TESTING AN ELECTRIC PROPULSION BATTERY BANK

It came time to test the batteries of BIANKA’s electric propulsion bank to make sure  
the suspect battery 1 was indeed bad and the others we're still good. To test the
batteries I first needed to empty out the locker so I could squeeze myself down into
the space.

Once that was done I gathered my tools and tester hoping I didn't forget anything
because working down below is a tight space for big guy like me and getting out of it
is much harder than going into it.
So I try to minimize going in and out of the space. The nice thing about down below
since I took out the diesel and put in electric propulsion is my clothes will remain pretty
clean and I won'tsmell of diesel and oil.

I use the Centech Battery Analyzer tester for quick checks on the batteries.
It tests the internal resistance of the battery and also the cold cranking amps
available.  It's not a load tester but can give you a quick look at the condition of
the battery. I'm particularly interested in battery 1 which seemed to have very
limited capacity when I used it last season.
Time to head down below and begin the testing:

As I suspected battery number one had tested numbers were way out of line
compared to the other three batteries in a 48 volt string.

While the voltage reading  on the battery Look good at 13.11 volts.  The internal
resistance of the battery was very high reading 35.8 milliohms.

Compared this to the next battery in the string which had an internal resistance
of 1.95 milliohms.
Also note at the top of the display screen. The one above has only one pixel
and says NG. While the one picture below pixels all the way across and says
good.

This confirmed my suspicion that there was definitely something wrong with
battery 1. Likewise batteries 3 and 4 had similar internal resistance specs to
those of battery 2 with regards to the internal resistance of the batteries.

Moving on to the  cold cranking amp tests  once again showed that battery
one was a indeed defective. The tester showed that there were only 85 cold
cranking amps available.

The  spec for the 8A4D battery is 1100 cold cranking amps. Tests of the
other three batteries showed  they were all over the 1100 spec for cold
cranking amps.

I tabulated the results and  and entered them into BIANKA’s logbook.

Now I also have a data on the three good batteries and can keep an eye
on them as they age. Only thing left to do is order a new 8A4D battery to
replace the defective battery 1.