Charging rate questions

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bonro001

Member
Joined
Feb 20, 2017
Messages
17
Hello all, have been thinking about charging quite a bit, and heat since I live in Texas. I commute with my leaf about 20 miles a day (early morning, afternoon)

I have the charge point charger, 15 amps I believe, installed and also the 110 volt charger. Have never needed a charging station away from the home.

To the question. Since I get home around 5 in the afternoon, I have 13 hours before I usually need the car again. Which would be better on my batteries:

1. Set the charging timer to be ready at 6 AM with the 15 amp charger. This lets the batteries get nice and cool and charges overnight, starting around midnight, to the cool part of the night.
2. Use the 110 volt charger and start charging when I get home. I suspect that this would have the car charged in the 12 hours overnight. Would charge when the car is hot, but at a way slower rate.

Boy I wish there were a 'charge after it's cool' timer!

Thanks in advance for any thoughts on this!

Rob
 
Yes, letting the battery pack cool is best. And the only "charger" involved is the one built into the car. You have a "charging cable" and a "charging station." Both are what is known as an "EVSE." That's a device that supplies the onboard charger with house current - either 120 or 208 to 240 volts.
 
On the option 1 comment, is there a reason that the 15 amp version would be better on the batteries?
 
bonro001 said:
On the option 1 comment, is there a reason that the 15 amp version would be better on the batteries?

Think of it like this, heat degrades the battery, high state of charge degrades the battery, put the two together and it isn't additive it is exponentially worse.

So the batteries have had a chance to cool until midnight, and charging is completely during the coolest time. In addition, bringing up the batteries at 15 amps has the added effect of leaving the batteries at a lower state of charge for a longer period of time.

As a final benefit, charging at L2 is more efficient than at L1 (110V ) due to the overhead losses inherent in charging.
 
Perhaps Texas is different from Colorado -- the coolest 3 hours of our day is early morning around 3am - 6am or 4am - 7am, depending on the season. If you really want to play this game, the car should be outside to be well ventilated underneath, and charging during the windy hours of the night would be an added bonus if the ambient temperature has already cooled down.
 
SageBrush said:
Perhaps Texas is different from Colorado -- the coolest 3 hours of our day is early morning around 3am - 6am or 4am - 7am, depending on the season.

Right. That makes sense. In most place and on most days, air temperatures near the surface (eg 6') reach a minimum just after sunrise.
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter3/daily_trend5.html

This based on a radiation balance. Obviously if there is strong horizontal advection of warm or cold air, minimum temperature can occur at a different time of day. Many people are surprised that air temperature is most often coolest that late in the 'early' morning.
 
I would simply plug in the car right when I got up in the morning. This should easily cover you for several days. Eventually you might want to plug in over night or something to boost your SOC.

But I do get up with enough time to relax up to an hour before getting ready for work. Everyone who knows me thinks I am crazy especially when considering I have work start times as early as 4 AM with 6 AM being the most common. But that is me.

I generally drive a lot but there has been slow periods at work or simply jobs close to home and that is what I do. You might want to check on the speed of that Chargepoint but for a 20 mile commute, I only need to plug in an hour a day to cover that.
 
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