RXV HV/LV BMS Shutdowns

[molfpedal]

I built a Nissan Leaf 14s pack using Sergio’s Cheap Chinese BMS schematic and have realized that a bms shutdown via the key switch input to the controller would cause and immediate brake lockdown and could result in injury to the unsuspecting driver/riders. This actually happened to me on a hill before I made the switch when a OEM battery cable broke. I almost went through the windshield.
I’m thinking of rewiring the HV/LV relay(K1) to cut off power from the key switch to the throttle instead of the controller.
For the RXV experts, Is this going to react like a throttle lift and bring the cart to a safe stop via Regen?
Wiring_Diagram.jpg

[Volt_Ampere]

I have a friend that had a bad solenoid do this twice before I helped him fix it. Scary when it happens at speed.

[molfpedal]

For the RXV owners that are thinking of making the switch to lithium and building your own pack or if you have one of the Techdirect packs and are having problems. Here is a drawing of Sergio's Cheap Chinese BMS relay setup that will safely shutdown a RXV in the event of an HV or LV incident.
By bypassing the Discharge side of the system you don't have to have the expensive high amp BMS and relays. I used this on my 2011 RXV with a danaher controller and 14 cell Nissan leaf battery with an Ant BMS. In the event of HV/LV shutdown from the BMS it simply cuts the 48V from the accelerator switch to the controller and the cart reacts like a throttle lift and rolls to a normal regen stop.
I used connectors that enable me to bypass the relays and get the cart home if I need to. I hope this will help someone!
Enjoy!

[dangme55]

Hi,



I have this project underway. Lots of gotcha's lol

Do you have a parts list and maybe some pix? Thanks!

[molfpedal]

Originally Posted by dangme55

Hi,



I have this project underway. Lots of gotcha's lol

Do you have a parts list and maybe some pix? Thanks!

Go to this thread and you will find the parts list for this setup:

http://www.buggiesgonewild.com/showthread.php?t=160302

[dangme55]

Thanks! for the parts link!!

[WalterM6]

molfpedal: I noticed that you made several changes from Sergios original drawing. Have you tested it to see if it actually works?

[molfpedal]

Originally Posted by WalterM6

molfpedal: I noticed that you made several changes from Sergios original drawing. Have you tested it to see if it actually works?

I have and it works flawlessly. Sergio’s drawing works well for almost all carts except the Ezgo RXV. With that relay setup on an RXV a HV or LV shutdown would kill the power to the controller and cause immediate wheel lock. At speed this could be dangerous. So I decided to use the accelerator switch circuit instead. I also got input from Sergio as to the best way to go about it. With this relay setup it merely acts as a throttle lift and the cart coasts to a stop with the help of the regen brake system. Much safer for the occupants and the batteries are still protected.


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[Pickensmd]

Thanks for all the great info molfpedal.

[MrBritGolfFan]

Originally Posted by molfpedal

For the RXV owners that are thinking of making the switch to lithium and building your own pack or if you have one of the Techdirect packs and are having problems. Here is a drawing of Sergio's Cheap Chinese BMS relay setup that will safely shutdown a RXV in the event of an HV or LV incident.
By bypassing the Discharge side of the system you don't have to have the expensive high amp BMS and relays. I used this on my 2011 RXV with a danaher controller and 14 cell Nissan leaf battery with an Ant BMS. In the event of HV/LV shutdown from the BMS it simply cuts the 48V from the accelerator switch to the controller and the cart reacts like a throttle lift and rolls to a normal regen stop.
I used connectors that enable me to bypass the relays and get the cart home if I need to. I hope this will help someone!
Enjoy!

This is excellent news. I have this issue, and i thought i may have to live with it. I use a navitas controller, and a 42.9v LiFePO4 battery from bigbattery - https://bigbattery.com/product/lifep...-cart-battery/

I have some issues where the navitas is shutting down on LV because this LF Pack range is 35-46.8v - however i dont like the immediate stops for sure!

Do you have any additional photos of how you did this on the RXV you can share please?