Sleep mode on Zeva BMS16 V3

[Bobbob]

I finished my 14S2P Nissan Leaf pack using Sergio circuit using small relays. When bench testing I found that the Zeva would not be in the sleep mode when powered up. I found this odd, according to the diagram the B- should of put it to sleep until the KSI switch was turned on.


I had used Sergio optional Auto sleep mode Relay K4. I found that when powered on Zeva will not go into sleep mode using the B- signal from the battery. The only ground that works to put Zeva to sleep is the ground next to the sleep terminal. I did try all B- terminals on circuit just to make sure I was not mistaken.

I found that if I disconnected com on K4 relay from B- and than connected it to the ground next to the sleep terminal it works as it should. When you power relay K1 with the KSI it takes the Zeva out of sleep mode like it should do.

The diagram I have shown below shows the correct way it should be hooked up. K2 relay is also wired a little different to allow the cheaper Chinese power supply’s to charge up before activating K2. That change was from a post after texting with Sergio on his original diagram.

Sergio if you or anybody else wants to comment feel free.




Sent from my iPad using Tapatalk

[Sergio]

I am not sure where that notation on the top left comes from, here is the original drawing I posted on that thread:

Is there a reason why you are trying to use the temp sensor "ground" terminal for K4 instead on B-?

Make sure K4 COM is B- and K4 N.C. is Zeva Sleep input

When I suggested that design I was not aware the cheap chargers drained power when not powered and had large filter capacitors that sparked heavily when first connected as I don't recall anyone mentioning before.

I did experience both of those events when I was doing my pack and came up with the zenner diode as a way to allow the charger to "pre-charge" before the relay closed.

Changing K3 COM terminal from B+ to Charger+ as You did will also delay K2 closing until the charger voltage rises to around 36v or longer if the Zeva was sleeping and woke up due to K3 being powered by 120Vac and closing.

[Bobbob]

I made the change on the original diagram and added the notation. Using B- through the K4 relay did not put the Zeva to sleep. I then disconnected the com terminal from B-. I hooked a jumper from the com terminal then went to every B- on the circuit. The only terminal that put Zeva to sleep was the ground terminal that is used with temp probe.

I have no idea why the normal B- did not put the Zeva to sleep.

I just sent a question to Zeva to see if B- and ground terminal are different.


Sent from my iPad using Tapatalk

[Sergio]

I think I misunderstood your question last night, since the Zeva BMS now has an isolated CAN bus, likely the power supply for the entire logic board is also isolated.

That means there is no reference to B- but since the K4 relay provides an isolated switch, using a "ground terminal" available on the Zeva board instead of B- as You shown in your diagram is the correct way to wire the sleep switch.

[Bobbob]

Sergio you are correct on your answer.

This was Ian response from Zeva:

Yes, with V3 the cell sampling electronics is fully isolated from the logic board (including sleep function), so B- and the ground terminals are not connected at all. This was primarily needed so that the CAN bus was isolated from the battery, allowing it to be connected safely to third party devices like battery storage inverters for example. But in most other applications it would be safe to connect Gnd and B- together with a wire at the BMS if you wanted it to be non-isolated.

I hope this helps anybody else who is building with your circuit to understand the difference between B- and ground on the version 3 Zeva BMS.


Sent from my iPad using Tapatalk