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Re: (ET) 30 year old tool finds battery screwup.
Amazing to me that the cell installed in reverse hasn't caused other
issues during this time.
Years ago, I installed a PakTrakr monitor on one of my tractors when I
knew I had a sagging pack of lead-acid 6-volters once I had been running
a while, but couldn't find it with a hand held meter by the time the
problem surfaced and I could get off the tractor and start jabbing at
battery terminals.
Anyway, the Paktrakr found it for me, and the drop was hard enough on
that one battery, I decided the aging pack (original with the tractor I
bought used) had done it's time.
I bought a new pack from a known brand and installed it, and left the
PakTrakr in place. Within an hour of operation it flagged a bad battery
and another that was lower then the other four, although the meter on
the ET dash wasn't indicating a big problem. I reported this to the
dealer where I had bought them (special order from an automotive tire
and batteries), and they started the stall tactics.
There isn't much joy in pulling the 66-pounders back out of the ETs, but
I took them back to the dealer after about a week, who couldn't test
them when I arrived. So I left those behind. Later the same day they
called to say the batteries tested perfect. I went back the next day
with my load tester (basic commercial hand held), and tested with that.
First battery went to red immediately. Second went to yellow.
Took the rest of the batteries back and got a refund.
From my perspective, that module level monitoring tool paid for itself
twice in that adventure.
Unfortunately, that product line went out of production many years ago.
Darryl
On 2025-10-31 5:34 p.m., Christopher Zach via Elec-trak wrote:
So about 30 years ago when I first got an Elec-trak I wanted to see if
the lead acid batteries were roughly in sync, or tell when a 6v battery
or cell was hitting zero volts so I could ease off on the power and
bring the tractor in for a charge.
I built a little circuit that used 2 color LEDs (red/green) with a pair
of zener diodes per 12 volt circuit to tell what the battery voltage
was. The code is:
Green: Over 14 volts. Fully charged.
Off: Between 13.8 volts and 10.x volts. Running voltage
Red: Dropping to 10 volts and below.
As a bonus the LEDs would light up brighter as the voltage passed the
setpoints. Thus if a battery was below 10 volts that LED would be bright
while one at 10.4 volts would be dim. Go above 15 volts and the green
LED would turn yellow (bad).
Just dug it out of a box I was cleaning out in the shed and figured I'd
try it on the Elec-trak with the NICD cells. Now the big tractor has 4
sets of cells in parallel so that won't work well but the smaller E15's
each run with a single string in the front.
Started hooking it up every 10 cells. Dark LED, Bright Red LED, Dark
LED....
Hm. The second set of cells had a voltage imbalance. Got my meter went
from cell to cell then spotted the problem.
Years ago when I replaced this pack I put one of the cells in backwards.
In other words it's been running backwards for at least 5 and maybe 10
years. That resulted in the second set being 1.2 volts low and thus the
red LED.
Pulled the cell and put in a spare that was at 1.0 volts. Light is out,
however when I moved the tractor the middle LED came on (showing that
the second set of 10 batteries has a low cell). Now it's on charge and
in theory all three LEDs should come to a nice green at the same time.
Kind of amazing this 30 year old thing helped me troubleshoot the pack
like this. I have the cell on my bench, it was empty but not shorted so
I'm charging it at 3.2a rate (at 1.4 volts) and will see if it's ok. To
be honest, it might be fine.....
Chris
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Darryl McMahon
Independent Project Manager (sustainable systems)
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