# [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge



## EVDL List (Jul 27, 2007)

I have 2 electric cars. One has a Curtis 900R Battery Fuel Gauge 
that works fine and the other has a PakTrakr. I like the the digital 
numbers for SOC with the PakTrakr much more than the 10 LED's of the 
Curtis. Still, the PakTakr has been acting strangely. I told the 
story earlier about losing 1/3 of my battery pack with no Alerts from 
the PakTrakr. Recently when I was testing the car's range, I had 
driven about 38 miles and it showed 56% SOC. Then it suddenly just 
went blank as I accelerated. When I slowed, it would come back on, 
but this time with 100% SOC. Needless to say, a meter that poops out 
when you need it the most is not too useful. It also has been giving 
some strange readings like "Needs water" (I check and the battery is 
fine) or "About to fail" (paraphrasing) etc. Then later all is 
fine. I have reset it by disconnecting it and have checked all 
connections. It is really strange and a bit scary. At the end of 
any drive is a 3.5 mile drive back up a pretty good hill to return 
home. It is kind of important to know in advance if I need to add a 
bit of charge (about 80 minutes seems to work on nearly empty) or can 
head on up. I have thought about adding a Curtis in just to be 
safe. They have them in 96 volts and 120 volts, but my system is 108 
volts. I could just get a 96 volt unit and hook it up to 16 instead 
of 18 batteries or I could get 2 meters (1 for the 36 volt pack in 
the front and 1 for the 72 volt pack in the middle). Suggestions on 
the PakTrakr or adding a Curtis or two?

Thanks,

John

---
John G. Blair Studio
Occidental, California
(about an hour north of the Bay Area)
http://www.jgblairphoto.com - general photography
http://www.johngblairstudio.com - commercial and stock photography
http://www.johngblair.com - author website





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## EVDL List (Jul 27, 2007)

Hi John,

Do either meters count AH?
>From what I remember when using my lithium Paktrakr, the Paktrakr deterines
SOC by voltage measurement, rather than actually measuring total charge
pulled from the pack.

Are you using the data logging feature of the paktrakr?
It flags a battery as failing when it notices one battery is sagging more or
earlier than the others. Have a look through your logs.

Matt

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of John Blair
Sent: Thursday, 30 October 2008 12:24 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

I have 2 electric cars. One has a Curtis 900R Battery Fuel Gauge that works
fine and the other has a PakTrakr. I like the the digital numbers for SOC
with the PakTrakr much more than the 10 LED's of the Curtis. Still, the
PakTakr has been acting strangely. I told the story earlier about losing
1/3 of my battery pack with no Alerts from the PakTrakr. Recently when I
was testing the car's range, I had driven about 38 miles and it showed 56%
SOC. Then it suddenly just went blank as I accelerated. When I slowed, it
would come back on, but this time with 100% SOC. Needless to say, a meter
that poops out when you need it the most is not too useful. It also has
been giving some strange readings like "Needs water" (I check and the
battery is
fine) or "About to fail" (paraphrasing) etc. Then later all is fine. I
have reset it by disconnecting it and have checked all connections. It is
really strange and a bit scary. At the end of any drive is a 3.5 mile drive
back up a pretty good hill to return home. It is kind of important to know
in advance if I need to add a bit of charge (about 80 minutes seems to work
on nearly empty) or can head on up. I have thought about adding a Curtis in
just to be safe. They have them in 96 volts and 120 volts, but my system is
108 volts. I could just get a 96 volt unit and hook it up to 16 instead of
18 batteries or I could get 2 meters (1 for the 36 volt pack in the front
and 1 for the 72 volt pack in the middle). Suggestions on the PakTrakr or
adding a Curtis or two?

Thanks,

John

---
John G. Blair Studio
Occidental, California
(about an hour north of the Bay Area)
http://www.jgblairphoto.com - general photography
http://www.johngblairstudio.com - commercial and stock photography
http://www.johngblair.com - author website





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## EVDL List (Jul 27, 2007)

Hi John,

I have had some similar problems with my PakTrakr. When I accelerate it
blanks out then comes alive again when I resume cruising. It forgets
the menu settings during it's blank period. I often get warnings about
Remote A or B errors at the same time. 

Not sure if this is a wiring problem of mine. As I have 7 batteries in
the back and 5 in the front I have two 6-battery PakTrakr remotes but
the red and black wires of the second unit have long lead runs to the
extra battery in the rear. Maybe this is causing pick up of noise.

BTW when I first installed the PakTrakr I had problems with bad
connections. The wires just fell out of the little 3 pin connectors,
and required re-soldering. The connectors also appear not be gold
plated and prone to bad connections (I have noticed some black gunk on
them).

So I would suggest some contact cleaner and/or checking of those
connectors as a first step. Once I work out why mine keeps blanking out
I'll post to this list. I am thinking of replacing those connectors
with similar radio control type 3-pin connectors - they are gold plated
and designed for high reliability.

Problems due to acceleration - could this be switching noise from the
controller?

Cheers,

David


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## EVDL List (Jul 27, 2007)

It sounds to me as the PakTrakr units on each battery are not
able to work on a heavily sagging battery.
NOTE that where the open (resting) voltage always needs to be
12V or higher (for a 6-cell battery) the voltage under heavy
accel can be significantly lower due to internal resistance.

Last week I connected my laptop to a Reva (48V 400A) controller
fed from 8 golfcart batteries and saw that on full accel the
battery monitor indicated that each battery was sagging from
6.3 to about 4.5V with just the 400A load on these 200Ah
batteries (2C discharge) and they were at least 80% SOC.
On a 12V battery, the monitors should see a drop to 9V under
the same conditon and I have recently read about the Rudman 
regs on a bad pack, where also some regs were rebooting and 
losing their settings when the voltage hits 9V so I would not
be surprised if the PakTrakr would reboot at even higher voltage.

It is easy to test: connect one of the PakTrakrs to a variable
power supply instead of to its battery and turn the supply
down from 12V until the communication fails. That is the limit
of the unit.
I think that battery monitoring units should be designed so
that they can work down to about half their nominal voltage
as even when loaded under racing conditions, batteries should
never sag to more than half their voltage, as that is the
point of maximum power delivery (in theory).

If it is not the voltage sag but noise then you can filter by
not attaching the PakTrakr directly to your battery but by
adding a filter in between, you need to experiment with
inductance and capacitance or measure the noise and calculate
the required low pass characteristic.

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 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040) 23117400x109 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of David Rowe
Sent: Thursday, October 30, 2008 12:41 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

Hi John,

I have had some similar problems with my PakTrakr. When I accelerate it
blanks out then comes alive again when I resume cruising. It forgets
the menu settings during it's blank period. I often get warnings about
Remote A or B errors at the same time. 

Not sure if this is a wiring problem of mine. As I have 7 batteries in
the back and 5 in the front I have two 6-battery PakTrakr remotes but
the red and black wires of the second unit have long lead runs to the
extra battery in the rear. Maybe this is causing pick up of noise.

BTW when I first installed the PakTrakr I had problems with bad
connections. The wires just fell out of the little 3 pin connectors,
and required re-soldering. The connectors also appear not be gold
plated and prone to bad connections (I have noticed some black gunk on
them).

So I would suggest some contact cleaner and/or checking of those
connectors as a first step. Once I work out why mine keeps blanking out
I'll post to this list. I am thinking of replacing those connectors
with similar radio control type 3-pin connectors - they are gold plated
and designed for high reliability.

Problems due to acceleration - could this be switching noise from the
controller?

Cheers,

David


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http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
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----------



## EVDL List (Jul 27, 2007)

Yes, good ideas with the voltage testing Cor.....

I did a bit of Googling on this. Some people have reported fixing the
problem with some ferrite clamps on the current sensor or other leads. 

Some one else reported that the 3V3 digital signal was quite noisy
(under and over shoot) and might benefit from a 100 ohm resistor in
series with the signal line. The didn't report if this made any
difference.

- David



> Cor van de Water wrote:
> > It sounds to me as the PakTrakr units on each battery are not
> > able to work on a heavily sagging battery.
> > NOTE that where the open (resting) voltage always needs to be
> ...


----------



## EVDL List (Jul 27, 2007)

Hi John,

I too have experienced some Trakr problems. I kept getting a B5 battery 
failure blinking not long after hooking it up. Everything was fine for the 
first couple weeks. I have 13 individual 6A chargers on the batterys and 
found really no problem. A few weeks later, the failure blinking increased 
to B5 and B6. So, I'm not sure what to make of it either.

Jim


----- Original Message ----- 
From: "John Blair" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Wednesday, October 29, 2008 10:23 PM
Subject: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge


>I have 2 electric cars. One has a Curtis 900R Battery Fuel Gauge
> that works fine and the other has a PakTrakr. I like the the digital
> numbers for SOC with the PakTrakr much more than the 10 LED's of the
> Curtis. Still, the PakTakr has been acting strangely. I told the
> story earlier about losing 1/3 of my battery pack with no Alerts from
> the PakTrakr. Recently when I was testing the car's range, I had
> driven about 38 miles and it showed 56% SOC. Then it suddenly just
> went blank as I accelerated. When I slowed, it would come back on,
> but this time with 100% SOC. Needless to say, a meter that poops out
> when you need it the most is not too useful. It also has been giving
> some strange readings like "Needs water" (I check and the battery is
> fine) or "About to fail" (paraphrasing) etc. Then later all is
> fine. I have reset it by disconnecting it and have checked all
> connections. It is really strange and a bit scary. At the end of
> any drive is a 3.5 mile drive back up a pretty good hill to return
> home. It is kind of important to know in advance if I need to add a
> bit of charge (about 80 minutes seems to work on nearly empty) or can
> head on up. I have thought about adding a Curtis in just to be
> safe. They have them in 96 volts and 120 volts, but my system is 108
> volts. I could just get a 96 volt unit and hook it up to 16 instead
> of 18 batteries or I could get 2 meters (1 for the 36 volt pack in
> the front and 1 for the 72 volt pack in the middle). Suggestions on
> the PakTrakr or adding a Curtis or two?
>
> Thanks,
>
> John
>
> ---
> John G. Blair Studio
> Occidental, California
> (about an hour north of the Bay Area)
> http://www.jgblairphoto.com - general photography
> http://www.johngblairstudio.com - commercial and stock photography
> http://www.johngblair.com - author website
>
>
>
>
>
> _______________________________________________
> 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
> 

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## EVDL List (Jul 27, 2007)

I'm having some problems with my new PakTrakr as well. This is on a new car and my first PT so I thought it might just be me.

I would expect the SOC to be accurate but it seems to stay at full even when the pack voltage is getting low. There were no instructions but I would imagine for it to determine a full pack it would need a baseline? Should it be plugged into a freshly charged pack?



Ben in SC

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of John Blair
Sent: Wednesday, October 29, 2008 11:24 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

I have 2 electric cars. One has a Curtis 900R Battery Fuel Gauge
that works fine and the other has a PakTrakr. I like the the digital
numbers for SOC with the PakTrakr much more than the 10 LED's of the
Curtis. Still, the PakTakr has been acting strangely. I told the
story earlier about losing 1/3 of my battery pack with no Alerts from
the PakTrakr. Recently when I was testing the car's range, I had
driven about 38 miles and it showed 56% SOC. Then it suddenly just
went blank as I accelerated. When I slowed, it would come back on,
but this time with 100% SOC. Needless to say, a meter that poops out
when you need it the most is not too useful. It also has been giving
some strange readings like "Needs water" (I check and the battery is
fine) or "About to fail" (paraphrasing) etc. Then later all is
fine. I have reset it by disconnecting it and have checked all
connections. It is really strange and a bit scary. At the end of
any drive is a 3.5 mile drive back up a pretty good hill to return
home. It is kind of important to know in advance if I need to add a
bit of charge (about 80 minutes seems to work on nearly empty) or can
head on up. I have thought about adding a Curtis in just to be
safe. They have them in 96 volts and 120 volts, but my system is 108
volts. I could just get a 96 volt unit and hook it up to 16 instead
of 18 batteries or I could get 2 meters (1 for the 36 volt pack in
the front and 1 for the 72 volt pack in the middle). Suggestions on
the PakTrakr or adding a Curtis or two?

Thanks,

John

---
John G. Blair Studio
Occidental, California
(about an hour north of the Bay Area)
http://www.jgblairphoto.com - general photography
http://www.johngblairstudio.com - commercial and stock photography
http://www.johngblair.com - author website





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Usage guidelines: http://evdl.org/help/index.html#conv
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## EVDL List (Jul 27, 2007)

Typically the accurate SOC (State of Charge) meters need to be
configured with the amount of Ah that the pack has, then they
measure the current multiplied by time (Ah) taken from or put back
into the pack, discount for efficiencies of high current operation
and give you a very accurate indication of actual charge level of
your pack.
Cheaper solutions only look at the voltage level of the batteries
and guesstimate how full or empty the pack is and reset themselves
based on seeing the voltage stay high for a while at the end of the
recharge.
I believe that the PakTrakr is the second type, it monitors every
battery but only the voltage, not the current so it actually has
no clue how the charge level of the pack is. It does not even know
how "large" the battery is that it is monitoring while variations
in temperature and internal resistance will have a profound effect
on the *voltage* response of the battery under load.
When it also resets at low voltage levels, then the usefulness
of such a device is just about zero, in fact by indicating a
reassuring value up to the point where you are actually already
damaging your batteries, they lead you down a dangerous path...

Get a good Ah meter like the E-meter or Link-10 or equivalent
OR get some confirmation for the energy use per mile of your EV,
calculate the best and worst case range and always try to stay
within the worst case range.
It helps to have a reliable trip ODO.

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 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040) 23117400x109 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Willis, Ben
Sent: Thursday, October 30, 2008 6:48 PM
To: 'Electric Vehicle Discussion List'
Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

I'm having some problems with my new PakTrakr as well. This is on a new
car and my first PT so I thought it might just be me.

I would expect the SOC to be accurate but it seems to stay at full even
when the pack voltage is getting low. There were no instructions but I
would imagine for it to determine a full pack it would need a baseline?
Should it be plugged into a freshly charged pack?



Ben in SC

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of John Blair
Sent: Wednesday, October 29, 2008 11:24 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

I have 2 electric cars. One has a Curtis 900R Battery Fuel Gauge that
works fine and the other has a PakTrakr. I like the the digital numbers
for SOC with the PakTrakr much more than the 10 LED's of the Curtis.
Still, the PakTakr has been acting strangely. I told the story earlier
about losing 1/3 of my battery pack with no Alerts from the PakTrakr.
Recently when I was testing the car's range, I had driven about 38 miles
and it showed 56% SOC. Then it suddenly just went blank as I
accelerated. When I slowed, it would come back on, but this time with
100% SOC. Needless to say, a meter that poops out when you need it the
most is not too useful. It also has been giving some strange readings
like "Needs water" (I check and the battery is
fine) or "About to fail" (paraphrasing) etc. Then later all is fine. I
have reset it by disconnecting it and have checked all connections. It
is really strange and a bit scary. At the end of any drive is a 3.5
mile drive back up a pretty good hill to return home. It is kind of
important to know in advance if I need to add a bit of charge (about 80
minutes seems to work on nearly empty) or can head on up. I have
thought about adding a Curtis in just to be safe. They have them in 96
volts and 120 volts, but my system is 108 volts. I could just get a 96
volt unit and hook it up to 16 instead of 18 batteries or I could get 2
meters (1 for the 36 volt pack in the front and 1 for the 72 volt pack
in the middle). Suggestions on the PakTrakr or adding a Curtis or two?

Thanks,

John

---
John G. Blair Studio
Occidental, California
(about an hour north of the Bay Area)
http://www.jgblairphoto.com - general photography
http://www.johngblairstudio.com - commercial and stock photography
http://www.johngblair.com - author website





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http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
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ANDERSON SCHOOL DISTRICT FIVE NOTICE: This email may contain business
related information that is PERSONAL AND CONFIDENTIAL. If you have
received this email in error, this does not constitute permission to
examine, copy or distribute the accompanying material.
If you receive this message in error, please notify the sender
immediately or call 864-260-5000.


_______________________________________________
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## EVDL List (Jul 27, 2007)

> Ben <[email protected]> wrote:
> > I'm having some problems with my new PakTrakr as well. This is on a new car and my first PT so I thought it might just be me.
> >
> > I would expect the SOC to be accurate but it seems to stay at full even when the pack voltage is getting low. There were no instructions but I would imagine for it to determine a full pack it would need a baseline? Should it be plugged into a freshly charged pack?
> ...


----------



## EVDL List (Jul 27, 2007)

I personally havent had mine long enough to know that I was having a real problem. Only when I saw some of the comments here did I decide to ask some questions. I plan to call Ken and the folks at QuickCharge as I seem to be having a problem getting a full charge as well.


Ben
________________________________________
From: [email protected] [[email protected]] On Behalf Of David Nelson [[email protected]]
Sent: Thursday, October 30, 2008 8:15 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge



> Ben <[email protected]> wrote:
> > I'm having some problems with my new PakTrakr as well. This is on a new car and my first PT so I thought it might just be me.
> >
> > I would expect the SOC to be accurate but it seems to stay at full even when the pack voltage is getting low. There were no instructions but I would imagine for it to determine a full pack it would need a baseline? Should it be plugged into a freshly charged pack?
> ...


----------



## EVDL List (Jul 27, 2007)

Speaking of the whole paktrakr, I have a question:

I'm planning on monitoring the Prizm. As a part of this I need to hook 
up a total of 8 remote sensing units to a 50 battery pack (2 strings of 
25 26ah batteries). I have all the parts and the plans are to run two 
paktrakr monitors, one per string. I am not monitoring current because I 
have an E-meter for that.

The big question/problem I have is balance: If I hook up the sensors 
then lift the pack (thus burying them in the pack for the next 2 years) 
I will have no way of turning them off. I know that the PT manual says 
they always pull a bit of power (4ma or so) from the first battery in 
the string.

So if I leave them alone, every day they will drag my pack out of 
balance, correct? This could be anathama to sealed batteries, for if I 
do not drive my car for a week that would be (4*24=100ma/day*7=700ma out 
of whack). And that's one battery, so it will tend to be undercharged.

I am putting on regs, but is that enough? One thought in my head was to 
wire the first black wire on each paktrakr to a small relay that would 
be controlled by the main contactor wire. Thus when the car was off the 
PT's would be off as well. When I fired up, the PT would come online and 
display the battery voltages.

Is this a bad idea? Or am I blowing this out of proportion?

Help?

Chris

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## EVDL List (Jul 27, 2007)

I guess you would lose SOC info every time you turn the car off,
so you lose its function as well.

Best check the manual before going this route.

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 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040) 23117400x109 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Christopher Zach
Sent: Friday, October 31, 2008 6:19 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

Speaking of the whole paktrakr, I have a question:

I'm planning on monitoring the Prizm. As a part of this I need to hook
up a total of 8 remote sensing units to a 50 battery pack (2 strings of
25 26ah batteries). I have all the parts and the plans are to run two
paktrakr monitors, one per string. I am not monitoring current because I
have an E-meter for that.

The big question/problem I have is balance: If I hook up the sensors
then lift the pack (thus burying them in the pack for the next 2 years)
I will have no way of turning them off. I know that the PT manual says
they always pull a bit of power (4ma or so) from the first battery in
the string.

So if I leave them alone, every day they will drag my pack out of
balance, correct? This could be anathama to sealed batteries, for if I
do not drive my car for a week that would be (4*24=100ma/day*7=700ma out
of whack). And that's one battery, so it will tend to be undercharged.

I am putting on regs, but is that enough? One thought in my head was to
wire the first black wire on each paktrakr to a small relay that would
be controlled by the main contactor wire. Thus when the car was off the
PT's would be off as well. When I fired up, the PT would come online and
display the battery voltages.

Is this a bad idea? Or am I blowing this out of proportion?

Help?

Chris

_______________________________________________
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)

An update - I managed to fix the problem I had with my PakTrakr by
looping the current sensor cable (one complete turn) through a ferrite
clamp:

http://rowetel.com/images/ev_paktrakr_ferrite.jpg 

Just passing the cable straight through didn't fix it, it needed the
loop.

Prior to this fix the Paktrakr was giving crazy measurements under
acceleration, like 48-320V, reporting failures of batteries and
resetting itself. Removing the current sensor cable made everything
settle down. I found this suggested fix (a ferrite clamp) by Googling.
The ferrite blocks RF so I guess it was controller noise coupling
through the current sensor.

I will also email Ken Hall about my experiences.

Cheers,

David

On Thu, 2008-10-30 at 19:58 +1030, David Rowe wrote:
> Yes, good ideas with the voltage testing Cor.....
> 
> I did a bit of Googling on this. Some people have reported fixing the
> problem with some ferrite clamps on the current sensor or other leads. 
> 
> Some one else reported that the 3V3 digital signal was quite noisy
> (under and over shoot) and might benefit from a 100 ohm resistor in
> series with the signal line. The didn't report if this made any
> difference.
> 
> - David
> 
> On Thu, 2008-10-30 at 02:13 -0700, Cor van de Water wrote:
> > It sounds to me as the PakTrakr units on each battery are not
> > able to work on a heavily sagging battery.
> > NOTE that where the open (resting) voltage always needs to be
> > 12V or higher (for a 6-cell battery) the voltage under heavy
> > accel can be significantly lower due to internal resistance.
> > 
> > Last week I connected my laptop to a Reva (48V 400A) controller
> > fed from 8 golfcart batteries and saw that on full accel the
> > battery monitor indicated that each battery was sagging from
> > 6.3 to about 4.5V with just the 400A load on these 200Ah
> > batteries (2C discharge) and they were at least 80% SOC.
> > On a 12V battery, the monitors should see a drop to 9V under
> > the same conditon and I have recently read about the Rudman 
> > regs on a bad pack, where also some regs were rebooting and 
> > losing their settings when the voltage hits 9V so I would not
> > be surprised if the PakTrakr would reboot at even higher voltage.
> > 
> > It is easy to test: connect one of the PakTrakrs to a variable
> > power supply instead of to its battery and turn the supply
> > down from 12V until the communication fails. That is the limit
> > of the unit.
> > I think that battery monitoring units should be designed so
> > that they can work down to about half their nominal voltage
> > as even when loaded under racing conditions, batteries should
> > never sag to more than half their voltage, as that is the
> > point of maximum power delivery (in theory).
> > 
> > If it is not the voltage sag but noise then you can filter by
> > not attaching the PakTrakr directly to your battery but by
> > adding a filter in between, you need to experiment with
> > inductance and capacitance or measure the noise and calculate
> > the required low pass characteristic.
> > 
> > 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 VoIP: +31 20 3987567 FWD# 25925
> > Tel: +91 (040) 23117400x109 XoIP: +31877841130
> > 
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]] On
> > Behalf Of David Rowe
> > Sent: Thursday, October 30, 2008 12:41 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge
> > 
> > Hi John,
> > 
> > I have had some similar problems with my PakTrakr. When I accelerate it
> > blanks out then comes alive again when I resume cruising. It forgets
> > the menu settings during it's blank period. I often get warnings about
> > Remote A or B errors at the same time. 
> > 
> > Not sure if this is a wiring problem of mine. As I have 7 batteries in
> > the back and 5 in the front I have two 6-battery PakTrakr remotes but
> > the red and black wires of the second unit have long lead runs to the
> > extra battery in the rear. Maybe this is causing pick up of noise.
> > 
> > BTW when I first installed the PakTrakr I had problems with bad
> > connections. The wires just fell out of the little 3 pin connectors,
> > and required re-soldering. The connectors also appear not be gold
> > plated and prone to bad connections (I have noticed some black gunk on
> > them).
> > 
> > So I would suggest some contact cleaner and/or checking of those
> > connectors as a first step. Once I work out why mine keeps blanking out
> > I'll post to this list. I am thinking of replacing those connectors
> > with similar radio control type 3-pin connectors - they are gold plated
> > and designed for high reliability.
> > 
> > Problems due to acceleration - could this be switching noise from the
> > controller?
> > 
> > Cheers,
> > 
> > David
> > 
> > 
> > _______________________________________________
> > 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
> > 
-- 
Free Telephony Project
open embedded IP-PBX hardware and software
http://www.rowetel.com/ucasterisk

_______________________________________________
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)

Great find!!!

I'll be adding this to mine over the weekend as I've had similar problems but had gotten used to it.


Ben in SC
________________________________________
From: [email protected] [[email protected]] On Behalf Of David Rowe [[email protected]]
Sent: Thursday, November 20, 2008 6:56 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge

An update - I managed to fix the problem I had with my PakTrakr by
looping the current sensor cable (one complete turn) through a ferrite
clamp:

http://rowetel.com/images/ev_paktrakr_ferrite.jpg

Just passing the cable straight through didn't fix it, it needed the
loop.

Prior to this fix the Paktrakr was giving crazy measurements under
acceleration, like 48-320V, reporting failures of batteries and
resetting itself. Removing the current sensor cable made everything
settle down. I found this suggested fix (a ferrite clamp) by Googling.
The ferrite blocks RF so I guess it was controller noise coupling
through the current sensor.

I will also email Ken Hall about my experiences.

Cheers,

David

On Thu, 2008-10-30 at 19:58 +1030, David Rowe wrote:
> Yes, good ideas with the voltage testing Cor.....
>
> I did a bit of Googling on this. Some people have reported fixing the
> problem with some ferrite clamps on the current sensor or other leads.
>
> Some one else reported that the 3V3 digital signal was quite noisy
> (under and over shoot) and might benefit from a 100 ohm resistor in
> series with the signal line. The didn't report if this made any
> difference.
>
> - David
>
> On Thu, 2008-10-30 at 02:13 -0700, Cor van de Water wrote:
> > It sounds to me as the PakTrakr units on each battery are not
> > able to work on a heavily sagging battery.
> > NOTE that where the open (resting) voltage always needs to be
> > 12V or higher (for a 6-cell battery) the voltage under heavy
> > accel can be significantly lower due to internal resistance.
> >
> > Last week I connected my laptop to a Reva (48V 400A) controller
> > fed from 8 golfcart batteries and saw that on full accel the
> > battery monitor indicated that each battery was sagging from
> > 6.3 to about 4.5V with just the 400A load on these 200Ah
> > batteries (2C discharge) and they were at least 80% SOC.
> > On a 12V battery, the monitors should see a drop to 9V under
> > the same conditon and I have recently read about the Rudman
> > regs on a bad pack, where also some regs were rebooting and
> > losing their settings when the voltage hits 9V so I would not
> > be surprised if the PakTrakr would reboot at even higher voltage.
> >
> > It is easy to test: connect one of the PakTrakrs to a variable
> > power supply instead of to its battery and turn the supply
> > down from 12V until the communication fails. That is the limit
> > of the unit.
> > I think that battery monitoring units should be designed so
> > that they can work down to about half their nominal voltage
> > as even when loaded under racing conditions, batteries should
> > never sag to more than half their voltage, as that is the
> > point of maximum power delivery (in theory).
> >
> > If it is not the voltage sag but noise then you can filter by
> > not attaching the PakTrakr directly to your battery but by
> > adding a filter in between, you need to experiment with
> > inductance and capacitance or measure the noise and calculate
> > the required low pass characteristic.
> >
> > 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 VoIP: +31 20 3987567 FWD# 25925
> > Tel: +91 (040) 23117400x109 XoIP: +31877841130
> >
> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]] On
> > Behalf Of David Rowe
> > Sent: Thursday, October 30, 2008 12:41 PM
> > To: Electric Vehicle Discussion List
> > Subject: Re: [EVDL] PakTrakr versus Curtis 900R Battery Fuel Gauge
> >
> > Hi John,
> >
> > I have had some similar problems with my PakTrakr. When I accelerate it
> > blanks out then comes alive again when I resume cruising. It forgets
> > the menu settings during it's blank period. I often get warnings about
> > Remote A or B errors at the same time.
> >
> > Not sure if this is a wiring problem of mine. As I have 7 batteries in
> > the back and 5 in the front I have two 6-battery PakTrakr remotes but
> > the red and black wires of the second unit have long lead runs to the
> > extra battery in the rear. Maybe this is causing pick up of noise.
> >
> > BTW when I first installed the PakTrakr I had problems with bad
> > connections. The wires just fell out of the little 3 pin connectors,
> > and required re-soldering. The connectors also appear not be gold
> > plated and prone to bad connections (I have noticed some black gunk on
> > them).
> >
> > So I would suggest some contact cleaner and/or checking of those
> > connectors as a first step. Once I work out why mine keeps blanking out
> > I'll post to this list. I am thinking of replacing those connectors
> > with similar radio control type 3-pin connectors - they are gold plated
> > and designed for high reliability.
> >
> > Problems due to acceleration - could this be switching noise from the
> > controller?
> >
> > Cheers,
> >
> > David
> >
> >
> > _______________________________________________
> > 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
> >
--
Free Telephony Project
open embedded IP-PBX hardware and software
http://www.rowetel.com/ucasterisk

_______________________________________________
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


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_______________________________________________
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Archives: http://evdl.org/archive/
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----------

