LFP Ext. Regulators: Why do Volts and Amps need to be sampled?

[rgleason]

@s/v Jedi Is it this resource that you are suggesting Arduino Sketches ? I programmed in pascal for DataCAD years ago. I am very humbled by C++ but have been compiling plugins for OpenCPN and trying to fix small bugs. The ability to program my own BMS would be quite attractive, but I am unsure of many BMS details (though I've gotten some distance down that road) and my coding prowess with arduino is totally unproven. I think I should probably stick to building plugins for the OpenCPN community! Goboatingnow was starting to work on a BMS and so were you I thought.


Is it true that the X2 BMS which joins LFP and FLA at specific times would not meet ABYC and ISO standards?
The simplicity appeals to me, and the fact that the boat does not go dark if there ever were a LFP issue.

[hjohnson]

Originally Posted by rgleason

Thank you all, for your excellent discussion and answers.

OK, so the answer is a regulator that measures current may have more reliable control of charging at the higher levels of SOC, to ensure that the "trailing current" is cut off where it has been set in the settings. Also current information stabilizes the regulator's algorithm and makes the charge slope more regular. The current parameter is not technically required. Have I missed anything?.

The other main reason I have it is so that I can deliberately kick the WS500 into “zero amp” mode, no matter the SoC. So say I’ve been out for 3 or 4 days on the hook, my battery is down to 20% or so, because, well, it’s LFP and I don’t really care. When motoring back to my marina, where I’m going to plug into shorepower, there’s no really good reason to spend the fuel and wear/tear on my engine/alternator setup to pour power into the battery.

Could I just disable the alternator? I suppose, but at the same time, it’s nice to have teh alternator do at least enough to keep the charge from dropping further, and just hold it at whatever state its in. In that situation, the regulator is just driving the field enough to keep the battery amps at zero. I burn a little less fuel, all is good.

[s/v Jedi]

Originally Posted by rgleason

@s/v Jedi Is it this resource that you are suggesting Arduino Sketches ? I programmed in pascal for DataCAD years ago. I am very humbled by C++ but have been compiling plugins for OpenCPN and trying to fix small bugs. The ability to program my own BMS would be quite attractive, but I am unsure of many BMS details (though I've gotten some distance down that road) and my coding prowess with arduino is totally unproven. I think I should probably stick to building plugins for the OpenCPN community! Goboatingnow was starting to work on a BMS and so were you I thought.

Is it true that the X2 BMS which joins LFP and FLA at specific times would not meet ABYC and ISO standards?
The simplicity appeals to me, and the fact that the boat does not go dark if there ever were a LFP issue.

The hardware for an Arduino based BMS is readily available for up to 8s batteries as all you need are precision voltage monitors. Using a breadboard for quickly building an experimental BMS only took me an hour, it’s really simple, see attached picture. The thread is here: https://www.cruisersforum.com/forums...ml#post3685128

The thing is, as soon as you can precisely measure cell voltages and temperature, you’re in business and can program whatever -you- want it to do. You will probably need a couple relays etc. to control things but all that is available like Lego for Arduino.

You don’t get fancy CAN bus integration with alternator regulators or Cerbo GX devices etc. but none of that is needed. People are tripping about stuffing as much gadgets into a BMS as possible but none of that is needed for a perfectly safe and healthy battery. It’s a money trap that locks people into technologies that are first to fail, causing whole chains of events when they do. Monitor cells, give warnings, protect cells when needed and report on all that to the user, that’s all the BMS needs to do.

Edit: about the picture… on the left a small 4s LiFePO4 battery with balance leads to the breadboard as well as powering an old Arduino Uno development board (a real board you would use is as small as your thumb). On the breadboard you can see 4 modules for measuring cell voltages at mV precision and a small display showing thise measurements. The four blue jumper wires going to each module from the balance cable are the inputs for the INA219 modules I use there.
This is one hour incl. programming. In the thread I add temperature, controlling the BlueSea contactors etc.

[hjohnson]

Originally Posted by s/v Jedi

You don’t get fancy CAN bus integration with alternator regulators or Cerbo GX devices etc. but none of that is needed.

It might not be needed, but it's really, really nice to have. Plus, CAN bus is a mature technology that's been around for decades in all sorts of rough environments. It's not like it's something that was newly invented for boats. If it's good enough for my car's engine to coordinate with the transmission and the braking system for the stability control while going down an icy road at 120kph, it's probably fine for managing the electrical system on the boat.

But you do you.

[s/v Jedi]

Originally Posted by hjohnson

It might not be needed, but it's really, really nice to have. Plus, CAN bus is a mature technology that's been around for decades in all sorts of rough environments. It's not like it's something that was newly invented for boats. If it's good enough for my car's engine to coordinate with the transmission and the braking system for the stability control while going down an icy road at 120kph, it's probably fine for managing the electrical system on the boat.

But you do you.

I have nothing against CAN bus but it simply isn’t needed for keeping a battery safe and healthy. There is no negative effect at all by leaving it out and was never used for BMS systems until people started flipping and being proud of their batteries, willing to spend a thousand bucks for a BMS with shiny precious parts.

Remember that there are plenty sailing for 10 years or more with LFP cells and no BMS at all. It doesn’t need much to create a good BMS.

So what I like is simplicity without giving up safety and lifespan, plus I want full control and nothing beats tweaking the firmware yourself by hooking up a laptop to the BMS and trying out new features in seconds

[rgleason]

Originally Posted by s/v Jedi

I have nothing against CAN bus but it simply isn’t needed...willing to spend a thousand bucks for a BMS with shiny precious parts.

So what I like is simplicity without giving up safety and lifespan, plus I want full control and nothing beats tweaking the firmware yourself by hooking up a laptop to the BMS and trying out new features in seconds

In the Small Boat BMS/LFP with Backup thread and its companion thread ABYC and ISO Li Reference , where we discussed use of a modified 3-way switch to quickly switch over to FLA in the event of an LFP "blackout" or shutdown, and your suggestion that an MLS-RBS would accomplish the same thing, I totaled the cost of all the equipment, including batteries and wire, $4200 and the REC BMS with moniteriing or TAOS BMS with monitering is $800-$1000. This is too much money to spend for the purpose.


So, I think your suggestion to begin slowly with an arduino test setup and small LFP batteries is a good idea, if I can do it. Do you have some documentation? Would I be able to safely charge using the early prototype Smart-alt-regulator which is now Wakespeed WS500 without using the Canbus?


The diagram for the X2 BMS is very simple, appears to parallel the LFP and FLA banks at times (against ABYC) but it offers features like "no blackout" that I believe are important and appears to be well thought out. Should I consider trying to make a DIY BMS like this?


X2 BMS comparison PS I've written them about the ABYC paralleling question.

[s/v Jedi]

Originally Posted by rgleason

In the Small Boat BMS/LFP with Backup thread and its companion thread ABYC and ISO Li Reference , where we discussed use of a modified 3-way switch to quickly switch over to FLA in the event of an LFP "blackout" or shutdown, and your suggestion that an MLS-RBS would accomplish the same thing, I totaled the cost of all the equipment, including batteries and wire, $4200 and the REC BMS with moniteriing or TAOS BMS with monitering is $800-$1000. This is too much money to spend for the purpose.


So, I think your suggestion to begin slowly with an arduino test setup and small LFP batteries is a good idea, if I can do it. Do you have some documentation? Would I be able to safely charge using the early prototype Smart-alt-regulator which is now Wakespeed WS500 without using the Canbus?


The diagram for the X2 BMS is very simple, appears to parallel the LFP and FLA banks at times (against ABYC) but it offers features like "no blackout" that I believe are important and appears to be well thought out. Should I consider trying to make a DIY BMS like this?


X2 BMS comparison PS I've written them about the ABYC paralleling question.

Sorry but I don’t even want to know what X2 BMS is.

I used to have an Ample Power Smart Alternator Regulator v5 I guess that’s a different one haha.
But I can only guess a regulator that allows programming of charge algorithm will be able to safely charge a battery. For the fail safe you simply disconnect it’s power feed so that it can’t generate the alternator field current anymore.

For components, do you go for 4s or 8s? I built that first BMS for 4s but later decided to go for 8s and the modules I used didn’t go up to that higher voltage so I changed to different modules. I will look them up and post them here.

For Arduino I recently switched to luxury models with Bluetooth and wifi, even Ethernet. But simple ones come as cheap as $7 or so and are still overkill for a simple BMS. Mine is sleeping most of the time.

[s/v Jedi]

These are the INA226 modules I use now. I recommend to use these even for 12V as I think they are a little better quality. They are twice as expensive as the INA219 but at $20 for five of them, that ain’t a problem :biggrin https://www.amazon.com/gp/product/B092HV21FJ

For temperature sensors: https://www.amazon.com/gp/product/B07MB1J43W/

These do use a different communication called OneWire or something like that and is very simple and has a nice ready to use package.

Here is the display I use: https://www.amazon.com/gp/product/B076WXR8N9
I have ones with yellow and blue too, much choice and at $8 fun to try.

The above are all links from my order history but it’s from 3 years ago.

When you search Amazon for Arduino you will see the Uno from my picture but also many mini’s, nano’s etc. for prices as low as a couple bucks. I recommend to buy that big Uno first and go for small ones when you actually build your BMS.

[rgleason]

Thanks, I've bookmarked those. The Arduino Uno Rev3 is about $28 but should I get a kit? Also there seems to be some issue with getting Chinese fakes. This appears to be relatively inexpensive. I need a 5vdc power supply don't I?

What do I do about programming? wiring circuit diagram?

I had an Ample Power Regulator too. The one I have that is precursor to Wakespeed is is Al Thompson's VSR Alternator Regulator Gen3

The X2 BMS diagram (that apparently does not comply with ABYC) is a possible very simple BMS system that could be emulated.

[s/v Jedi]

Originally Posted by rgleason

Thanks, I've bookmarked those. The Arduino Uno Rev3 is about $28 but should I get a kit? Also there seems to be some issue with getting Chinese fakes. This appears to be relatively inexpensive. I need a 5vdc power supply don't I?

What do I do about programming? wiring circuit diagram?

I had an Ample Power Regulator too. The one I have that is precursor to Wakespeed is is Al Thompson's VSR Alternator Regulator Gen3

The X2 BMS diagram (that apparently does not comply with ABYC) is a possible very simple BMS system that could be emulated.

You can simply order from the Arduino store: https://store-usa.arduino.cc/collect...rice-ascending

About any of these will work, but I recommend to select one that is based kn 5V technology instead of 3.3V. The reason is that with 5V you can directly drive big MOSFET’s from Arduino ports.

You need a collection of input and output ports, plus I2C bus ports.

[rgleason]

Are you using the https://github.com/Zanduino/INA library for the INA226 or the Adafruit library?
https://www.cruisersforum.com/forums...ml#post3685123


Also you wrote earlier: "I’m trying to make it work with 3.3V vcc this time so we can use newer Arduinos with wifi and Bluetooth."


LATER: Thanks, just saw your post from below. Use 5vdc.

[s/v Jedi]

Originally Posted by rgleason

Are you using the https://github.com/Zanduino/INA library for the INA226 or the Adafruit library?
https://www.cruisersforum.com/forums...ml#post3685123


Also you wrote earlier: "I’m trying to make it work with 3.3V vcc this time so we can use newer Arduinos with wifi and Bluetooth."

I use the Adafruit library. Yes, I got a 3.3V new model to work. You can use this one that is on special now: https://store-usa.arduino.cc/product...lectedStore=us

And combine it with this shield: https://store-usa.arduino.cc/collect...ove-compatible

The shield does all the conversions.

[rgleason]

Using that link I found


Arduino Uno Rev3 $27 which is 5v

Digital I/O Pins 14 (of which 6 provide PWM output)
PWM Digital I/O Pins 6
Analog Input Pins 6
DC Current per I/O Pin 20 mA
DC Current for 3.3V Pin 50 mA
USB 5vdc for power or use an AC-DC adapter or battery.
16 MHz ceramic resonator (CSTCE16M0V53-R0)
power jack
ICSP header and a reset button. It contains everything needed

They also make an Arduino Uno Rev3 SMD version and Arduino Uno Rev3 Wifi.

There is also the $27 Arduino Uno R4 wifi with the same ports etc plus

Circuit operating voltage 5 V (ESP32-S3 is 3.3 V)
UART Yes, 4x
I2C Yes, 1x
SPI Yes, 1x
CAN Yes 1 CAN Bus

[s/v Jedi]

Originally Posted by rgleason

Using that link I found


Arduino Uno Rev3 $27 which is 5v

Digital I/O Pins 14 (of which 6 provide PWM output)
PWM Digital I/O Pins 6
Analog Input Pins 6
DC Current per I/O Pin 20 mA
DC Current for 3.3V Pin 50 mA
USB 5vdc for power or use an AC-DC adapter or battery.
16 MHz ceramic resonator (CSTCE16M0V53-R0)
power jack
ICSP header and a reset button. It contains everything needed

They also make an Arduino Uno Rev3 SMD version and Arduino Uno Rev3 Wifi.

There is also the $27 Arduino Uno R4 wifi with the same ports etc plus

Circuit operating voltage 5 V (ESP32-S3 is 3.3 V)
UART Yes, 4x
I2C Yes, 1x
SPI Yes, 1x
CAN Yes 1 CAN Bus

The nice thing of the old V3 is that it has clear labels identifying all the pins and it has the old DIL chip of the microcontroller on a socket so you could later move it into your own circuit board.

Even though I have Arduinos 100x as fast, I like to develop on this one

My BMS has an Arduino Mini which was developed by Adafruit but I got a knockoff. They are out of fashion now but a Nano or something is very much like it

[rgleason]

I need to correct something I said with regard to the X2 BMS by BatteryBalance
Mikael Garten , US Sales BatteryBalance wrote back in response to my questions


rgleason wrote:

We are in the US and ABYC is the marine guide that the insurance companies follow. Your system appears to parallel the LFP and FLA batteries at times which protects the alternator and provides the no blackout feature, however it does not appear to comply with ABYC guidelines.

Am I correct about this or is there some more refined way of looking at
the system that makes it compliant?

Thank you.

Mikael Garten BatteryBalance wrote:

X2-system do not “parallel" because there is a relay (contactor) in between lithium and FLA (starter / Aux)X2 BMS manage this relay with an algorithm that will only close the relay during charging.
X2 Tech has an advanced algorithm preventing the batteries to charge / discharge each other.
The algorithm consist of 100+ conditions. Controlled by a High Speed 16-Bit Flash Microcontroller (PIC).

There is another company, Victron Energy, that has a similar solution. The only difference is how the Cyrix relay is controlled.
We need to say Victron’s Cyrix relay is not controlled by advanced algorithm nor advanced PIC, why it in some situations will disconnect during full charge which will create voltage spike.

We may assume Victron Energy comply with ABYC as well.. (?)
Image below from Victron; Charge relay is a “Cyrix” with "simple electronics" inside (the brain is inside the relay and then the BMS will only communicate (low signal) when charging not allowed).

https://www.victronenergy.com/upload...-BMS-V2-EN.pdf

From Mikael's highly detailed (not included) response, I have learned a more nuanced understanding about what is considered "paralleling LFP and FLA" and what is not.

Thank you Mikael. I apologize for any misleading statements. It appears to me that the X2 BMS should be considered for Marine LFP. In fact I like a number of features in this system.