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SBox - do I need to open precharge relay to run
Posted: Mon Feb 09, 2026 12:27 pm
by FFMan
Using the Sbox and assumed the order would be:-
1) Neg & precharge contactors close and wait (0xA6)
2) Positive contactor close and wait (0xAA-all close)
3) Precharge contactor open
I can't find a way of making step 3 work, perhaps it isn't necessary ?
what have people done when using the SBox ?
Re: SBox - do I need to open precharge relay to run
Posted: Mon Feb 09, 2026 12:42 pm
by tom91
Precharge does not open when using zombie.
Re: SBox - do I need to open precharge relay to run
Posted: Mon Feb 09, 2026 12:47 pm
by FFMan
tom91 wrote: ↑Mon Feb 09, 2026 12:42 pm
Precharge does not open when using zombie.
ok thanks - seems to be ok then in operation
Re: SBox - do I need to open precharge relay to run
Posted: Mon Feb 09, 2026 1:18 pm
by FFMan
Does anyone know which messages are sent. I ask because with a resistance meter across the positive in & out terminals, i can see precharge has 160ohm resistance when I close negative and precharge contactors (0xA6)
When I switch to all closed (0xAA) the resistance stays at 160, where I know if i close the positive contactor on its own I see less than 1 ohm.
This suggest that all_close is not closing the positive contactor.
Re: SBox - do I need to open precharge relay to run
Posted: Mon Feb 09, 2026 2:30 pm
by tom91
What setup are you using to control the SBox? This has been implemented in Zombie code, so just have a look there.
Re: SBox - do I need to open precharge relay to run
Posted: Mon Feb 09, 2026 4:04 pm
by FFMan
tom91 wrote: ↑Mon Feb 09, 2026 2:30 pm
What setup are you using to control the SBox? This has been implemented in Zombie code, so just have a look there.
I am using a Teensy 4.1, i didn't go the official zombie route as when i did my first conversion some 4+ years ago I started with the Prius inverter with Damiens drop in board. After a while i swapped that in favour of using the Phev inverter which is really easy to control. When all this lot was in my BMW 320d conversion that was all ok, there wasn't much involved in keeping the car alive and driving the dash.
Switch to now and I'm doing the same in a Jimny, but it has no need of the clever zombie stuff to keep systems working as there is no can bus in the car, so i am once again using my own VCU based on a Teensy 4.0, coupled with a Teensy 4.1 which does all the house keeping and UI.
My original build used stand alone hard wired contactors with hardware timing for pre-charge, i figured i never wanted a code hang to cause a contactor drop mid flight. I think I have got over that fear and have an SBox to use.
I'll have a look at some zombie code - good suggestion