# [EVDL] Practical CALB SE100AHA 50% and 75% discharged voltage data



## EVDL List (Jul 27, 2007)

1989 VW Cabby
Impulse 9 motor
Z1K-HV Motor Controller
52 SE100AHA cells (~170V)

Hi all -
I've been using my lithium batts for a year and a half, and usually go no
further than 20 miles or so.
I have a smart battery meter that measures amphours expended, and usually
this never goes above 30 Ah. Theoretically, I can go much further than
this, but I am trying not to get stuck somewhere where I would need a tow to
get back home.

So, two questions.
1) How far can I *practically* go on amphours discharged, based on normal
driving with hardware above? I would appreciate NON-THEORETICAL data from
folks who have similar batteries.
2) I have seen the CALB discharge voltage curves, and of course they are
flat, but not completely. The voltage per cell moves between 3.4VPC and
3.1VPC. Where would I consider the average (unloaded) pack voltage as the
50% and 75% discharged state? 
Full charge = 173.5V (3.33VPC)
50% discharged = ??
75% discharged = ??

Knowing the answers to these questions will give me more confidence in
longer trips! Thanks in advance!

Rob

-----
Electro, the Cabby-EV
http://chaosmgmt.blogspot.com 
http://www.evalbum.com/1426 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3819532.html
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## EVDL List (Jul 27, 2007)

Rob,

Your amp-hour counter is far more accurate at telling you state of
charge than voltage is. Do NOT go by voltage to determine how far you
can go. Temperature variations do affect the open circuit voltage of
the batteries. You can reliably drive until you have used 70-80Ah from
your pack with no ill effects on your batteries. I have used 180Ah
from my 200Ah TS pack and only near the end did I notice much
difference in the drive-ability of my car.

To answer your first question we need more data from you. When you go
20 miles how many Ah did you use? This can be used to estimate rather
closely the answer to your question. Better yet, just drive until you
have used 70-80Ah and note the distance.



> Rob Trahms <[email protected]> wrote:
> > 1989 VW Cabby
> > Impulse 9 motor
> > Z1K-HV Motor Controller
> ...


----------



## EVDL List (Jul 27, 2007)

Hi David -
Good tip on the voltage - didn't think about temperature variations.

My daily commute is about 13 miles, and I expend 22-27Ah, depending on
hills, traffic, freeway speeds, etc.
So that *roughly* is 1.7-2.1 Ah/mi. Being conservative and extrapolating
from that, my 50% discharge is 50 Ah/(2.1 Ah/mi) = *23.8 mi* and 80%
discharge is 80 Ah/(2.1 Ah/mi) = *38.1 mi*.

So effectively, with 100Ah cells and my normal energy usage, I should drive
no further than ~38 miles, just to be safe.

Does that sound right? Any other practical experiences with CALB cells,
100AH or otherwise? I know I can't read voltage, but is instantaneous
current draw affected near the 80% discharge mark? Will I notice any
"softness" in acceleration/large current draws that deep into the cells? Or
should it remain pretty much the same right up to 80%?

Thanks,
Rob

-----
Electro, the Cabby-EV
http://chaosmgmt.blogspot.com 
http://www.evalbum.com/1426 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3819685.html
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## EVDL List (Jul 27, 2007)

Good evening Rob, You and I have close to the same pack. I have gone 90 miles and think I can go more. I did the 90 miles with the BMS letting me know with two cells going to 2.5v. You and I should go on a good trip some sunny afternoon. Al




> Rob Trahms wrote:
> 
> > 1989 VW Cabby
> > Impulse 9 motor
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Al -
90 miles - impressive! How many AH of the 100AH did you expend doing that -
did you get close to 80% discharge, or beyond it? What was your experience
with "performance" of the pack toward the end of the trip?

I would imagine your Auto Union expends considerably less energy per mile
than does my cabby (while small, the cabby still is around 2500 lbs. You
also know how I drive  ).

A drive sometime sounds good! Let me make sure my estimated range is
correct first though! Should be doing this range testing out over the next
couple of weekends.

Rob



-----
Electro, the Cabby-EV
http://chaosmgmt.blogspot.com 
http://www.evalbum.com/1426 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3819750.html
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## EVDL List (Jul 27, 2007)

> Rob Trahms wrote:
> 
> > 1989 VW Cabby
> > Impulse 9 motor
> ...


----------



## EVDL List (Jul 27, 2007)

Hi Rob,



> Rob Trahms <[email protected]> wrote:
> > Hi David -
> > Good tip on the voltage - didn't think about temperature variations.
> >
> ...


----------



## EVDL List (Jul 27, 2007)

http://www.evalbum.com/1426

I find no mention, in your EVAlbum page or your EVDL post, of BMS.
If you are running without BMS, it would be best to state that fact.

If you don't have something to tell you when a single cell drops below 
a low threshold of perhaps 2.5v, I don't believe you can comfortably 
get below the last 20%-30% of your pack. Indeed, it seems you are 
having trouble getting down below 50%.

If you DO have a BMS that warns you when a cell goes low, then you just 
drive until you get that alarm to test the true capacity of your pack. 
Do that once and you have confidence that you know where the bottom of 
the pack is and future trips will have less anxiety.

-- 
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 86 days 21 hours 15 minutes

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## EVDL List (Jul 27, 2007)

Hi Willie -
Yes, sorry, forgot to mention that. I have an EV Power BMS configuration
(monitors on all cells tied to an MCU). I will get an alarm when any cell
goes below 2.5V for more than 10 seconds.

Rob

-----
Electro, the Cabby-EV
http://chaosmgmt.blogspot.com 
http://www.evalbum.com/1426 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3820280.html
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## EVDL List (Jul 27, 2007)

> Rob Trahms wrote:
> 
> > 1989 VW Cabby
> > Impulse 9 motor
> ...


----------



## EVDL List (Jul 27, 2007)

> Rob Trahms wrote:
> > Hi Willie -
> > Yes, sorry, forgot to mention that. I have an EV Power BMS configuration
> > (monitors on all cells tied to an MCU). I will get an alarm when any cell
> ...


----------



## EVDL List (Jul 27, 2007)

AL, OK, but what are your aerodynamics like? My brick-shaped van 
would be lucky to get 500Wh/mile at 55mph or so. I bet Robs car would 
be twice as good as that - what do you drive for comparison purposes? 
MW



> Al Swackhammer wrote:
> 
> > Good evening Rob, You and I have close to the same pack. I have
> > gone 90 miles and think I can go more. I did the 90 miles with the
> ...


----------



## EVDL List (Jul 27, 2007)

Corbin, Rob, Al - EVERYone - Comparing ranges without specifying the 
conditions is completely pointless. At 70mph you use twice the power 
used at 50mph, and 10 times as much used at 20mph. So, seriously, can 
we have some slightly more scientific guesstimations, puh-lease?

Corbin, my 160Ah (x38) TS cells took my hopelessly inefficient van 60+ 
miles at 50-55 mph so I think Rob's car should do at least that with 
his vastly superior aerodynamics.

But Rob, please prove me wrong! Do a test and let us know. MW



> corbin dunn wrote:
> 
> >
> > On Sep 16, 2011, at 7:27 PM, Rob Trahms wrote:
> ...


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## EVDL List (Jul 27, 2007)

Back to your original question not that we know you have cell level 
monitoring and an amp-hour counter.



> Rob Trahms wrote:
> 
> > So, two questions.
> > 1) How far can I *practically* go on amphours discharged, based on normal
> ...


----------



## EVDL List (Jul 27, 2007)

Martin, It is a 1960 Auto Union 1000. www.evalbum.com/2430 Pretty aerodynamic compared to the VW cabby. I did revise my stats as to an speedo error. I did very close to 78 miles on that charge and used 22KW to recharge with Zivan NG3 charger @ 240v. Al




> Martin WINLOW wrote:
> 
> > AL, OK, but what are your aerodynamics like? My brick-shaped van
> > would be lucky to get 500Wh/mile at 55mph or so. I bet Robs car would
> ...


----------



## EVDL List (Jul 27, 2007)

> martinwinlow wrote:
> >
> >
> > As for relying on the pack voltage for measuring SOC, I wouldn't
> ...


----------



## EVDL List (Jul 27, 2007)

Data point #1 (drive today)

28.2 miles, half freeway driving, half 30-40 mph.
51.4 Ah expended, just over theoretical halfway on the batts.

No noticeable performance differences, no complaints from any cells (nor do
I expect any here).

Tomorrow I go for 75% discharge!

-----
Electro, the Cabby-EV
http://chaosmgmt.blogspot.com 
http://www.evalbum.com/1426 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3821064.html
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## EVDL List (Jul 27, 2007)

The difference is that you were using more than just voltage. You had
a bottom balanced pack for one, and you also watched the trip meter
for the other. Remove those two and I don't think you would be quite
as comfortable using only voltage.

Did you also take into account pack temperature or did you just not
drive to as low or a SOC when they were colder? In the last 24 hours
my pack voltage dropped nearly 1V due just to a drop in pack
temperature from around 23=B0C to 17=B0C.



> AMPhibian <[email protected]> wrote:
> >
> > martinwinlow wrote:
> >>
> ...


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## EVDL List (Jul 27, 2007)

Data point #2:

32.5 mi, all freeway driving @ ~65 MPH this time except the last mile home,
significant headwinds
64.8 Ah expended (about 65% of theoretical)

Again, so far no noticeable performance differences in acceleration, etc
toward the end of the drive, and no BMS alarms.

Inching my confidence toward 80Ah...

-----
Electro, the Cabby-EV
http://chaosmgmt.blogspot.com 
http://www.evalbum.com/1426 
--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3822102.html
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## EVDL List (Jul 27, 2007)

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## EVDL List (Jul 27, 2007)

> Rob Trahms wrote:
> 
> > Inching my confidence toward 80Ah...
> 
> ...


----------



## EVDL List (Jul 27, 2007)

Me first post on this list - 6-month lurker - this topic is very relevant to my EV experiences 'cept for using 60Ahr CALB cells: 

At 12Ahr average consumption for on a single-leg segment of a daily commute my pack gets routinely to 20% SOC (2x roundtrips between charges) and no degradation in performance is observed.

Cells are monitored individually and have never touched the 2.1V low-side threshold - acceleration segments for strictly surface street usage routinely demands 8c from the pack using single speed transmission - cruising is more grade / aero-drag dependant but generally falls in the 2C-3C realm.

The setup used for charging is terminal-voltage deficient - can only reach 3.47V per cell and the charger disconnects when the pack-draw drops to around 100mA.

Admittedly the low budget circumstanstance for my ev endeavors are a driving element - however this data-point is happy about their CALB cells - never have taken measures to balance the pack since the cells were purchased 9/2010 and after ~90 charge cycles the cells are only 1mV apart.

/Steve 



-----Original Message-----
>From: Rob Trahms <[email protected]>
>Sent: Sep 18, 2011 8:42 AM
>To: [email protected]
>Subject: Re: [EVDL] Practical CALB SE100AHA 50% and 75% discharged voltage	data
>
>Data point #2:
>
>32.5 mi, all freeway driving @ ~65 MPH this time except the last mile home,
>significant headwinds
>64.8 Ah expended (about 65% of theoretical)
>
>Again, so far no noticeable performance differences in acceleration, etc
>toward the end of the drive, and no BMS alarms.
>
>Inching my confidence toward 80Ah...
>
>-----
>Electro, the Cabby-EV
>http://chaosmgmt.blogspot.com 
>http://www.evalbum.com/1426 
>--
>View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Practical-CALB-SE100AHA-50-and-75-discharged-voltage-data-tp3819532p3822102.html
>Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.
>
>_______________________________________________
>| Moratorium on drag racing discussion is in effect.
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## EVDL List (Jul 27, 2007)

Hi Steve,

> Cells are monitored individually and have never touched the 2.1V low-side threshold - acceleration segments for strictly surface street usage routinely demands 8c from the pack using single speed transmission - cruising is more grade / aero-drag dependant but generally falls in the 2C-3C realm.
>

I think that 2.1V for the low side may be a bit low if this is static
voltage. Also, you do know that pulling 8C from your cells regularly
will shorten their life, right?

> The setup used for charging is terminal-voltage deficient - can only reach 3.47V per cell and the charger disconnects when the pack-draw drops to around 100mA.
>

My testing and experience using 3.485vpc and now 3.465vpc with TS
cells shows that you are getting very close to 100%SOC with that
charging procedure. I wouldn't change it if I were you.

> Admittedly the low budget circumstanstance for my ev endeavors are a driving element - however this data-point is happy about their CALB cells - never have taken measures to balance the pack since the cells were purchased 9/2010 and after ~90 charge cycles the cells are only 1mV apart.
>

When are you making the voltage measurements? Immediately at the end
of charge? If not the 1mV difference is nearly meaningless. If you
don't have any cell level monitoring you might want to get a
Batt-Bridge or half-pack voltage comparison circuit of some sort.
Check my blog if you want to see how I did it.

-- 
David D. Nelson
http://evalbum.com/1328

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| Please take those discussions elsewhere. Thanks.
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## EVDL List (Jul 27, 2007)

> [email protected] wrote:
> > Me first post on this list - 6-month lurker - this topic is very relevant to my EV experiences 'cept for using 60Ahr CALB cells:
> 
> Do you have an EVAlbum page?
> ...


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## EVDL List (Jul 27, 2007)

Good points David and consistent w/ what I read on this list.

The emphasis (for me) is on a desired performance level and there are many constraints at play such as pack volume and weight - somewhat trumps pack longevity concerns particularly given there are no thermal gradient issues as sampled albeit at a modest 95F ambient worst case.

Regarding cell balance measurements - at minimum 4hrs resting time is practiced sometimes more. Low-side monitoring is active (under load) and based on overall pack droop I don't think any cell has ever dropped lower than 2.5V.

Also employed is 3.6V high-side monitoring on each cell when charging - never tripped that threshold either so me thinks all combined the pack is in a safe area of operation and it should last hopefully 5-yrs - enough time to save the pennies for the next generation cell technology.

/Steve

-----Original Message-----
>From: David Nelson <[email protected]>
>Sent: Sep 18, 2011 11:39 AM
>To: [email protected], Electric Vehicle Discussion List <[email protected]>
>Subject: Re: [EVDL] Practical CALB SE100AHA 50% and 75% discharged voltage data
>
>Hi Steve,
>
>> Cells are monitored individually and have never touched the 2.1V low-side threshold - acceleration segments for strictly surface street usage routinely demands 8c from the pack using single speed transmission - cruising is more grade / aero-drag dependant but generally falls in the 2C-3C realm.
>>
>
>I think that 2.1V for the low side may be a bit low if this is static
>voltage. Also, you do know that pulling 8C from your cells regularly
>will shorten their life, right?
>
>> The setup used for charging is terminal-voltage deficient - can only reach 3.47V per cell and the charger disconnects when the pack-draw drops to around 100mA.
>>
>
>My testing and experience using 3.485vpc and now 3.465vpc with TS
>cells shows that you are getting very close to 100%SOC with that
>charging procedure. I wouldn't change it if I were you.
>
>> Admittedly the low budget circumstanstance for my ev endeavors are a driving element - however this data-point is happy about their CALB cells - never have taken measures to balance the pack since the cells were purchased 9/2010 and after ~90 charge cycles the cells are only 1mV apart.
>>
>
>When are you making the voltage measurements? Immediately at the end
>of charge? If not the 1mV difference is nearly meaningless. If you
>don't have any cell level monitoring you might want to get a
>Batt-Bridge or half-pack voltage comparison circuit of some sort.
>Check my blog if you want to see how I did it.
>
>-- 
>David D. Nelson
>http://evalbum.com/1328

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## EVDL List (Jul 27, 2007)

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## EVDL List (Jul 27, 2007)

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## EVDL List (Jul 27, 2007)

Steve,

You need to get that up on EVAlbum! It looks like you did a very clean job.

BTW, as you might have noticed, the list doesn't accept HTML or
attachments, only plain text. I was able to extract the url to the
picture from the url left in your response to see it.




> <[email protected]> wrote:
> > An HTML attachment was scrubbed...
> > URL: http://lists.sjsu.edu/mailman/private/ev/attachments/20110918/594131=
> 22/attachment.html
> ...


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## EVDL List (Jul 27, 2007)

Also, the rest of your pics are password protected on your site so I
can't see them.



> David Nelson <[email protected]> wrote:
> > Steve,
> >
> > You need to get that up on EVAlbum! It looks like you did a very clean jo=
> ...


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## EVDL List (Jul 27, 2007)

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