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Discussion Starter #1
I came across an interesting voltage reading while checking the batteries
in my T-125 pack. After a long drive, ONE battery was 1V lower than the
rest. Even after charging/equalizing it only reads 5.3V - obviously very
weak or dead.

Funny thing is, if I put the DVM probe on the (+) terminal lug instead of
the battery's lead pad, I read 6.3V instead of 5.3V, which is more in line
with the rest of the pack. Same thing with the heater on (~10A load). In
fact, if I read all batteries "from the lugs" they look identical... What
gives?

BTW, the dead battery is the only one I've had any corrosion issues with.
It had a temporary copper lug that accumulated a bit of green crust on the
positive terminal. Cleaned it all up and replaced the lug with a heavy
duty tinned lug. The green cruft is slowly growing back but the connection
looks generally clean.

-Adrian

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70 Posts
Discussion Starter #2
Hello Adrian,

The positive post is becoming oxidize by the electrolyte leaking up through
the post seal. I have seen this even on new batteries, so I specific that
all post shall be a light lead color. Sometimes this reaction does not show
up until you do several charge cycles which I specified a replacement at
that time.

And it may not show up after the warranty period is up. To prevent this
reaction, I use those red and black corrosion control ring pads that slip
over the post and then use a heavy duty copper plated battery clamps around
the post that is torque to 75 inch lbs.

I also set the batteries in a 1/2 thick bed of baking soda in the bottom of
the battery box. Use plenty of air circulation by exhausting the battery
box with a totally enclose pvc plastic fan. My batteries after 8 years look
just like new.

When install a new set of batteries of this type and torqueing them to 75
in.lbs. I will then check all the connections in 5 miles. It is normal to
lose about 5 in.lbs which is sometimes call shrink back of the new lead
surface contact. Then I re-torque them again.

I had one guy stop by with his EV and said he has weak power. Looking at
his batteries, look like yeast got loose from baking bread on the batteries.
I had him clean up the batteries with Windex that has ammonia in it. The
ammonia neutralizes the H2SO4 on the post and battery tops.

Before I install the links with the battery clamps onto the post, I remove
the battery clamp bolt and roll up a small paper towel which I push into the
battery clamp post hole. Then I paint the positive with that red rubber
tool handle dipping stuff. I also do the negative with the black stuff.
Look on the instructions on this stuff, and you will see it can be use for
battery connections.

I then install the red and black heat shrink over the barrels of the battery
clamp.

I find that at times that if I just touch the battery post with test leads,
the voltage may not be as high if I really push in hard past the oxidation
that may be even a darker gray color. Using my battery analyzer tester
which has those large high tension cable clamps, the display will come up
and say Wiggle Test Clamps.

Another test I do, is to test the voltage of each cell. And you say how do
I do that. Well you cannot do this test with seal batteries, but with the
batteries you have. I use a battery cell tester made by
Cal-Van No. 545 that has cadmium coated long test prods. You insert the
prods into two adjacent cells so it just touches the electrolyte and will
read the cell voltage between these two cells.

I use a plastic washer so as to hold the prods at the correct height. The
reading between two cells from electrolyte to electrolyte will read
different then the two end cells when one prod is in the electrolyte and one
is on the post will show a lower voltage than then the others. You then
have to add up all the readings to get a total battery voltage.

After a while, you will notice what the voltage of each cell should be for a
normal battery voltage.

Roland






----- Original Message -----
From: "Adrian DeLeon" <[email protected]>
To: <[email protected]>
Sent: Saturday, November 13, 2010 10:30 AM
Subject: [EVDL] Strange flooded battery measurement


> I came across an interesting voltage reading while checking the batteries
> in my T-125 pack. After a long drive, ONE battery was 1V lower than the
> rest. Even after charging/equalizing it only reads 5.3V - obviously very
> weak or dead.
>
> Funny thing is, if I put the DVM probe on the (+) terminal lug instead of
> the battery's lead pad, I read 6.3V instead of 5.3V, which is more in line
> with the rest of the pack. Same thing with the heater on (~10A load). In
> fact, if I read all batteries "from the lugs" they look identical... What
> gives?
>
> BTW, the dead battery is the only one I've had any corrosion issues with.
> It had a temporary copper lug that accumulated a bit of green crust on the
> positive terminal. Cleaned it all up and replaced the lug with a heavy
> duty tinned lug. The green cruft is slowly growing back but the connection
> looks generally clean.
>
> -Adrian
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>

_______________________________________________
| REPLYING: address your message to [email protected] only.
| Multiple-address or CCed messages may be rejected.
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