there would be a 0.7 V drop across the diode so then the system voltage would be 12-9.8V instead of 12.7 to 10.5 (taking 10.5 as the voltage at which your batte

there would be a 0.7 V drop across the diode so then the system voltage would be 12-9.8V instead of 12.7 to 10.5 (taking 10.5 as the voltage at which your batteries are well and truly dead) I've used diodes [0] to isolate redundant power supplies, but we turn up the voltage on the power supply to compensate. However other than redundant applications I've never isolated batteries. I've just googled this and mostly found posts recommending not to use diodes and one that didn't comment on whether or not cross-discharging was actually a problem, but said not to use a diode but to use a mosfet[1]. It generally doesn't appear to be a problem for most people. The most interesting part of the blog post for me was the eye opener for the author; 200 W of solar and 250 Ah of battery isn't enough to run a computer day in and day out. I would have gone for something like 1200 A-h of battery but not lead-acid, as well as added an AC powered battery charger so I could plug in. 0: https://www.phoenixcontact.com/online/portal/ca?uri=pxc-oc-itemdetail:pid=2907719&library=caen&pcck=P-22-02-02-01&tab=1#drawings https://www.phoenixcontact.com/online/portal/ca?uri=pxc-oc-i... 1: http://www.homemade-circuits.com/2013/08/connecting-batteries-in-parallel.html http://www.homemade-circuits.com/2013/08/connecting-batterie...