until the pedal is pushed far enough to send a throttle signal to turn on the MOSFETs.

If you are getting a voltage between M- and B+when the pedal is completely up, the controller is bad. (Shorted MOSFETs)

[Timberwolflt]

I am getting voltage between B+ and M- without depressing the pedal... I’m guessing that the b- isn’t backing in from the motor... curiously... the M- doesn’t show continuity with B-

Additionally, only one lead is hot on the F/R and the lug that lines up with it isn’t hot so I’m guessing F/R #3 has bit the big one... gonna pull it in the morning and educate myself some

On a scale of 0% to 100%... How sure are we that the controller’s bad assuming that the information I’ve provided is accurate? I’d like to be relatively sure before I have the lady spend $300 on a new one

[JohnnieB]

Originally Posted by Timberwolflt

I am getting voltage between B+ and M- without depressing the pedal... I’m guessing that the b- isn’t backing in from the motor... curiously... the M- doesn’t show continuity with B-

Additionally, only one lead is hot on the F/R and the lug that lines up with it isn’t hot so I’m guessing F/R #3 has bit the big one... gonna pull it in the morning and educate myself some

On a scale of 0% to 100%... How sure are we that the controller’s bad assuming that the information I’ve provided is accurate? I’d like to be relatively sure before I have the lady spend $300 on a new one

I was about 99.9% sure the controller was bad based on getting a M- to B+ voltage reading until I took another look at the picture of the customer's controller you posted, now I'm not so sure. The top of the controller has a layer of dirt on it, so the is the possibility of a phantom current path between B- and M- and if you are using a high input impedance voltmeter, like most DVMs, you might get a reading. Give the controller's top a good cleaning and that voltage reading will likely go away.

The motor's only connection to B- is through the MOSFETs that are physically and electrically located between B- and M-. In other words, B+ is hardwired to the motor (via the solenoid and F/R switch contacts) while B- has to go through an electronic metering valve.

Attached is a Diode check for series controllers. It is for an Alltrax AXE, but they all work about the same at the block diagram level, so you'll get continuity with one test lead polarity and open with the opposite test lead polarity. Also, be sure the continuity function selected has a diode symbol on it since Ohmmeter functions on DVMs typically don't apply enough voltage to forward bias a PN junction.

When the pedal is pushed just far enough to make solenoid click, you should have battery pack voltage on all four of the F/R studs. Since there is pack voltage only on less than four, that is the problem, or at least one of the problems.

At this point, I suspect the M- to B+ reading iffy and the controller might be good.

[Timberwolflt]

Thanks a bunch Johnnie... I cleaned up the controller like you suggested and fixed the F/R and got it going. They have crappy cables... had some loose ends and lots of corrosion. Cleaned it all up... put some new ends on some of the cables and it seems to be functioning properly.

A couple of the bad cable ends were on the F/R and had sunk the main lug into the plastic... how wise of those engineers to set lugs that are prone to heating in plastic. I’m gonna have to find out which F/R is the one we want in the future.

Their Powerwise charger shuts down at about 42V.... mine goes to about 44V... Is 42 enough?

[JohnnieB]

Originally Posted by Timberwolflt

Thanks a bunch Johnnie... I cleaned up the controller like you suggested and fixed the F/R and got it going. They have crappy cables... had some loose ends and lots of corrosion. Cleaned it all up... put some new ends on some of the cables and it seems to be functioning properly.

A couple of the bad cable ends were on the F/R and had sunk the main lug into the plastic... how wise of those engineers to set lugs that are prone to heating in plastic. I’m gonna have to find out which F/R is the one we want in the future.

Their Powerwise charger shuts down at about 42V.... mine goes to about 44V... Is 42 enough?

The HD or SD F/R assembly carts Unlimited sells is the heaviest duty one that I know of.

I agree about mounting the F/R contacts in plastic. Must be a better way.

The cutoff on the PW-28115 charger is 45V +/-1V or in the 44V to 46V range. 42V is not high enough.

Check the on-charge voltage between the red and black wires on the charger's control board, that is where the charger measures the 45V that shuts it off.

If there are some cables or connections between the heat sink and transformer center tap inside the charger and the battery pack's main terminals that have excessive resistance due to corrosion or looseness or whatever, the charger's control board will see a higher voltage than what is measured at the battery pack.

Clean up or fix the charging loop.