Tuning your RXV for a Lithium Battery

[AlexBen]

Originally Posted by kgsc

If you are using the original charge port when you unplug the charger cord the internal circuit will provide power to the blue wire. When wiring the new end you only need the main + and - wires.

This implies that perhaps the charge port has a mechanical aspect wherein when the plug is put in place, that the (+) line going to the controller from the receptacle is disconnected from the interlock-blue lead by the physical presence of the charging plug... and when you pull the plug out... the receptical is sort of spring loaded to re-connect the (+) lead to the interlock blue lead...

Do I have this right now?

[kgsc]

I know on the old style port there actually was a switch in the port that when the plug was in it broke the activation circuit. Not sure on the new one but something similar but might be magnetic or electrical.

[AlexBen]

Originally Posted by kgsc

I know on the old style port there actually was a switch in the port that when the plug was in it broke the activation circuit. Not sure on the new one but something similar but might be magnetic or electrical.

Thanks for confirming my suspicion/conclusion.

I didn't realize the receptacle "did the work" until just today. I was thinking maybe I'd have to put an ignition switch on the dash if I built my own battery and used an off brand charger...

I think there are some posts in the forum implying or saying that the controller is responsible for this aspect of managing the interlock signal.... that seems inaccurate now.

But all along I planned on re-using the receptacle and cutting off the plug from the charger I got with the used cart if the charger wasn't up to Lithium use... and splicing it onto a new appropriate charger.

I was mislead I think by a YT video where a guy doing a Lithium swap said that it wouldn't work unless you put the interlock-blue to the (+) lead on the battery. I'm going to assume in retrospect that he had taken all the wires off his receptacle, not realizing that when the plug was out, it was tying the interlock to the (+) lead.

[TheCartBoy]

Ok some more pictures to make it more clear. The modern RXV charge receptacle does not have a physic switch inside to toggle the interlock signal, instead its something electric, and requires the signal pin (upper pin) on the plug to have + voltage on it. If you leave this pin floating or connected to ground on the plug, the cart will not 'see' the charger connected.

Charger receptacle (attached to the cart) has 4 wires.
Black = B- stud on battery.
Red = B+ stud on battery.
Grey = B+ stud on battery.
Blue = Interlock signal to controller.

If you deleted the charge receptacle, you had to tie the blue wire (interlock signal) to B+ to allow the cart to drive.

When the interlock signal is grounded, the controller thinks the charger is connected. When the interlock signal is pulled high, the controller thinks the charger is disconnected and allows drive.

So when you add the ezgo 3 pin charger plug to your lithium charger, the + wire must connect to both the signal and B+ pins on the plug. In the attached photo of the plug, this is a mirrored view of the pinout compared to looking at the charger receptacle from the cart exterior.

[AlexBen]

Originally Posted by TheCartBoy

The modern RXV charge receptacle does not have a physic switch inside to toggle the interlock signal, instead its something electric, and requires the signal pin (upper pin) on the plug to have + voltage on it.

Thank you so much for walking me through this.

I am stuck at work for the next 36 hours, can't possibly go look at my cart. You mention "modern RXV" Mine is a 2013. Was there a production run change where maybe the early ones were physical disconnects and just 3 wires or something?

I can imagine that over time, if they started with one design, found flaws in longevity, that they changed the design to what you refer to as "modern RXV".

So helpful, thank you.

About the only way I can REALLY pay back is what I will do. I'll post a thread with details on all that I did for (I hope) a successful start to finish conversion of a 2013 model RXV showing at least one path to success.

Unless I get tripped up over other details, I've switched gears, will build a battery
48V x 105 ah, use a JK BMS.... while I've bought a shunt and gauge from Victron, I may shift gears if I can't figure out how to use the the JK itself to trigger an idiot light on the dash for low voltage warning. Perhaps it will make sense to just buy the JK display unit, and put that on the dash. Not the end of the world.

[TheCartBoy]

You're welcome.

Modern is probably a poor choice of words lol, everything modern will be old at some point. In fact the factory lithium cars (ELITE), this signal pin is used to communicate between the BMS and charger.

I'm not sure when ezgo switched to this style, solid state receptacle. Possible it's been there longer than the RXV. Kgsc, do you recall what carts had the mechanical switch? Marathon maybe?

[TheCartBoy]

Looking forward to seeing your build Alex!

[TheCartBoy]

Originally Posted by TheCartBoy

Some chargers like deltaq quiq (which can be reprogrammed for lithium) have an interlock signal already available, you'd have to check their wiring instructions. It's essentially an internal relay to switch the interlock pin to B+ or B- when AC is connected.

Added page from deltaq manual.

[AlexBen]

Originally Posted by TheCartBoy

Charger receptacle (attached to the cart) has 4 wires.
Black = B- stud on battery.
Red = B+ stud on battery.
Grey = B+ stud on battery.
Blue = Interlock signal to controller.

Thank you so much for this. I do in fact have the 4 wire version as you've shown here. Let us call it Modern? I've got my old useless corroded batteries out, and I'm taking stock of the mess that remains. Bought it used, and told "ran when parked".

The black lead above seems to have a resistor or something with a ring termination integral to it for the B(-) stud. The ring terminal is falling off, virtually useless. Does anyone know what that black rectangular box is on the end of the lead? If its a resister anyone know the spec? It's not in a wire diagram so graciously supplied by a member when I asked about the extra unused plug on my dash. (SOC gauge my fleet model lacks)

I want to release the E-brake on this cart so I can roll it. Im hoping a Dewalt 18V battery will suffice, it should. But I want to have all the connections right either way to install the battery bank I'm building.

[kgsc]

Originally Posted by TheCartBoy

Ok some more pictures to make it more clear. The modern RXV charge receptacle does not have a physic switch inside to toggle the interlock signal, instead its something electric, and requires the signal pin (upper pin) on the plug to have + voltage on it. If you leave this pin floating or connected to ground on the plug, the cart will not 'see' the charger connected.

Charger receptacle (attached to the cart) has 4 wires.
Black = B- stud on battery.
Red = B+ stud on battery.
Grey = B+ stud on battery.
Blue = Interlock signal to controller.

If you deleted the charge receptacle, you had to tie the blue wire (interlock signal) to B+ to allow the cart to drive.

When the interlock signal is grounded, the controller thinks the charger is connected. When the interlock signal is pulled high, the controller thinks the charger is disconnected and allows drive.

So when you add the ezgo 3 pin charger plug to your lithium charger, the + wire must connect to both the signal and B+ pins on the plug. In the attached photo of the plug, this is a mirrored view of the pinout compared to looking at the charger receptacle from the cart exterior.

I’m confused. You said if the signal pin is grounded it disables the controller but then you said when wiring the replacement plug to tie B+ to the signal pin. Wouldn’t that allow the cart to be driven?