# Battery Box Air Circulation



## poprock (Apr 29, 2010)

Hi, Research the regulating authority in your country for requirements. Talk to approved consulting engineers. If the box is inside the passenger compartment then it will need forced ventilation to the outside of vehicle outline, not just underneath. RMS NSW. .gov.au have a good set of regulations which will give you an idea, but you will still be bound by your local laws.


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## polodiy (Oct 25, 2015)

poprock said:


> Hi, Research the regulating authority in your country for requirements. Talk to approved consulting engineers. If the box is inside the passenger compartment then it will need forced ventilation to the outside of vehicle outline, not just underneath. RMS NSW. .gov.au have a good set of regulations which will give you an idea, but you will still be bound by your local laws.


poprock, thank you for your reply.
There is no regulations for this, it's not a car - it's 'golf cart' type of thing.
I am asking in terms of safety. Do this batteries become hot under usage? And is it required/recommended to have some kind of ventilation? 
Or could i just place them in closed box and don't worry about it?

Thanks


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## Sunking (Aug 10, 2009)

You are putting your batteries in a steel box? That violates about every safety code you can think of.


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## major (Apr 4, 2008)

Sunking said:


> You are putting your batteries in a steel box? That violates about every safety code you can think of.


I think all the OEMs use steel battery enclosures. I know mine does.


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## Sunking (Aug 10, 2009)

major said:


> I think all the OEMs use steel battery enclosures. I know mine does.


Is it lined with non conductive material?


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## major (Apr 4, 2008)

Sunking said:


> Is it lined with non conductive material?


No, just painted steel.


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## polodiy (Oct 25, 2015)

Sunking said:


> You are putting your batteries in a steel box? That violates about every safety code you can think of.


Good point, i will have rubber layer on the top side of batteries to prevent possible shorts.

I am asking more in terms of temperature/air ventilation recommendations.


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## poprock (Apr 29, 2010)

polodiy said:


> Good point, i will have rubber layer on the top side of batteries to prevent possible shorts.
> 
> I am asking more in terms of temperature/air ventilation recommendations.


Regardless of battery chemistry heat will be produced. A vented box is a must . Perhaps a couple of el cheapo PC type cooling fans to draw in outside air and expel heat would give an even operating temperature.


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## major (Apr 4, 2008)

Ventilation requirements are determined by the application. My OEM EV has a completely enclosed (in steel) battery with no vents or coolant. The system is not capable of more than 2C discharge or C/8 charge.  It does monitor temperature on all cells. 30,000 miles and counting.


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## winzeracer (Apr 3, 2012)

poprock said:


> Regardless of battery chemistry heat will be produced. A vented box is a must . Perhaps a couple of el cheapo PC type cooling fans to draw in outside air and expel heat would give an even operating temperature.


I would say it is a "must" to have a pressure relief of some type in case of an electrical event.

As for a vent, this depends on many factors, what is your average and max C rate? Do your chosen batteries make much heat at these rates? What is the average and max ambient temp where you will operate the vehicle? How well do you need the box to be sealed? Are you worried about water intrusion for your application?

I suggest testing your cells at the C rates you will be using them at to find out how quickly they rise in temperature.

Generally speaking CALBs are fairly stable and if used below specs do not make enough heat to worry too much about. However I still like to test my own cells and draw conclusions based on evidence.



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## 67BGTEV (Nov 1, 2013)

major said:


> Ventilation requirements are determined by the application. My OEM EV has a completely enclosed (in steel) battery with no vents or coolant. The system is not capable of more than 2C discharge or C/8 charge. It does monitor temperature on all cells. 30,000 miles and counting.


Major, if you are taking about Leaf, it doesn't monitor individual cells but only 3 cells. Yes, these are enclosed in waterproof, painted steel enclosure. 

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## 67BGTEV (Nov 1, 2013)

As suggested by others, a active fan cooling should be good for the batteries. If you place the box under the body/shade is desirable. 

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## dougingraham (Jul 26, 2011)

polodiy said:


> Guys i am building aluminium battery box for 8 100ah calbs cells.
> The box will contain cells with installed MiniBMS cell modules.
> 
> I need to make it close type box so i can close it on lock.
> ...


My best guess is that you do not need any cooling. If you approach the 300 amps continuous for 20 minutes discharge rate you would need to provide some cooling before you put it back on the charger. If you are using this like a golf cart and the currents are 100 amps for a few minutes and then a few minutes of resting you are not going to heat the cells much at all.


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## major (Apr 4, 2008)

67BGTEV said:


> Major, if you are taking about Leaf, it doesn't monitor individual cells but only 3 cells. Yes, these are enclosed in waterproof, painted steel enclosure.


Not a Leaf, but a 2011 Think City with an EnerDel battery, 384 cells using 192 thermistors, one on each buddy pair. All cells are monitored for temperature.


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## 67BGTEV (Nov 1, 2013)

Thanks, Good to know. 

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## polodiy (Oct 25, 2015)

dougingraham said:


> If you are using this like a golf cart and the currents are 100 amps for a few minutes and then a few minutes of resting you are not going to heat the cells much at all.


dougingraham, you are totally right with the range.
Tested with clamp meter and it shows 100amp continuous.
So will monitor temp for couple of days just in case.


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## polodiy (Oct 25, 2015)

Guys what non-conductive material I can use to put/cover insides of the box?

I was thinking smng like this.


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