ok, poor choice of words. Â after all I'm just an alarm installer as uno
 who loves to point out how ignorant we are.  how about documentation
correct. Â which is more than your method gives. Â to answer your question
according to the $100 plastic box with alligator clips if a 4 Ah  falls
below 2.6 Ah it is bad. Â if a 7 Ah falls below 4.55 Ah it is bad.
Hmmm. Why would a 7Ah require more life than a 4 Ah to be considered
good? I would think that either (a) both would require the same ( just
for the sake of keeping it simple) or (b) the 7 Ah could accept a
lower reading because of it's larger capacity it could sustain a drain
of a specific amount of current for longer period of time.
Or that the current draw and amount of perscribed standby requirement
for the system the battery was being used in ..... over what period
of time .... would be thrown into the calculations.
Not just a preset number. (?????)
  it
takes less than a minute and if it's wrong I can blame the manufacturer.
 not some box I made.
Regardless where you got the reading ..... it would be wrong.
 As for changing readings, not that I would, but
if anyone were to falsify the data I'm sure they would just say the
battery was bad so they could sell another battery which would in no way
jeopardize the operation of the system.
Even with the recent increase in battery cost, I'm of a mind that it's
better to change a battery, if it's been in for a few years, even if
it reads good. I don't feel I'm just "selling them another battery".
I'm taking precautions that surely reduce the possibility of a battery
failure. It's not a "rip off" That's what they pay me for ..... to
anticipate and head off potential problems. I'm sure they'd rather do
it that way then wait until they get a low battery signal and have to
pay me for a service call just to change a battery that I could have
changed a year ago .... the last time I was there.
 I'm also pretty sure that your
method is acceptable for testing batteries. Â I just needed something for
the AHJ that was industry wide acceptable and gave me a reading that I
could 'document'.
When Yuasa, first came on the scene, finally providing the trade with
reliable rechargeable batteries, the method I use was recommended by
them. Since I do primarily residential now, and in the event that all
else fails, the newer alarm systems provide a low battery alert,
there's no reason for me to have to document a battery condition. So
I just continue to go with what's worked for so many years. (Other
than a burned finger every once in a while)
)
