I just spent two nights reading both manuals for the Chargery BMS8T and the Tiny BMS. They are extremely close in abilities. I distilled it down to the following using info gleaned here at diysolarforum and elsewhere:
The BMS8T:
The manual has lots of Chinese-as-a-first language issues but they're manageable.
The unit appears to be very well done.
The schematics show the relays in the high side and the shunt in the low side. The unit does balance at 1.2A but slows down the balancing if the unit is roasting.
Jason's covered all the bases and ALSO provide precharging with a little board but doesn't actually call it that. Just "Low Current" and "High Current" discharge relays driven from a small board with selectable delay between the Low Current and High Current closing outputs.
Pros:
Does most everything.
Has highest balance out there. 1.2A
Has a built in display/program unit. Once programmed the display is not required, starts up and runs as programmed without it.
Cons:
Doesn't seem to have any wireless status ability
what-so-ever.
The display is an annoying blue background but certainly usable.
Only 2 temp sensors.
The standard resistive shunts waste about 15W at 200A. Considerably more than most power relays! (4-10W)
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Tiny BMS
Pros:
Seems seriously engineered.
A No Chinglish manual.
Uses a sophisticated LEM (expensive, high quality hall effect type current sensor (loss-less no shunt drop)) The current sensor is a dual unit that has two inside it that switch off with one for sub 70A loads the other for over 70A up to 750A loads allowing a considerable accuracy improvement.
Can do 64(?) temp sensors on a temp sensor comm bus so you can have more than one per battery (if you're psychotic) but at least one per battery is straight forward. (This can quickly clue one in to a problem that could easily shorten a packs lifetime and not be discoverable with only two temp sensors.
Cons:
Puny joke balancing. 150mA**
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**There are active balance boards that do nothing but try to keep battery stacks balanced.
Example:
r Active Balancer
Possibly install an active balancer on top of the Tiny BMS and get large balancing power. Weirdness is that some of these balancers only balance to the neighboring cell. If a cell's high it's balancer sends the power up to the next cell, then the next, then the next, until the weak one receives the energy. I guess that would work. You would definitely want a BMS watching this to alarm if an active balancer went crazy.
Have heard rumors of cheap active balancers running-a-muck and draining cells well below 2V. May need a way to disconnect the entire A-balancer if the BMS decides the cell voltages are going out of whack.
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Note: Lots of talk about chargers of all kinds being extremely pissed-off about having their outputs disconnected while charging. It generally toasts them 80% of the time. To be avoided! So either the BMS should digitally signal the chargers, be them solar or grid, to cease charging and they'd better damn well respond or they need to have their sources opened which doesn't hurt any of them. With a solar charger that means you disconnect the array from the charger or with a grid-tie you dump a relay/contactor that is supplying the grid power to the charger.
I believe I'm going with the Tiny BMS. Ultimately the communications seems very flexible. I could see some off-the-shelf MODBUS server-to-the-cloud working well for a world-wide connection and certainly a local house-net server.