I just got the chargery bms8t (its the same as the bms16 and bms24, but only monitors 8 cells and has smaller control box). I been putting it through its paces for the past week.
I got it hooked up to my 220ah lifepo4 which is connected to a 240watt solar panel and 20 amp ecoworthy mppt. I decided to get the chargery to replace the 4 dollar 30amp bms I was previously using. The cheap bms don't work well with solar, everytime the bms triggers to stop charging I would get voltage surges that destroyed many 12 voltfans.
The chargery comes with no instructions in the box, you need to download from website, it took me a while to find them. Its basically a display box, control box (that goes by your battery), and a shunt (i got the 100amp). The display box (lcd) is connected to the control box by a coiled wire(like on a telephone) and you can place the the display box in a convenient area.The control box gets its power from the balance connectors or external source. If you power from the balance connectors, I notice the readings for the cells were all over the place, I decided to use an external source (actually the same battery 13.3 volts) the external plug is not included but I found out that an opus btc3100 plug will fit perfectly on the unit. With external power, the cell voltage read perfectly.
You need to supply your own contactors I been using a 30 amp automotive relay (its all I need for my system), The control box can power larger contactors, much higher amps then most bms. The chargery is failsafe in design, the connectors that supply the contactors are always powered on, if the bms decides to shutoff the charging the contactor is deenergized. If the chargery loses power, the contactors will shutoff charging. The method of controlling the contactors is not changeable, they are always energized, so you need a contactor that are always normally open(when deenergized). If using large contactors, they will be consuming power all the time, I see that as a negative unless you have a very large battery bank. I actually decided not to use a contactor for over discharge, since I rarely use more then 30 amps in a day. I'll rely on the audio alarm.
The chargery can count the amps going in/out of the battery, but it displays in watt hours, myself I prefer to monitor the amp hours but that is not an option with the unit. In the settings you set the battery amp hours but I don't know how the unit uses it since it doesnt show up in the main screen. As a coulombmeter the unit is useless for that purpose, though it should be able to do it. Also on the main screen any usage of less then 1 amp charge/discharge isn't displayed.
Besides the ability to control the contactors to disconnect charge/discharge, it also has a beeper alarm and a flashing light that will go off when limits are exceeded. And it has 2 temperature probes that monitor battery temp, they will also disconnect charging/discharging if temps are exceeded. The cells over/under voltage are fully programmable. Also the chargery can balance at 1.2 amps per cell, which also allows to set the voltage you want it to start balancing. I am using active balancers on my lifepo4 packso was unable to test the balance feature.
As far as longevity, the unit seems very well built. I like the ability to see the cells voltage in real time. I like it so far, cost me 86 dollars including shipping.