diy solar

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Valence XP Super Thread

I also think active balancers with no voltage cut in set point that work on every cell individually instead of in groups of four like the one above are also a bad idea. The voltage curve is so flat that even the slightest imperfection in a voltage sample can cause the active balancer too create imbalances throughout the time in which the voltage is in the flat part of the curve which will cause overvoltage conditions when you try and top balance. Maybe it was just imperfections in the design but this has been done in real world testing finding the above results.
 
Honestly I don't think I'd even use them in regular lithium ion where the voltage curve isn't so flat because if you had a week or lower capacity sell dive in voltage under a heavy load you would have the active balancer charging that cell at that moment which could again cause a problem during top balancing. The problem wouldn't be so pronounced though because the voltage would hopefully very enough between the cells after the imbalance was caused to cause it to rebalance. But do you really want microcycles like that? I think active balancing is best done only in the steep parts of the voltage curve near top balancing or bottom balancing whichever method suits your batteries use. I like the bottom balancing personally because lower voltages equals slower degradation but the problem there is that you would have to drain your battery dead in order to accomplish that bottom balancing. When you're off grid no one wants a dead battery. Maybe in something a little easier to drain dead like an eBike.
 
I purchased some gently used U24-12XP batteries and wanted to share my positive experience modifying/using these with a non-Valence external BMS.

First I opened the side waterproof compartment to locate the 4S balance wires:
20220819_101343_resized.jpg


Was very happy to see it was similar to a traditional 6S JST balance connector.
20220819_101924.jpg

So I removed the proprietary Valence BMS cables (saved them) and pulled the JST-like connector through the same hole. Then I sealed up the holes to make them waterproof again. All of this is removable and the battery can be returned to the factory Valence configuration easily.

20220819_105315.jpg

All sealed up and ready to be connected to my BMS of choice!

20220819_110011.jpg

Some initial cell readings before charging/balancing:

20220819_110126_resized.jpg
 
I have 4P of U27-12XP in my RV. Can anyone provide optimal settings profiles for Victron MPPT 100/50 and Magnum MS2812 inverter/charger with ME-ARC?
 
I purchased some gently used U24-12XP batteries and wanted to share my positive experience modifying/using these with a non-Valence external BMS.

First I opened the side waterproof compartment to locate the 4S balance wires:
View attachment 107578


Was very happy to see it was similar to a traditional 6S JST balance connector.
View attachment 107579

So I removed the proprietary Valence BMS cables (saved them) and pulled the JST-like connector through the same hole. Then I sealed up the holes to make them waterproof again. All of this is removable and the battery can be returned to the factory Valence configuration easily.

View attachment 107580

All sealed up and ready to be connected to my BMS of choice!

View attachment 107581

Some initial cell readings before charging/balancing:

View attachment 107582

What BMS are you using and how will you handle temp?
 
What BMS are you using and how will you handle temp?
I'm using an ANT BMS in a 12s (3 x U24-12XP) configuration. It supports 4 temperature sensors. However, I'm running parameters that max charge at 3.5v per cell so the batteries stay relatively cool. The batteries are in an insulated garage so ambient temperature is under control.
 
Was very happy to see it was similar to a traditional 6S JST balance connector.

All sealed up and ready to be connected to my BMS of choice!
Can anyone help me figure out what type of JST connectors there are? They are not JST-XH 2.54, the edges are raised and do not fit... there are too many different JST versions out there!!

I connected a Daly 16s Active balancer to a 48v string of 4 u27-12xp's. Added an ESP32 board to the UART port on the Daly and loaded esphome onto the board. Now my valence batteries all connect to wifi and I was able to load all of the individual cell voltages into Home Assistant.

Here is my dashboard, (I'm doing some top balancing at the moment on a few misc batteries)
 

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For the record, I was able to locate the connectors. They are Molex Mini-Lock 53375 Series (on the circuit board) and the other end is a Molex 51103 (wire end)
 
I ripped open one of my packs, heres photos in case anyone is interested..

You can see the location of the 4 temp probes, and the balance leads too.
 

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I have 4P of U27-12XP in my RV. Can anyone provide optimal settings profiles for Victron MPPT 100/50 and Magnum MS2812 inverter/charger with ME-ARC?
I have the same sort of setup, I use top charge of 13.8 bulk, 13.4 as the rest voltage, and low cut at 12.1 for my draw appliances. They aren't very much used, but they are 'old' so I'm going easy on them. And it's been like that for 4 straight years of my ownership. Zero hassles. I'm assuming my 4 batteries to have 100ah x 4 (400ah) of usable power, instead of 138ah x 4 as they are rated.
 
I've read through this, wow this is a lot of great info. I came across a pair of U27-XP's that I'm planning on using in parallel with an inverter/charger to function as essentially a high-capacity UPS. I'm trying to figure out how much of the "non existent BMS" functionality I actually need to worry about. I've gotten as far as the following... would love comments or corrections here.

Set the charger profile for 14.4v / 13.6v. This is narrower than the spec for the batteries, I'm not terribly capacity constrained and they're old cells so I'm not concerned about squeaking every last Ah out of them.

Set the inverter low-voltage cutoff at 10.5v. I don't expect these batteries to be cycled often at all (other than periodically where I'll have control of it) but even a cutoff at 10.5 should be sufficiently high to keep the batteries in decent shape, without the internal BMS needing to be present.

Speaking of the internal BMS, is there much value in dealing with the effort of getting it up and running? I've read tons about the laptop and talking to it and reading data from the cells -- this is all very cool but goes on my "one day" list, not on the "day one" list of stuff to do. So my questions...

1) is it safe / sane to just leave these with their internal BMS in sleep mode persistently, given that I have high and low voltage cutoffs in the inverter, and they'll be in a temperature controlled environment?

2) is there a trivial way to keep the basic sanity checking parts of the internal BMS up and running without doing all the USB/RS485 stuff? From reading through this, it MIGHT just be as simple as "plug the batteries into each other, then run 5v across these here two wires on one of the plugs" -- is that true or is there more to it **if I don't need the monitoring and control stuff** ?

thanks :)
 
I have the same sort of setup, I use top charge of 13.8 bulk, 13.4 as the rest voltage, and low cut at 12.1 for my draw appliances. They aren't very much used, but they are 'old' so I'm going easy on them. And it's been like that for 4 straight years of my ownership. Zero hassles. I'm assuming my 4 batteries to have 100ah x 4 (400ah) of usable power, instead of 138ah x 4 as they are rated.
I have about 70 (yep, at least, probably more) of the V1 U2712XP modules and, despite have been left uncharged in 'professionally' converted EVs in a yard for 3 years and then left sitting around for another 5 years since I've had them, about 80% have at least 120Ah of capacity. Really, these things are pretty much bullet-proof in terms of abuse. The only thing I have found yet that really kills them is draining them down to nothing and leaving it for a week or two. Even then, it is usually only one cell bank that has sacrificed itself to save the rest. So there is then scope for making one good module out of 2 bad ones...
 
I've read through this, wow this is a lot of great info. I came across a pair of U27-XP's that I'm planning on using in parallel with an inverter/charger to function as essentially a high-capacity UPS. I'm trying to figure out how much of the "non existent BMS" functionality I actually need to worry about. I've gotten as far as the following... would love comments or corrections here.

Set the charger profile for 14.4v / 13.6v. This is narrower than the spec for the batteries, I'm not terribly capacity constrained and they're old cells so I'm not concerned about squeaking every last Ah out of them.

Set the inverter low-voltage cutoff at 10.5v. I don't expect these batteries to be cycled often at all (other than periodically where I'll have control of it) but even a cutoff at 10.5 should be sufficiently high to keep the batteries in decent shape, without the internal BMS needing to be present.

Speaking of the internal BMS, is there much value in dealing with the effort of getting it up and running? I've read tons about the laptop and talking to it and reading data from the cells -- this is all very cool but goes on my "one day" list, not on the "day one" list of stuff to do. So my questions...

1) is it safe / sane to just leave these with their internal BMS in sleep mode persistently, given that I have high and low voltage cutoffs in the inverter, and they'll be in a temperature controlled environment?

2) is there a trivial way to keep the basic sanity checking parts of the internal BMS up and running without doing all the USB/RS485 stuff? From reading through this, it MIGHT just be as simple as "plug the batteries into each other, then run 5v across these here two wires on one of the plugs" -- is that true or is there more to it **if I don't need the monitoring and control stuff** ?

thanks :)
No it's not safe to run without a balancer. You absolutely must have a balancer that engages only at the upper voltages. Of course you can do this by keeping the board awake. Now it's arguably safe enough to run without a BMS as long as you have the balancer. Set your low voltage cut off to 12 volts. There's no power down below 12 volts anyway. Yes there's a way to modify the board to keep it awake but it will be discharging the battery so you won't want to let it sit like this for months at a time. Somebody had posted the modification on a Facebook forum but I have since yet to find it. It was by far the easiest choice for people running 12 volt systems. Your next easiest choice is to just simply buy an aftermarket 12 volt BMS for each battery and rip out the one that's in there. Yeah sure you can plug in the laptop if you want to keep the boards awake but that's a pain in the rear and windows is constantly updating and crashing so it's not safe.
 
I've got a raspberry pi dedicated to this build -- is there an easy enough way to have it do whatever needs to be done to keep the internal BMS awake enough to not cause trouble?
 
I've got a raspberry pi dedicated to this build -- is there an easy enough way to have it do whatever needs to be done to keep the internal BMS awake enough to not cause trouble?
There are at least one or two threads about using the raspberry. Not in this super thread though. There might be a link to it somewhere in this super tread. If you know your way around a raspberry it's probably easy enough. I've never done it myself.
 
I've got a raspberry pi dedicated to this build -- is there an easy enough way to have it do whatever needs to be done to keep the internal BMS awake enough to not cause trouble?
No, not an easy way using raspberry pi.

It is easy however to install an external BMS, Just simply connect the 5 balance wires on the side and the negative terminal to the bms and throw the valence bms in your spare parts bin.

A 40A JK BMS is $44 and will give you high and low voltage disconnects, individual cell monitoring, active balancing, high and low temp cutoffs, and a bluetooth connection too.

40A model BD4A8S4P is $44
100A model B1A8S10P is $67


Also if you are connecting a 48V setup with 4 batteries in series you only need one BMS, you dont have to buy one for every single battery. (You could if you wanted though... some of th jk bms support up to 24 cells.) Or if you want to save a few bucks the Daly BMS's work fine too, but I wasnt happy with their quality so I returned mine and the JK's have been bulletproof.

This link has more info on various brands on BMS, I found this to be very helpful designing my system
 
I've got a raspberry pi dedicated to this build -- is there an easy enough way to have it do whatever needs to be done to keep the internal BMS awake enough to not cause trouble?
You can use a USB-RS485 adapter and Python script.
I attached the one I used on my Windows machine that someone provided on this forum that I slightly modified.
For just keep alive, you can probably just reduce it to this;

while 1: sPort = '<Name of Your COM Port>' payloadW = [0x00,0x00,0x01,0x01,0xc0,0x74,0x0d,0x0a,0x00,0x00] s = serial.Serial( port = sPort, baudrate=9600, parity=serial.PARITY_MARK, stopbits=serial.STOPBITS_ONE, bytesize=serial.EIGHTBITS, timeout=1 ) s.write(serial.to_bytes(payloadW)) #print("Woke up serial device") s.flush() s.close()
 

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Hmm. This thing is killing me. I have wired up a connector with what I'm pretty sure is the correct pinout. I have a USB<->RS485 converter that I know works, because I can send/receive data from my battery monitor with it. But when I plug this thing into the Valence battery, nothing happens. I've tried multiple python scripts (they're all based on the same concepts so quite similar) and I can see the TX activity light on the USB/rs485 converter blinking, so I know it's sending the bytes down the wire (or at least thinks that it is...)

Any ideas here what to try next? I can't think of any way to "confirm" that I've got the pinouts working, what other thoughts do people have? The LED on the battery is flashing green every 30 seconds, and the main module itself reads 13.05v.

help?!?!?!
 
I cant help you with the scripting part, but for testing your cable, connect the Valence XP Software and see if you can talk to the battery that way. Also, the light flashing every 30 seconds indicates that the BMS is sleeping. Once you wake it up by talking to it via software then the light changes to flashing every 5 seconds
 
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