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Long overdue build update here... Finally have pretty much everything installed and running. Surprisingly, very few issues to speak of. I'm very pleased to report that my approach to separate-port battery protection seems to be working well (one 'winter' design flaw, more on that later). As...

This is where your specific setup will need to dictate the device(s) required for disconnecting loads and charging. As an example, for my 48V bank, the only loads I have are the inverters (nothing else connected to the batteries), and those inverters have on/off switches that specifically turn...

What are you using to disconnect charging? Are you running your setup as common or separate port?

I ended up going with a TinyBMS from Energus. It’s working ok. My setup is similar to the Batrium in that I don’t have any current going through the BMS (I use a 5A SSR to in line with the inverter’s power switch to control the loads, and a 40A SSR on the positive line of the PV panels to...

No. System voltage is not a factor. I come to the same conclusion as iamrich. 300w/hr is ~25% duty cycle for a 1200w (10A @ 120V) mini split. Unless you think it will need to run less than 15 min of every hr (and you don't need ANY power for ANYTHING else), it's probably not going to work.

I assume you're looking at the WatchMon4 with the blockmon cell monitors? I considered that option for my build, but decided it was a bit out of my price range. I believe you are correct that no current flows through the Batrium BMS, so the current limits are a function of the...

I already sent mine back and have a new board on the way. Hopefully the new board works!

Not sure what you were looking to use the Bluetooth/PC connections for, but another path to consider would be to use a 'dumb' BMS along with a separate 'smart' battery monitor. A 4S-100A BMS from JBD is only $20 on AliExpress. Two of those (for a 4p2s configuration) plus a smart shunt...

I don't have any experience setting up a 12V pack, but based on everything I've read on this form, if I were going to build a DIY 12V battery, I would probably go with an JBD (Overkill) 120A BMS (one per 4S pack). At 12V, having two batteries in series just makes a lot of sense to me (lower...

I attempted to diode-protect my Mean Well HRPG-300 using a series of 30A schottky diodes. I just couldn't get the power supply to work when the diodes were in line. To overcome the voltage drop (the ones I used had 0.5 V forward drop), the supply would have to increase the voltage above the...

So, after finishing up the low-pass filter for the current sensor, I turned my attention back to the BMS-to-MCU-to-Inverter Comms. I was making some great progress on getting the 'dialog' between the MCU and the Inverter ironed out. I coded in the CheckSum calculation, so that is happening...

No, I went with the TinyBMS s516 in a 16s configuration. I’m running in separate port mode with external relays for charge and discharge. Charge relays are 200V/40A on the PV in lines, and discharge relays are 80V/5A wired in line with the inverter switches on/off switches. Now that I’ve got...

Parts finally came in for the active low pass filter that I'm adding to the current sensor. As a reminder, I'm currently using a TinyBMS with an external current sensor (LEM DHAB S/133). I've been fighting variability in my current readings since I hooked up the inverters. I put together a...

I'm also looking for a good solution for racking 300W panels on a metal roof (9:12 pitch, trapezoidal 'PBR' panels, perlins 2' OC, on edge). I'm currently leaning towards the Tamarack system (offered by Alte-store), but the attachment system is definitely the sticking point. I'm considering...

Well, I've now tried two cables on two different computers. The second computer seemed to have more success uploading the firmware (it made it through the "program" and "verify" steps; however, the inverter would never restart after the update. It would just keep beeping. And after powering...

Really glad to hear this. I'm in the same spot (firmware updater completed the erase, then hit a 'Unhandled Exception' error, and now it won't do anything!). I'll try a new cable. Not sure where to find another PC...

Quick Update: So, after some reading and reflection, I decided that using SoftwareSerial on the Nano was not the best idea. I moved everything over to an ESP32 so i could use one of the hardware serial pins. This change, along with adding some delays to allow time for the data to come in/go...

My understanding is that the PC-to-Inverter comms follow a completely different protocol than the BMS-to-Inverter Comms (PylonTech's RS232 protocol). I have a copy of the Growatt Modbus RTU protocol, and it doesn't follow the data format of the Pylontech comms, nor does it include any registers...

The inverter is sending the 'get analog values' request. The protocol states that the response to that request includes the "INFOFLAG", which I'm assuming is the same as the "DATAFLAG", which is summarized in the table pasted below. In the response that I've been sending, I've got the flag set...

Update on BMS-Inverter Comms: I managed to make a few small steps forward today. I'm now able to calculate checksum values, so I'm able to change values in the response string and have those changes reflected on the inverter. I have to say, the the checksum value for the length calculation is...

Sorry everyone. I really should have dug deeper into figuring this out before asking for any help. I realize that Excel is NOT the appropriate tool for this project, I'm just using it to try to learn how it works before jumping into the coding. And yes, once again, I put the wrong info into...

Getting a handle on it? Ha. That's very generous.

46, 44, 35, and 33 are the HEX equivalents of the ASCII characters F, D, 5, and 3 (which also correspond to the '30+' decimal equivalents, as you've pointed out). The protocol employs ASCII characters for pretty much all values. For example, the cell voltage values are provided as 30, 44, 34...

Yeah...you're right on all counts. Need to slow down a bit on these posts. I've created a simple sketch that calculates the checksum values, which seem to match all the examples in the protocol. That's a relief. I'm pretty sure my sums will never exceed 65536, so I think i can probably...

I managed to find an interesting thread about using an Arduino to 'hack' the RS-485 comms on Valance batteries, but in that case, the communication protocol was completely DIY. I'm really hoping that I can emulate the PylonTech RS232 protocol. I'm not finding any examples of that on the...

UPDATE ON BMS COMMS - While I wait for some parts to come in, I turned my attention to communications. Specifically, getting my MCU to communicate with my Growatt SPF-series inverters. This has been quite a learning experience, but I'm finally starting to make some progress. I've got the...

I think adding a heat sink is a great idea. I've been struggling with limiting the amount of heat, as my heating pads are in direct contact with my aluminum compression plates. If I were to add a thick (maybe 1/4") sheet of aluminum under the cells, along with thin sheet of something less...

The LEM DHAB S/133 sensor that came with my BMS is a dual range sensor (0-75A, and 0-750A), so it actually has two completely independent signal output lines: one with a sensitivity of 27mV/A, and one with 2.7mV/A). That’s why I think I need a dual input op-amp. I’ll read through your linked...

So, after posting about my balancing issues on another thread, it was pointed out by several members that my core balance issue was likely not related the my BMS's low balancing current, but rather an issue with the bank itself. After analyzing some fairly strange individual cell voltage...

Hi mnm1501. Your timing is perfect. I took my first crack at communicating with my Growatt (SPF 3000 LVM 48P) yesterday, and realized very quickly that I have absolutely no idea what I'm doing. I have no experience with CANBUS or MODBUS, and to be honest, I'm not even sure which one the...

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Makes sense. I noticed that my BMS is currently tracking current and updating SOC at intervals of 100ms, but that does seem a bit overkill. I was considering 500ms as well. Even if there was a high magnitude 'spike' in current shorter than 500ms, at that time scale, shouldn't have much impact...

Understood. I really just bought it as a backup plan in case I can’t get all these separate circuits to work as needed. In that case, I may end up abandoning the Hall effect sensor and going with a shunt.

I ended up including an INA228 chip with my latest mouser order, just to try it out. The 228 seems to be pretty close in specs to the 226, just with an 80V upper voltage limit. I couldn't find any of the TI 80V chips on a pre-soldered breakout, so I'll have to try my hand at soldering it on to...

So, I realize this discussion has moved over to the Cal's DIY BMS thread, but I had some question specifically about the coulomb counting aspect of this project. Specifically, 1) at what frequency (ie, time interval) are you planning to calculate coulombs, 2) what are you planning to use for...