[Power] Testing A Battery

James Cameron quozl at laptop.org
Sun May 31 20:45:10 EDT 2015


G'day Sora,

The XSCE project knows about servers that can be powered directly from
12V DC, you might ask them.

History of use will be best indicator of battery health; if the
batteries have been on the solar charger and the panels have been
working for those years, the batteries should be healthy.

Look for places where people may have connected other things to the
batteries; scrape marks on terminals, and so on.  If so, the batteries
are less likely to be healthy.

Giving a load to the batteries while measuring voltage is the best
method you have to test health.

To maximise the load, open and turn on all the laptops you have for 15
minutes, without connecting charger cable; this will force the laptops
into thinking they need a charge.

Then slowly connect all the laptops using the charger cables, while
watching the voltage measured at the batteries.

Make a table with three columns; time HH:MM, number of laptops
charging, and voltage.

Then show us the table.  The experts will look at the fall in voltage
to judge if it looks reasonable for the load.

Also, send a photograph of the battery tops, showing how the wires are
connected.

I agree this system is very suitable for charging those tiny tablet
computers, called phones.  Charging one XO would be about the same
power cost as charging four phones.

-- 
James Cameron
http://quozl.linux.org.au/


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