Boatboy
Here is a link to a pdf doc which has some good explanations in it.
http://redflow.com/wp-content/uploads/2015/03/Redflow-Understanding-the-Redflow-Battery.pdf
2. The Redflow ZBM at a Glance
From a strictly electrical point of view, the ZBM battery presents very good
characteristics. In its base configuration, addressed as ZBM, it is a 210Ah, 48V nominal
battery (a nominal energy storage and delivery capacity of 8kWh at a typical roundtrip
efficiency of 80%), with a voltage ranged between 36V and 57V.