# temperuature extremes management Lithiums



## bjfreeman (Dec 7, 2011)

done a lot of reading in this area but yet have to actually test.
I use death valley at peak summer and 8,000 feet in winter to state temp extremes.
batter packs will be exposed to refluctive heat and wind chill .
I am planning on inserting fluid temperature panels. between the lithium cells so I I can control the temp of the cells
any thoughts from experience


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## dtbaker (Jan 5, 2008)

perhaps if you concentrate on good cabin temp control heat/AC, and circulate cabin air thru cells they would act as a massive heat sink and stabilize right where you want them at 70-75 deg F.


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## bjfreeman (Dec 7, 2011)

my understanding is the batteries are in the engine compartment, in the cabin area and in the trunk.
I my case they are in the undercarriage of the Bus where no heat from the cabin is available.
here are two scenarios that I have not solved using cabin Heat.
1)vehicle sits over night in 20F temp. How much heat do you have to produce to heat the batteries properly. Do you really want lithium to get to 20F.
2) your drving a road that is 110F your cabin temp at 85F because the AC can not handle the heat dissipation. 

my thought is by using the Dc heater and a separate cooling for the oil and the plates you can regulate the temp with less power, even when the vehicle is not not moving. The batteries stay in optimal operating temps.

For EV they will be plugged in, For RV" buses, they will have onboard Generator.


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## DIYguy (Sep 18, 2008)

running heating cooling plates between cells ends up taking a lot of space and probably not required. Enclose/insulate battery box and heat bottom with aluminum heat spreader. If using prismatics, they have spaces to channel heat between. For cooling, some air flow with fans is likely more than enough. Most just open up box in summer for lifepo4 with "in-spec" current draws....


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## bjfreeman (Dec 7, 2011)

I have 2 112 cells stacks in parrallel
the 112 stack are in 4 ea 28 cell groups that will be banded.
These are in a container in the undercarraige.
can you point me to a similar setup that will handle 110f to 20F.


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> I have 2 112 cells stacks in parrallel
> the 112 stack are in 4 ea 28 cell groups that will be banded.
> These are in a container in the undercarraige.
> can you point me to a similar setup that will handle 110f to 20F.


What brand/type/model of battery do you have?


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## bjfreeman (Dec 7, 2011)

DIYguy said:


> What brand/type/model of battery do you have?


for my edification can you explain how that information is related to temperature control methods?
I am more interested in design info than end user info.


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> for my edification can you explain how that information is related to temperature control methods?
> I am more interested in design info than end user info.


There are many chemistries and packages for 'lithium" batteries. Each has similar but somewhat different characteristics. I would not approach the heating of prismatics the same way I would approach cylindricals. Additionally, the heating/cooling system should take into consideration not only the ambient temps but those influenced by the battery load and packaging. For example a battery used in -20C may have x amount of voltage drop at y current. If this is adequate for your application (worst case) then less aggressive (watts per area or volume) may be an option. 
Charging is a different case again. 

I live in Canada. This is what I did. http://www.diyelectriccar.com/forums/showthread.php?t=54878
Well, actually I did a bit more than that... but the thread gives some ideas, feedback, examples etc. Hopefully, u will get something out of it.


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## bjfreeman (Dec 7, 2011)

I have included the lithium polymer cell.
I have my own BMS


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> I have included the lithium polymer cell.
> I have my own BMS


yikes. 

u have a spec sheet?


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## bjfreeman (Dec 7, 2011)

DIYguy said:


> yikes.
> 
> u have a spec sheet?


these were purchased many years ago.
when large cell lithium were first available in bulk orders.
It seems the ability to order them has dried up, unless you know of a source.
I may have to go to Winston/thudersky
Typical Capacity 100 ah.
Nominal voltage 3.7
Charged voltage 4.2
Max charge and continous discharge Current 100 amps.
Peak Discharge 200 amps
cut off discharge volts 2.7


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> I have included the lithium polymer cell.
> I have my own BMS



I know this thread is suppose to be about temp management. . . but I must comment on the battery. First thoughts are; that is an extremely large looking form factor for a 16 ah pouch cell. Secondly, why would you use li-poly in a bus?
I really think you need to stick to lifepo4 and unless you want a ton of extra work, you should consider prismatic cells. You can get lifepo4 in pouch cells, but for your application, it seems not the best choice. 
I think that the Thundersky/Sinopoly/Winston saga has evolved to the point of unobtainium, for the moment at least. You may want to look at CALB/CALIB (old Sky Energy). They have a factory distribution set up in Pamona now. Of course there are other choices but a proven lifepo4 supplier of prismatics like Calb, GBS or even HiPower is a better choice IMHO for this application. Most Li-poly cycle life is in the hundreds where lifepo is in the thousands. . . not to mention inherent safety factor.
Unless you are trying to stuff a lot of power into a small project, pouch cells don't make a lot of sense to me. Prismatics will save you many many hours of work. CALIB sells a 400Ah prismatic I believe.


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## bjfreeman (Dec 7, 2011)

My only defense is the year bought which is a long time ago and they were the only large charge and discharge. did I put 16 ah I meant 100 ah and now I want 300 amp.
I agree with you.
Even though I am up to about 1,000 charges.
I have gone through a Single motor Gear box iteration already. I am now doing a motor per wheel for 4 wheel direct drive. I have another thread on this so will not get into details here.
Each wheel has its own battery pack, Utltra capacitor, Controller.
So yes I will be redesigning my batteries.
My understanding of New Models that you mention is the Case swells.
In way I digress, I have notice that the Packs II have get to warm to touch at full discharge.
to the purpose of this thread was otheres that had experience in high discharge 100-300 amps packs and how they dealt with heat.


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> My only defense is the year bought which is a long time ago and they were the only large charge and discharge. did I put 16 ah I meant 100 ah and now I want 300 amp.
> I agree with you.
> Even though I am up to about 1,000 charges.
> I have gone through a Single motor Gear box iteration already. I am now doing a motor per wheel for 4 wheel direct drive. I have another thread on this so will not get into details here.
> ...



I read 16ah on the pouch in the picture.
300 amps is nothing. I pull 1000 amps out of my CALB 180's regularly, albeit briefly. Swelling only happens if they are abused with over charge or over discharge. Li-poly does the same. I consider the strapping to be more to prevent inter-cell connection movement. Yes, it can help control swelling. . but treated properly, you shouldn't ever have to deal with it.


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## bjfreeman (Dec 7, 2011)

DIYguy said:


> I read 16ah on the pouch in the picture.
> 300 amps is nothing. I pull 1000 amps out of my CALB 180's regularly, albeit briefly. Swelling only happens if they are abused with over charge or over discharge. Li-poly does the same. I consider the strapping to be more to prevent inter-cell connection movement. Yes, it can help control swelling. . but treated properly, you shouldn't ever have to deal with it.


Great do you have numbers about charge/discharge characteristics in 20F to 110F ambient temps.
The batteries are used for prolong acceleration after the Ultras Are Discharged and for Regen storage after the Ultra caps are maxed out.


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> Great do you have numbers about charge/discharge characteristics in 20F to 110F ambient temps.
> The batteries are used for prolong acceleration after the Ultras Are Discharged and for Regen storage after the Ultra caps are maxed out.


20F = -6.7 C
110F = 43.3 C

Calb recommends charging between 0 and 45C, discharging between -20 and +55C. 

Based on your question, you need to address the low charge temperature. One way to achieve this is to charge directly after use. This typically means the cells have some level of heat.
The other extremes are ok if you keep from surpassing. Just realize that the extremes still have an impact. As an example, if it was 110F ambient, your cells were in enclosed, insulated boxes and u had high discharge rates with no ventilation, it could cause some issues. I think the electrolyte starts breaking down up around 60C or so. Calb recommends that ventilation temp for energizing fans is 40C.
For all but the most extreme heat areas, the need to ventilate is driven mostly by the use of insulated enclosures . . . made to keep them warm in colder temps.


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## bjfreeman (Dec 7, 2011)

yes I read the tech sheets, was hoping for some personal experience.
these are in enclosed cases that can not be vented or opened.
so I am back to using my thermal plates for temperature control.
thanks for you effort.


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> yes I read the tech sheets, was hoping for some personal experience.


 what kind of experience are you after? I don't charge my cells below 0 C if that is what you mean. As for 20 F, we wear shorts here at those temps 



bjfreeman said:


> these are in enclosed cases that can not be vented or opened.


Why is that? 



bjfreeman said:


> I am back to using my thermal plates for temperature control.
> thanks for you effort.


Ok, have fun with that.. lol


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## bjfreeman (Dec 7, 2011)

DIYguy said:


> Why is that?


They are in the undercarriage under the floorboards.
http://roadwarrior.free-man.com/


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> They are in the undercarriage under the floorboards.
> http://roadwarrior.free-man.com/


That shouldn't prevent designing vented boxes. Mine are under the truck bed between the frame rails. They have thermostatically controlled heat and ventilation as well as monitoring signals to show status and individual cell termination to exposed terminal strips. 
But hey, its a free country, U get to do it anyway u like.

Certainly is a great "big" project. That thing is big enough to actually get some small benefit from PV panels! lol


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## bjfreeman (Dec 7, 2011)

DIYguy said:


> That shouldn't prevent designing vented boxes. Mine are under the truck bed between the frame rails. They have thermostatically controlled heat and ventilation as well as monitoring signals to show status and individual cell termination to exposed terminal strips.
> But hey, its a free country, U get to do it anyway u like.
> 
> Certainly is a great "big" project. That thing is big enough to actually get some small benefit from PV panels! lol


you miss the fact that "Vent ed" lets in Moisture and dust. The then get deposited on the bms electronics and caused failure of BMS functionality.
and I do have the electronics potted in non corrosive RTV, except for the heat generating components.

I don't want to mess with the batteries while on the road for about 5 years.
I have 4 *FLEX POWER MAT (75 watt each).

*


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## DIYguy (Sep 18, 2008)

bjfreeman said:


> you miss the fact that "Vent ed" lets in Moisture and dust. The then get deposited on the bms electronics and caused failure of BMS functionality.
> and I do have the electronics potted in non corrosive RTV, except for the heat generating components.
> 
> I don't want to mess with the batteries while on the road for about 5 years.
> ...


Well, get rid of the BMS then.  . . or u can run with centralized instead of distributed.... 
If they shunt to balance,. . there is more heat to get rid of in those 110F days with sealed boxes.  
Unless ur boxes are hermetically sealed, ur still going to have moisture similar to ambient air. It's the mist and rain u wanna keep out.

I just seal up the vents in the winter and open them in the summer. I don't use a BMS. If I did though, I wouldn't need to mount anything inside my battery boxes.


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## bjfreeman (Dec 7, 2011)

I prefer to add an 1/4 inch between each battery for temp regulation. space is not a problem. So far the BMS has not created the heat that is necessary to heat sink them. I have thermal couples on them so if they register, I will deal that at that time.
I am taking my lead from the Hybrid Metro buses, that are closer to the operating model I use.
thanks for you input


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