I have one of those solar (remote panel) motion security lights on my porch with a 5 cell Ni-Cad battery that has died for the second time. 5x1.25v would be in the range of 2x3.25v (LiFePo4) but you don't see 2 cell LiFePo4 BMS around. This system had a 11v open circuit solar panel on it and some sort of charger circuit but I still want to protect the cells. I had some 6.8v zeners, so I put one in parallel with the two series cells. It has been working fine for about 2 weeks. We have had a couple of sunny days in a row, so yesterday I checked the voltage. My DDM showed it at 6.92v. Seems like a reasonable solution.
