LiFePO4: Help me choose a BMS

[Davidhoy]

I'm getting ready to upgrade my house bank to LiFePO4, and have planned a 600Ah bank built from 12 Sinopoly SP-LFP200AHA 3.2v/200Ah cells. I've been researching battery management systems, and there are quite a few to choose from. I'd like to hear from people who have actually installed a LiFePO4 bank, which BMS they used, and its pros and cons.

I have multiple charge sources - AC shore power, 8Kw AC diesel genset, 100A DC engine-driven alternator, and 2x Victron SmartSolar MPPT 100/30 controllers connected to 700watts of solar panels. My current inverter/charger is a Xantrex SW3000, which acts as both a charge source and a load, and can also automatically start the generator if needed. To control the charge and load buses I am looking at the Blue Sea ML-Series 500A latching solenoids to do the actual switching.

I've seen some interesting systems that might do the trick, and would welcome any other suggestions.
* REC Active BMS - CAN, RS485 interfaces
* 123Smart BMS - Bluetooth interface
* Orion Jr BMS - RS232 interface

Regards,
David

[CatNewBee]

I have the REC ABMS and I like it, completely configurable and custom programming possible by the manufacturer for special requirements, great support! My setup is 4 1000Ah Winston cells, Victron Quattro 12-5000/220 100-100 and Mastervolt MassSine 2000 inverter plus Victron smart solar 150/100 MPPT, 5x330Wp solar panels, 9 kW Onan gen, standard altrnators / chargers...

I know instals with the 123 smart bms, that work too, but I prefer the concept of a single encapsulated unit over dedicated cell modules.

I dont know the orion jr bms, so no comment on that.

[john61ct]

Are you going to connect your kombi style inverter to the charge or loads buss?

[CatNewBee]

I will connect it to the load bus, however, it is controlled separately by the bms charge and discharge signals.
I guess, it is the safest / best compromise. The risk of broken optocoupler on the discharge side can be handeld by the solenoids, on the charge side there are also 2 level of protection
1. the voltage settings of the quattro, 2. the bms optocoupler signals.

I can even use a signal from the charge opto to disconnect the load relay for the victron too, the inverter is on a separate ML RBS solenoid, so i can control the 12V side of the inverter independantly from the 12V charge bus and the 12V load bus. But I guess, it is an overkill to do so. The charge side is only used on generator or shore power - means rarely in my use case.

[Davidhoy]

Originally Posted by john61ct

Are you going to connect your kombi style inverter to the charge or loads buss?

I was planning on connecting the inverter/charger to the charge bus. The reasoning behind this is that I can connect the BMS's low-voltage cutoff relay to LVC contactor *AND* the remote inverter control so that it will shut off the inverter, rather than physically disconnecting it (the LVC contactor will handle the load bus). Additionally, I can set the inverter's low voltage level to just above the BMS's LVC, giving a double level of protection. Similarly, I can program the automatic genset start to kick in at that point, and since the charge bus is still connected the charger will start replenishing the bank. If the inverter/charger were connected to the load bus, and an LVC event disconnected it, then I would not be able to charge without manual override of the LVC contactor.

Does this all make sense? I'm still learning, and plan on testing various configurations off the boat before I do the actual install.

[Davidhoy]

Originally Posted by CatNewBee

I have the REC ABMS and I like it, completely configurable and custom programming possible by the manufacturer for special requirements, great support! My setup is 4 1000Ah Winston cells, Victron Quattro 12-5000/220 100-100 and Mastervolt MassSine 2000 inverter plus Victron smart solar 150/100 MPPT, 5x330Wp solar panels, 9 kW Onan gen, standard altrnators / chargers...

I know instals with the 123 smart bms, that work too, but I prefer the concept of a single encapsulated unit over dedicated cell modules.

I dont know the orion jr bms, so no comment on that.

I've heard other good comments on the REC Active unit, good to hear it's working well for you. If I go that route I may come pick your brain ;-)

The 123Smart is an interesting unit. I like the simplicity of the wiring, and don't really have a problem with small boards attached to the top of the cells. If they are not already conformal coated, I will likely do this to protect them against corrosion. I can also design and 3d-print some casings for them.

One particularly interesting thing about the 123Smart unit is the built-in Bluetooth. Being able to configure and monitor the system without a physical connection sounds quite handy. How have you found the remote connection for the REC Active unit? Would I be correct in assuming you're using a USB-to-RS485 cable to connect to your laptop? How is the software for managing the system?

[bdbcat]

Another thumbs up for the REC BMS. It just works OOB.

Probably the best build quality of any BMS I have seem. Automotive grade components used, evidently. Buy the pre-made wiring harness. Nice....

Dave

[Typhoon]

I use a House BMS system made by


About CleanPowerAuto LLC



But they have been absorbed by Lithionics



It was and still is a great system , still working perfectly .


Regards John.

[Davidhoy]

Originally Posted by ColdEh Marine

I use a House BMS system made by
About CleanPowerAuto LLC
But they have been absorbed by Lithionics
It was and still is a great system , still working perfectly .
Regards John.

I don't think it's still available. Certainly nothing about it on Lithionic's website. That's why it was not on my list already, no point looking at something you can't buy... :-(

[CatNewBee]

about the REC, I bought all components except the bi-stable driver, solenoids and shunt.
software is ok, i use the serial interface to configure the settings, also the remote display is nice, it connects also to the serial interface and shows all important values, there are pictures of it on the web site.

I have built a custom interface to the ML RBS to cteate the impulses out of static relay signals, easy stuff.

connecting to the lfp cells is also easy, just 5 wires.

The other wiring you need with any other bms too to control the solenoids and the signal inputs of your gear.

[mbartosch]

Originally Posted by john61ct

Are you going to connect your kombi style inverter to the charge or loads buss?

Ours is connected to the load bus, HVC is handled via a normally closed relay on the shore power AC side. Simple and efficient solution.
See https://www.entropypool.de/2015/05/1...system-design/
section „Shore power charger/inverter“ for details.

[shawndear]

I have just upgraded to synopoly as well. I have two banks of 600AH 12v, one in each side of my cat. I am using two BMS123 smart controllers (one on each bank) and purchased a third set as spares, fortunately, as one of the input boards did not work. Its easy to set up and so far works well. I have a common power bus which has both alternators connected to it, two windgens and currently 925W of solar.

[alctel]

I have the Orion JR BMS which is really powerful and fairly easy to configure (once you get over how the main charge/discharge relays are configured - it's a bit arse-backwards but has decent documentation). It also has an amp-counting state of charge calculator built in which you'll need to buy separately otherwise.

One thing to think about is the Victron kit - I think the BMS has integrated relays which would make everything a lot neater - though it probably costs more.

[john61ct]

Do you mean to say Victron sells BMS independently of their cells-included packaged systems?

[CatNewBee]

Hi John, what they call BMS is a solenoid with a bus interface, the balancer logic and cell voltage measurement is inside the batteries. You can use the so called BMS with other Sytems if you wire it accordingly and use it as a smart switch / breaker.

What is inside the batteries is not sold separately.