Small sailing cat electrical refit - LiFePO4, Victron goodies, and NodeRed / MQTT integration.

[picklz]

My wife and I recently bought a new-to-us Gemini 105M sailing cat, she's in pretty good shape overall but the electrical, wiring specifically, is in need of some attention so I'm planning on rewiring a good share of the boat, swapping out the FLA batteries for Lithium, and making some other improvements along the way. I'm still working out some of the details and trying to add more to my proposed diagram, but it's to the point where I thought I'd start a thread to chronical the project and get some additional input from you guys.

The overall plan is to have integration between the Victron equipment, the Chargery BMS, a raspberry pi Running the VenusOS software from Victron, as well as some other apps like Node Red and MQTT to be able to make intelligent decisions, such as slowing or shutting off charging if an individual cell is approaching High Voltage Cutoff, or alerting me to a single cell approaching Low Voltage Cutoff. I am also hoping that I can make it easy to adjust charging profiles so I can have the batteries sitting at 60% most of the time, but remotely command them up to 90 or 100% if we're planning on taking more of an extended trip on her by way of NodeRed, MQTT, and Wifi/VPN.

The inverter/charger DO both leverage the Charge bus. I felt the benefits of the separate port design were still worth pursuing even with that being the case, Chargery has confirmed there should be no technical issues doing that as far as the DCC's and BMS are concerned, just that a low voltage condition triggering the load bus to disconnect would not stop the inverter from drawing power still. Being the inverter can be commanded off via software, AND the fact that the inverter won't see all that much use most of the time, I was okay with the compromise.

The diagram:

https://imgur.com/a/apsOUxY

Unless otherwise noted Yellow and Black signify negative (-) DC connections

Some questions I know I need answers to yet, if anyone has any input or questions on these or anything else design related (or otherwise) let me know:

• Should I fuse some/all of the outputs from the main DC Positive Busbar or is that overkill being the battery is fused and most of them connect to the boats DC load panels?
  • Any suggestions for quality covered BusBars that are rated for 300A+ ?
• I was thinking of installing a Victron Orion DC Charger that would be setup to charge from the house bank to the starting battery to keep it topped up when we're away from the boat or out are out anchored or sailing and not motoring for extended periods of time. I need to fuse the output from the DC Charger to the Battery, should that be near the start battery or the charger on the output side?
• I am thinking that under normal circumstances it makes the most sense to just keep the starting battery and alternator (25hp outboard) isolated from the house bank, I 'think' I am going to leave an existing switch to allow connecting the house bank to the start batt / engine / alternator should it be needed for some reason.
• I'm probably going to see about calibrating the Chargery BMS to use the Victron SmartShunt instead of having to install two shunts in series unless anyone see's a reason to have both installed.
• Does anyone have a good suggestion for a power supply to use for Balancing the cells? I'm thinking probably this one at Amazon, I'd like to get something that is 20-40A and/or has more features, but I'm having a hard time justifying the additional cost.

Planned Equipment List:
Custom LiFePO4 Battery - Lishen 272AH Cells (4S) - (Might eventually expand this to 2P4S for ~544AH but we'll see)
305W LG Solar Panel (planning to add 2 more panels to the pilothouse roof for 200-400 additional watts but need to sort those details out yet.)
Victron MultiPlus Compact 12/2000 Charger/Inverter
Victron BlueSolar 100/30 MPPT Charge Controller (2 eventually)
Victron Orion TR DC Charger to keep the starting battery topped up.
Victron 500A Smart Shunt
VictronOS running on Raspberry Pi with a 7" Pi Touch Screen
Chargery 8T BMS with 2x 300A DCC's
300A T Fuse at the battery
2/0 Cabling between Battery, Shunt, DCC's, Busbar(s) and MultiPlus


The BlueSolar MPPT, Smart Shunt, and cables for the Victron gear showed up today and the MultiPlus is supposed to be here Wednesday so I'm hoping to mock things up and start playing with the VenusOS software on the Raspberry Pi to see how that all works over the Thanksgiving break. I expect it will be a little while before I see the Chargery BMS and LFP cells.

 

[Freep]

I'd go with the Eve 280ah cells. I have the 271ah Lishen cells myself and I'm very happy with them but the 280's are cheaper, at least last time I checked, and more people here use them.

I'd also consider going 24 volt for your battery( 8s instead of 4s)

I've recently upgraded my truck camper with mostly Victron equipment and I wish I had done the above. But overall I'm happy with my choices. I'm quite happy with the Victron equipment and it's worth the premium, IMO.

I will likely add another 271 battery though.

The Orion should be as close to the battery it is charging as possible. I don't know how it would work in the configuration you're considering. I've thought about doing something similar in case I even need to jump start the truck but I figured I'd just pull the batter and use jumper cables if it came down to it.

I'll be following your project as I'm interested in what you end up doing with Venus OS, NodeRed and MQTT. I use Home Assistant on a PI and have been thinking a lot about creating another HA instance in the camper. Maybe I shouldn't. Now I have to do some research on Venus OS. Thanks for that.

 

[Freep]

I'd go with the Eve 280ah cells. I have the 271ah Lishen cells myself

Scratch that. I haven't been paying attention to the latest prices. The Eve cells jumped a bit in price.

 

[Fallingaway]

I’m curious too, what are you planning to do with MQTT? I’ve been thinking about using Arduino nanos to monitor my cells, then using a pi as a MQTT broker that will subscribe to the nanos. I haven’t really looked into node red much. Does it have the ability to use MQTT so you can monitor your system?