LITHIUM SMART BMS

[mahendra]

http://files.ev-power.eu/inc/_doc/attach/StoItem/4493/User_Manual_123SmartBMS_v_1.0.pdf

http://www.ev-power.eu/Battery-Management/BMS123

Guys check these out tell me what you think according to the manual it serves all the functions/setting one would desire in an off grid pv lithium setup.

[mike90045]

I get
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So, my thoughts anyway.   After watching a lot of "discussions", I personally would skip the BMS, with it's many wires and failure points, and use a "Bottom Balance" system to keep the cells in the flatter part of the discharge curve,  and avoid the lower 20% and the upper 10%.  That keeps the cells away from the troublesome areas that kill them.   it does require you to perform a initial conditioning charge for each cell, then a discharge cycle, and you set the pack for the lowest cell.

Then you program your inverter LVCO and the charge controller HVDC and you are set.  Some can be refined.

[Cniemand]

As Mike states, it would be simpler and more reliable to "Bottom Balance" the system. From the PDF it looks like it is using the voltage range of 2.5v and 3.5v.  Within these voltages you do not really find issues so long as you balanced your pack at the 100%DOD point or ~2.75.  Personally, for maximum cycle life I wouldn't take them below 3.1v each or roughly 80%DOD. You could occasionally bring them to 100%DOD so long as they are all balanced and thus do not kill each other. 100%DOD = 2000 cycle life. Though keeping to 80 would give 3000, while 70% supposedly grants 5000. It's still a bit early on the market to tell their real life cycle-life. Then again... many kill their Lead Acid batteries far too early as well.

Maybe more people would realize high cycle life with LFP batteries due to their being very little in the way of "maintainance" which most people do not keep up with.

You can easily keep these cells in check with a Midnite Classic controller with proper set points and end amps.

I personally do not trust a bunch of tiny lead wires and PCBs with blinkers all over to not fail throughout the lifetime of an off-grid system.

[mahendra]

point noted