Basic Nissan Leaf 7 module Lithium setup with Generic Chinese BMS

[trevinom]

Sergio,
Thank you for the response.
So, this means I would have to bypass the OBC to hook up the batteries.
I would also need to use a different charger.
I guess I could hack the current 3 pin plug to bypass everything and charge the lithium batteries directly.

Would I need to do anything with the regenning? Or would bypassing the OBC take care of that?

[Texpie]

Sergio
How did you resolve regen current when the batteries are close to 100% SOC?

[Volt_Ampere]

My recommendation is to never charge to 100%. I charge to about 95% which leaves plenty of room for regen. We don't have any long down hill runs so regen is mostly in place of normal braking which does not add that much charge.

[Sergio]

My Regen brake management is a combination of "headroom" and the Alltrax XCT current/voltage limiting capability.

I charge my Leaf cells to 4.05v and have my BMS HV set to 4.19v in order to allow for "headroom" after the pack is fully charged.

I have my Alltrax "Over Voltage" set to 4.18vpc or 58.5v.

The "Max Regen Armature amps" is 120 amps and the "Max Regen Battery amps" is 80 amps.

I also have a custom interface that only gradually activates Regen brake when I touch the brake pedal (it coasts freely with Accel Pedal up).

After a full charge I am able to get 70 amps and drops to around 35 amps as the pack voltage raises near the 58.5v limit setting on the Alltrax.

After I drive for a while I can get easily 85 amps of Regen brake but since the cart is so much lighter than it was with the FLA that is more than enough to provide a good brake.

I seldom need to press the brake pedal hard to engage the mechanical brake.

[Volt_Ampere]

Hi Sergio, how do you set up the regen on the brake pedal? I just have my Alltrax regen limited somewhat but it's only on the throttle. (Yamaha cart)

[Sergio]

That project has been a journey, V1 used the same Attiny85 board I used to defeat the speed limit of the stubborn Curtis controller in my Excell cart.

After using it for I while I realized it was unnecessarily complex and I could leverage more of the features of the Alltrax to accomplish the task.

The simpler V2 interface worked well and it was a replacement for the FNKS switch, but after using it for a while I decided there was no need for 3 manual modes.

Once I upgraded to Lithium it was also obvious that the fast throttle rate that is fun for forward driving can also be an issue when going in reverse, and I also prefer the cart not to roll freely in reverse when the accelerator pedal is up.

Which bring us to the current compact V3 interface below.

It interfaces with the Alltrax 3-pin FN connector, gets signal and 12v power from the pedal switch, it also taps into the reverse signal so it automatically lowers the throttle rate and adds about 30 amps of pedal up brake in reverse.

I also added another extra input wire for a "mild mode" switch that has some pedal up brake that I mostly use for "hill assist" brake when going downhill with a full cart.

I have enough parts to build a few more and may do that over the holidays for fun.

[Volt_Ampere]

Nice work, Sergio! Do you have info on how it interfaces with the Alltrax? I might want to fool around with something like that too. I have fairly aggressive regen set up on low throttle - I don't use the brakes to slow down for corners. My home grown BMS uses an Arduino for the brains and some real nice differential A/D converters to monitor cell voltages. My display shows all battery voltages, motor and ambient temp, SOC, Date, Time as well as Speedometer and Odometer. It was a fun project that took me over a year to complete in my spare time. It also does top balancing and overcharge protection during charging. For undercharge, I just have a very loud alarm - set very conservatively.

[jhornbr225]

Volt_Ampere, did you put any write-up on your Arduino setup on BGW?

[Volt_Ampere]

No - I sent it to a few that PM'd me.

[smbenson]

I am starting a Leaf upgrade on my 01 36V Txt using the stock controller. This one has regen.

Debating on going with the Zeva BMS vs the cheaper low amp BMS. This may not be the thread to ask, but would the relays be necessary using the Zeva unit? Or does the Zeva have HV/LV cutout because you can run the output though the BMS?

In your wiring you are using the Gigavac relay, can the original Solenoid be used? I am trying to keep it as simple as possible. Obviously, I need to add an onboard lithium charger and 36V to 12V converter to handle the lights/horn.

Any help would be appreciated