Carryall OBC Bypass for Summit Charger

[PMD3454]

Tomorrow I will finally have a chunk of time to tackle removal of the OBC from the Carryall so I can switch to the new Summit smart charger. Based on all of the guidance in troubleshooting the original electrical problem, my plan of attack is below. Is there anything here that sounds wrong?

> Remove the 4 ga wire running from the battery neg through the OBC to B-, and run it directly from battery neg to B-, bypassing the OBC.
> At the OBC cut off the 10 ga black that runs from the fuse of the charging receptacle, add a terminal, and connect that wire directly to battery negative.
> Remove the 10 ga black wire that runs from the OBC to B-
> Remove the grey receptacle sensing wire from the OBC and pull it back to the receptacle. Coil it and secure it, or cut it off. Will not be used.
> Cut off the Multi-pin connector where the 6 wires come out of the OBC. Jumper blue to white. For now my plan is to wire nut or tape the other four wires while I test the new setup. If all works well I will go back and attempt the pin removal process that I've seen in the forum, or will dip the ends of each wire in electrical sealant used for buried/submerged wiring.
> The colors of those remaining four wires are noted below. The wiring diagram shown in the prior post shows 2 of the 6 wires in the connector as the grey sensing wire and the 10 ga black from the receptacle. That's not accurate, They are both separate connections to the OBC and are not part of the multi-pin connector.
> The four remaining wires are:
>>yellow - from controller??
>> red - ???
>> brown/white - dash light?? Wiring diagram shows a "dash light" and a "warning light" . Cart has the typical battery warning light, but I see no evidence of dash light.
>> purple - ??

Once I remove the OBC is there anything that will no longer work? The battery warning light??

Any input would be greatly appreciated. Don't want to mess up my new charger.

[Volt_Ampere]

The OBC does control the battery warning light. It won't work without a working OBC. As far as the charger is concerned, all you have to do is connect the charge plug negative to battery negative and disconnect the third wire (yellow) that goes through a fuse to the OBC.

[PMD3454]

From reading through the OBC bypass sticky, I came away with the impression that if the OBC had failed, which mine has, I needed to do the other things that I detailed in my prior post. Is my understanding incorrect?

I went through the process of doing the OBC checks and shared it on the forum and got confirmations that the OBC is bad. Currently, I can't charge the cart (charger is confirmed to be operational) and the warning light alternates on for 15 seconds and off for 4 seconds. This happens even with the key off.

[PMD3454]

Also, the third wire on this receptacle is grey. It shows as grey on the wiring diagram also. That wire goes to a spade on the OBC. Is that the same as what you refer to as yellow? There's no fuse in the grey wire but there is a butt connector where there may have been one in the past.

Thank you for the guidance.

[Fairtax4me]

Don’t know which yellow wire he’s referring to.

Brown/white is the battery warning light. So that will not work with the OBC gone. This can be used as a negative for a voltmeter if you jump it to the B- connection.
Red is 48v in from the pack. This can be capped off.
Yellow is throttle signal as a wake-up signal. Can be capped off.
Purple wire? Not sure and I don’t see that on a wire diagram, but it might go to the controller. Cap it off.
White is tow run switch input. Use this to provide power for the interlock.
Light Blue is interlock control. The OBC pulls this to negative to activate the charge interlock. It provides pack voltage to de-activate (makes the cart operational). This needs to have 48v applied via jumping to the white wire for the cart to work.
You can also connect the Grey wire from the receptacle to the Lt Blue wire to use the chargers interlock function. Set the charger interlock to active low in the connect app, and the cart will be disabled when the charge cord is plugged in.
You’ll need a 10k ohm 1/2w resistor connected between the white wire and light blue wire, and this will provide power on the interlock pin so the cart works when the charger is unplugged.

Cut the two black wires coming out of the OBC and join the two ends together with a yellow butt connector.

[Volt_Ampere]

It's been a while since I helped a golfing buddy with his OBC problems but I was able to find a schematic for his cart and it was easy to bypass the OBC. If it were my cart, I would probably remove the OBC completely once it's not needed or wanted.

[PMD3454]

Apologies for being thick, but I'm confused. I'm not sure if you mean to do the connection both ways or choose one of the two. If its either/or I can't figure out why the resistor is between white and light blue when using the grey wire for charger interlock control. In recent OBC tests I think we jumpered light blue to white (with no resistor) and cart worked, but charging didn't. When grey went to battery negative charging worked, but with no control.

So in this case is the resistor in the circuit to allow for voltage sensing with reduced amperage to both the charger and the controller?

Also, this cart had the fuse removed from the grey wire. Should I put a fuse back in there?

Thanks again for the help.

[Fairtax4me]

Normal OBC operation is to enable the controller interlock to prevent the cart from driving while the charger is plugged in. It does this by pulling the Lt Blue wire to low reference, so it has 0v on it. When the charger is unplugged the OBC then applies 48v to the Lt Blue wire, which turns off the interlock and allows the cart to run.

Just to bypass the OBC you would jump the white directly to the Lt blue and that provides power on the controller interlock pin to disable the interlock and allow the cart to drive. This also means the cart can operate while the charger is plugged in, since the interlock pin has 48v applied whenever the Tow Run switch is in Run, which is where the White wire gets 48v from.

You can leave it that way and it works just fine with any smart charger, just remember not to attempt to drive the cart while it is plugged in and charging.

OR you can use the interlock function of the Summit charger, by using the grey wire from the receptacle as the interlock control. This will work the same way as the OBC would. When the charger is plugged in it will pull the Lt blue wire to negative and the controller will get 0v on the interlock pin, it will disable the controller and prevent the cart being driven while the charge cord is plugged in.
So where the 10k resistor comes in is to allow voltage to pass from the white wire to the Lt blue when the charger is unplugged, so the interlock will be disabled.
The 10k resistor is necessary because otherwise the white wire would just be shorted to ground when the charger gets plugged in.

[PMD3454]

Thanks for the additional details. I think I've got it now. So if I go with the charger interlock I would splice grey to light blue, then add the resistor between that and white. Correct?

Any thoughts on putting the fuse back in place on the grey wire? If yes how do I find out the fuse size for this cart?

Curiosity-type question... wondering if the resistor fails does it result in a short that damages the controller, or would a resistor typically fail in a way that creates an open circuit.

[Fairtax4me]

No need for a fuse. The original fuse is there due to a possible failure in the OBC that would result in a short. Removing the OBC removes the possibility of that failure.

The resistor never fails. But if it did nothing else would be affected.