On Sun, 21 May 2017 19:49:32 -0400, "Jim Wilkins"
wrote:
"Larry Jaques" wrote in message
news
On Fri, 19 May 2017 16:13:34 -0400, "Jim Wilkins"
wrote:
....................
I bought this which has an easily set low voltage disconnect and
handles up to +/-30A,
https://www.amazon.com/DROK-Display-...ct_top?ie=UTF8
Hmm, there are 3 different pictures of the back of those. One has a
built-in shunt, another a pair of relays, and another is bare.
Which
is the real meter pic for the "30a w/ relay"?
The 30A model I received has a shunt and blue NC relay on the base
module. The display module has a small red+black pigtail for external
power if you don't use a USB connection. At first the USB connection
on mine was poor and it intermittently shut off, or switched to
wireless without losing power. The correct accumulated totals
reappeared when it reconnected.
It displays current to 2 decimal places but is accurate only to 1
place +/-, for example 0.478A on a Fluke 8600A reads as 0.48A on the
10A "Electrical Parameter Tester", and 0.65A on the 30A unit.
A layer of Gorilla tape tightened the USB plug in the base unit
against the circuit board contacts and it has remained connected when
moved.
Duct tape to the rescue again.
You showed another link for a milliamp/millivolt-resolution meter a
few weeks ago, too. How's that working for you?
The 33.00V/3.000A meter is my favorite for recharging and equalizing
batteries slowly from my solar panels. It clearly shows when a small
AGM's charging current has decreased to 1% of the C/20 capacity, like
45mA for a 4.5A-h AGM battery. Currents around 1% are recommended end
points for trickle charging.
http://www.trojanbattery.com/pdf/Tro...UsersGuide.pdf
Diagram 4 gives 1-3% for flooded, Diagram 5 gives 0.5% for AGM.
I've downloaded both guides you've mentioned in the past several days
and will have to compare them. Each one will have tidbits of info the
other doesn't. That's the true benefit of research: gleaning tidbits.
As mentioned, the current rises in older batteries and is an indicator
of declining condition.
That sounds like something I should pay attention to.
The first one measures charge and discharge current separately and
counts the Amp-hours up or down accordingly, though the Watt-hours
total is the positive sum of both (???). It has a more accurate
voltmeter and a better timer that counts seconds and stops when the
relay opens, allowing a pause in the measurement and a record of
battery run time. Unfortunately the current resolution is 0.1A
despite
the display, so it doesn't handle small AGMs well.
The former part is cool. Not having proper resolution for decent
data
is never fun, though.
I first learned how to make accurate measurements as a chemist whose
results might have to stand up in court, then when building very
precise automatic test equipment for the semiconductor industry.
Analog Devices' op amps and voltage regulators were tested on machines
whose performance I was responsible for.
https://en.wikipedia.org/wiki/Automatic_test_equipment
Cool! Nice legacy.
The second one matches other ammeters to 1 or 2 digits and I use
both
in series for discharge loads up to 10A. Together they each make up
for the deficiencies of the other. The 12V,12Ah battery is
discharging
on them at 0.5A.
I forgot to ask what you meant by that. Are they drawing half an amp
or showing that discharge rate?
Did I ever ask you why you didn't use a real battery for that? g
(real being 12v 35-275Ah) I set one up for use with the 45w HF trio
of panels and was able to power a 14" electric chainsaw with the 2kW
modified sine wave inverter, also from HF. It would have taken days
to recharge it (or more panels if needed for continued use.)
I do have "real" batteries that will run the fridge for about 20
hours. Once I'm satisfied with my discharge testing setup I'll get to
them. For now I'm testing and risking smaller, older, less valuable
jumpstarter and UPS AGMs.
Smart.
These tests are too long to watch and if the
low voltage disconnect fails the battery could be drained flat before
I notice.
That wouldn't be fun. How often do the disconnect programs (or
hardware/relays) fail?
--
In today’s academia and mainstream media,
we’re all guilty of hate until proven leftist.
--Robert Knight, senior fellow, American Civil Rights Union