"Larry Jaques" wrote in message
...
On Mon, 22 May 2017 12:34:09 -0400, "Jim Wilkins"
wrote:

.....
I forgot to ask what you meant by that. Are they drawing half an
amp
or showing that discharge rate?

I kept the current from the battery close to 0.5A by tweaking the
rheostat load. Surplus phone chargers power the meters and the relay
independently from the battery, since I won't be wasting my backup
by
running these discharge tests into a dummy load during a power
outage.

Some of my homebrew test equipment runs on AC power for better
accuracy, some on DC from the battery being tested or the solar
panels
so it will still show demand or charging rate during a power outage.
The load current varies too much for accurate measurement and
battery
remaining life prediction, but all I really need to know is if the
batteries can run the fridge overnight.

OK, so your -fridge- demands 0.5A? titter It's hard for me to
conceptualize a half amp draw at 12v, as few things operate at that
level.

Maybe I should have repeated that I was discussing a different battery
closer to the mention of the fridge? I post all this to practice
clear, concise technical writing and then try to determine why it's so
often misinterpreted.

The fridge takes 120W initially, slowly dropping to 80W, as measured
with a Kill-A-Watt on wall AC. When the power goes out it runs from an
APC1400 SmartUPS pure sine inverter with two external 12V Group 31
batteries. Discharge tests on them could end in the middle of the
night and let my fridge warm up, so I bought equipment to automate the
capacity measurement with safe loads.

I'm checking out that equipment on less valuable batteries that don't
take nearly as long to discharge. I've been posting a summary of
significant observations, not a daily diary of my experiments, so I
haven't always clearly indicated which battery or test load they came
from. The 0.5A test was to measure the C/20 capacity of a smaller AGM
battery from a 350W UPS.

...
Are you trying to (or not to) tell me about a box full of 18650s
you're putting together to run your fridge when the power's out?
Testing those with a 6w drain just might be the connection my mind
continues to search for with your bloody half amp thing.

I found a source of tabbed Li-ion 18650s for $2 each and hope to
restore old laptop batteries etc with them. They appear to have been
in storage long enough that some dropped below their low voltage
safety disconnect, but still accept a charge applied directly to the
tabs.

-jsw