Cold Lithium Cell Question

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Cold Lithium Cell Question

Mike Nickerson
Hello everybody,

I have a question about operation of ThunderSky LiFePo4 cells in the cold.
I don't know how much experience people have with this situation, but I'm
gathering opinions.

As people might recall, I'm running a Honda del Sol with 45 100Ah cells.
(www.evalbum.com/2778).  The cells are not in boxes, so they are exposed to
environmental heat and cold.

As the weather gets colder (22F, -5C this morning), I'm seeing performance
decreases. In summer,  I used to be able to pull 300A without too much
voltage drop.  I'm now limited to about 150-200A before the voltage drop
becomes too excessive.  Also, in order to keep the same speed on the
highway, I'm drawing more amps.  Instead of taking 100-110A to hold 60 MPH,
I now need 120A or so.  As the weather gets colder, I'm sure this trend will
continue.

Assuming I can get enough performance from the cells to hold highway speeds,
I'm fairly OK with the situation.   I have enough range to lose quite a bit
and still have the car work for me.   However, I don't want to continue
doing this if it risks damage to my cells.  Searching the archives, I don't
see much in the way of issues with cold operation (beyond voltage drops),
but since I don't see much in the way of information at all, I still wonder.

I have the option of taking the car off the road for the winter, building
some boxes that can keep the batteries warmer in the winter and (maybe)
cooler in the summer.  If cold weather operation risks damage, I would
certainly head that way. It's harder to justify just for better performance.
There are other reasons that boxes would be good, but tearing apart the
batteries is a fairly large task I've been putting off.

Thoughts?  Comments?

Mike

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Re: Cold Lithium Cell Question

David Nelson-5
On Wed, Nov 2, 2011 at 8:03 PM, Mike Nickerson <[hidden email]> wrote:
> Hello everybody,
>
> I have a question about operation of ThunderSky LiFePo4 cells in the cold.
> I don't know how much experience people have with this situation, but I'm
> gathering opinions.
>

I've had some of the same questions. I noted that the TS spec sheet
said charging was to be above 0°C and discharge could be below that. I
hadn't been able to find what would happen to the batteries if they
were charged when below 0°C until I read technical paper on the
electrolytes used in various Lithium batteries including LiFePO4
cells. The paper is at
http://parts.digikey.com/1/parts/50903-cap-alum-3900uf-100v-20-snap-eco-s2ap392da.html

On page 4363, the first two full paragraphs summarize what happens.
"Thus, at temperatures lower than the liquidus temperature (usually
above -20 °C for most electrolyte compositions),50e,159,160 EC
precipitates and drastically reduces the conductivity of lithium ions
both in the bulk electrolyte and through the interfacial films in the
system. During discharge, this increase of cell impedance at low
temperature leads to lower capacity utilization, which is normally
recoverable when the temperature rises. However, permanent damage
occurs if the cell is being charged at low temperatures because
lithium deposition occurs, caused by the high interfacial impedance,
and results in irreversible loss of lithium ions. An even worse
possibility is the safety hazard if the lithium deposition continues
to accumulate on the carbonaceous surface.

At temperatures higher than 60 °C, various decompositions occur among
the electrolyte components, electrode materials, and SEI or surface
layers, while LiPF6 acts as a major initiator or catalyst for most of
these reactions.152,310,332,333 The damage caused by high-temperature
operation is permanent. Because gaseous products accumulate, a safety
hazard
is also likely. Therefore, the specified temperature range for the
normal operation of most commercial lithium ion cells is -20 °C to +50
°C. While sufficient for most consumer purposes, the above range
severely restricts the applications of lithium ion technology for
special areas such as military, space, and vehicle traction uses."

I wasn't able to determine if there is any damage by pulling the cell
voltages down into the 1-2V range with in spec currents. The batteries
will warm up as they are used. Of course the wind might be cooling
them off too fast for the temperature rise to be noticeable.

If it gets really cold here I'll still try to charge when my batteries
are over 0°C but it looks like no permanent damage will be done as
long as they are above -20°C. I do have 3/4" of insulation around my
batteries and a nearly sealed box.

--
David D. Nelson
http://evalbum.com/1328
http://2003gizmo.blogspot.com

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Re: Cold Lithium Cell Question

David Nelson-5
Here is the correct link: http://www.tinhoahoc.com/Battery/cr030203g.pdf

On Wed, Nov 2, 2011 at 9:28 PM, David Nelson <[hidden email]> wrote:

> On Wed, Nov 2, 2011 at 8:03 PM, Mike Nickerson <[hidden email]> wrote:
>> Hello everybody,
>>
>> I have a question about operation of ThunderSky LiFePo4 cells in the cold.
>> I don't know how much experience people have with this situation, but I'm
>> gathering opinions.
>>
>
> I've had some of the same questions. I noted that the TS spec sheet
> said charging was to be above 0°C and discharge could be below that. I
> hadn't been able to find what would happen to the batteries if they
> were charged when below 0°C until I read technical paper on the
> electrolytes used in various Lithium batteries including LiFePO4
> cells. The paper is at
=====>>> correct link: http://www.tinhoahoc.com/Battery/cr030203g.pdf

>
> On page 4363, the first two full paragraphs summarize what happens.
> "Thus, at temperatures lower than the liquidus temperature (usually
> above -20 °C for most electrolyte compositions),50e,159,160 EC
> precipitates and drastically reduces the conductivity of lithium ions
> both in the bulk electrolyte and through the interfacial films in the
> system. During discharge, this increase of cell impedance at low
> temperature leads to lower capacity utilization, which is normally
> recoverable when the temperature rises. However, permanent damage
> occurs if the cell is being charged at low temperatures because
> lithium deposition occurs, caused by the high interfacial impedance,
> and results in irreversible loss of lithium ions. An even worse
> possibility is the safety hazard if the lithium deposition continues
> to accumulate on the carbonaceous surface.
>
> At temperatures higher than 60 °C, various decompositions occur among
> the electrolyte components, electrode materials, and SEI or surface
> layers, while LiPF6 acts as a major initiator or catalyst for most of
> these reactions.152,310,332,333 The damage caused by high-temperature
> operation is permanent. Because gaseous products accumulate, a safety
> hazard
> is also likely. Therefore, the specified temperature range for the
> normal operation of most commercial lithium ion cells is -20 °C to +50
> °C. While sufficient for most consumer purposes, the above range
> severely restricts the applications of lithium ion technology for
> special areas such as military, space, and vehicle traction uses."
>
> I wasn't able to determine if there is any damage by pulling the cell
> voltages down into the 1-2V range with in spec currents. The batteries
> will warm up as they are used. Of course the wind might be cooling
> them off too fast for the temperature rise to be noticeable.
>
> If it gets really cold here I'll still try to charge when my batteries
> are over 0°C but it looks like no permanent damage will be done as
> long as they are above -20°C. I do have 3/4" of insulation around my
> batteries and a nearly sealed box.
>
> --
> David D. Nelson
> http://evalbum.com/1328
> http://2003gizmo.blogspot.com
>



--
David D. Nelson
http://evalbum.com/1328
http://2003gizmo.blogspot.com

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Re: Cold Lithium Cell Question

Roger Stockton
In reply to this post by David Nelson-5
David Nelson wrote:

> If it gets really cold here I'll still try to charge when my batteries
> are over 0°C but it looks like no permanent damage will be done as
> long as they are above -20°C. I do have 3/4" of insulation around my
> batteries and a nearly sealed box.

I don't believe the bit about no permanent damage as long as they are above -20C is a safe assumption.

I've seen literature stating that the charge rate has to be reduced (significantly) below 0C to minimise/avoid the lithium plating issue.   "Significantly" appears to mean charge rates similar in magnitude to the current at which charging normally completes; a percent or two of the C-rating at most.

Specific cell makes may vary, so if possible consult with the manufacturer of your cells for their recommendations; otherwise, the safest bet is to charge slowly when your cells are cold.

Cheers,

Roger.


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Re: Cold Lithium Cell Question

gottdi

http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures

Li‑ion batteries offer reasonably good charging performance at cooler temperatures and allow fast-charging in a temperature bandwidth of 5 to 45°C (41 to 113°F). Below 5°C, the charge current should be reduced, and no charging is permitted at freezing temperatures. During charge, the internal cell resistance causes a slight temperature rise that compensates for some of the cold. With all batteries, cold temperature raises the internal resistance.
Many battery users are unaware that consumer-grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a subfreezing charge. The plating is permanent and cannot be removed with cycling. Batteries with lithium plating are known to be more vulnerable to failure if exposed to vibration or other stressful conditions. Advanced chargers, such as those made by Cadex, prevent charging Li-ion below freezing.
Manufactures continue to seek ways to charge Li-ion below freezing and low-rate charging is indeed possible with most lithium-ion cells; however, it is outside the specified (and tested) limits of most manufacturers’ products. Low-temperature charging would need to be addressed on a case-by-case basis and would be manufacturer and application dependent. According to information received from university research centers, the allowable charge rate at –30°C (–22°F) is 0.02C. At this low current, a 1,000mAh Li-ion could only charge at 20mA, and this would take more than 50 hours to reach full charge.
Some Li-ion cells developed for power tool and EV applications can be charged at temperatures down to –10°C (14°F) at a reduced rate. To charge at a higher rate, Li-ion systems for automotive propulsion systems require a heating blanket. Some hybrid cars circulate warm cabin air through the batteries to raise the battery temperature, while high-performance electric cars heat and cool the battery with a liquid agent
http://onegreenev.blogspot.com/
No need to wait any longer. You can now buy one off the shelf. You can still build one too.
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Re: Cold Lithium Cell Question

Evan Tuer
It's interesting, and something I've asked about before, but does it
apply to LiFePo4?
I repeatedly charged mine last winter without any heating after cold
soak in -10 to -20C overnight temperatures.  No cell failure or
noticeable degradation in performance a year later.


On Thu, Nov 3, 2011 at 2:36 PM, gottdi <[hidden email]> wrote:

>
> http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures
>
> Li‑ion batteries offer reasonably good charging performance at cooler
> temperatures and allow fast-charging in a temperature bandwidth of 5 to 45°C
> (41 to 113°F). Below 5°C, the charge current should be reduced, and no
> charging is permitted at freezing temperatures. During charge, the internal
> cell resistance causes a slight temperature rise that compensates for some
> of the cold. With all batteries, cold temperature raises the internal
> resistance.
> Many battery users are unaware that consumer-grade lithium-ion batteries
> cannot be charged below 0°C (32°F). Although the pack appears to be charging
> normally, plating of metallic lithium can occur on the anode during a
> subfreezing charge. The plating is permanent and cannot be removed with
> cycling. Batteries with lithium plating are known to be more vulnerable to
> failure if exposed to vibration or other stressful conditions. Advanced
> chargers, such as those made by Cadex, prevent charging Li-ion below
> freezing.
> Manufactures continue to seek ways to charge Li-ion below freezing and
> low-rate charging is indeed possible with most lithium-ion cells; however,
> it is outside the specified (and tested) limits of most manufacturers’
> products. Low-temperature charging would need to be addressed on a
> case-by-case basis and would be manufacturer and application dependent.
> According to information received from university research centers, the
> allowable charge rate at –30°C (–22°F) is 0.02C. At this low current, a
> 1,000mAh Li-ion could only charge at 20mA, and this would take more than 50
> hours to reach full charge.
> Some Li-ion cells developed for power tool and EV applications can be
> charged at temperatures down to –10°C (14°F) at a reduced rate. To charge at
> a higher rate, Li-ion systems for automotive propulsion systems require a
> heating blanket. Some hybrid cars circulate warm cabin air through the
> batteries to raise the battery temperature, while high-performance electric
> cars heat and cool the battery with a liquid agent
>
> -----
> If you don't understand, be patient, you will. Now I understand. :)
> --
> View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Cold-Lithium-Cell-Question-tp3984152p3986104.html
> Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.
>
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Re: Cold Lithium Cell Question

Roger Stockton
Evan Tuer wrote:

> It's interesting, and something I've asked about before, but does it
> apply to LiFePo4?

Yes.  The information provided in TI seminar at Battery Power 2011 specifically shows LiFePO4 charging prohibited below -20C and permitted only at low rate between 0C and -20C (charging also prohibited above 85C and restricted to low rate between 60C and 85C).

The precise limits are different for LiFePO4 than for other types, but still exist.  For instance, the same presentation presents the Japanese (JEITA) charge requirements for notebook cells, and these require both reduced voltage and current below 10C and above 45C, with charging prohibited entirely below 0C or above 50C.

> I repeatedly charged mine last winter without any heating after cold
> soak in -10 to -20C overnight temperatures.  No cell failure or
> noticeable degradation in performance a year later.

Similarly, some people don't use BMSes because they don't see immediate or dramatic failures ;^>

If your cells are large enough compared to your charger output, then you may be able to charge between 0 and -20C without taking any special measures (because your maximum charge rate is less than the low temperature limit for your cells anyway).  If your charge rate is too high for the size of cell and temperature, then you will plate lithium and gradually reduce both the cell capacity and safety.

Cheers,

Roger.


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Re: Cold Lithium Cell Question

Evan Tuer
On Thu, Nov 3, 2011 at 5:26 PM, Roger Stockton <[hidden email]> wrote:

> Evan Tuer wrote:
>
>> It's interesting, and something I've asked about before, but does it
>> apply to LiFePo4?
>
> Yes.  The information provided in TI seminar at Battery Power 2011 specifically shows LiFePO4 charging prohibited below -20C and permitted
> only at low rate between 0C and -20C (charging also prohibited above 85C and restricted to low rate between 60C and 85C).
>
> The precise limits are different for LiFePO4 than for other types, but still exist.  For instance, the same presentation presents the Japanese
> (JEITA) charge requirements for notebook cells, and these require both reduced voltage and current below 10C and above 45C, with charging
> prohibited entirely below 0C or above 50C.
>

Thanks Roger.

>> I repeatedly charged mine last winter without any heating after cold
>> soak in -10 to -20C overnight temperatures.  No cell failure or
>> noticeable degradation in performance a year later.
>
> Similarly, some people don't use BMSes because they don't see immediate or dramatic failures ;^>
>

Oh, sure, I'm not recommending it though!  Only that in the absence of
firm information I didn't know any better and seemed to get away with
it.
My charge rate was about 0.1C.

Regards
Evan

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Re: Cold Lithium Cell Question

EVDL Administrator
In reply to this post by David Nelson-5
On 2 Nov 2011 at 21:28, David Nelson wrote:

> Therefore, the specified temperature range for the normal operation of
> most commercial lithium ion cells is -20 °C to +50 °C.  ... the above
> range severely restricts the applications of lithium ion technology for
> ... vehicle traction uses."

This makes me wish all over again that Stan Ovshinsky had been a little more
careful with the rights to NiMH technology.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: Cold Lithium Cell Question

Lee Hart
David Nelson wrote:
>> Therefore, the specified temperature range for the normal operation of
>> most commercial lithium ion cells is -20 °C to +50 °C.  ... the above
>> range severely restricts the applications of lithium ion technology for
>> ... vehicle traction uses."

EVDL Administrator wrote:
> This makes me wish all over again that Stan Ovshinsky had been a little more
> careful with the rights to NiMH technology.

It does look like lithiums will need battery heaters, just like
lead-acid, to work in cold climates.

Nickel-based batteries (nicad, nimh, nife) are the least affected by
cold temperatures, though they still suffer a bit. Even so, EVs with
them still restrict charge/discharge rates at low temperatures. The
Prius for example cuts back peak currents in its nimh pack below
freezing (older Priuses actually displayed a turtle icon when this was
in effect).

Judging from "The Car That Could", Stan Ovshinski did everything
possible to promote his nimh cells, much to the chagrin of GM. They were
constantly at war over it, with Stan wanting to sell them to everyone,
and GM wanting to sell to no one. I think Stan did the best he could
under very difficult circumstances.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen

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Re: Cold Lithium Cell Question

Peter Gabrielsson
In reply to this post by EVDL Administrator
I don't see why. My EV-95 NiMH are not particularly peppy on cold
morning and I live in LA so it doesn't really get cold here. On the
high end they won't take much of a charge over 40 degree C and they
have an exothermic charge reaction so active cooling is required. Self
discharge also becomes a noticeable problem on hot days.

Temperature wise I'd say Lithium is a step up from NiMH. Granted,
maybe NiMH could have been improved further if it hadn't been so
restricted by the patents.


Their longevity is their best attribute.



On Thu, Nov 3, 2011 at 1:33 PM, EVDL Administrator <[hidden email]> wrote:

> On 2 Nov 2011 at 21:28, David Nelson wrote:
>
>> Therefore, the specified temperature range for the normal operation of
>> most commercial lithium ion cells is -20 °C to +50 °C.  ... the above
>> range severely restricts the applications of lithium ion technology for
>> ... vehicle traction uses."
>
> This makes me wish all over again that Stan Ovshinsky had been a little more
> careful with the rights to NiMH technology.
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> EVDL Information: http://www.evdl.org/help/
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> email address from the webpage http://www.evdl.org/help/ .
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>
>
>
> _______________________________________________
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--
www.electric-lemon.com

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Re: Cold Lithium Cell Question

David Nelson-5
In reply to this post by gottdi
On Thu, Nov 3, 2011 at 7:36 AM, gottdi <[hidden email]> wrote:
>
> http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures
>

My concern with accepting the battery university info is it doesn't
site any credible references. How do we know they aren't just
repackaging tidbits of stuff from unverified sources? At least Kang Xu
comes with a good reputation and strong background in battery
research. The article I referenced was published in 2004 so may not
include the current state of the typical TS and CALB LiFePO4 cells we
use. It is, however, a paper with 563 references the reader can follow
if the desire is there.

I wish there were credible specs on low temperature charging such as
temperature vs. max C rate.

As long as I use my Zivan NG1 to charge the rate is a max of 0.07C. My
NG3 only charges at 40A so 0.2C and together only 0.27C. Most of the
time I'm likely ok but I would still like to know for sure how low of
a temperature I can charge at with a 0.07C rate and not plate out any
Li.

--
David D. Nelson
http://evalbum.com/1328
http://2003gizmo.blogspot.com

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Re: Cold Lithium Cell Question

Mike Nickerson
In reply to this post by Evan Tuer
Thanks everybody, for the very interesting discussion.  I'm charging at .125C from 120V, so I need to be careful with the lithium plating.  The weather has warmed up some here (above freezing at least), so I'm doing some temperature experiments to see what my battery temperature is compared to ambient.  This evening, it looks like it is about 10F above ambient under the hood (some airflow) and 15F above ambient in the trunk.  I blocked off the front grill, so I'm getting less airflow under the hood than I used to.

I'm most worried about charging at work since the car is outside.  When I'm home, it's garaged and I could wait a while to charge after arriving home.

I'm not sure I want to go with battery boxes yet, but if I don't, I know the days I need to leave the car parked at home now!

Mike

> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf Of Evan Tuer
> Sent: Thursday, November 03, 2011 1:19 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Cold Lithium Cell Question
>
> On Thu, Nov 3, 2011 at 5:26 PM, Roger Stockton <[hidden email]>
> wrote:
> > Evan Tuer wrote:
> >
> >> It's interesting, and something I've asked about before, but does it
> >> apply to LiFePo4?
> >
> > Yes.  The information provided in TI seminar at Battery Power 2011
> > specifically shows LiFePO4 charging prohibited below -20C and permitted
> only at low rate between 0C and -20C (charging also prohibited above 85C
> and restricted to low rate between 60C and 85C).
> >
> > The precise limits are different for LiFePO4 than for other types, but
> > still exist.  For instance, the same presentation presents the
> > Japanese
> > (JEITA) charge requirements for notebook cells, and these require both
> > reduced voltage and current below 10C and above 45C, with charging
> prohibited entirely below 0C or above 50C.
> >
>
> Thanks Roger.
>
> >> I repeatedly charged mine last winter without any heating after cold
> >> soak in -10 to -20C overnight temperatures.  No cell failure or
> >> noticeable degradation in performance a year later.
> >
> > Similarly, some people don't use BMSes because they don't see
> > immediate or dramatic failures ;^>
> >
>
> Oh, sure, I'm not recommending it though!  Only that in the absence of firm
> information I didn't know any better and seemed to get away with it.
> My charge rate was about 0.1C.
>
> Regards
> Evan
>
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Re: Cold Lithium Cell Question

Mike Golub-2
In reply to this post by Roger Stockton


Sent from my iPhone

On Nov 3, 2011, at 9:26 AM, Roger Stockton <[hidden email]> wrote:

> Evan Tuer wrote:
>
>> It's interesting, and something I've asked about before, but does it
>> apply to LiFePo4?
>
> Yes.  The information provided in TI seminar at Battery Power 2011 specifically shows LiFePO4 charging prohibited below -20C and permitted only at low rate between 0C and -20C (charging also prohibited above 85C and restricted to low rate between 60C and 85C).
>
> The precise limits are different for LiFePO4 than for other types, but still exist.  For instance, the same presentation presents the Japanese (JEITA) charge requirements for notebook cells, and these require both reduced voltage and current below 10C and above 45C, with charging prohibited entirely below 0C or above 50C.
>
>> I repeatedly charged mine last winter without any heating after cold
>> soak in -10 to -20C overnight temperatures.  No cell failure or
>> noticeable degradation in performance a year later.
>
> Similarly, some people don't use BMSes because they don't see immediate or dramatic failures ;^>
>
> If your cells are large enough compared to your charger output, then you may be able to charge between 0 and -20C without taking any special measures (because your maximum charge rate is less than the low temperature limit for your cells anyway).  If your charge rate is too high for the size of cell and temperature, then you will plate lithium and gradually reduce both the cell capacity and safety.
>
> Cheers,
>
> Roger.
>
>
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Re: Cold Lithium Cell Question

Jukka Järvinen-2
Insulation and right sizing of the pack is everything when working
outside the cell operating temperature area.

We can do just fine even in -35C. Charging and discharging. But even
for the sake of the efficiencies it's reasonable to do everything to
keep the cells in the optimal operating condition.

A 600 kg battery pack just does not cool off. It has a lot of mass
that can maintain the heat in the active materials. This is why the
plastic insulator case is used with Winston-type cells. It helps to
maintain the operating conditions in the cell. And for some reason
we've been reading the bad words on the bad design how these cells do
not cool off as well as pouch and stainless casings. Change the cell
design and you'll do all kind of compromises on the way.

Now.. if you have cool but not yet cold cells (say -25C) the
electrolyte still remins liquid. By changing the electrolyte
composition you can keep it more viscose at even lower temps but then
you'll have to do a compromise again. Lithium plating occurs at some
conditions but it is not that black and white as the documents linked
to this thread may imply.

Have you guys (should I say persons ?) ever thought that how much mass
is in the electrolyte and how much energy it is requires to heat just
that component out in the cell ? Wy heat all external parts of it if
it is not really required ?

I'll refer to the patent later when it's out.

-akkuJukka

http://www.google.com/profiles/jarviju#about



2011/11/4 Mike Golub <[hidden email]>:

>
>
> Sent from my iPhone
>
> On Nov 3, 2011, at 9:26 AM, Roger Stockton <[hidden email]> wrote:
>
>> Evan Tuer wrote:
>>
>>> It's interesting, and something I've asked about before, but does it
>>> apply to LiFePo4?
>>
>> Yes.  The information provided in TI seminar at Battery Power 2011 specifically shows LiFePO4 charging prohibited below -20C and permitted only at low rate between 0C and -20C (charging also prohibited above 85C and restricted to low rate between 60C and 85C).
>>
>> The precise limits are different for LiFePO4 than for other types, but still exist.  For instance, the same presentation presents the Japanese (JEITA) charge requirements for notebook cells, and these require both reduced voltage and current below 10C and above 45C, with charging prohibited entirely below 0C or above 50C.
>>
>>> I repeatedly charged mine last winter without any heating after cold
>>> soak in -10 to -20C overnight temperatures.  No cell failure or
>>> noticeable degradation in performance a year later.
>>
>> Similarly, some people don't use BMSes because they don't see immediate or dramatic failures ;^>
>>
>> If your cells are large enough compared to your charger output, then you may be able to charge between 0 and -20C without taking any special measures (because your maximum charge rate is less than the low temperature limit for your cells anyway).  If your charge rate is too high for the size of cell and temperature, then you will plate lithium and gradually reduce both the cell capacity and safety.
>>
>> Cheers,
>>
>> Roger.
>>
>>
>> _______________________________________________
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>
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Re: Cold Lithium Cell Question

martinwinlow
In reply to this post by gottdi

On 3 Nov 2011, at 14:36, gottdi wrote:

>
> http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures
>
> Li‑ion batteries offer reasonably good charging performance at  
> cooler
> temperatures and allow fast-charging in a temperature bandwidth of 5  
> to 45°C
> (41 to 113°F). Below 5°C, the charge current should be reduced, and  
> no
> charging is permitted at freezing temperatures. During charge, the  
> internal
> cell resistance causes a slight temperature rise that compensates  
> for some
> of the cold. With all batteries, cold temperature raises the internal
> resistance.
> Many battery users are unaware that consumer-grade lithium-ion  
> batteries
> cannot be charged below 0°C (32°F). Although the pack appears to be  
> charging
> normally, plating of metallic lithium can occur on the anode during a
> subfreezing charge. The plating is permanent and cannot be removed  
> with
> cycling. Batteries with lithium plating are known to be more  
> vulnerable to
> failure if exposed to vibration or other stressful conditions.  
> Advanced
> chargers, such as those made by Cadex, prevent charging Li-ion below
> freezing.
> Manufactures continue to seek ways to charge Li-ion below freezing and
> low-rate charging is indeed possible with most lithium-ion cells;  
> however,
> it is outside the specified (and tested) limits of most  
> manufacturers’
> products. Low-temperature charging would need to be addressed on a
> case-by-case basis and would be manufacturer and application  
> dependent.
> According to information received from university research centers,  
> the
> allowable charge rate at –30°C (–22°F) is 0.02C. At this low  
> current, a
> 1,000mAh Li-ion could only charge at 20mA, and this would take more  
> than 50
> hours to reach full charge.
> Some Li-ion cells developed for power tool and EV applications can be
> charged at temperatures down to –10°C (14°F) at a reduced rate.  
> To charge at
> a higher rate, Li-ion systems for automotive propulsion systems  
> require a
> heating blanket. Some hybrid cars circulate warm cabin air through the
> batteries to raise the battery temperature, while high-performance  
> electric
> cars heat and cool the battery with a liquid agent
>
>

Nice piece.

I get the feeling that we are saying that - ignoring balancing and  
over/under charge protection, we should be equally concerned by  
potential irreversible damage caused by charging outside of  
temperature limits.

Sounds like another reason to need a BMMS to me.

Regards, Martin Winlow
Herts, UK
http://www.evalbum.com/2092
www.winlow.co.uk



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Wanted: Siemens motor controller

Osmo Sarin
In reply to this post by Jukka Järvinen-2
Hello all,

does anyone have a Siemens Simovert Short, or other inverter suitable  
to run Siemens PV5133 motor for sale?

Thanks,
Osmo
evalbum.com/3933

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Re: Wanted: Siemens motor controller

Collin Kidder
No, a lot of people wish that such things were available. There were,
perhaps, a few hundred PV5133 motors from the Ford Ranger EV program
that were sold to the general public. I've got one of them. But, the
controllers were never available as far as I can tell. DMOC445
controllers can (theoretically) be used to drive them. You can't order
a new DMOC445 right now but you might find a used one. Siemens motor
controllers, if you can find one, are priced by people who don't
apparently need to sell any controllers. They aren't even remotely in
the realm of reason price-wise.

Personally, I am building my own controller to drive this motor. A man
named Eric Tischer did the same thing. He has a website detailing how
he went about it. Actually, so do I.

His site: http://etischer.com/awdev/

My site: http://code.google.com/p/revolt-ac-controller/

I hope you find something which will work for you. Best of luck!

On Fri, Nov 4, 2011 at 5:53 AM, Osmo Sarin <[hidden email]> wrote:

> Hello all,
>
> does anyone have a Siemens Simovert Short, or other inverter suitable
> to run Siemens PV5133 motor for sale?
>
> Thanks,
> Osmo
> evalbum.com/3933
>
> _______________________________________________
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Re: Wanted: Siemens motor controller

rodhower
Eric did an awesome job on that conversion!
I guess Tesla was also impressed, he's a Senior Controls Engineer there,
http://www.linkedin.com/profile/view?id=95825328&authType=NAME_SEARCH&authToken=0Q_7&locale=en_US&srchid=97bdee6e-b5d0-408a-8fd9-4f32da95da2b-0&srchindex=1&srchtotal=4&goback=%2Efps_PBCK_*1_Eric_Tischer_*1_*1_*1_*1_*2_*1_Y_*1_*1_*1_false_1_R_*1_*51_*1_*51_true_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2_*2&pvs=ps&trk=pp_profile_name_link


or just go to www.linkedin.com and type in his name, it's the first one to come
up.


----- Original Message ----
From: Collin Kidder <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Sent: Fri, November 4, 2011 8:42:29 AM
Subject: Re: [EVDL] Wanted: Siemens motor controller

No, a lot of people wish that such things were available. There were,
perhaps, a few hundred PV5133 motors from the Ford Ranger EV program
that were sold to the general public. I've got one of them. But, the
controllers were never available as far as I can tell. DMOC445
controllers can (theoretically) be used to drive them. You can't order
a new DMOC445 right now but you might find a used one. Siemens motor
controllers, if you can find one, are priced by people who don't
apparently need to sell any controllers. They aren't even remotely in
the realm of reason price-wise.

Personally, I am building my own controller to drive this motor. A man
named Eric Tischer did the same thing. He has a website detailing how
he went about it. Actually, so do I.

His site: http://etischer.com/awdev/

My site: http://code.google.com/p/revolt-ac-controller/

I hope you find something which will work for you. Best of luck!

On Fri, Nov 4, 2011 at 5:53 AM, Osmo Sarin <[hidden email]> wrote:

> Hello all,
>
> does anyone have a Siemens Simovert Short, or other inverter suitable
> to run Siemens PV5133 motor for sale?
>
> Thanks,
> Osmo
> evalbum.com/3933
>
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere.  Thanks.
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>

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Re: Wanted: Siemens motor controller

EVDL Administrator
In reply to this post by Osmo Sarin
On 4 Nov 2011 at 11:53, Osmo Sarin wrote:

> does anyone have a Siemens Simovert Short, or other inverter suitable  
> to run Siemens PV5133 motor for sale?

I hope you got that motor for free.  It's an orphan.  There are no Siemens
controllers available to mate with it.

IMO it's a crime to waste a good motor, but that's how it is; thus spake
Siemens.  I'm afraid that unless you have the engineering chops to "roll
your own," you're stuck with an expensive doorstop.

I will hold my tongue about the people who sell these motors for outrageous
prices on Ebay, except to say that I think a fair price for them would be
perhaps 50% above scrap value.

David Roden - Akron, Ohio, USA
EVDL Administrator

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