Simp BMS

[tom91]

You will always require OEM cell monitoring circuits(CMU). You can wire up cells to compatible OEM CMU, people have done this with succes.

Are there really no BMW or VW hybrids were you are based?

[Ctwidle]

Aus has been very slow to jump on the ev train so numbers on the road are still very low. Range anxiety has been a huge factor - or maybe they are just such careful drivers! I keep searching but ebay offerings are all from Europe and I haven’t found a local wrecker with anything. Maybe I just need to be patient.

[m.art.y]

From my reading SimpBMS (and its successor) seem to have been designed around reusing OEM BMS systems, can it be configured to handle a pack of 96s cells?

If you have a SimpBMS already then you can use OEM BMS slave boards from Tesla battery modules. A few of us went that route when original BMS for a pack is non existent or not an option. So you can do the same with any cells that you can find. I too have those Tesla slave boards for sale, they are very easy to wire up. I have a contact in Australia who is dealing with battery packs will ask if he has anything suitable for you.
Also check out this thread where a guy from Australia imported batteries from China he gives out all the costs:
viewtopic.php?p=30509&hilit=LTO#p30509

[Ctwidle]

Hmm, maybe the Chinese are a little less concerned about shipping Lithium! I’m Surprised I hadn’t seen that thread, he’s only an hour or so from me, wonder if he’s finished yet?
No I wasn’t able to find a simpBMS without a ridiculous shipping fee from the US and had been looking at Tom’s newer version, particularly the VCU. I’m basically trying to get all my ducks lined up before I reach for the hammer and break open the piggy bank.
I’d appreciate any contact details for battery packs, I still have one plan to try after the weekend, there is a nationwide ‘wrecker’s hotline’ that might be worth a phone call.

[7yatna]

I just had an aborted attempt to buy a BMW pack from the UK but the seller didn’t realise the complexity of international freight for lithium and eventually the best he could come up with was a port to port shipment for an additional £2000.
Local sources of secondhand packs are at best sketchy and all I have been able to find readily available are 94Ah cells. From my reading SimpBMS (and its successor) seem to have been designed around reusing OEM BMS systems, can it be configured to handle a pack of 96s cells?

Hi there,

yes I can confirm that SImp BMS can control and work with OEM Slave BMSs.

i have Simp BMS controlling my BMW 530 E Plug in hybrid Pack .

it is 96 Cell Pack.

the 94Ah is bmw I3 i believe so it can do that as well with no problem

[Ctwidle]

Sorry, didn’t make myself clear. I was wondering if Simp could be configured to work with 96 individual cells without an OEM cell balancing system. It has been confirmed by Tom that an OEM system is required although m.art.y has suggested that it might be possible to use one from a different manufacturer.
In the mean time I continue to chase a pack from closer to home.

[Bratitude]

m.art.y has suggested that it might be possible to use one from a different manufacturer.

i wired a gen 1 volt bms to a gen 2 volt battery, running simpbms.

vwbrady wired tesla slaves to some obscure battery and is running simpbms.

just a bit of work.

[Cristian85]

No it does not feel free to port it over like others have.

I have created a new product using the Teensy 4.0, this is no longer open source.

Hi Tom.
I got Simpbms 2.4 board with Teensy 3.2
The old board 2.4 will be compatibile with Teensy 4.0?
I want to use VW ID4-5 8S for powerwall. Where is possible to found the Code for that?
Thank you

[royhen99]

.

[tom91]

I want to use VW ID4-5 8S for powerwall. Where is possible to found the Code for that?

Yes check the topics on this. https://openinverter.org/forum/viewtopic.php?t=1948

[domoticasolar]

@tom91
1. When i start simpBMS i get 96 cells and errors! When i observed debugg screen i found system is counting 12 cells and 8 strings as it should, but it also shows cell 12 as 0V. I noticed it starts to count at cell 0?
VW cells1.jpg
I am using latest VW software...

hi, thanks for this wonderful product
i have the same problem using vw latest firmware (VWBMSV2.ino.TEENSY32.hex from 2 months ago, i don't know how to compile some new changes)
i see from cell0 to cell12 (13 cells) and last one is always at 0.0V
i have check on battery settings and "cells in series per string" is 12.
check on debug and "cell present reset" is 12 too.
what i'm doing wrong?
best regards

[tom91]

hi, thanks for this wonderful product
i have the same problem using vw latest firmware (VWBMSV2.ino.TEENSY32.hex from 2 months ago, i don't know how to compile some new changes)
i see from cell0 to cell12 (13 cells) and last one is always at 0.0V
i have check on battery settings and "cells in series per string" is 12.
check on debug and "cell present reset" is 12 too.
what i'm doing wrong?
best regards

Nothing. The read out is not adjusted to the amount of cells present it will provide the CAN fields even if they are 0 or N/A.

This can be ignored it has not impact on the function of the BMS, you set a minimum voltage for the BMS to ignore the cells that are not physically there.

[LRBen]

Has anyone else found their Tesla slave boards not balancing with SIMP? I've had my setup in for a couple months now and sorted out all the issues I had with voltage readings, which was caused by poor soldering of cell taps onto the boards.

I have played around with the balance settings quite a bit, it will say that it is balancing when a cell hits a set voltage as it should do. However I can leave it overnight multiple times and there will be 0 difference in the delta. Although it does seem to be changing slowly over very long periods. It looks like I have lowered my delta by around 20mV in 3 months. Although it has not been on 24/7 for all that time and they are 53aH cells. Could it just be a case that these boards are not really designed to balance that fast?

This is from the 28th September

This is from this morning at a very similar high cell voltage.

[martii]

Yes check the topics on this. viewtopic.php?t=1948

Tom it looks like Teensy 3.2 is RIP - do you mind if I'll start porting job of your code to Teensy 4.0 (via GitHub fork) and base new PCB on your old design?
(Teensy 4.0 pins are only 3.3V capable)

Happy New Year !

[tom91]

Tom it looks like Teensy 3.2 is RIP - do you mind if I'll start porting job of your code to Teensy 4.0 (via GitHub fork) and base new PCB on your old design?
(Teensy 4.0 pins are only 3.3V capable)

Happy New Year !

I have designed a new product the EVS-BMS https://citini.com/product/evs-battery- ... nt-system/

You are allowed to port it, it is opensource for a reason. However I will refuse to provide support to anyone who is not running the SimpBMS firmware as is on SimpBMS hardware.

[martii]

Sure thing about support - Happy New Year !

[evMacGyver]

Although it does seem to be changing slowly over very long periods. It looks like I have lowered my delta by around 20mV in 3 months. Although it has not been on 24/7 for all that time and they are 53aH cells. Could it just be a case that these boards are not really designed to balance that fast?

Tesla board balance is really slow by its design, for your almost 200mV delta I would recommend balancing somehow different to get it closer to zero. My tesla S pack did have 12mV delta and now I've been balancing it in the garage while not driving ev conversion during winter. Something like 1mV balancing for a week is my best guess.

I haven't found documentation for balaceDuty value. It is 50% by default for Tesla S, it would speed up balancing but is there some limiting factors to set it higher?

[tom91]

I haven't found documentation for balaceDuty value. It is 50% by default for Tesla S, it would speed up balancing but is there some limiting factors to set it higher?

It exists due to certain boards/slaves having issues like heating up the traces/smd fuses that have caused issues in the past. For the Tesla model s this is not present. Due to the way the balancing works it should not be an issue, as its a timer and the command is issued every "read cycle", so at a bout 500ms intervals.

[nilsvr]

Hello, i know that kind of the same question was already asked some time back in this forum, but I am not fully satisfied by the answers.

The question is about contactor control for charging.
My idea is to have a similar setup as it exists in the Model S already:
Battery then the contactors (main, negative and precharge) and behind that the inverter and charger.

To switch the contactors I was thinking of running a ground switched OR configuration from both the openinverter board (for driving) and the simpBMS (for charging).

I already got an answer from johu that the inverter has no problem with HV connected while its 12V supply is off, but precharge of course is still necessary.

Now to my two problems:
As far as I can tell the simpBMS has no ground switched precharge pin. Do I see that correctly? (Not a huge problem. Solvable by a 12v switched relay that then ground switches the precharge contactor.)
The bigger problem is that the simpBMS seems to not do a precharge at all when going into charge mode. (At least thats what the documentation tells me... I am not at home currently and therefore cant test it.)

I know there are less complicated systems to wire your 12v charging and driving setup but I like the simplicity on the HV side (plus I am stubborn and want it like that).

Does anyone see a huge flaw with my system and is it even possible to make the simpBMS do a precharge when entering charge mode?

[tom91]

As far as I can tell the simpBMS has no ground switched precharge pin. Do I see that correctly? (Not a huge problem. Solvable by a 12v switched relay that then ground switches the precharge contactor.)

Correct

The bigger problem is that the simpBMS seems to not do a precharge at all when going into charge mode. (At least thats what the documentation tells me... I am not at home currently and therefore cant test it.)

Incorrect, it will precharge and handle contactors normally if you tell it the Charger is on the HV bus and not direct to battery.

[nilsvr]

Thank you Tom for the quick answer. That is great news.

[JaniK]

Is there an Outlander charger working code for the original SimpBMS?

I found this: https://github.com/jamiejones85/VW-bms/ ... WBMSV2.ino

But it says it's for a modified board, I have old unmodified SimpBMS from @tom91 for VW from the time there was no balancing.
I want to update the SimpBMS firmware to support: ISA Shunt, e-golf balancing and Outlander charger.

[tom91]

E-Golf balancing is on the latest VW firmware, so is the ISA Shunt.

Just Outlander Charger is not on the SimpBMS firmware. Should not be alot of work to add, so could potentially have a look at it.

[vwbrady]

J5 is input

J4 has the outputs on it, these are matched to BMS states. Pin 13 is the 12V charge enable, so if the BMS is in the charge state this output is on.

https://github.com/tomdebree/SimpBMS/bl ... 0V0.21.pdf

I realize the above is a very old post, but after spending hours on this I haven't been able to find an answer.

A/C is present | cell voltage limit not reached, but BMS stays in Ready or Drive state. Why?

ran output debug and charge enable is cycling.

I am not using a current sensor or temp sensors.
I need to get the charge enable output working and this seems to be the missing piece.

Data

debug:

Screenshot 2023-03-05 224422.jpg (24.53 KiB) Viewed 23540 times

Batt Settings:

Chg Settings:

[royhen99]

This came up in another thread a few weeks ago. The hysteresis value is too high and also the battery is almost fully charged. I am not totally sure on this but If you reduce the charge hysteresis to 100mV it might work.