# [EVDL] Battery Testing - Midtronic Battery Tester



## EVDL List (Jul 27, 2007)

>1. What is Conductance? Conductance is a measurement of the battery's
ability to produce current.

Conductance is the inverse of resistance.

Ie conductance = 1/resistance.

I agree that measuring at a low load and extrapolating is a very poor way to
test. 
At test like this assumes internal resistance doesn't change with load (in
amps) (it does)

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of drdhdmd
Sent: Sunday, 12 April 2009 10:52 PM
To: [email protected]
Subject: [EVDL] Battery Testing - Midtronic Battery Tester

I would like the groups opinion.

One of my Deka 9A31 batteries is failing quite significantly. It no longer
can maintain its voltage under a load. While the other batteries stay
between 11 and 12 volts, this one drops down below 10 volts even at currents
of less than 50 amps.

When I brought this battery back to AutoBarn, where I purchased it, they use
a Midtronic Batery Tester set for the 800 CCA listed on the label and it
checks out "GOOD". So they say it must be good.

I sent this inquiry to Midtronics:
We have a number of Deka 9A31 AGM batteries that are supposed to be rated
at 800 CCA and 1000 CA. In our application, an electric vehicle the
batteries do not perform up to their specification, ie they are not able to
supply even 500 amps at 50 degrees F. Your tester says they are "GOOD" but
they are obviously not. Your tester does not test the batteries under a 500
- 1000 amp load so how can it properly test for CCA and CA?

This was their response:
David,

Our pass-fail threshold is consistent with that off the BCI (Battery Council
International) specifications for proper load testing of batteries. Just
because we do not use a load, does not mean we do not properly test for CCA
as you have indicated. Simply put, there's more than one way to skin a cat.
Not only do our results correlate with a conventional load test, we offer
many advantages. 

Please know that our testers are required by virtually every auto-maker in
the world. In as much as I like think that we have an excellent sales and
marketing team, we couldn't pull the wool over that many people's eyes -and
we're not pulling wool over anyone's eyes for that matter. Our technology
and products are proven worldwide. 

I have attached a couple of documents that I would encourage you to read,
and then give me a call sometime next week to discuss should you still have
questions or concerns regarding our products. The pdf file is something
we've put out for all to see for some time, and I think you'll find it quite
helpful. The second piece is an abbreviated version, yet has some different
information -which is why I've included it. The latter piece hasn't been
updated in terms of customers cited -the list is much longer now. Thank
you, 

Sincerely,
Jeffrey Popaeko

I uploaded the documents he made reference to, to the Files section and
described them as Midtronic Battery Tester info 1 and 2.

I read their documents and I find much to be skeptical about. In light of
their opening statement ...

1. What is Conductance? Conductance is a measurement of the battery's
ability to produce current.

I find it hard to believe anything they have written. I do not believe they
even have the definition of conductance correct.

I would like the groups opinion.

Thank you,

Dave Delman
eLectricDeLorean.com
evalbum.com/1482





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## EVDL List (Jul 27, 2007)

The technical definition of conductance is the inverse of resistance. If
something has a resistance of 10 ohms, it has a conductance of 0.1 mhos. (
mhos is the unit of conductance)
Their definition of conductance was probably written my someone in
marketing.


IF a lead acid battery behaves like a voltage source in series with a
resistance ( any comments here??) then all you would have to know about a
battery is its nominal voltage and its conductance ( or resistance) and you
would know how many amps it would supply at any voltage.

For instance, if a 12V battery had an internal resistance of 0.005 ohms, in
theory it could supply 400 amps at a terminal voltage of 10V. ( 12V
-10V)/0.005 ohms =3D 400 amps; or, maybe : (12.5V-10V)/0.005 ohms =3D 500 a=
mps)

So, it sounds like these guys might somehow be trying to measure the
battery's conductance( without drawing high current) , and then applying
this formula, which might or might not apply to this particular type of
battery.
They test that way because it's convenient, cheap, and it may work OK for
most batteries under most ( non-EV) applications.

Phil Marino
Rochester, NY



> drdhdmd <[email protected]> wrote:
> 
> > I would like the groups opinion.
> >
> ...


----------



## EVDL List (Jul 27, 2007)

Why are they testing it at 800 CCA for a deep cycle battery? That's only 
good for a certain amount of seconds. A EV needs to go for about a hour or 
more. Look up the battery spec sheet and look at the Reserved minutes at 
its ampere load.

Lets say its 120 Reserved minutes @ 75 amps, therefore it should discharge 
at about the following rate:

60 minutes to 12.10 volts - 50% SOC
30 minutes to 12.46 volts - 75% SOC
15 minutes to 12.62 volts - 90% SOC
7.5 minutes to 12.68 volts - 95% SOC

Either use a battery analyzer to show the comparison of all the batteries in 
the pack when fully charge, and then do a comparison when discharge while 
driving at a 75 amp for a certain number of minutes.

Or use the standard 75 amp load tester on that one battery when fully charge 
and again after its been discharge as per instructed from my battery tech 
engineer from the Trojan Company. I than had to adjust my 300 amp load test 
to a 75 amp load tester for these type of batteries.

It is best to test a battery when discharge to 50% to 70% SOC, because A 
test on a battery that is bad that is fully charge will show good if you use 
a CCA tester. You are just taking off the surface charge off the plates 
like a cranking type thin plate battery does for 10 to 15 seconds.

After the first initial discharge of the surface charge, the battery plates 
now go into diffusion time, meaning how long it takes for the acid deep 
inside of the plates to come to the surface.

You test a deep cycle battery for the diffusion time, not how long it will 
crank a motor at a high cranking amp.

Roland



----- Original Message ----- 
From: "drdhdmd" <[email protected]>
To: <[email protected]>
Sent: Sunday, April 12, 2009 7:52 AM
Subject: [EVDL] Battery Testing - Midtronic Battery Tester


I would like the groups opinion.

One of my Deka 9A31 batteries is failing quite significantly. It no longer 
can maintain its voltage under a load. While the other batteries stay 
between 11 and 12 volts, this one drops down below 10 volts even at currents 
of less than 50 amps.

When I brought this battery back to AutoBarn, where I purchased it, they use 
a Midtronic Batery Tester set for the 800 CCA listed on the label and it 
checks out "GOOD". So they say it must be good.

I sent this inquiry to Midtronics:
We have a number of Deka 9A31 AGM batteries that are supposed to be rated 
at 800 CCA and 1000 CA. In our application, an electric vehicle the 
batteries do not perform up to their specification, ie they are not able to 
supply even 500 amps at 50 degrees F. Your tester says they are "GOOD" but 
they are obviously not. Your tester does not test the batteries under a 
500 - 1000 amp load so how can it properly test for CCA and CA?

This was their response:
David,

Our pass-fail threshold is consistent with that off the BCI (Battery Council 
International) specifications for proper load testing of batteries. Just 
because we do not use a load, does not mean we do not properly test for CCA 
as you have indicated. Simply put, there's more than one way to skin a cat. 
Not only do our results correlate with a conventional load test, we offer 
many advantages.

Please know that our testers are required by virtually every auto-maker in 
the world. In as much as I like think that we have an excellent sales and 
marketing team, we couldn't pull the wool over that many people's eyes -and 
we're not pulling wool over anyone's eyes for that matter. Our technology 
and products are proven worldwide.

I have attached a couple of documents that I would encourage you to read, 
and then give me a call sometime next week to discuss should you still have 
questions or concerns regarding our products. The pdf file is something 
we've put out for all to see for some time, and I think you'll find it quite 
helpful. The second piece is an abbreviated version, yet has some different 
information -which is why I've included it. The latter piece hasn't been 
updated in terms of customers cited -the list is much longer now. Thank 
you,

Sincerely,
Jeffrey Popaeko

I uploaded the documents he made reference to, to the Files section and 
described them as Midtronic Battery Tester info 1 and 2.

I read their documents and I find much to be skeptical about. In light of 
their opening statement ...

1. What is Conductance? Conductance is a measurement of the battery's 
ability to produce current.

I find it hard to believe anything they have written. I do not believe they 
even have the definition of conductance correct.

I would like the groups opinion.

Thank you,

Dave Delman
eLectricDeLorean.com
evalbum.com/1482





_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev 

_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------



## EVDL List (Jul 27, 2007)

Battery testers usually do not charge the battery before
testing it if there still is some life in it.
I do not knnow about your battery, but the ones that
went bad in my truck could stay at 12V for a short while,
then dropped like rocks when the first bad cell ran out
of its reduced capacity.

So, you could partially discharge your batteries until
the open voltage is still good but the lightest load
will drop voltage due to the excessive resistance of the
first bad cell.
That way even their tester should get an idea about
how bad these batteries are.

BTW, their tester is not in any way useful for EV
battery capacity testing purpose, only starting batteries,
so that is one of the disconnects.

The other thing is that if their tester is used in many
places then that does not necessarily mean it is doing a 
good job, just that it shows what many people want to see.
Kind of like a politician, but let's not go there....
Good that they sent specs, that will tell the (limited)
value of their tester. Typically a battery tester will
load the battery only for a very short period (seconds)
instead of an hour or so as should be needed for EVs.
In other words - it does not say anything about the
capacity of the battery or its usefulness after a little
discharging.
That is why I suggest you discharge the battery to show 
the behavior that you want to show: too high resistance
to supply enough current and voltage dropping...

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 magicJack: +1 408 844 3932
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of drdhdmd
Sent: Sunday, April 12, 2009 8:22 PM
To: [email protected]
Subject: [EVDL] Battery Testing - Midtronic Battery Tester

I would like the groups opinion.

One of my Deka 9A31 batteries is failing quite significantly. It no
longer can maintain its voltage under a load. While the other batteries
stay between 11 and 12 volts, this one drops down below 10 volts even at
currents of less than 50 amps.

When I brought this battery back to AutoBarn, where I purchased it, they
use a Midtronic Batery Tester set for the 800 CCA listed on the label
and it checks out "GOOD". So they say it must be good.

I sent this inquiry to Midtronics:
We have a number of Deka 9A31 AGM batteries that are supposed to be
rated at 800 CCA and 1000 CA. In our application, an electric vehicle
the batteries do not perform up to their specification, ie they are not
able to supply even 500 amps at 50 degrees F. Your tester says they are
"GOOD" but they are obviously not. Your tester does not test the
batteries under a 500 - 1000 amp load so how can it properly test for
CCA and CA?

This was their response:
David,

Our pass-fail threshold is consistent with that off the BCI (Battery
Council International) specifications for proper load testing of
batteries. Just because we do not use a load, does not mean we do not
properly test for CCA as you have indicated. Simply put, there's more
than one way to skin a cat. Not only do our results correlate with a
conventional load test, we offer many advantages. 

Please know that our testers are required by virtually every auto-maker
in the world. In as much as I like think that we have an excellent
sales and marketing team, we couldn't pull the wool over that many
people's eyes -and we're not pulling wool over anyone's eyes for that
matter. Our technology and products are proven worldwide. 

I have attached a couple of documents that I would encourage you to
read, and then give me a call sometime next week to discuss should you
still have questions or concerns regarding our products. The pdf file
is something we've put out for all to see for some time, and I think
you'll find it quite helpful. The second piece is an abbreviated
version, yet has some different information -which is why I've included
it. The latter piece hasn't been updated in terms of customers cited
-the list is much longer now. Thank you, 

Sincerely,
Jeffrey Popaeko

I uploaded the documents he made reference to, to the Files section and
described them as Midtronic Battery Tester info 1 and 2.

I read their documents and I find much to be skeptical about. In light
of their opening statement ...

1. What is Conductance? Conductance is a measurement of the battery's
ability to produce current.

I find it hard to believe anything they have written. I do not believe
they even have the definition of conductance correct.

I would like the groups opinion.

Thank you,

Dave Delman
eLectricDeLorean.com
evalbum.com/1482





_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


_______________________________________________
General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev


----------

