wrote in news:1165722539.265878.179840@
73g2000cwn.googlegroups.com:
The experts I
consulted for my Concorde AGMs said best practice would include:
ú when possible, recharge every day the battery bank is used and as
soon as possible after use;
True of ANY float battery, like lead acids. By the way, the Lithium-Ion
batteries in your cellphone, laptop and other gadgets is a FLOAT battery,
too, and should be fully recharged asap, even if you discharged it just a
little.
ú when not in use, maintain the bank at 100% State of Charge by
continuous float charging;
I like float chargers that come on at 13.2 and go off at 14.4V and don't
come on again until the cell voltage drops to 13.2, once again...leaving
a 1.2V hysteresis gap so you don't gas them much. The little 1.5A
Schumaker or now called Vector or Black and Decker chargers are perfect!
ú avoid Depths of Discharge approaching or greater than 80% of
amp-hour capacity;
He sells batteries. It's understandable. Change the 80 to 50% and make
me happy, ok? I'm a BUYER...(c; If you need 400AH of use before
recharging, just double it and figure out how you're going to float and
store it....no matter how it's packaged.
ú avoid recharging after shallow discharges of less than 10% of
capacity; and
Nonsense and wrong. That car out in the garage does EXACTLY this EVERY
TIME it starts, normally. You crank the car for 1.5 seconds, then turn
this huge recharging alternator loose on it to INSTANTLY recharge it to
14.4VDC at some god-awful charging current, as much as it will stand,
even though you used 2% of its starting CCA rating for only 1.5 seconds.
How old is the car battery? 4 years, you say!
ú never discharge the bank to or below 11.8 volts.
Too deep. Too vague. Look at the chart on page 3 of:
http://www.homepower.com/files/battvoltandsoc.pdf
Those lines are DISCHARGE CURRENT lines. Capacity/100 amps (C/100) to
(C/3) Let's say it's a 225AH boat battery, deep cycle of course. C/100
= 2.25A If the load current is light, 2.25A, his 80% discharged point
comes (from the graph) at 12.1VDC because the current through the series
cell resistance is so small....
If we discharged it to 11.8V, from the graph at 2.25A, you're nearly
DEAD-dead to lower it that far...way too deep for comfort!
Now look at C/3..225/3=75A..same battery. 75A causes a LOT MORE voltage
drop pulled through the internal cell resistance. At HIS, not mine, 80%
discharge level at 75A load battery voltage is way down to 10.35V! So,
his flat statement is useless. This is a warm battery, by the way, 78F
on page 5 with the discharge chart on it. Temperature varies it as it
varies internal cell resistance.
So what does Joe Boater do with HIS voltmeter? He opens that battery box
with the Battery Switch to OFF and measures 13.5VDC with NO LOAD,
declares the batteries in great condition because they are AGM batteries
and closes it back up. "It doesn't need maintenance.", he declares to
noone in particular. "These are Cadillac Supreme AGM batteries I paid
$1299 each for!", proudly. Joe has no idea cell 3 is deader'n a doorknob
because he didn't LOAD TEST the cell. Dead cells have great voltage with
NO LOAD!
Larry
--
Why is it, in any city, all traffic lights act as if they have rotary
timers in them, like they did in 1955, and are all set to create
maximum inconvenience and block traffic movement, entirely?