Controller Resistor and diode change

[beach cart]

I have a DCX 650 alltrax. This is a pretty newbie question, but I have run without diode and resistor for almost 2 years with no problem. I see the importance of them after reading daily on here. My question is should I remove main positive and negative to add these, or just positive. Of course run/tow will be shut off first key switch off in f/r off.

[JohnnieB]

Either or both. Or any of the interconnecting cables within the battery pack. Whatever is easiest for you.

Before shutting it down, use your voltmeter to determine which of the solenoid's small terminals has the positive wire on it. (If it's a PDS, it should be the one with a Yellow wire on it, if it's a DCS, it should be the one with three Red wires.)

The banded end of the diode connect to that terminal.

Also, when you make the final connection to the battery pack, you are going to get a spark, so touch the cable end to the lead part of the battery post a couple time before touching the stud.

[Sir Nuke]

if it were me.....after you put the run/tow switch on tow.....just disconnect the main negative lead, that will take all the power out of the system.

[beach cart]

Thanks Johnnie and Sir Nuke for the quick reply. I don't know how I missed this one, hope no damage has been done.

[JohnnieB]

FWIW:

The diode reduces/prevents arcing of the contacts in whatever mechanical switch that opens the solenoid coil circuit. In a series cart, the pedal microswitch gets hammered every time the pedal gets lifted. In a sepex cart (DCS & PDS), the pedal switch tells the controller to open/close the circuit, and the electronic switch in the controller that actually makes/breaks the circuit has voltage spike protection built into the design, so the only time a mechanical switch gets hammered is when the Key or Run/Tow or F/R switch turns the system off while the solenoid is still energized. In other words, I doubt if much if any switch damage has been done.

On the other had, the resistor reduces arcing on the solenoid contacts. Basically, when B+ is removed from the filter capacitors in the controller (and there are a bunch of them), they start discharging. The instant the solenoid contacts close, the capacitors try to draw an infinite number of Amps to charge themselves to the applied voltage. The contacts bounce a few times before they stay closed, so arcing can, and does, occur if the amp demand is high during the settling period. The resistor across the solenoid contacts keeps the filter capacitors nearly fully charged (about 3-5 volts less than B+), so the Amp demand while the contacts are bouncing is far less. (The caps would effectively be in the fourth or fifth TC on the exponential charge curve rather than the first.)

When properly adjusted, as the pedal is pushed, there is a deadband between when the solenoid clicks and when the controller starts passing amps to the motor, and the controller has a throttle response curve, so it delays sending amps to the motor for a few moments so the contacts can settle.

With a DCX650, you most like have a Super-Duty (400A) solenoid, or at least a Heavy-Duty (200A) one. Either of which is far less susceptible to pitting than the stock unit (85A), so little, if any, damage has been done.

[beach cart]

Johnnie thanks for the great explanation. This makes it real clear and have wondered how this all interconnects. This whole issue started with a problem I have with an EX-RAY VOLT changing screens while driving on its own. Tony from ex-ray said I needed the resistor and diode first before I should run with pack voltage input to the display. EIther way they are ordered and I will run his tests after install.

[beach cart]

After really looking things over I found I have been running an Albright sw80-1275 100amp solenoid on DCX 650. Its been that way for almost 2 years with no problem. My cart was built but since being on here I know eventually it will breathe majic smoke. Just ordered the superduty 400 from carts unlimited. This a long with resistor and diode should fix things up.

[yurtle]

The caps will try to pull the amount of current they are physically limited to, but if you are backing out of your garage, rather than "punching it", it's much easier on your solenoid contacts. This is for the resistor. The diode is for low current switches.

[JohnnieB]

Originally Posted by beach cart

After really looking things over I found I have been running an Albright sw80-1275 100amp solenoid on DCX 650. Its been that way for almost 2 years with no problem. My cart was built but since being on here I know eventually it will breathe majic smoke. Just ordered the superduty 400 from carts unlimited. This a long with resistor and diode should fix things up.

The studs on the Super-Duty solenoid are bigger, so you'll have to bore out the holes in your cable lugs.

I'm not sure if you will see any performance improvement, but the 400A unit ought to run cooler and a lot less likely to fail out in the middle of nowhere.

[beach cart]

Thanks Johnnie I did not know that. I looked at the lugs on the 1275 last night and thought they were 3/8 but it was late when I checked my f/r after it got wet riding home in some bad rain, Rib helped me with his post to blow and dry things out. All works again.