Anyone have thermal data for the Sky Energy 100ah cells, charge and discharge temp rise?

[ianaudio]

I considering what to do about power dissapation in the battery box.  I've got 96 of the SE 100ah cells in a closed box, an old US Electricar S10.  I've also got an Elithion BMS.  I haven't been able to find any power dissapation information for either the cells or the BMS.  Has anyone observed the temperature rise on charge and discharge with one of these setups?  I'm contemplating adding 2 4" fans to each side of the battery box, but I don't want to cut the holes if I don't need to.  I figure since the BMS is measuring temperature and has fan control outputs, there must be a reason to supply a little air motion over the cells.

Paul Wallace

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[Elithion]

> I haven't been able to find any power [dissipation] information for
either the cells...

That's because it is a function of internal resistance of the cell, and
cell manufacturers either don't know how to measure it, or would rather
not talk about it. My very rough estimate is that you'll see something on
the order of 500 W dissipation while driving, 10 W while charging.

>.. or the BMS.

Please see:
http://liionbms.com/php/cell_boards.php#Specifications
"Cell load current ... Balancing, at 3.6 V (LiFePO4) ... 200 mA"

Max power: P = 3.6 V x 0.2 A x 96 cells = 69 W

But that's a max, and only at the end of charging. Averaged over the
typical charge cycle, that's more like 5 W.

So, the dissipation from the cells while driving will be the predominant
source of heat.

D'de
Davide Andrea



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[Lee Hart]

[hidden email] wrote:
> I considering what to do about power dissapation in the battery box.  I've got 96 of the SE 100ah cells in a closed box, an old US Electricar S10.  I've also got an Elithion BMS.  I haven't been able to find any power dissapation information for either the cells or the BMS.  Has anyone observed the temperature rise on charge and discharge with one of these setups?  I'm contemplating adding 2 4" fans to each side of the battery box, but I don't want to cut the holes if I don't need to.  I figure since the BMS is measuring temperature and has fan control outputs, there must be a reason to supply a little air motion over the cells.

I'd say you had better cut the holes and provide the ventilation. From
what I've read, this is a dissipative battery balancing system. It will
need to burn up the charging current times the pack voltage as heat near
the end of a charge cycle when most of the cell regulators are bypassing
current.

--
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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[tomw]

My SkyEnergy cells came with documentation showing state of charge at time of shipment and internal resistance.  The latter ranges from 0.021 to 0.025 mOhm.  So I would expect around 5W per cell at 150A pack current, assuming the cells are all in series.

Tom

ianaudio wrote:

I considering what to do about power dissapation in the battery box.  I've got 96 of the SE 100ah cells in a closed box, an old US Electricar S10.  I've also got an Elithion BMS.  I haven't been able to find any power dissapation information for either the cells or the BMS.  Has anyone observed the temperature rise on charge and discharge with one of these setups?  I'm contemplating adding 2 4" fans to each side of the battery box, but I don't want to cut the holes if I don't need to.  I figure since the BMS is measuring temperature and has fan control outputs, there must be a reason to supply a little air motion over the cells.

Paul Wallace

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[Morgan LaMoore]

On Tue, Nov 10, 2009 at 9:27 PM, tomw <[hidden email]> wrote:
>
> My SkyEnergy cells came with documentation showing state of charge at time of
> shipment and internal resistance.  The latter ranges from 0.021 to 0.025
> mOhm.  So I would expect around 5W per cell at 150A pack current, assuming
> the cells are all in series.
>
> Tom

Tom,

.021 to .025 mOhm is amazingly low; if the cells were that good, they
could perform like A123.

I expect that they measured the internal "resistance" at 1kHz, which
could be quite a bit lower than the DC internal resistance.

Based on their spec of max current of 4C for 20s, I expect at worst
1.2V sag, or 3mOhm impedance. I don't think they would be better than
1mOhm; otherwise they could rate the cells for more current.

If Sky Energy cells have virtually no voltage sag even at maximum
current, I'm wrong, but I don't expect that.

-Morgan LaMoore

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[tomw]

Whoops, typo!  Make that an order of magnitude lower, about 0.23 mOhm on average.  Don't know why I stuck that zero in there.  Thanks for correcting me Morgan.

Tom

Morgan LaMoore wrote:

On Tue, Nov 10, 2009 at 9:27 PM, tomw <[e-mail]> wrote:
>
> My SkyEnergy cells came with documentation showing state of charge at time of
> shipment and internal resistance.  The latter ranges from 0.021 to 0.025
> mOhm.  So I would expect around 5W per cell at 150A pack current, assuming
> the cells are all in series.
>
> Tom

Tom,

.021 to .025 mOhm is amazingly low; if the cells were that good, they
could perform like A123.

I expect that they measured the internal "resistance" at 1kHz, which
could be quite a bit lower than the DC internal resistance.

Based on their spec of max current of 4C for 20s, I expect at worst
1.2V sag, or 3mOhm impedance. I don't think they would be better than
1mOhm; otherwise they could rate the cells for more current.

If Sky Energy cells have virtually no voltage sag even at maximum
current, I'm wrong, but I don't expect that.

-Morgan LaMoore

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[Morgan LaMoore]

0.23 mOhm still seems unreasonably low for DC resistance; that would
be .092V sag per cell at 4C discharge, which is about right for A123
but far too good for these cells.

I would guess that numbers based on measurements of high-current
discharge will be much less impressive.

-Morgan

On 11/11/09, tomw <[hidden email]> wrote:

>
> Whoops, typo!  Make that an order of magnitude lower, about 0.23 mOhm on
> average.  Don't know why I stuck that zero in there.  Thanks for correcting
> me Morgan.
>
> Tom
>
>
> Morgan LaMoore wrote:
>>
>> On Tue, Nov 10, 2009 at 9:27 PM, tomw <[hidden email]> wrote:
>>>
>>> My SkyEnergy cells came with documentation showing state of charge at
>>> time of
>>> shipment and internal resistance.  The latter ranges from 0.021 to 0.025
>>> mOhm.  So I would expect around 5W per cell at 150A pack current,
>>> assuming
>>> the cells are all in series.
>>>
>>> Tom
>>
>> Tom,
>>
>> .021 to .025 mOhm is amazingly low; if the cells were that good, they
>> could perform like A123.
>>
>> I expect that they measured the internal "resistance" at 1kHz, which
>> could be quite a bit lower than the DC internal resistance.
>>
>> Based on their spec of max current of 4C for 20s, I expect at worst
>> 1.2V sag, or 3mOhm impedance. I don't think they would be better than
>> 1mOhm; otherwise they could rate the cells for more current.
>>
>> If Sky Energy cells have virtually no voltage sag even at maximum
>> current, I'm wrong, but I don't expect that.
>>
>> -Morgan LaMoore
>>
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>>
>>
>
> --
> View this message in context:
> http://n4.nabble.com/Anyone-have-thermal-data-for-the-Sky-Energy-100ah-cells-charge-and-discharge-temp-rise-tp585148p585869.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
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[Kent.Barnes]

I've requested removal from mail list twice already. What else do I need to
do to stop the emails????

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf
Of Morgan LaMoore
Sent: Wednesday, November 11, 2009 12:36 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Anyone have thermal data for the Sky Energy 100ah
cells,charge and discharge temp rise?

0.23 mOhm still seems unreasonably low for DC resistance; that would be
.092V sag per cell at 4C discharge, which is about right for A123 but far
too good for these cells.

I would guess that numbers based on measurements of high-current discharge
will be much less impressive.

-Morgan

On 11/11/09, tomw <[hidden email]> wrote:

>
> Whoops, typo!  Make that an order of magnitude lower, about 0.23 mOhm
> on average.  Don't know why I stuck that zero in there.  Thanks for
> correcting me Morgan.
>
> Tom
>
>
> Morgan LaMoore wrote:
>>
>> On Tue, Nov 10, 2009 at 9:27 PM, tomw <[hidden email]> wrote:
>>>
>>> My SkyEnergy cells came with documentation showing state of charge
>>> at time of shipment and internal resistance.  The latter ranges from
>>> 0.021 to 0.025 mOhm.  So I would expect around 5W per cell at 150A
>>> pack current, assuming the cells are all in series.
>>>
>>> Tom
>>
>> Tom,
>>
>> .021 to .025 mOhm is amazingly low; if the cells were that good, they
>> could perform like A123.
>>
>> I expect that they measured the internal "resistance" at 1kHz, which
>> could be quite a bit lower than the DC internal resistance.
>>
>> Based on their spec of max current of 4C for 20s, I expect at worst
>> 1.2V sag, or 3mOhm impedance. I don't think they would be better than
>> 1mOhm; otherwise they could rate the cells for more current.
>>
>> If Sky Energy cells have virtually no voltage sag even at maximum
>> current, I'm wrong, but I don't expect that.
>>
>> -Morgan LaMoore
>>
>> _______________________________________________
>> 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
>>
>>
>>
>
> --
> View this message in context:
> http://n4.nabble.com/Anyone-have-thermal-data-for-the-Sky-Energy-100ah
> -cells-charge-and-discharge-temp-rise-tp585148p585869.html
> Sent from the Electric Vehicle Discussion List mailing list archive at
> Nabble.com.
>
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[Bob Rice-2]

----- Original Message -----
From: "Kent.Barnes" <[hidden email]>
To: "'Electric Vehicle Discussion List'" <[hidden email]>
Sent: Wednesday, November 11, 2009 12:38 PM
Subject: Re: [EVDL] Anyone have thermal data for the Sky Energy 100ah
cells,charge and discharge temp rise?


> I've requested removal from mail list twice already. What else do I need
> to
> do to stop the emails????


 Talk Politics!! Obama care, Illegal immigration, oil cartel!

> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
> Behalf
> Of Morgan LaMoore
> Sent: Wednesday, November 11, 2009 12:36 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Anyone have thermal data for the Sky Energy 100ah
> cells,charge and discharge temp rise?
>
> 0.23 mOhm still seems unreasonably low for DC resistance; that would be
> .092V sag per cell at 4C discharge, which is about right for A123 but far
> too good for these cells.
>
> I would guess that numbers based on measurements of high-current discharge
> will be much less impressive.
>
> -Morgan
>
> On 11/11/09, tomw <[hidden email]> wrote:
>>
>> Whoops, typo!  Make that an order of magnitude lower, about 0.23 mOhm
>> on average.  Don't know why I stuck that zero in there.  Thanks for
>> correcting me Morgan.
>>
>> Tom
>>
>>
>> Morgan LaMoore wrote:
>>>
>>> On Tue, Nov 10, 2009 at 9:27 PM, tomw <[hidden email]> wrote:
>>>>
>>>> My SkyEnergy cells came with documentation showing state of charge
>>>> at time of shipment and internal resistance.  The latter ranges from
>>>> 0.021 to 0.025 mOhm.  So I would expect around 5W per cell at 150A
>>>> pack current, assuming the cells are all in series.
>>>>
>>>> Tom
>>>
>>> Tom,
>>>
>>> .021 to .025 mOhm is amazingly low; if the cells were that good, they
>>> could perform like A123.
>>>
>>> I expect that they measured the internal "resistance" at 1kHz, which
>>> could be quite a bit lower than the DC internal resistance.
>>>
>>> Based on their spec of max current of 4C for 20s, I expect at worst
>>> 1.2V sag, or 3mOhm impedance. I don't think they would be better than
>>> 1mOhm; otherwise they could rate the cells for more current.
>>>
>>> If Sky Energy cells have virtually no voltage sag even at maximum
>>> current, I'm wrong, but I don't expect that.
>>>
>>> -Morgan LaMoore
>>>
>>> _______________________________________________
>>> 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
>>>
>>>
>>>
>>
>> --
>> View this message in context:
>> http://n4.nabble.com/Anyone-have-thermal-data-for-the-Sky-Energy-100ah
>> -cells-charge-and-discharge-temp-rise-tp585148p585869.html
>> Sent from the Electric Vehicle Discussion List mailing list archive at
>> Nabble.com.
>>
>> _______________________________________________
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>> http://evdl.org/help/index.html#conv
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>>
>>
>
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[David Roden-3]

On 11 Nov 2009 at 12:38, Kent.Barnes wrote:

> I've requested removal from mail list twice already. What else do I need to do
> to stop the emails????  

I  normally reply to these messages offlist, but for the sake of those who
may want to unsubscribe or suspend email, just this once, I'll remind
everybody of the procedure.

First, you should know that mailing lists are (ta-da) self-service.  Sorry,
posting that you want to be removed doesn't work.  All it does is annoy some
of the other list members.

It's actually pretty easy to unsubscribe yourself.  Not only did you get
instructions when you subscribed, the listserver also puts a link for
subscription options at the bottom of every message sent from this list -
including this one.

Follow that link and you'll find the instructions for unsubscribing,
suspending your email while you're away on holiday, et cetera.  

You can also find instructions for unsubscribing here :

http://www.evdl.org/help/index.html#usub

David Roden - Akron, Ohio, USA
EVDL Administrator

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[David Roden-3]

On 11 Nov 2009 at 12:50, Bob Rice wrote:

>  Talk Politics!! Obama care, Illegal immigration, oil cartel!

Good one.  Touche'.  ;-)

David Roden - Akron, Ohio, USA
EVDL Administrator

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