Mild Cold weather DC charging

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EVMan

Well-known member
Joined
Feb 25, 2017
Messages
340
Location
USA, DC
Curious Question , about battery temperature , when DC charging in winters .

In mild winters 10 - 20 C ( California weather ) ,the i3 takes longer to charge than in summers.
The energy consumption ( KWH) also decrease by the car as per the charger in 30 mins

Is it
A) Battery is cold, and the energy is being used by heaters to heat up the battery ?
Unlikely - as total energy consumption is less in 30 mins along with charge percentage , compared to summers .

B)
Battery is cold, and even charging does not increase the battery temperature enough to bring it to optimum temperature .
The heater in the car is not being used , and is probably used only in extremely cold conditions
It be be also a case , where the heater is slow and needs longer to heat up the battery, and so not useful in DC charging

This also means the battery generate little/insignificant heat with DC charge.
 
The onboard heaters are only 1Kw, so in 30-minutes, you'd only use 500W, and not warm the batteries all that much. Batteries can't be charged at full rate when they are either cold or hot...there's a sweet spot. Sounds like 30-minutes on a CCS unit is not enough to get them into optimum range, regardless of what the internal heaters are doing. But, since you were driving to get to the CCS unit, I'd expect the batteries to be closer to the optimum. Interesting observation.
 
Yea,
It looks like the temperature change just by DC charging is not significant.
In mild winters , its not even able to bring battery temperature to optimum warmth by fast DC charging.

On the other , on a longer distance trip , if u drive and charge , the batteries do get overheated in summers. Charging speed is reduced , as i have experienced more than once , on a hot summer day.

The sweet spot is rather narrow .

I really don't understand how come VW , and Nissan sell DC capable cars without active cooling ?
In case of VW, i think , they did not have the space to put the larger cooled batteries , like they did in the ford , or the T in the volt
Nissan did not do active cool , even in the second generation.

I guess it may be more acceptable in a NON- DC quick charge car.
 
From what I've heard, the earliest Leafs had some significant problems in places like Phoenix because of the heat damaging batteries when charging. The Germans tend to be very good, sometimes fanatic, when it comes to engineering solutions. That's one reason why I don't have any problems with charging my i3 up and don't worry about battery life. I may regret it long-term, but I doubt it. They worked on the i3 for years collecting info on how people drove their EVs and what was going on before they finalized the design. Not saying others haven't, but then, at the price point, the i3 should be better with fewer compromises. Active cooling/heating costs money, and adds weight...you have to decide what's most important to you. Time will tell...
 
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