Game changers and customer benefits: Integrating a range of battery types into storage systems

Hello Sarah

One of the set backs in using multi-cell lead acid batteries is that cells can become unevenly charged requiring a lengthy episode of float charging to equalize cells and even then there is no guarantee that this will happen. At such times the battery is unavailable for regular use.

Linear Technology provide the DC2043B – LTC3305EFE Demo Board | Lead Acid Battery Balancer for 2-4 Cells. http://www.linear.com/solutions/6025 I would expect a progressive company such as SMA to provide this or similar technology to ensure customers obtain the maximum life from their lead acid batteries especially in the domestic market.

Can you please provide awareness of this to your design effort.

SMA has an advanced BMS built into the Sunny Island range, as I understand it. However, there are new technologies which have totally different requirements to a lead acid or lithium chemistry, such as flow batteries. At a high level, flow batteries are going to have constraints on charge and discharge currents (they are effectively high impedance), and completely go against the grain of current chemistries by discharging to zero – in fact flow batteries need to regularly discharge to avoid dendrite build-up which might damage the cell membrane. The flow technology for which I have an interest is Zinc Bromine; I suspect that there is a common tendency of flow battery developers to have developed their own BMS, in the same way that Lithium battery manufacturers attempt to protect their cells from discharge.

I also understand that there is the option of turning battery management off. It would seem that without necessarily developing a one-size-fits-all BMS in SI, intelligently accommodating conditions that would represent faults in most chemistries will allow the maximum interworking potential. The fact that Home Manager can apply an overview set of rules also offers a way of accommodating new technology.

In other words, preventing the SI from shut-down at zero stack voltage, for example by using the BATEMP sensor as a ‘stack still alive, wait for me’ signal, and being able to provide charging current into a 0V stack would prevent a multiplicity of failures. All of this can be locked away under expert mode.

It is obvious that there will be many offerings and that few will make the transition from good idea to commercial success, but a few basic keyholes will allow a potentially massive expansion in utility of Home Manager, allowing more sophisticated interworking with the winners, or development of a standardised intelligent BMS interface allow smart batteries to talk with SI and Home Manager.