Simp BMS

[Boxster EV]

I know the docs say this works with “other Tesla modules” but I didn’t find anything in here specifically for the Mercedes B class batts. Is this compatible?

Yes the B class modules, 7S modules are compatible I personally tested this. They are not good modules however from experience.

Why do you say that?

I think the SOH isn’t overly robust.

[tom91]

I know the docs say this works with “other Tesla modules” but I didn’t find anything in here specifically for the Mercedes B class batts. Is this compatible?

Yes the B class modules, 7S modules are compatible I personally tested this. They are not good modules however from experience.

Why do you say that?

Voltage breakdown to the metal feet of the modules and the general functioning of the modules outside the factory specs is just hard sagging.
Have a look at the Mercedes B Class electric these were used in and its specs are very underwhelming.

[PatrcioEV-ATX]

Yes the B class modules, 7S modules are compatible I personally tested this. They are not good modules however from experience.

Why do you say that?

Voltage breakdown to the metal feet of the modules and the general functioning of the modules outside the factory specs is just hard sagging.
Have a look at the Mercedes B Class electric these were used in and its specs are very underwhelming.

My daily driver is a 2016 B250e. Compared to the 2012 LEAF I had before, it has much better performance. It's not very efficient but really none of the converted ICE vehicles are. I've always assumed that Mercedes imposed a lot of limits on the design (much less power than the motor is capable of, very conservative on battery capacity usage, etc). Even at that, you break the tires loose and traction control takes over if you even try to floor it. It's also very heavy as all Mercedes cars are. I can say that in the years I've owned it, I've only come across one production EV I would replace it with (if I needed to, which I don't) and that is the XC40 Recharge. There has never been a single problem with my B (other than dealers in TX knowing nothing about it) and I've not noticed any battery degradation. Granted, it only has 44k miles on it. Frankly, if my conversion has similar power and range as my B, I will be thrilled. Regardless, those are the batteries I have, so I'll have to make due.

[tom91]

those are the batteries I have, so I'll have to make due.

If your requirements are inline with the base vehicle and not stretching it too far they will work fine. please check if there is any voltage between the battery terminals and the two ally feet on the modules. Also be carefull not to lay it down on the wide side as it can easily damage the cell fuse wires, they are very poorly protected.

[PatrcioEV-ATX]

those are the batteries I have, so I'll have to make due.

If your requirements are inline with the base vehicle and not stretching it too far they will work fine. please check if there is any voltage between the battery terminals and the two ally feet on the modules. Also be carefull not to lay it down on the wide side as it can easily damage the cell fuse wires, they are very poorly protected.

Thanks for the input. Yes, they sides are VERY poorly protected. I'll check the feet too. Right now, they're sitting on a wooden cart I built for them, so I wouldn't have noticed anything.

[alexbeatle]

Hello, folks.
Love the SIMPBMS! I was looking through the manual and found that it can be configured based on the different setup of the contactors.
I was planning to put my contactors (+ve, precharge and -ve) inside the battery box and drive them with the Demien's openinverter Tesla SDU controller. Reading this made me realise I need to somehow engage the contactors for charging. Is anybody else driving the main contactors from different sources - inverter, BMS, etc.?
Also, do you know if I need to go through the pre-charge stage when charging?
Thanks in advance.

[Bratitude]

Also, do you know if I need to go through the pre-charge stage when charging?

if you are counting your charger and inverter threw the same contacts, then yes you'll need precharge for the inverter. you can never directly connect hv to a power stage without first precharging.

but i would not recommend you have your charger wired with the inverter. your power stage would be "on" when charging.

I was planning to put my contactors (+ve, precharge and -ve) inside the battery box and drive them with the Demien's openinverter Tesla SDU controller.

you could have the charger negative connected to the negative contactor, and the positive to the positive end of the battery(with or with out a additional contactor.) this way theres no hv at the inverter when charging.

[alexbeatle]

Also, do you know if I need to go through the pre-charge stage when charging?

if you are counting your charger and inverter threw the same contacts, then yes you'll need precharge for the inverter. you can never directly connect hv to a power stage without first precharging.

but i would not recommend you have your charger wired with the inverter. your power stage would be "on" when charging.

I was planning to put my contactors (+ve, precharge and -ve) inside the battery box and drive them with the Demien's openinverter Tesla SDU controller.

you could have the charger negative connected to the negative contactor, and the positive to the positive end of the battery(with or with out a additional contactor.) this way theres no hv at the inverter when charging.

So my charger is actually a 6kWh charger + DC/DC combo - Elkton TC. The DC/DC will provide the 12VDC to the system, which is why now think that I should let SIMPBMS control the contactors, but use enable signals for the charger and the drive, to select one or the other.

[Bratitude]

let SIMPBMS control the contactors, but use enable signals for the charger and the drive, to select one or the other.

As long as the the inverter is controlling it’s own contactsors. if something else where to switch the main contactors off during drive, there’s a high Possibility of the inverter blowing up.

[RandallATX]

I'm asking Polykup to add support to their MCU for Simp, but in order to do that, they asked the following question:

What is the proper byte for SOC? From the manual it looks like there are multiple

Also, what's the difference between LSB and MSB?

[EV_Builder]

I'm asking Polykup to add support to their MCU for Simp, but in order to do that, they asked the following question:

What is the proper byte for SOC? From the manual it looks like there are multiple
Screenshot_53.png

Also, what's the difference between LSB and MSB?

Easy...
SOC = State Of Charge.
Grab the 0.01% one.

Byte 4 and Byte 5.
Together they make a 16 Bit INT with 0.01% resolution.

Couldn't Polykup come up with this?

[RandallATX]

I'm not here to defend them or not, just trying to solve my challenges on my build.

Thank you for the confirming information!

[EV_Builder]

I'm not here to defend them or not, just trying to solve my challenges on my build.

Thank you for the confirming information!

Yeah; sure no problem. Let us know how it goes.

[meman124]

Hi,

a question: what is the best fork of simpbms to start from to build a bms that gets all its input data

* cell voltages, cell temperature via canbus
* pack voltages and amps via cabus (IVT-S)
* Elcon chargers and DC/DC controller (canbus)

Thanks for helping!

Best regards,
Bart

[EV_Builder]

I would fork a CanBus one and adapt the messages for that one.
Mitsubishi?

[tom91]

a question: what is the best fork of simpbms to start from to build a bms that gets all its input data

The "versions" of the firmware are all based on the kinds of BMS slaves.
The canbus based slaves I would classify in two sets:
-Always broadcasting all data
-Requires a command to send data

The Outlander variant does not require a command to broadcast so the code does not generate one. So this version could be a good starting point.

[meman124]

Thanks. Another set of questions:

1. i discovered the simpcharge hardware to provide J1772 functioning - did i understand this right?
2. where can i buy both the simpbms and simpcharge hardware?
3. what firmware to use?
4. i have a hardware board that can do the J1772 protocol handshake. But it has a Teensy 4.1 onboard. Can we easily port the simpbms to teensy 4.1?


Thanks for helping.

Best regards,

Bart

[tom91]

1. i discovered the simpcharge hardware to provide J1772 functioning - did i understand this right? Correct
2. where can i buy both the simpbms and simpcharge hardware? - There are resellers so please let me know your location, you can use direct messageis if you want.
3. what firmware to use? Depends on your battery slaves used
4. i have a hardware board that can do the J1772 protocol handshake. But it has a Teensy 4.1 onboard. Can we easily port the simpbms to teensy 4.1?It all depends on your own coding skils, what is the other code/controls on this board?

[Turbopete]

Quick one for Tom - I have simp bms running on a teensy with a bmw hybrid battery pack and it has been working great. I spent some time today monitoring can bus signals and at some point I seem to have fried something! Now when I connect the csc modules I’m not receiving and can data at all. Using a canalyst-ii I can see the can bus traffic from simp bms but as soon as I connect the last module all traffic stops. Also the 5v line to the modules is drawing 2 amps which is why I suspect I’ve cooked something. I appreciate this is all user error but if you’ve encountered anything similar or have any tips it would be massively appreciated!

[tom91]

Also the 5v line to the modules is drawing 2 amps

So you are saying you can get some can traffic and module information and the last module kills the canbus?

You also say there is a 2 amp draw on the 5V line, can you please test the canbus traffic and 5V draw with one module then 2 ect.

[Turbopete]

Hi Tom,

i can see can traffic but simpbms does not see any modules at all now. I have tried connecting and disconnecting the modules to see the effects:

Modules connected system current draw can traffic simpbms modules seen
1 0.12A YES 0
1+2 0.17A NO 0
1+3 0.12A YES 0
1+3+4 0.12A YES 0
1+3+4+5 0.17A YES 0
2 0.13A NO 0
3 0.09A YES 0
4 0.09A YES 0
5 0.12A YES 0
5+4 0.14A YES 0
5+4+3 0.14A YES 0
5+4+3+2 0.14A YES 0
5+4+3+2+1 0.27A NO 0
5+3+2+1 0.22A NO 0
5+4+2+1 0.22A NO 0

so from that it looks to me like CSC number 2 has issues and potentially number 5 aswell!

[Turbopete]

To add to that - when i connect module 2 on its own the voltage for hcan goes to 3.68v where as it normally is at 1.54v

[Turbopete]

Ok - i think ive made some progress - i am pretty sure its wiring related as the problem moves with the connectors.

[mjc506]

Also bear in mind the loom is daisychain, and not entirely obvious which order!

[tom91]

Good news everyone,

VW GTE Balancing is confirmed to work after the work I have down in the past week.

The firmware has been updated, verified working and published to Github.

Note: VW E-Golf modules will still required to be verified if they are compatible with the balancing coding.