[RE-wrenches] AGS quiet time

[Zeke Yewdall]

I used to be a firm believer in only operating lithium batteries in open
loop, because trying to do closed loop with most requipment was such a
disaster of communications tinkering at best.  I would still try to operate
the AGS with SOC based controls as much as possible, but still have a
voltage catch in case the SOC drifted off from reality.  Outback would let
you have both at the same time.  But still no comms with the batteries.

But, if you can have the batteries and inverter from the same manufacturer,
which is more and more possible, so you know closed loop communications are
going to work, that is much nicer than trying to determine voltage based
start and stop points on a lithium battery.   So I'm coming around to using
closed loop communications since starting using matched equipment.

I get not taking the SOC all the way to 100% with the generator to leave
some room for solar.  But I think it depends on your climate.  If you
have some winter sun and can still get to 100% regularly, I think that can
make sense.  But if you have no winter sun (like where I am now -- typical
PSH well under 1 for Dec and Jan -- I've measured as low as 0.25PSH for the
month before --  then I am still a believer in getting the batteries to
100% regularly (once every week or two), even if that takes a generator.
Otherwise the SOC indicated by the BMS can drift from reality.  Some BMS's
will recalibrate their SOC if they get a voltage reading at rest at an SOC
lower than 100%, but many BMS's will only recalibrate the SOC calculation
when they reach 100% (same as ah counting SOC meters that have to reach
100% to recalibrate/reset).
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