EZGO conversion - wiring demon - Bad solenoid?

[Kyle263611]

Alright, I'll give the upfront to keep it simple:

-1995 medalist, originally DCS, picked up gutted
-Installed D&D series motor, AXE4844m controller, and a 48v trojan pack
-Added high amp solenoid for 48v (since previous was 36v)
-Added F/R contactor solenoids (since it previously had dcs fnr switch)

Don't judge my wiring, still testing and cleaning it all up.

Everything was installed, one first day of testing, F/R contactors would click when the direction selector was moved, and controller would come on (along with main solenoid clicking) when pedal was pressed but no motor movement. Bench tested motor using 12v. Also noticed no voltage being passed to motor from controller (using monitoring in the axe software). No errors on controller, I figured I had boogered up the wiring that Scotty sent, but double checked and I had it right.

Today I went out and double checked all of that, and the symptoms have changed (the only other thing to change is that it got cold). Now, on pedal press, controller comes on, but the FNR contactors are not clicking anymore. I started back at the beginning, and noticed I had 1-5v being passed through the solenoid with nothing but key on. Is that right?

If it is, I have other questions, but I'll save them for this answer.

https://www.youtube.com/watch?v=6y6YSP_8pz4

[JohnnieB]

The reversing contactor solenoids not clicking issue may be temperature related. Bad connection or switch someplace. Just a matter of tracing B+ from the source to the F/R toggle switch and from there to the respective solenoid coils.

The voltage being measured on the main solenoid's controller side large terminal is the voltage stored on the dozen or so filter capacitors inside the controller. For safety reasons, the capacitors have bleeder networks and the moment the solenoid contacts open, they start discharging the charge on the capacitors.

Solenoid contact bounce for about 30 milliseconds or so as they close and the amps the completely discharged filter capacitors (up to a Farad or more) try to draw is huge (1000A+) so the arcing is significant during contact bounce and the solenoid contacts don't live as long as they would have without the arcing.

To prolong the solenoid's contacts usable lifespan, a pre-charge resistor was added between the main solenoid's large terminal to keep the filter capacitors charged to just below the battery pack voltage. For a 48V system, a 470Ω - 10W resistor is needed.

Attached is a picture of the power board in a Curtis 1206SX controller showing a dozen 1,000µF filter capacitors for a total of 1.2 Farads. The Alltrax AXE will have a similar amount of filtering.

[Kyle263611]

Understood. So the bleed is normal and likely not related to my other issue?

[JohnnieB]

Originally Posted by Kyle263611

Understood. So the bleed is normal and likely not related to my other issue?

Yes. But you should install a 470Ω - 10W resistor to prolong the life of the main solenoid contacts.

The solenoid coils (all of them) are low amp devices and fed by thin wires (16Ga or 18Ga or so) while the solenoid contacts are high amp devices fed by thick cables (should be 4Ga or thicker), so there are two, more or less, separate circuits.

[Kyle263611]

Thanks so much everyone for the help. I ended up getting the cart up and going and it looks great. I ended up with Scotty's reversing contactors, a curtis 500amp controller, a d and motor (2 actually.. first one was used and didn't last 2 hours). I built my own 12 volt system using the sparkles 12v reducer, and am very happy with how everything came out. Pics to follow.

Again, thanks for all the free help and info, this forum saved me a lot of heartache by getting things done right the first time!

Special shout out to Scotty for his excellent customer service and quick responses!

[Kyle263611]

[Kyle263611]

https://www.youtube.com/watch?v=pA1btlq8hSs