Need advise on canbus

[Triggertrevor]

Hi all id like some advise on the connection from your battery storage management unit to your battery bank.

I originally looked at the Sofar ME3000SP and pylontech US series of batteries as i already have 4.5kw solar setup running a Sofar inverter so thought continuity with the same manufacturer.
Now after number crunching i realise that to build a 9.6kw system or above i need to have deep pockets.I received some good advise from a guy on this forum regarding picking the right batteries and at the moment i have been looking at 16 280ah lofepo4 batteries which would give me added storage over what i require but that can only be a good thing.
Now the reason why i posted this was because i'm a little unsure what extra bits and bats i would need using the Sofar ME3000SP,would i need a bms,or is this built into the the controller. Now i do believe that the pylontech batteries communicate with the controller via the canbus but if i build my own batteries would i be able to add a canbus so i can see whats going on with the state of the battery and what charge i have in the batteries,whether i'm pulling from the grid or when i need to charge the batteries from the grid etc.

hope i haven't gone on too long but i'm not the best at explaining things

cheers Kev

 

[gnubie]

Canbus defines how to communicate but it doesn't say what the communications contain. Yes, you could setup with canbus for your own battery, there's probably even BMSes out there that have canbus as their way to communicate, but you'd then need translate the messages between the devices as they almost certainly wouldn't be asking and answering the right questions to allow them to chit-chat.

Do-able with a microcontroller / arduino sure, but definitely not for the beginner.

 

[Triggertrevor]

Canbus defines how to communicate but it doesn't say what the communications contain. Yes, you could setup with canbus for your own battery, there's probably even BMSes out there that have canbus as their way to communicate, but you'd then need translate the messages between the devices as they almost certainly wouldn't be asking and answering the right questions to allow them to chit-chat.

Do-able with a microcontroller / arduino sure, but definitely not for the beginner.

cheers for your reply,so how do you think the Sofar ME3000Sp talks to the pylontech batteries to be able to show the info it shows on its front screen,like battery level,solar production,whether its pulling from the battery or pulling from the grid.

cheers Kev

 

[gnubie]

The firmware in it would be set up to communicate with the pylon. It's not the only unit that can talk to pylon batteries, some model MPP solar units can too. Victron's GX can talk to them too.

 

[Triggertrevor]

The firmware in it would be set up to communicate with the pylon. It's not the only unit that can talk to pylon batteries, some model MPP solar units can too. Victron's GX can talk to them too.

I dont know your setup or experience but can you point me in the right direction regarding what i'm trying to achieve. i think ive got my head around the battery side of things but i need to be able to monitor things to make it worth while and with me being in the uk its not always the sunniest country so i'll be using a time of use tariff to top things up when the solar falls short but if i cant monitor this it makes it more difficult to make things cost effective.

cheers Kev

 

[gnubie]

You're going down a deep rabbit hole with this

Pylontech canbus

That'll let you discover what the pylontech battery is transmitting on the canbus. I saw some arduino links in there so odds on you can find out how to use one of them to do canbus communications. The arduino takes readings from your BMS in what ever way the BMS provides that, yet more fun there because if its not plain text you'll need to find out how the BMS communicates, or monitors the battery itself via some method, and ADC board etc, then periodically transmits that on the canbus as if it were a pylontech battery.

If the Sofar is just listening to the periodic transmissions from the pylontech that may be enough to get you going.

 

[Triggertrevor]

You're going down a deep rabbit hole with this

Pylontech canbus

That'll let you discover what the pylontech battery is transmitting on the canbus. I saw some arduino links in there so odds on you can find out how to use one of them to do canbus communications. The arduino takes readings from your BMS in what ever way the BMS provides that, yet more fun there because if its not plain text you'll need to find out how the BMS communicates, or monitors the battery itself via some method, and ADC board etc, then periodically transmits that on the canbus as if it were a pylontech battery.

If the Sofar is just listening to the periodic transmissions from the pylontech that may be enough to get you going.

So would i be right in saying that unless i go with say a plug and play battery then i'm going to run into these kind of problems or is there some kind of work around to be able to view this battery info i.e 3rd party software or somtehing a little easier than what you proposed.

cheers Kev

 

[gnubie]

I think that is going to be the case. Someone out there may well have already been there, done that, and have a solution for making a 3rd party battery be able to communicate with the Sofar, but finding it is going to be the trick.

 

[Triggertrevor]

I think that is going to be the case. Someone out there may well have already been there, done that, and have a solution for making a 3rd party battery be able to communicate with the Sofar, but finding it is going to be the trick.

Well thanks for getting back to me,should i just wait to see if anyone gets back to me or should i post this in another part of the forum.

cheers Kev

 

[gnubie]

Anything's possible but probably no one here has done it, I was really referring to the many 'open source' style projects you can find with Google etc.

 

[Triggertrevor]

Anything's possible but probably no one here has done it, I was really referring to the many 'open source' style projects you can find with Google etc.

So in your opinion what kind of information is possible to get from a DIY battery and a ac battery inverter
Cheers kev

 

[gnubie]

With a smart BMS with serial comms of some sort it'd be possible to make it look like a pylontech battery as far as your sofar inverter would be concerned but this is all very hypothetical. Someone with hands on both your make / model inverter. BMS and pylontech battery would be able to make it work, so if you want to ship both of them to me

 

[Triggertrevor]

With a smart BMS with serial comms of some sort it'd be possible to make it look like a pylontech battery as far as your sofar inverter would be concerned but this is all very hypothetical. Someone with hands on both your make / model inverter. BMS and pylontech battery would be able to make it work, so if you want to ship both of them to me

Let me box em up and they'll be on there way?
So your saying they should be a possible workaround to get the information that I would like to see for the day to day running.

 

[gnubie]

We started making your batteries look like pylontech's so that all this info would be presented via your sofar inverter, if you can do away with that aspect of things you could just get a smart BMS with bluetooth and then be able to see the state of your DIY battery down to the cell level.

If I've misread and you aren't making your own battery just buying off the shelf units with a dumb BMS fitted it'd be more difficult but you could get basic stats using a current shunt etc but the level of difficult is changing all the time here. Still not something for the beginner.

 

[Triggertrevor]

We started making your batteries look like pylontech's so that all this info would be presented via your sofar inverter, if you can do away with that aspect of things you could just get a smart BMS with bluetooth and then be able to see the state of your DIY battery down to the cell level.

If I've misread and you aren't making your own battery just buying off the shelf units with a dumb BMS fitted it'd be more difficult but you could get basic stats using a current shunt etc but the level of difficult is changing all the time here. Still not something for the beginner.

No I want to build my own batteries but the front panel of the sofar battery inverter shows
1 what's coming in off your panels
2 battery level
3 if the battery is charging from the grid or the panels
4 if I'm pulling from the grid
So I didn't know whether I'd get that sort of info by hooking DIY battery.
Also if I'm using a time of use tariff and hooking up a DIY battery would the sofar ac battery inverter know when I want to charge the battery using the tariff if there's no coms/canbus.?
Cheers kev

 

[gnubie]

Sorry, there's nothing more that I can say here. As I said, its all hypthetical, probably do-able, but I can't say exactly what may or may not be possible with your stuff.

 

[Triggertrevor]

Sorry, there's nothing more that I can say here. As I said, its all hypthetical, probably do-able, but I can't say exactly what may or may not be possible with your stuff.

Thanks for the info.
All I don't want to do is spend all this money on a system that only half works.
If I had a system that got me there in the end but wasn't as straight forward as plug and play I'd be happy but to go out and spend say £2000-£2500 on the hope it's all going to work is too much if a risk.

 

[Jeremiah]

A friend has a SOFAR hybrid inverter. seems it only allows him to use 1 of 3 manufacturers if he wants to upgrade to Lithium.
There is a generic "Lithium" mode but it wants to communicate on the CAN or RS485 bus with the bmS of the battery or it won't work. Seems they are partners with their overpriced Lithium batteries that are approved. There is also no way to set absolute voltage for charging etc that I have found. Do you see this anywhere on yours?
Pretty strange for a pricey inverter to not allow such customization. I guess they are just trying to force people to buy from their partners so they get kickbacks.

 

[sergea]

Thanks for the info.
All I don't want to do is spend all this money on a system that only half works.
If I had a system that got me there in the end but wasn't as straight forward as plug and play I'd be happy but to go out and spend say £2000-£2500 on the hope it's all going to work is too much if a risk.

if your inverter can only be use with supported bms battery, you're out of luck. According to the documentation sup

if you really want to have a DIY batterie BMS connect with CAN to your inverter , you will need to:
- collect the BMS CAN protocol supported by your inverter

 

[sergea]

According to the inverter documentation supported batteries are


1.DARFON DARFON
EAA01 2.7KWH
DARFON EIA02 5KWH

2.PYLON
PYLONTECH US2000B
(BMS firmware should be B62 or newer)

3.TELE
TELE LEAD CRYSTAL

4.DEFAULT
LEAD ACID / AQUION



So what you need to do is :

- #1 to emulate the bms protocol of one of this batteries. you will need the BMS protocole specification (BTW
your inverter supporte pylontech on the rs485 port, not CAN port) , and you will probably want to know what subset of this protocol your inverter is using (no need to emulate the full protocol).


- #2 chose a bms for your battery with a documented BMS protocol specification


- #3 use a esp32 (or arduino or rasberry) to translate from one protocole to the other.


let say, you going to emulate pylontech battery.
- pylontech bms specs are not public, but you can find it

- you still need to get the messages your inverter exchanges with the bms. (so you need to only emulate a subset of pylonthec bMS protole)

- some bms on the market have documented specification (eg: daly), in general this document are very limited and not always readable, with no tutorial or code examples.


[inv]-rs485---------[esp32]---rs485-or-CAN---------[yourBMS]-[your-battery]

The more complicated task is to understand your BMS documentation, because most of them are really sparse.


ofcourse it would be easier if you can get a BMS compatible with pylontech protocol and a rs485 interface



BTW if someone can capture the msg exchange by a MPPsolar inverterbwith pylonthec I'am interested