'Use the batteries for 5 days but get 4 cycle days Free because we deficit charged
the badboys each day but the fifth day '.
It's not a deficit charge. It's a long, slow continuous discharge with loads being offset by incoming RE power. But the incoming does not meet loads long term, so the batteries undergo a five day long (or whatever) discharge down to 50% (or whatever).
I don't know who thought up that off-grid deep-cycle batteries have to be fully charged every single day. They don't. Batteries don't give a flyin' crap about one complete revolution of the earth like people do. Every time a battery is discharged and fully recharged, that's a cycle. It don't matter if that cycle is one Earth Day long, or five Earth Days as long as it's brought back to full charge on a frequent enough basis to prevent sulfation problems. <snip-ith>
--
Chris
<Snip from The Lost Bigtime Battery Studies >
Also, the finish-charge
efficiency can be very low at less than 50%.
Finish-charging is assumed to be accomplished
by the engine generator since it requires
dispatchable power.
The interval between
finish-charges can be as short as one cycle or
in excess of 20-cycles, depending on system
and battery requirements.
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Note: This was BOB. (Before Old Bill)
With AOL. (After Old Bill) we 'Aquarius Power' the dispatchable power for the finish charge
how WE Likes it with a completely autonomous Power Block.
<Snip from The Lost Bigtime Battery Studies>
(Sorry no Link since the Studies are Lost AGAIN.)
Guess old Bill will control that 'Knowledge Vault' now,
as part of his '90 Day Wonder' training.
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<Snip>
The PV Hybrid Battery Test Procedure
attempts to answer the following questions:
(1) How often does the battery need a
finish-charge to maintain capacity?
(2) What charge parameters are needed to
maintain battery capacity in a PV hybrid?
The test procedure includes the following
system and battery parameters:
(1) bulk-charge termination voltage,
(2) finish-charge regulation voltage (in the
tests in this report, 1 and 2 are the same),
(3) charge and discharge rate,
(4) discharge termination voltage,
(5) interval between finish-charges, and
(6) finish-charge duration.
Using this information, the number of deficit
and finish-charge intervals required to obtain
battery capacity trends was established.
A
deficit charge is used in this report to mean a
charge that does not bring the battery back to
the same state of charge at which it began the
previous discharge.
For example, if 50 amp-hours are discharged and 45 are recharged,
then that is a deficit charge.
In addition, if 50 amphours are discharged and 55 are recharged, that is probably also a
deficit charge because the battery inefficiency at high states of charge is well below 100%.
It is important to understand that if system charge and discharge rates or system parameters
deviate significantly from the chosen rates and parameters, then the test results may also
change. For example, the PV hybrid may be operated more like a stand-alone PV system than
like a hybrid. The stand-alone PV system will cycle the battery to a much shallower depth of
discharge every day and recharge every day based on available solar resource.
The PV hybrid system will usually discharge the batteries to a much deeper
depth of discharge and probably won't recharge the battery to a
high state of charge every day.
In the case of the stand-alone system the effect of shallow daily cycles between 10 to 20%
depth of discharge (DOD) every day
would minimize the need for the higher regulation voltage because the shallow cycling and daily
recharge results in less electrolyte stratification and degradation to the battery.
In addition to the effects of the daily depth of discharge, the age of the battery will also greatly
impact the recharge characteristics. As the battery ages there may be a significant increase in
gassing current affecting battery efficiency, maintenance, and electrolyte stratification.
Therefore, regulation voltage or finish-charge time may need to be adjusted to compensate for
the aging battery. These adjustments can include the regulation voltage, finish-charge time, and
finish-charge interval.
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So say-ith The Legendary Sandia National Labs.
'Your Tax Dollar giving you a straight story (and some fun) without all the me, me, me.
Bill Blake