Hunt for a 300A - 500A BMS

Having settled on a modular battery pack architecture with 2 BMSs, so begins the search for suitable candidates.
 
QUCC's QJ-34U can support up to 500A. Several brands offer this model. It costs $200 on Aliexpress with the relays and hall sensor.
Switching is done with relays, and current is measured via a hall sensor. It supports either same or split port charging, and even a precharge relay / resistor. Communication can be done via UART, RS485, or CAN ports. It looks like a pretty flexible and capable system. Diagram example:
Unfortunately, after contacting their support team it appeared that most of its parameters are non configurable. They are fixed, based on the selected cell chemistry. I want more flexibility than that. And "QJ34U has no temperature protection function" during charge or discharge. Oh well, sayonara...

QUCC also offers the 300A QJ-38XS. It costs $145 on Aliexpress.
However, most of its parameter are fixed, based on the cell chemistry. A proprietary display can be attached for basic configuration and monitoring, but there is no standard comm port. It also has no temperature protection, and does not measure the current to protect against out of spec current draws. Oh well, au revoir...
 
Heltec has a "Hardware BMS" family, i.e. simple non configurable hunks of electronics, like the $65 4S 330A LiFePo4 sku 1397.
However, it does not have configurable parameters, or a comm port. And their support replied "can not be used in parallel" with another BMS / string. Instead they recommended the Heltec Relay Smart BMS which is similar to the QUCC QJ-34U above. Oh well, auf wiedersehen...
 
That left the Daly products that can support up to 400A (500A in a special version).
They come with seemingly configurable parameters, separate charge and discharge high + low temp protection ([Update] this may be incorrect, more on that below), UART comm port, and integrated current switching & measurement.
However, the high current models use an active fan for cooling, which is not ideal for long term reliability or enclosed assemblies. And there is much confusion out there due to a whimsical start-up process. They also do not seem to have a stellar reliability track record.
 
  Update   the Daly BMS is limited to 1000AH per cell. This van's Winter pack is 5x280 = 1400AH per cell. Meaning that the BMS's min-SOC protection might shut off the pack after only 71% of its capacity has been used ? Contacting Daly to see if the SOC protection can be disabled or fooled...
 
  Update2   Got clarification from Daly. SOC is just a monitoring value and not part of the BMS protection parameters. More in this post: Battery Pack 2.0 with BMS done !

Daly focuses primarily on electric scooter applications, now branching out into power storage. Their official quality policy, from the 2nd line of their What About Us page, is "Only safety, not to be"...

And that's all the affordable high current BMSs I could find. If you know of any other, please drop a comment ?
 
The only technically viable option with configurable parameters and comm port being Daly, I went with their $250 Smart BMS 4S 12V 400A LiFePO4 model. It is way oversized at 400A. But I might end up mounting one of the BMSs in a hermetically closed box with no ventilation. So, operating its MOSFETs way below their max current will hopefully improve reliability and longevity.
 
And compared to its primary use case, which is scooters, monitoring a van's house load is orders of magnitude less stressful (temp, cycling, peaks...). That should also help on the reliability front.
 
Very well, Daly it is then. Crossing fingers that I am not rolling the dice too much here...
 
Note that a special 'Parallel' version of the Daly Smart BMS, along with a Daly Parallel Module, are required in each pack when connecting packs in parallel. This provides current sharing, protection against large SOC differences between packs, precharge resistor, etc. Although this van will theoretically ultimately support the Winter & Summer packs in parallel, I will just be using a regular Daly Smart BMS model thanks to specific precautions and procedures that will be explained once the Summer pack gets built.   Update [Sept'23]   paralleling packs is no longer in plan since the addition of a gasoline heater
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