Victron VenusOS driver for serial connected BMS - LLT/JBD / Daly Smart / ANT / JKBMS / Heltec / Renogy

jamiegreen

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The JK converter is most likely an isolation device. This is a safety device that makes sure the power from the battery has no way to get the the RS485 bus and on to your PC/GX. Most isolation devices use a opto chip. Essentially a man on either side of the river showing flags to the guy on the other bank, and that man talks on the phone to relay the message.
If they use different voltage then they cannot hurt each other.
It's the same reason you don't connect the V+
I assume the signal pins operate at the same voltage though? Or does that sound dumb.
 

jamiegreen

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OK, thanks for the explanation.

It seems mine has a slightly different connector on the BMS side and separate ones for RS485 and GPS.
Ah well that may well explain why the BMS with "GPS" included has the +voltage pin too, it's possibly there to power the GPS module directly from the battery.
 

jamiegreen

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LLT, RS232 and RS485 each have their own voltages they work at. (3.3, 13V, 5V if I remember correctly)
So it's all pretty standard, the BMS will output (5v?) Signals through its rs485 and the rs485 converter box will accept those voltage signals, I'll probably buy a converter with a ground connection too to rule out any problems there.
No doubt someone will probably get around to testing before me, I'm waiting on the BMS to probably arrive early December and a few bits to get ready beforehand too, so probably closer to Christmas time.
 

jamiegreen

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Well let me know if you figure it out. Otherwise I'm using whatever I can make fit, I've got some 3 pin PC fan cables here, maybe some filing might be in order.
 

jimcalf

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I am building two 8S 230ah battery packs, and had purchased two JBD 8S 100A BMS, with UART/BT dongle. After reading through all the comments, it seems that running two JBD BMS in parallel isn't really supported yet by this driver. Would you recommend that I swap out the 2 100A BMS for a 200A 8s single BMS, with 485 and BT this time, and configure my cells as 2P8S to fully take advantage of BMS reporting to my Cerbo GX?
 

Louisvdw

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two JBD BMS in parallel isn't really supported yet by this driver
So the multi bank is not supported, but that does not mean it will not work. If you have the 2x 100A BMS I would suggest you keep them. You will get power from both BMS and you will see both in the device list section of the Remote Console, but they will override each other so it will seem that there is only one BMS.

Here is some pictures that might better explain (as this is how I am currently running it.
Here is the JBL and JKBMS both in the device list:
1637603517500.png

But in the dashboard you only see the JBL and it's values (see the 30% SOC)
1637603604071.png
And in VRM you will also only see the one.

The system itself will function fine. It will charge and discharge both. But the settings and limits will only come from the one.
 

Horsefly

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So the multi bank is not supported, but that does not mean it will not work. If you have the 2x 100A BMS I would suggest you keep them. You will get power from both BMS and you will see both in the device list section of the Remote Console, but they will override each other so it will seem that there is only one BMS.

Here is some pictures that might better explain (as this is how I am currently running it.
Here is the JBL and JKBMS both in the device list:
View attachment 73206

But in the dashboard you only see the JBL and it's values (see the 30% SOC)
View attachment 73207
And in VRM you will also only see the one.

The system itself will function fine. It will charge and discharge both. But the settings and limits will only come from the one.
My situation is somewhat similar to @jimcalf. I'm putting together 2 4S 280Ah batteries with 100A JBD BMS's. You haven't said it specifically, but it sounds like it is the Cerbo GX / VenusOS that can only see the world as one battery. Is that right?

In my situation, I have a VE SmartShunt that the combined batteries will hook up to. I don't like giving up the BT settings for the two separate BMS's / Batteries, but can't the SmartShunt be the source of info for the GX? That is, I'm leaning towards keeping the BT dongles on both BMS's, and have the SmartShunt represent the pair of batteries (the battery "bank") as the "battery" for the Cerbo GX / VenusOS. Does that sound reasonable?
 

jimcalf

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So the multi bank is not supported, but that does not mean it will not work. If you have the 2x 100A BMS I would suggest you keep them. You will get power from both BMS and you will see both in the device list section of the Remote Console, but they will override each other so it will seem that there is only one BMS.

Here is some pictures that might better explain (as this is how I am currently running it.
Here is the JBL and JKBMS both in the device list:
View attachment 73206

But in the dashboard you only see the JBL and it's values (see the 30% SOC)
View attachment 73207
And in VRM you will also only see the one.

The system itself will function fine. It will charge and discharge both. But the settings and limits will only come from the one.
Thanks! I should have my batteries shortly, as well as the Victron gear (both on order) and will definitely implement this. Since both 8S battery banks will be identical, and I'll work very hard to ensure equal cable resistance, etc., they should charge and discharge in a very similar way. I was thinking of extending the UART port to an easy to reach connection, so I can easily swap in the BT dongle when I wanted to change any settings, but otherwise, have both BMS connected to the Cerbo GX.
I also have a SmartShunt as part of my Victron order. Do you see a compelling reason to have that installed in addition to the connected BMSs, which as you've noted before, have their own shunts? Perhaps to see "Actual" charge and discharge for both batteries combined, vs. only the predictive offered by the BMS?
 

Horsefly

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I also have a SmartShunt as part of my Victron order. Do you see a compelling reason to have that installed in addition to the connected BMSs, which as you've noted before, have their own shunts? Perhaps to see "Actual" charge and discharge for both batteries combined, vs. only the predictive offered by the BMS?
My experience is that the VE SmartShunt seems much more accurate than the BMS for SoC, and that is one of the reasons I thought it better to give the Cerbo GX something to display graphically, even though it is for the combination of two batteries.
I can easily swap in the BT dongle when I wanted to change any settings, but otherwise, have both BMS connected to the Cerbo GX.
This won't work in my situation. I'm doing this work for someone else, and if I tell him he'll need to swap out the UART connection to plug in the BT dongle he will just stare back at me like a deer facing headlights.
 

jimcalf

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This won't work in my situation. I'm doing this work for someone else, and if I tell him he'll need to swap out the UART connection to plug in the BT dongle he will just stare back at me like a deer facing headlights.
Yeah, I'm a very curious technologist, and this stuff is challenging for me. If I were to ever sell the rig, I'd likely just leave the BMS plugged into the Cerbo and say "don't touch anything". Being able to change settings via BT can be dangerous for folks who just want to play around without understanding the ramifications.
 

Louisvdw

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Do you have this functionality on your roadmap
Yes it is on the todo https://github.com/Louisvdw/dbus-serialbattery/issues/8

it is the Cerbo GX / VenusOS that can only see the world as one battery
The VenusOS does have the ability to handle multiple batteries. It is called banks. But combining the values is done in the battery and not in the GX. Normally in a battery there will be a master battery that you select with a switch in your setup, but the driver has to do this in software. There is a few steps to complete in the plan to get this all done.

can't the SmartShunt be the source of info for the GX
Do you see a compelling reason to have the Smartshunt installed in addition to the connected BMSs
Yes you can use the shunt as the source for the battery, but there is a few issues with that. As a shunt the smartshunt is more acurate, but as a source of SOC the BMS is king by far. Read this post for more detail info on why I say this.
I think you would be better of with the BMS data from one battery that can alert you, than just the SOC from a SmartShunt, but you can choose which one to use inside the GX. If you have 2x duplicate batteries just double the current and power you see in the Remote Console. But the SOC will be more acurate with the BMS and that is what you need. The current and power is just nice and is not used in any logic in in the GX.

swap in the BT dongle when I wanted to change any settings
To be honest once you have set up your BMS you don't need the bluetooth anymore. My bluetooth connection has been in my drawer for more than a year as all I need to see is in the GX and VRM.
 

Horsefly

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Yes you can use the shunt as the source for the battery, but there is a few issues with that. As a shunt the smartshunt is more acurate, but as a source of SOC the BMS is king by far. Read this post for more detail info on why I say this.
I think you would be better of with the BMS data from one battery that can alert you, than just the SOC from a SmartShunt, but you can choose which one to use inside the GX. If you have 2x duplicate batteries just double the current and power you see in the Remote Console. But the SOC will be more acurate with the BMS and that is what you need. The current and power is just nice and is not used in any logic in in the GX.
Well, I guess we will just disagree. The SmartShunt is far better at Coulomb counting that the JBD BMS, and despite what you said in the post you linked to, accurate history of the current that has gone into and out of the battery is the best indication of SoC. This is especially true of LFP batteries, which - because they are so efficient - get close to the current out that you put in.

Your other post suggests that because the BMS knows cell voltages, it somehow can give a better SoC estimate. For LFP, that is especially wrong. Voltage is not any indication of SoC. You also said the BMS knows something about cell resistance, and somehow the BMS factors that into its more accurate estimate of SoC. I don't get that, and I know that my JBD BMS has no idea of cell resistance.

I've observed my JBD BMS and my Victron SmartShunt for months now, and went for over two months doing small discharges now and then but not charging the pack back up. The Shunt had the correct number of Ah delivered, which - for the most part - is all that you need to know to know SoC. Meanwhile the the BMS was showing at 15% lower SoC that was clearly wrong.
 
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Louisvdw

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The SmartShunt is far better at Coulomb counting that the JBD BMS
As a shunt the smartshunt is more acurate
Yes, that is what I also said :). But Coulomb counting is not the SOC of a battery.
And that is why I cannot agree that an external shunt gives a better SOC. It might give a better energy counter.

I am also not saying the cell voltages is gives a better SOC. You cannot mearure the SOC from the voltage in Lithium batteries. But adding those voltages into you prediction does give a better estimation.

No 2 cells are the same. They drift over time. The smartshunt will know nothing about what is happening inside your battery. While your battery is new it might be fine, but when your cells do start to drift or their capacity depreciates the smartshunt will give you a far worse SOC estimation, while the BMS has the inputs that will adjust this. That is where the cell voltages come in.

In your JBD app you have set of voltage cell limits. When a cell goes over those limits it will adjust the SOC values from what it's internal shunt calculated. So those cell voltages are used to correct the SOC and keep it in check. This is more acurate over the life of your battery.
You will also notice that those cell voltages set up are very close each other between 30-70% and then jump faster to the extreme sides. So there are a larger chance for an adjustment if a cell out of what from the others which you will see in those extremes.

PS. You do have the option to calibrate your JBD shunt using the PC software. Do that and you will have best of both worlds.

JBD BMS has know idea of cell resistance
Correct the JBD does not. But others do. I don't know the exact formulas and input for each BMS, but you can figure out the basics each one use.
JKBMS for instance does have the cell resistance as one of it's inputs.

Screenshot_20211123-163506.jpg
 

Martijn

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Well let me know if you figure it out. Otherwise I'm using whatever I can make fit, I've got some 3 pin PC fan cables here, maybe some filing might be in order.
I've got a PC case fan here as well, but on the female connector, the pin holes are 2.5mm apart.

I just checked my BMS, pins are 1.25mm apart, so that won't fit.

I did find these, 3 or 4 pins available:
 
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jamiegreen

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I've got a PC case fan here as well, but on the female connector, the pin holes are 2.5mm apart.

I just checked my BMS, pins are 1.25mm apart, so that won't fit.

I did find these, 3 or 4 pins available:
I received my BMS today and see what your saying about the pins, they are very small unusual things. I'm not going to order anything from ali etc as if I do that I might as well order the proper JK one.

I don't know if maybe the female pins on this converter may fit in there, I'll order it and fine out... there's always a way.
 

Martijn

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I received my BMS today and see what your saying about the pins, they are very small unusual things. I'm not going to order anything from ali etc as if I do that I might as well order the proper JK one.

I don't know if maybe the female pins on this converter may fit in there, I'll order it and fine out... there's always a way.
Yep, very small. I ordered a set of the cables I mentioned, and the USB-serial converter. Let's see.

I couldn't find an 'official JK' thing with a female 3-pin slot, so that puzzled me. And you still need the USB converter after that.

When the stuff arrives, I'll let you know, current expectation is that this will be somewhere in December ;)
 
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