RXV HV/LV BMS Shutdowns

[MrBritGolfFan]

Originally Posted by Sergio

My suggestion would be:

Red wire from Solenoid big post goes to the relay coil terminal.

The same terminal post as the red wire gets the side of the diode with the "Stripe".

The other relay coil terminal where the "non-stripe" end of the diode is connected has a Black wire that connects to the red wire of the P1/Led.

Black wire from P1 led goes to BMS C-.

That allows for an easy visual inspection of the diode proper orientation and the Series connection between relay, P1 and BMS.

I had to look closely as it appeared the diode was installed backwards since the "Stripe" was on the black wire side.

I like that, thanks Sergio, and agree much better visual inspection!

When i had finished all the wiring last night, i turned cart to R, and the red light on the box went on, but then i noticed the reverse gear didnt engage, and i had a red LED flicker on the navitas. It would do one long red flash and three short ones. I then saw that i had unplugged the lead from the charging receptacle which has a small inline fuse going over to the controller. Looking online it said that error code was something to do with motor brake. The inline fuse on this wire is one of those that allow you to pull the wire apart from the fuse and check the fuse. I reconnected it and all fine. The wire and small fuse seem really fragile, has anyone upgraded that?

[MrBritGolfFan]

Originally Posted by Sergio

My suggestion would be:

Red wire from Solenoid big post goes to the relay coil terminal.

The same terminal post as the red wire gets the side of the diode with the "Stripe".

The other relay coil terminal where the "non-stripe" end of the diode is connected has a Black wire that connects to the red wire of the P1/Led.

Black wire from P1 led goes to BMS C-.

That allows for an easy visual inspection of the diode proper orientation and the Series connection between relay, P1 and BMS.

I had to look closely as it appeared the diode was installed backwards since the "Stripe" was on the black wire side.

Hi Sergio. Can I add a switch between the COM and NO side of the relay. Thought process is that the switch would always be off. But if I get a faulty relay I can turn the switch on to bypass the relay. Is that going to cause an issue? I would simply just connect the output wires together via a switch?

[Sergio]

You could but most likely any failure (or active protection) that prevents the K1 relay from closing would be from the BMS itself and you should be very carefully before just by-passing it and continue to drive.

I recommend just using matting connectors in the input and output wires as I did on my build so it can still be by-passed but not accidentally:

https://www.buggiesgonewild.com/show...0for%20closing

[MrBritGolfFan]

Originally Posted by Sergio

You could but most likely any failure (or active protection) that prevents the K1 relay from closing would be from the BMS itself and you should be very carefully before just by-passing it and continue to drive.

I recommend just using matting connectors in the input and output wires as I did on my build so it can still be by-passed but not accidentally:

https://www.buggiesgonewild.com/show...0for%20closing

Ok thanks Sergio.

[MrBritGolfFan]

Here is an update to the diagram where i have added a 400A selector switch between the controller, the fuse and a direct connection to the battery positive. I did this just in case the 300A fuse blew and i was out an about and needed to just get home. I also like it as it gives me a quick way to shut down the power to the controller side if i need to do that for some reason.

I also added on the diagram the bypass switch. I have a SPST switch added across the COM and NC of the relay. Again this was a get me home scenario if the relay busted for some reason. Good call from Sergio saying that it is more likely the BMS having an issue than the relay, so use the bypass with caution. Based on Sergio’s feedback I’m going to go a little OTT and add a key switch in series with the SPST switch :) just to make sure its not accidentally switched.

574D3C80-5047-462A-9FDF-F6FA8FB4F31A.jpg

B57788A0-3F52-4210-AFF9-861F3126F7EA.jpg

And i really hate the mess of wires, trying to consider if i redo all those wires going over the new lifepo4 battery or just leave it be. When i had lead acids, all those wires went to the right of the cart where the 12v accessory battery was located. The new lifepo4 unit was so wide i had to put the 12v accessory battery behind, which is why all those cables are going over. I dont like it, so i may go reroute them all for neatness.

I should also Say I have not put my cart back together yet, as was spraying it (which is done), so I’m tidying more tonight :)

[MrBritGolfFan]

Spent the time to reroute all of the 12v accessory wires. Much better.

D78841AD-DC98-4D14-84ED-8DB3ABC81DFB.jpg

[MrBritGolfFan]

Originally Posted by Sergio

You could but most likely any failure (or active protection) that prevents the K1 relay from closing would be from the BMS itself and you should be very carefully before just by-passing it and continue to drive.

I recommend just using matting connectors in the input and output wires as I did on my build so it can still be by-passed but not accidentally:

https://www.buggiesgonewild.com/show...0for%20closing

Hi Sergio

I got everything else I was doing on the cart sorted. Jacked up the back wheels and went to test going forward or reverse. The little LED is on, and I hear the solenoid click as normal when I put in forward or reverse. But the pedal does nothing.

If I use my bypass switch and key it works. It’s like the relay is not working?

Any thoughts?

Cheers

[MrBritGolfFan]

Originally Posted by MrBritGolfFan

Hi Sergio

I got everything else I was doing on the cart sorted. Jacked up the back wheels and went to test going forward or reverse. The little LED is on, and I hear the solenoid click as normal when I put in forward or reverse. But the pedal does nothing.

If I use my bypass switch and key it works. It’s like the relay is not working?

Any thoughts?

Cheers

Update. I’ve put 47v across the relay from a power source and it clicks and works. When using this circuit it does not. The voltage from the pack is currently 43v. Could that be why? Looking at the data sheet I’m sure it says minimum is 5v to drive the coil?

[molfpedal]

What is your pack nominal and full charge voltage?


Sent from my iPhone using Tapatalk

[Sergio]

You may need a smaller load for P1 if your normal voltage ranges are that low.

The original values I chose were based on a Leaf cell chemistry, it was a compromise between keeping the relay coil cooler by using less voltage across the coil but still allow the relay to click at low pack voltage.

Once closed that relay will hold the contacts until around 5v so no chance of dropping under load.

The guaranteed turn ON voltage is 36v but usually they close with less voltage.

There is also a "fudge" factor on those 12v lights as different manufactures use slight different resistors depending on the brightness they want, and different LED colors provide a larger "constant" voltage drop that affects its interaction with the circuit as the pack voltage drops.


Anyway, the best thing to do is to measure the voltage between:

1. Solenoid Big Post on Controller side to BMS C-
   
2. Measure the voltage between the relay coil terminals (1/4 quick connectors).

Once we know how much effect that 12v light is having in the circuit we can make adjustments.