# Battery Cooling for DC Fast Charge



## john61ct (Feb 25, 2017)

Better for the cells' lifespan, to keep C-rates lower than the point where internal temperature rise becomes significant, or even detectable.

That rise is a symptom of lifecycles-reducing stress, not a cause.

Artificially keeping them cool from the outside is a safety precaution, to prevent the pack exploding into flames

and to allow the vendor to cite higher performance figures by stretching the "safety envelope".

Liquid cooling systems are too much expensive complexity, IMO not worth it for most DIYers


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## alexbeatle (Jul 28, 2020)

So simply having a (computer) pump running a collant through the batteries won't do?


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## john61ct (Feb 25, 2017)

Sure go for it if you think you got the skillz

but if you then really rely on that DIY TMS, better be sure to build in active monitoring, redundancy etc

more points of failure


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## alexbeatle (Jul 28, 2020)

Hmm..is that why so far I haven't seen a DIY conversion with a DC charge!? Maybe!?


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## john61ct (Feb 25, 2017)

DC charge is not in itself the problem.

Determining the right amps level and keeping the flow capped, 

or actually limiting current based on a detected temp rise is the challenge

and these take pretty high level components and skillz to implement


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## alexbeatle (Jul 28, 2020)

Is that what BMSs are for?


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## Isaac97 (Jun 3, 2019)

BMS watches all the cells and makes sure they don't get too high or too low (too high = boom, too low = die). Also some monitor temperature.

DC charge is pretty difficult but not impossible, I had it in my car until I did a rebuild (CHAdeMO), going back in once I get a new shunt.
I see you posted in this thread, Jack Bauer (Damien) is the one who made the CHAdeMO hardware I'm using, I rewrote the software to work with his hardware.
Temperature monitoring is coming next after CHAdeMO has been used some more. At that point it wouldn't be difficult to add temperature-based charging.
I'll be testing up to 100A into my pack and see how the temperatures behave, chances are the batteries will be fine.


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## remy_martian (Feb 4, 2019)

alexbeatle said:


> Hello all,
> 
> DC fast charge heat up batteries more than other (Levels 1 & 2 charging, driving, etc.).
> * * * Planning CHAdeMO (CCS once available) implementation in my diy convertsion.


That is simply not true. 

The car asks for a max current level for charging. 

So, for example if you go to a public charger and don't ask for more than you charge Level 2 at home, there simply is no difference in DC charging a pack.


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## alexbeatle (Jul 28, 2020)

So after watching the EV Bolt dismantle and reading other info there's a separate heating/cooling system to keep the batteries at the ultimate temp.





Having a dedicated heating/cooling line what makes me ask how the DIYers approach this side of things.


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## Isaac97 (Jun 3, 2019)

OEM EVs have to be able to handle large temperature ranges without problems - 0 to 120 F or so. DIYers tend to ignore things like this, maybe adding a manual battery heater if necessary.
Tesla likes to condition their batteries a lot -- but they have a specific chemistry and charge/discharge very quickly.


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## john61ct (Feb 25, 2017)

Yes of course manufacturers pay many millions to large teams of top engineers.

Does not translate to something a backyard DIYer must try to reproduce


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## alexbeatle (Jul 28, 2020)

Isaac97 said:


> OEM EVs have to be able to handle large temperature ranges without problems - 0 to 120 F or so. DIYers tend to ignore things like this, maybe adding a manual battery heater if necessary.
> Tesla likes to condition their batteries a lot -- but they have a specific chemistry and charge/discharge very quickly.





john61ct said:


> Yes of course manufacturers pay many millions to large teams of top engineers.
> 
> Does not translate to something a backyard DIYer must try to reproduce


Does that mean that DC charge will not damage the battery, even if not cooled/heated during charge? Or you're saying that BMS in communication with the charge station will let know to lower current if overtemp. threshold, i.e. have it charge slower?


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## Isaac97 (Jun 3, 2019)

alexbeatle said:


> Does that mean that DC charge will not damage the battery, even if not cooled/heated during charge? Or you're saying that BMS in communication with the charge station will let know to lower current if overtemp. threshold, i.e. have it charge slower?


I don't really know, not having access to a laboratory and a year or so of full scale testing.

But my CHAdeMO system is going to have overtemperature limits at some point (translate: when I get around to adding it) and the same probably goes for any similar solution. I've got 2 temperature sensors in each battery module, so that should be plenty of monitoring. That will either cut back the charge current or shut it off altogether (probably going to have setpoints for both of those).


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## john61ct (Feb 25, 2017)

The issue has nothing to do with DC charging, as such.

I am saying that you "should" keep the amps C-rate low enough that the cells do not get significantly hot.

My preference is simplicity, both for safety and reliability.

It may be possible for you to design a fancy circuit to lower the current as a response to temperature rising

never heard of that yet being done IRL.


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## Isaac97 (Jun 3, 2019)

Usually a BMS can monitor pack temperatures. With the chargers and charger controllers that some of us DIYers use, it is trivial to add a backoff triggered by higher temperatures. Plenty safe and plenty reliable 
But I agree that heating is a symptom of other problems -- you're probably charging too fast if the cells are getting too warm.


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## remy_martian (Feb 4, 2019)

alexbeatle said:


> Does that mean that DC charge will not damage the battery, even if not cooled/heated during charge?


You seem really freaked out over "DC charge"

This will totally wad your panties up...your AC charger (Level 1 or Level 2) charges the pack with, gasp, DC.

Determine that charge limit, which you or somebody, have deemed to work for the battery pack design you have and that's the current you limit your public charging at with the protocol of that charging method. For DIY, you likely won't get Tesla-levels of charge rate unless you have serious technical skills.

You ask for 500 amps, you'll get it and watch your home project likely go off in fireworks (don't ask how I know 18650's go off like Roman Candles), possibly being the drowning swimmer that sinks the public charger as well. Ask for 50 Amps and you wont get more.

My strong suggestion for what I sense to be your skills level -- stay away from DC charging or have someone competent set it up for you.


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## alexbeatle (Jul 28, 2020)

Isaac97 said:


> Usually a BMS can monitor pack temperatures. With the chargers and charger controllers that some of us DIYers use, it is trivial to add a backoff triggered by higher temperatures. Plenty safe and plenty reliable
> But I agree that heating is a symptom of other problems -- you're probably charging too fast if the cells are getting too warm.


So what I'm getting is that the ambient temperature could be hot which causes the batteries to heat and that's why in the video provided earlier EV Bolt (maybe Tesla too) has dedicated battery cooling/heating system? 
And should the BMS be set to the appropriate charging rate specified by the battery datasheet, the fast or slow charge won't increase battery temperature significantly (unless there's a damaged cells or else)?


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## Isaac97 (Jun 3, 2019)

First - I guess so? Tesla definitely actively heats the battery before supercharging Introducing V3 Supercharging and might cool it down if temps get too high.

Second - yes. Although the BMS doesn't usually control charging, it advises the charging device, whatever that may be. With enough charging power, the batteries will definitely heat -- but that's up to the individual to worry about.


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## oudevolvo (Mar 10, 2015)

In my conversion I am implementing both active heating and active cooling for the batteries. These states are triggered / set by my BMS via either a heat or cool request (analog+over CAN). So all temperature "intelligence", setting and monitoring is done in the BMS. My own EV peripherals controller handles switching on the airconditioning compressor, battery heater, valves, pumps, etcetera. I also have a pre-heat for fastcharging feature and a stationary pre-heat mode.
Not on the road yet, so cannot say anything about actual temperatures.


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## remy_martian (Feb 4, 2019)

alexbeatle said:


> So what I'm getting is that the ambient temperature could be hot which causes the batteries to heat


No

Charging heats the battery, with heat energy increasing with the square of charge current, roughly.

Thanks for ignoring all of my posts so far.


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## oudevolvo (Mar 10, 2015)

alexbeatle said:


> So what I'm getting is that the ambient temperature could be hot which causes the batteries to heat and that's why in the video provided earlier EV Bolt (maybe Tesla too) has dedicated battery cooling/heating system?


Confirming what @*remy_martian *just wrote, the heat does not come from the "outside". However if it is hot outside there is not enough "delta T" to passively cool the batteries using a radiator and a fan given the ideal temperature range of 25 to 35 degrees. That is where active cooling comes in.



alexbeatle said:


> And should the BMS be set to the appropriate charging rate specified by the battery datasheet, the fast or slow charge won't increase battery temperature significantly (unless there's a damaged cells or else)?


Due to the internal resistance cells do heat up while charging or discharging. However, the internal resistance varies over temperature.


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## alexbeatle (Jul 28, 2020)

oudevolvo said:


> In my conversion I am implementing both active heating and active cooling for the batteries. These states are triggered / set by my BMS via either a heat or cool request (analog+over CAN). So all temperature "intelligence", setting and monitoring is done in the BMS. My own EV peripherals controller handles switching on the airconditioning compressor, battery heater, valves, pumps, etcetera. I also have a pre-heat for fastcharging feature and a stationary pre-heat mode.
> Not on the road yet, so cannot say anything about actual temperatures.


Sounds like an interesting build.anywhere I can follow it?


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## Ladogaboy (Apr 25, 2010)

Batteries (lithium in particular) like the same temperatures humans do, so your emphasis shouldn't be on AC versus DC charging. Rather, your emphasis should be on ensuring that your battery stays in that nice temperature zone given your use case. 

The reason GM (and others) use the air conditioning loop to cool the battery is because OEM EVs are expected to operate in environments where ambient temperatures exceed that nice temperature zone. DC fast charging can exacerbate that, sure, but even just driving, I've seen my Chevy Bolt EV's battery temperature exceed 100 F. When it's 100 F to 115 F outside, simply running coolant through a radiator wouldn't be enough to cool the battery satisfactorily. The heat needs to be removed through a chiller plate looped to the AC coolant system (again, so the battery can stay the same, nice 65 F to 85 F temperatures you likely enjoy). 

I will be adding active battery cooling and heating to my Ford Ranger EVs that I am restoring, and yes, that is partially because I will also be adding a DC fast charging option. However, it's also because my normal environment includes regular summertime temperatures that exceed 100 F. 

Now, I haven't decided exactly how I am going to do that yet, but for battery heating, it's going to be fairly straightforward. The Ford Ranger EV already provided heating plate options, but I'm likely going to leverage the inefficiency of the induction motor to scavenge waste heat and loop it through the battery. For cooling, the stock radiator coolant system is sufficient for the motor and controller, but it probably won't be good enough for keeping the battery temperature below 90 F (the upper limit of where I'd want it). 

One option is to create a loop that ties to the AC, but without additional programming that would really prefer to not to have to do, that would likely requirement to leave the truck on with the AC running while charging. Another option is to make a separate cooling system tied to the temperature sensors inside the battery. That could be a secondary AC unit or Peltier devices. The benefit of the latter is that they can both heat and cool (and can even generate electricity when used as a thermoelectric generator, or TEG). 

Again, though, I'm really early on in my design process, and my focus right now is on getting the trucks functional, sourcing the batteries, and ensuring that I can get the basic systems integrated. Active battery thermal management might be Stage 2 or 3, and DC fast charging might be Stage 3 or 4 in the process. Basically, it's a bridge I'll cross when I get to it.


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## john61ct (Feb 25, 2017)

alexbeatle said:


> So what I'm getting is that the ambient temperature could be hot which causes the batteries to heat


Wut?

Where did you get that? We are specifically talking about the damage / dangers *internally* caused by charging at too high an amps rate (whether from AC or DC sources) 

Of course if ambient is 40°C then it will take a lower C-rate to heat the internal cells up to hit a given temp

but then when cells are hot, the overtemp setpoint can be set higher, less damage (loss of longevity) is suffered by fast charging.

When ambient is low is when you really need to be careful about your rate of charge, hence the OEMs pre-heating then.

These issues are not reflected, or only crudely so, in cell data sheets.


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## ishiwgao (May 5, 2011)

remy_martian said:


> No
> 
> Charging heats the battery, with heat energy increasing with the square of charge current, roughly.
> 
> Thanks for ignoring all of my posts so far.



off-topic: This is my favourite post of this thread so far!


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## alexbeatle (Jul 28, 2020)

Ladogaboy said:


> Batteries (lithium in particular) like the same temperatures humans do, so your emphasis shouldn't be on AC versus DC charging. Rather, your emphasis should be on ensuring that your battery stays in that nice temperature zone given your use case.
> 
> The reason GM (and others) use the air conditioning loop to cool the battery is because OEM EVs are expected to operate in environments where ambient temperatures exceed that nice temperature zone. DC fast charging can exacerbate that, sure, but even just driving, I've seen my Chevy Bolt EV's battery temperature exceed 100 F. When it's 100 F to 115 F outside, simply running coolant through a radiator wouldn't be enough to cool the battery satisfactorily. The heat needs to be removed through a chiller plate looped to the AC coolant system (again, so the battery can stay the same, nice 65 F to 85 F temperatures you likely enjoy).
> 
> ...


Which batteries are you planning on using?
Reading that Nissan Leaf is using air-cooled batteries, even in their newer Leafs, which has a CHAdeMO fast charge. Their claim is if you distribute the energy amongst many batteries (large surface area), air cooling is sufficient.


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## Ladogaboy (Apr 25, 2010)

alexbeatle said:


> Which batteries are you planning on using?
> Reading that Nissan Leaf is using air-cooled batteries, even in their newer Leafs, which has a CHAdeMO fast charge. Their claim is if you distribute the energy amongst many batteries (large surface area), air cooling is sufficient.


I'm likely going to use either Chevy Bolt EV or Nissan LEAF modules. In either case, I will be looking to include some sort of active cooling/heating. The Ranger Electrics came stock with an air cooler for the battery, but I'm not convinced that will be effective enough. The Chevy Bolt EV comes with an aluminum chiller plate (oddly, at the bottom of the battery), so their modules are already designed to work with that. The LEAF modules, on the other hand, are designed to dissipate heat through conduction, but that should still work with a chiller plate. 

As far as I know, no LEAF has ever had active air cooling (only the e-NV200 did). People thought Nissan might have added it for their LEAF e-Plus, but it turns out they didn't. Nissan's belief was that people don't drive their cars hard enough or for long enough for it to be required and that conductive cooling through the aluminum chassis was sufficient. That turned out to be absolutely false, which is why their upcoming Ariya will come with a liquid-cooled battery.


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## brian_ (Feb 7, 2017)

alexbeatle said:


> Reading that Nissan Leaf is using air-cooled batteries, even in their newer Leafs, which has a CHAdeMO fast charge. Their claim is if you distribute the energy amongst many batteries (large surface area), air cooling is sufficient.


The Leaf pack isn't even effectively air-cooled. There have been packs with forced ventilation through the pack case for cooling, but a Leaf pack is just a sealed box without even any attempt to bond the modules to the outer case for thermal conduction, so dissipating heat to the surrounding air (and car) is slow.


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## brian_ (Feb 7, 2017)

Ladogaboy said:


> The Chevy Bolt EV comes with an aluminum chiller plate (oddly, at the bottom of the battery), so their modules are already designed to work with that. The LEAF modules, on the other hand, are designed to dissipate heat through conduction, but that should still work with a chiller plate.


The chiller plate location does not seem odd to me. Heat flow by conduction has nothing to do with gravity, so top or bottom is irrelevant. The LG Chem modules in the Bolt (and Chrysler Pacifica, etc) have aluminum plates between cells, with the long edges of the plate folded over to form a thermally conductive face on one side of the module, which is the face pressed against the thermal management plate. Since it is mechanically easiest to support the module with the thermal management plate, it is sensibly on the bottom.

I don't think the plate will work very well with a Leaf module, since the plate would be against one face of the module, and so against one side of the end cell of the stack of cells in the module. This is different from being against the edge of every cell, and is part of that difference in design to work with active cooling. Of course heat will eventually make it out of the Leaf cells to a chiller plate no matter how it is located or attached, but at a high rate of heat flow the difference of temperature between cells will be relatively large.


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## Ladogaboy (Apr 25, 2010)

brian_ said:


> The chiller plate location does not seem odd to me. Heat flow by conduction has nothing to do with gravity, so top or bottom is irrelevant. The LG Chem modules in the Bolt (and Chrysler Pacifica, etc) have aluminum plates between cells, with the long edges of the plate folded over to form a thermally conductive face on one side of the module, which is the face pressed against the thermal management plate. Since it is mechanically easiest to support the module with the thermal management plate, it is sensibly on the bottom.
> 
> I don't think the plate will work very well with a Leaf module, since the plate would be against one face of the module, and so against one side of the end cell of the stack of cells in the module. This is different from being against the edge of every cell, and is part of that difference in design to work with active cooling. Of course heat will eventually make it out of the Leaf cells to a chiller plate no matter how it is located or attached, but at a high rate of heat flow the difference of temperature between cells will be relatively large.


Those are fair points. I suppose the additional heat transfer through convection within the Bolt EV pack isn't significant enough to matter. For the LEAF modules, the dissipation would be worse with a chiller plate, it's true, but the cladding of the modules themselves should be able to transfer a decent amount of heat to the chiller plate.


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## alexbeatle (Jul 28, 2020)

Ladogaboy said:


> I'm likely going to use either Chevy Bolt EV or Nissan LEAF modules. In either case, I will be looking to include some sort of active cooling/heating. The Ranger Electrics came stock with an air cooler for the battery, but I'm not convinced that will be effective enough. The Chevy Bolt EV comes with an aluminum chiller plate (oddly, at the bottom of the battery), so their modules are already designed to work with that. The LEAF modules, on the other hand, are designed to dissipate heat through conduction, but that should still work with a chiller plate.
> 
> As far as I know, no LEAF has ever had active air cooling (only the e-NV200 did). People thought Nissan might have added it for their LEAF e-Plus, but it turns out they didn't. Nissan's belief was that people don't drive their cars hard enough or for long enough for it to be required and that conductive cooling through the aluminum chassis was sufficient. That turned out to be absolutely false, which is why their upcoming Ariya will come with a liquid-cooled battery.


Curious, are Tesla battery packs too expensive, which is why you opted-out of them? They seem to have nice cooling setup, with the coolant going through each modules. Model S blocks and SmartForTwo are very versatile and popular ones.


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## Ladogaboy (Apr 25, 2010)

alexbeatle said:


> Curious, are Tesla battery packs too expensive, which is why you opted-out of them? They seem to have nice cooling setup, with the coolant going through each modules. Model S blocks and SmartForTwo are very versatile and popular ones.


I consider Tesla batteries to be hobbyist packs compared to other second-life EV packs. In my opinion, cylindrical cells are a waste of materials with added weight and complexity when used for automotive purposes. The NCA chemistry is also more volatile, degrades faster, and overall, I've just been less impressed by its performance. The price is just the icing on the cake (I think people might be overvaluing the packs on the secondary market because of their association with Tesla). My order of preference would be:

Second-life prismatic our pouch cells (BMW i3, Chevy Bolt EV/Volt, and Nissan LEAF are the most available in my region)
LiFePO4 prismatic cells (can be bought new, but are still expensive with only a few versions acceptable for automotive use, in my opinion)
Cylindrical-cell packs (available, but expensive without justification)
Also, for my specific build, I'm very limited in the voltages I can run. Someone already did the work to modify the Ranger Electric's systems to talk to Tesla Model S packs, which they were able to fit into the battery case, but I'm choosing to go a different direction.


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## alexbeatle (Jul 28, 2020)

Ladogaboy said:


> I consider Tesla batteries to be hobbyist packs compared to other second-life EV packs. In my opinion, cylindrical cells are a waste of materials with added weight and complexity when used for automotive purposes. The NCA chemistry is also more volatile, degrades faster, and overall, I've just been less impressed by its performance. The price is just the icing on the cake (I think people might be overvaluing the packs on the secondary market because of their association with Tesla). My order of preference would be:
> 
> Second-life prismatic our pouch cells (BMW i3, Chevy Bolt EV/Volt, and Nissan LEAF are the most available in my region)
> LiFePO4 prismatic cells (can be bought new, but are still expensive with only a few versions acceptable for automotive use, in my opinion)
> ...


I would've though the size of the Tesla batteries vs. capacity is better than that of others, plus the aforementioned liquid cooling through each module. Hard to imagine others have other modules with (other than EV bolt) with 60kwh pack.


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## Ladogaboy (Apr 25, 2010)

alexbeatle said:


> I would've though the size of the Tesla batteries vs. capacity is better than that of others, plus the aforementioned liquid cooling through each module. Hard to imagine others have other modules with (other than EV bolt) with 60kwh pack.


Intertwining a cooling ribbon is Tesla's approach, but consider that Rivian, which is also using cylindrical cells for their packs, are using chiller plates instead. The BMW i3 probably has the best, most effective battery thermal management of any production EV, but I'm not sure how well it would translate to a DIY project. The Chevrolet Volt batteries also have highly effective thermal management systems with cooling plates sandwiched between each pair of cells. 

Tesla battery energy density is very good at a pack level, but it's not necessarily industry leading at the cell or module level. I haven't broken down all of the various EV battery modules by energy density, but if you're interested, I suggest checking out Pedro Lima's articles on PushEVs. He does a really good job of objectively analyzing the current battery offerings of various EV automakers without playing favorites (unlike many other EV publications). 

For me, complexity, cost, and energy density are the primary concerns, which is why I'm leaning toward Chevy Bolt EV or Nissan LEAF modules.


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## brian_ (Feb 7, 2017)

alexbeatle said:


> Hard to imagine others have other modules with (other than EV bolt) with 60kwh pack.


The various recently-introduced high-priced EVs have packs larger than 60 kWh, but they're not practical as salvage packs because they're too new and uncommon. The Leaf Plus now has a 62 kWh pack, but again is very new (and many new Leafs will still have the 40 kWh pack). The various Tesla Model S/X variants and the Chevrolet Bolt do seem like the practical sources of modules to build a 60+ kWh pack without paralleling modules, but the other side of the same issue is that you need to use the entire pack worth of modules to reach the typical 360 V nominal operating voltage, if that's what you're aiming for.


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## Ladogaboy (Apr 25, 2010)

brian_ said:


> The various recently-introduced high-priced EVs have packs larger than 60 kWh, but they're not practical as salvage packs because they're too new and uncommon. The Leaf Plus now has a 62 kWh pack, but again is very new (and many new Leafs will still have the 40 kWh pack). The various Tesla Model S/X variants and the Chevrolet Bolt do seem like the practical sources of modules to build a 60+ kWh pack without paralleling modules, but the other side of the same issue is that you need to use the entire pack worth of modules to reach the typical 360 V nominal operating voltage, if that's what you're aiming for.


That's another reason to consider BMW i3 modules, which will string together for ~350 V packs while still only requiring 20 to 30 kWh of total energy.


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## alexbeatle (Jul 28, 2020)

Ladogaboy said:


> That's another reason to consider BMW i3 modules, which will string together for ~350 V packs while still only requiring 20 to 30 kWh of total energy.


Tesla SmartForTwo Class B is actually 54Vdc 3kwh per unit.


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## Ladogaboy (Apr 25, 2010)

alexbeatle said:


> Tesla SmartForTwo Class B is actually 54Vdc 3kwh per unit.


Yeah, so that would be close to that 20 kWh for a ~350 V nominal pack, as opposed to the Bolt EV modules, which would result in a _minimum_ 60 kWh size for a ~350 V nominal pack.


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## alexbeatle (Jul 28, 2020)

Collecting all thoughts, and outside research, I should follow the below practices for Li-Ion, for any type of charging and use active cooling\heating (not simply running coolant through the batteries). This complicates things a little, as I'd need to add some kind of compressor for the cool down (important in Cali weather). For pre-heating, as it's been mentioned somewhere above, a simple heater could do.
"The charging should generally take place at room temperature only (approx. 18°C - 21°C). Avoid charging a cold battery as this damages the cells. Especially in case of cold outside temperatures in the winter, always allow the battery to first warm up to room temperature in order to then charge it under optimum conditions."
"Also high temperatures damage the battery. Never leave the battery or your device case in the car exposed to the sun on hot sunny days. At temperatures above +60°C the Li-ion battery loses capacity constantly and thus performance capability."

Looking at batteries, I am still attracted to Tesla Model S packs, though EV Bolts are looking good too. BMW i3's seem a little too low on kWh - the entire pack is only 22kWh on eBay, but maybe that's just what's available in my area.

Please correct me if I'm wrong.


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## Ladogaboy (Apr 25, 2010)

alexbeatle said:


> Collecting all thoughts, and outside research, I should follow the below practices for Li-Ion, for any type of charging and use active cooling\heating (not simply running coolant through the batteries). This complicates things a little, as I'd need to add some kind of compressor for the cool down (important in Cali weather). For pre-heating, as it's been mentioned somewhere above, a simple heater could do.
> "The charging should generally take place at room temperature only (approx. 18°C - 21°C). Avoid charging a cold battery as this damages the cells. Especially in case of cold outside temperatures in the winter, always allow the battery to first warm up to room temperature in order to then charge it under optimum conditions."
> "Also high temperatures damage the battery. Never leave the battery or your device case in the car exposed to the sun on hot sunny days. At temperatures above +60°C the Li-ion battery loses capacity constantly and thus performance capability."
> 
> ...


I would say the thread somewhat spiraled out of scope. You were asking specifically about thermal management options, but it seems like you are still unclear about which batteries you intend to use. Selecting the best batteries for your use case should come first. Then you can assess the need and best options for thermal management after. If you have already decided on Tesla Model S modules, you should look into specifically what thermal management options work best for your use case and pack.


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## remy_martian (Feb 4, 2019)

"Also high temperatures damage the battery. Never leave the battery or your device case in the car exposed to the sun on hot sunny days. At temperatures above +60°C the Li-ion battery loses capacity constantly and thus performance capability."

Taken from your iPhone user manual?

You have zero listening skills. Many experienced people provided input to you here, and you're still pontificating about "research" nonsense, including something you lifted from a consumer electronics user guide.

Your first step in all this is missing. How are you planning to use the vehicle? That defines what complexity of charging you need. MOST people are happy charging overnight (which I do with my Bolt EV -- it's only been on a fast charger twice on a trip I could have used my ICE truck), many in a temperature moderated garage. For that, you don't really need any pack heating/cooling at all. You also are not responsible for an 8 or 10 year battery warranty, so the motivation to eke out 2000 charge cycles vs 1500 is questionable.

I get the sense you're a 12 year old who wants to build an EV - great if you are, but stuffing it full of nuts and bolts you don't need (or understand) is both expensive and a recipe for failure.

K.I.S.S. (Keep It Stupidly Simple)


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## alexbeatle (Jul 28, 2020)

remy_martian said:


> "Also high temperatures damage the battery. Never leave the battery or your device case in the car exposed to the sun on hot sunny days. At temperatures above +60°C the Li-ion battery loses capacity constantly and thus performance capability."
> 
> Taken from your iPhone user manual?
> 
> ...


You are correct.


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## alexbeatle (Jul 28, 2020)

Ladogaboy said:


> I would say the thread somewhat spiraled out of scope. You were asking specifically about thermal management options, but it seems like you are still unclear about which batteries you intend to use. Selecting the best batteries for your use case should come first. Then you can assess the need and best options for thermal management after. If you have already decided on Tesla Model S modules, you should look into specifically what thermal management options work best for your use case and pack.


Starting the topic, I was under the impression that there's a universal cooling method for batteries from different suppliers (except Leaf, as it's aired), but as this thread progressed learnt there're different approaches. This lead me to start weighing different options to decide on the approach, e.g. if I go with Tesla - do this, if I go with EV Bolt - do that. That's why the thread sidetracked a bit.


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## remy_martian (Feb 4, 2019)

alexbeatle said:


> Starting the topic, I was under the impression that there's a universal cooling method for batteries from different suppliers (except Leaf, as it's aired), but as this thread progressed learnt there're different approaches. This lead me to start weighing different options to decide on the approach, e.g. if I go with Tesla - do this, if I go with EV Bolt - do that. That's why the thread sidetracked a bit.


No

AGAIN, you need to decide HOW you are using the battery _first_.

A Tesla module can be perfectly happy with its cooling system disconnected.


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## brian_ (Feb 7, 2017)

alexbeatle said:


> BMW i3's seem a little too low on kWh - the entire pack is only 22kWh on eBay, but maybe that's just what's available in my area.


It's easy to find what has been available in the BMW i3, but BMW has confused the situation by describing the capacity in amp-hours, rather than in energy capacity.

This is the battery spec summary from the Wikipedia page for the i3:

*i3 60 Ah*: 22 (18.8 usable) kWh lithium-ion battery
*i3 94 Ah*: 33 (27.2 usable) kWh lithium-ion battery
*i3 120 Ah* 42.2 kWh lithium-ion battery
You are finding only the smallest battery pack, which was the only size prior to 2017 and so the only one likely to be readily available as salvage.


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