# LiFePo4 battery box placement within the car



## frk2 (Jan 2, 2009)

In my new EV i'm trying to make sure the lithiums are AS 'out-of-sight' as possible. However the car is a Daihatsu Charade and I dont have much room in the engine bay to house all of them. 

What I have done is made a custom compartment under the rear seat (having removed the fuel tank) which would house roughly 24 Cells. However this compartment is pretty sealed and will have a rubber cover on the top (after which we will put the rear seat on top of it).

my question is that its going to be mostly air-tight in there. Do these lithiums need venting? And do they also require cooling? Should I open vent-holes on either side to make sure nothing bad happens?

Thanks. Input is appreciated.


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## dtbaker (Jan 5, 2008)

frk2 said:


> ...custom compartment under the rear seat ...this compartment is pretty sealed and will have a rubber cover on the top ...Do these lithiums need venting? And do they also require cooling? Should I open vent-holes on either side to make sure nothing bad happens?



LI cells do not vent during charge or normal operation... no gassing like floodies. They do like to be warm, but not HOT. They may get warm under heavy draw and need venting, but from what I have read, most urban/suburban driving won't require any forced cooling.

I plan on enclosing mine pretty tight, and coming back to add vents only if I need to. It seems much better to plan on an insulated heated compartment for the winter than worry about overheating in summer....


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## PTCruisin (Nov 19, 2009)

What Dan said.

Given the arid climate of Karachi, I'd say you might need to watch the temperature of the batteries in the summer and maybe add ventilation if they get too warm. Although I really don't know heat affects the chemistry/performance of the cells in a string.


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## newbcake (Aug 5, 2010)

How hot are we talking about here? LFP cells actually perform better in the heat, up until it gets too hot and the performance starts decreasing again.


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## dexion (Aug 22, 2009)

I have a removable slat in the front and back of my battery compartment (where the fuel tank was) in the summer i remove them in the winter i put them back in. Ambient around detroit is abut 85F in the summer and 20F in the winter. I really cant say it wouldnt have been bad keeping them in all year round since I only take about .7C to drive with 1.8C to accelerate at the worst point. They dont seem to care and stay around ambient in the summer.


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## chinaev (Jul 29, 2010)

frk2 said:


> In my new EV i'm trying to make sure the lithiums are AS 'out-of-sight' as possible. However the car is a Daihatsu Charade and I dont have much room in the engine bay to house all of them.
> 
> What I have done is made a custom compartment under the rear seat (having removed the fuel tank) which would house roughly 24 Cells. However this compartment is pretty sealed and will have a rubber cover on the top (after which we will put the rear seat on top of it).
> 
> ...


do you have a BMS(Battery Management System)with your lifepo4 battery?you could find out what is happened from the Smartscreen.


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## tomofreno (Mar 3, 2009)

> I really cant say it wouldnt have been bad keeping them in all year round since I only take about .7C to drive with 1.8C to accelerate at the worst point. They dont seem to care and stay around ambient in the summer.


 My experience is they would handle this easily. My 180Ah CALB cells are in steel boxes with 0.5" insulation and plywood tops with carpet over them. In 98 F outside temperatures they heat up only a few degrees above ambient, reaching 100 to 102 F with no ventilation for typical highway/secondary road driving drawing less than 3/4C on average. If you are going to push them at higher currents for extended periods, I think they may well require cooling in hot weather.


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