Grid Scale Battey Storage -

A Houston based company, KeyCaptureEnergy is but one of many international companies engaged in this technology. It is at or near competitiveness with the peaker Gas Fired generators.

Residential Lithium Battery Storage

I see residential storage as a method to artificially extending the daylight hours, if you have a large array, and overproduce. Additionally, being an EV guy, I am exploring the recommended practice with smaller lithium batteries. The recomended practice is to monitor the health of the cells in a Li pack. And actively monitoring the cell voltage and temperature. Monitor the cell voltage beacuse over discharging the cells, or over charging the cells is a bad thing. Do not want them too overheat and let the smoke out. To monitor the cell voltage, one has to develop a printed circuit, that is isolated and transmits the voltage and temperature to a central microcontroller. The isolation is accomplished thru optoisolators. The transmission process can either be parallel or serially. There are several formats of data transmission.

To avoid cell damage, either a person stops the process of over-charging or over-discharging that battery pack, or it is automatic, and built in to the microcontriller. The former is called a Battery Monitoring System, and the latter is called a Battery Management System. A good source of information about available Battery Management Systems is Here.

The path I have taken (and I am not an expert) is to build a parallel Battery Monitoring System. In the below picture, 8 each of a 160 amp hour cell are connected in series. This is a nominal 24 volt system, storing 24 volt x 160 ah = 3840 watt hour. Battery management is to follow with a circuit board that includes a resistor to dissipate energy during the charge cycle. Each cell is monitored, and the data is sent to a master microcontroller (Arduino UNO). The cell boards were developed by Cyclotronics.