LiFePo protection

[mitchk]

So I have 3 of these Valence batteries in similar shape as yours. This might be a dumb/ obvious question but if I buy the victron charge controller it says it comes with a low voltage/ low temp sensor. If that is the case there isn't a reason for me to have to program a device to stop charging correct? The only benefit to your system for me would be the automatic fans? Or am I missing something?

[somewhereinusa]

Originally Posted by mitchk

if I buy the victron charge controller it says it comes with a low voltage/ low temp sensor. If that is the case there isn't a reason for me to have to program a device to stop charging correct? The only benefit to your system for me would be the automatic fans? Or am I missing something?

I have a Victron charge controller as well as a Victron inverter charger. They have a low voltage and temp sensor. The temp sensor on the charger isn't really adjustable for that.

The compartment cooling fan is just an extra benefit I put it there because I can. The main reasons are for worst case scenarios to disconnect the battery bank if all else fails. It also controls the battery heaters so they can't get charged below 34° F. The other parameters are over temp, over/under volt. I am presently working on adding a temperature sensor for each battery that will be mounted inside of the BMS cover.

[mitchk]

Originally Posted by somewhereinusa

I have a Victron charge controller as well as a Victron inverter charger. They have a low voltage and temp sensor. The temp sensor on the charger isn't really adjustable for that.

The compartment cooling fan is just an extra benefit I put it there because I can. The main reasons are for worst case scenarios to disconnect the battery bank if all else fails. It also controls the battery heaters so they can't get charged below 34° F. The other parameters are over temp, over/under volt. I am presently working on adding a temperature sensor for each battery that will be mounted inside of the BMS cover.

So the temp censor on the charge controller is just for overheat?

[somewhereinusa]

Originally Posted by mitchk

So the temp censor on the charge controller is just for overheat?

That is my understanding.

[somewhereinusa]

This is all done and installed for testing except for actually hooking up the main relay. It has changed a bit since my first post. I've added a temperature sensor inside of each battery. It logs to a memory card and sends data to my phone via bluetooth. I was surprised to find that I can get the data from inside the house. Unfortunately, now that it's spring I can't test the cold weather part but, I did thoroughly bench test it.

Overview of system.



1. Arduino Mega
2. Voltage regulator
3. 9 DS18B20 temp sensors
4. Switchdoc labs INA3221 voltage sensor
5. 4 SS relays

Relay 1----Main Disconnect
Relay 2----Victron Charge controller
Relay 3----Cabin cooling fan
Relay 4----Battery heat

Temp sensor 1 Battery #1
Temp sensor 2 Battery #2
Temp sensor 3 Battery #3
Temp sensor 4 Battery #4
Temp sensor 5 Battery #5
Temp sensor 6 Battery #6
Temp sensor 7 Cabin temp
Temp sensor 8 Battery heat temp
Temp sensor 9 Outside temp


Relay 1 disconnects battery bank from everything *
Relay 2 turns solar controller ON/OFF *
Relay 3 turns ON/OFF compartment cooling fan
Relay 4 turns ON/OFF battery heating
*In all cases relay 1 turns on before relay 2 and relay 2 turns off before relay 1.



voltage < 9.5 open relay 1&2
voltage > 15 open relay 1&2
any batt temp 1-6 > 175° F open relay 1&2
any batt temp 1-6< 40° F open relay 1&2
temp sensor 7> 90° F close relay 3
temp sensor 8< 45° F close relay 4
temp sensor 8> 50° F open relay 4


Sends data via bluetooth to phone.
Used real time clock to keep track of date and time.
Saves data to memory card. Every ten minutes. If something triggers relay 1 and 2 logs every 10 seconds.

Overall system.This is mounted on back side of bedroom wall. Everything on left side of picture.



The batteries on floor of same area.



Screenshot of data on phone.



Another view of the control panel.

[TheArgobus]

I'd like you to know that this post inspired me to do something similar for my bank, although my set up only turns a vent fan on. Thanks for sharing this--these kinds of projects are what skoolie.net was made for!

[somewhereinusa]

Originally Posted by TheArgobus

I'd like you to know that this post inspired me to do something similar for my bank, although my set up only turns a vent fan on. Thanks for sharing this--these kinds of projects are what skoolie.net was made for!

Thanks, your's inspired me to do something with flow sensors although it may have to wait until next winter, that is, if this one ever goes away. I think I need to get the solar panels operational first.

[DrDanger]

I am building a remarkably similar set up to yours (Victron inverter/charger and Valence batteries). I am waiting on a new MK3 USB adapter to run Victron Connect to change the settings to handle the Lithium batteries. Did you have to connect your homemade BMS to the Multiplus to control turning the charger/inverter off? I was just reading Victron's manual about connecting non-Victron lithium batteries to a Multiplus and it seemed to indicate that you should have a BMS that "talked" to the Multi. I definitely didn't know anything about that so I am wondering if I can still hook up the batteries without a BMS for now.


I was looking at getting this after-market BMS, but I'm not sure if it will do all that it needs to be able to do.
https://www.thunderstruck-ev.com/val...ttery-bms.html


Any help would be much appreciated!

[somewhereinusa]

Originally Posted by DrDanger

I am building a remarkably similar set up to yours (Victron inverter/charger and Valence batteries). I am waiting on a new MK3 USB adapter to run Victron Connect to change the settings to handle the Lithium batteries. Did you have to connect your homemade BMS to the Multiplus to control turning the charger/inverter off? I was just reading Victron's manual about connecting non-Victron lithium batteries to a Multiplus and it seemed to indicate that you should have a BMS that "talked" to the Multi. I definitely didn't know anything about that so I am wondering if I can still hook up the batteries without a BMS for now.


I was looking at getting this after-market BMS, but I'm not sure if it will do all that it needs to be able to do.
https://www.thunderstruck-ev.com/val...ttery-bms.html


Any help would be much appreciated!

The muptiplus doesn't have any way to turn on/off with an external device. The solar controller does. I have built mine things to simply disconnect the batteries from the multiplus if things go south.

I have briefly looked at the thunderstruck device. In my opinion it isn't ready yet. Promises of future upgrades, in my opinion. rarely work out the way I want.

[DrDanger]

Originally Posted by somewhereinusa

The muptiplus doesn't have any way to turn on/off with an external device. The solar controller does. I have built mine things to simply disconnect the batteries from the multiplus if things go south.

I have briefly looked at the thunderstruck device. In my opinion it isn't ready yet. Promises of future upgrades, in my opinion. rarely work out the way I want.

This is from Victron:
"BMS Above mentioned signals need to be two separate potential free contacts that can be wired to the Multi. On the side of the Multi this is an analogue voltage measurement non-isolated with pullup resistor. Drawing 1 mA is enough for a ‘closed’- signal. Since there is no isolation in the Multi, there needs to be isolation on the BMS side. The recommended and most easy way to implement this is with a small potential free relay contact. Alternatively it is also possible to use an opto-coupler. Multi or Quattro The Multi or Quattro needs to be updated to the latest firmware version. (19xx2xx/20xx2xx or 26xx4xx/27xx4xx) See the VEConfigure3 Requirements document available on our webpage: http://www.victronenergy.com/support...oads/software/ The Multi or Quattro needs to be of a recent type that has auxiliary inputs"


from the pdf found here: https://www.victronenergy.com/suppor...s-multiplus-ii


I'll be honest, that mostly seems like Greek to me, that is why I asked if you connected your BMS to the Multi.


I guess I'll just hook up the batteries to the charger and roll with it until I can figure out a system like yours.

[dzl_]

Originally Posted by somewhereinusa

The muptiplus doesn't have any way to turn on/off with an external device. The solar controller does. I have built mine things to simply disconnect the batteries from the multiplus if things go south.

The Multiplus can be switched on/off remotely, it is actually the inverter/charger recommended by some of the BMS makers that rely on remote control of external devices because (with the 3000W model) inverting and charging can even be switched separately. The 2000W model can be switched as well, but it may or may not be possible to control charging and inverting separately if that is important.

[DrDanger]

I have been operating my system without a BMS since fall of 2020. Originally I just had the Multiplus inverter/charger, but I added solar panels and Victron charge controller in summer of 2021. This fall I added a Victron Smart Shunt to give me an accurate state of charge that took the solar input into account (since the Multiplus only accounts for AC input when displaying state of charge). I hooked up the second wire of the Smart Shunt to monitor the midpoint voltage of my battery bank. When I did this I discovered that one of my batteries is mismatched, that is to say one battery in a series was reading several volts lower than the other (this manifested when I accidentally discharged the batteries much lower than I should have). After recharging the batteries they seemed to even out a bit, but I still occasionally get voltage variation of 5-10%. The problem seems to get worse when charging, but better when discharging. So here are my questions...

1. Is the battery with the lower voltage dying? Is there any way to save it?
2. Is it dangerous to continue using it?


I have finally ordered the USB cable that will allow me to connect to the battery diagnostic ports and see what is actually going on inside. I'll report back once I receive it.

[dzl_]

Edit: Misunderstood the question/situation.


Can you clarify a couple things.


1. what specifically do you mean when you say "one battery in a series was reading several volts lower than the other". Are you referring to an actual battery/pack or a single cell? And how is your battery bank configured?


2. Can you be more specific than: "was reading several volts lower than the other" what specific voltages are you talking about?


3. You say you are running without a BMS (not a good idea in the vast majority of cases), but then later you say "I have finally ordered the USB cable that will allow me to connect to the battery diagnostic ports and see what is actually going on inside. I'll report back once I receive it." This makes it sound as if you have a BMS or you have pre-built batteries (which would/should have an internal BMS). Can you clarify?

[DrDanger]

Originally Posted by dzl_

Edit: Misunderstood the question/situation.
Can you clarify a couple things.
1. what specifically do you mean when you say "one battery in a series was reading several volts lower than the other". Are you referring to an actual battery/pack or a single cell? And how is your battery bank configured?

Four total batteries (Valence, 12V), configured as two parallel sets of two batteries in series to create a 24V bank.

Originally Posted by dzl_

2. Can you be more specific than: "was reading several volts lower than the other" what specific voltages are you talking about?

During the unfortunate incident the total bank voltage was 20V. One of the pairs in series was very evenly balanced (both 10V), but in the other pair one battery was 7V and the other was 13V.

Originally Posted by dzl_

3. You say you are running without a BMS (not a good idea in the vast majority of cases), but then later you say "I have finally ordered the USB cable that will allow me to connect to the battery diagnostic ports and see what is actually going on inside. I'll report back once I receive it." This makes it sound as if you have a BMS or you have pre-built batteries (which would/should have an internal BMS). Can you clarify?

Valence batteries have an internal BMS as I understand it (I could be wrong about this, more reading to do), but they also have cable leads coming out of them that allow you to connect multiple batteries together and then attach the entire series to a BMS (Valence made a BMS for these but I haven't seen one for sale on eBay lately). The work around from the internet is to get a cable that allows you to connect to the cable from the battery to your computer via USB and then use Valence software to see what is going on inside your batteries. Sorry for the caveman explanation, that is my best understanding right now. I obviously need to educate myself better about all of this. Currently reading this thread: https://diysolarforum.com/threads/va...r-thread.5683/