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Discussion Starter · #1 ·
In order to maximize the use of the free charging my work offers I would like to be able to have some control over the charging at home and can't quite get my head around it.

I have a 240 Level 2 at home.

I charge to full at work and typically get home with around 15-20 miles and 4 bars of battery left.

I leave home at 6am.

I would like to do the math to figure out what delayed start time to use in order to add about 15 miles of charge.

I am thinking that it charges about 10 miles per hour.

So to charge the fill 30-35 would take 3.5 hours, to charge the 15 I want would take 1.5 ? (this is a question :)

So I want to start charging at 4:30 to get the 15 miles and add another 2 to the theoretical full.

So I think I want to set "Ready by 8am"

Does this make sense? Am I overlooking something?
 

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Seems like an inordinate amount of effort to save very little. How much does one or two kWh cost?

But if you're committed you are on exactly the right track. Figure ten miles per hour for charging and set your departure time for 7:30 or 8:00 AM. If you stop charging at 6:00 AM when you leave this will leave you short of a full charge by 15 or 20 miles. You'll have to experiment with the times. Typically the car underestimates the time needed to charge so it finishes slightly earlier than the time set, so you might want to start with 7:30 AM and see what happens.
 

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Discussion Starter · #4 ·
So you own a vehicle that is worth 35,000 dollars, but your worrying about 30 cents in electrical costs, that you want your employer to cover? ... Yah, your overlooking something.
Great input, thanks :cool: You took more time answering this than the thought I have put into it. Employer provides free charging as a benefit why not use it? Perhaps you should give up a little pay if it's not important to you. 30c per day over 3 years is around $120 - if you just want to send me a check for that amount then I won't bother.



Seems like an inordinate amount of effort to save very little. How much does one or two kWh cost?
.
How is it an inordinate amount of effort? I spent around 5 minutes thinking about it, and 1 minute writing this post. Then another 30 seconds to set the timer on the car? Plus it's a challenge I kind of enjoyed trying to figure out.
 

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Your goal is to roll in to work in the morning with almost no charge left on the battery!

You will need to adjust your estimate in winter since you will drain more and need to keep a larger buffer.

Of course be aware that your strategy leaves no room for side trips and detours. Charging at home is still cheaper than dipping in to gas.


My work charges 10 bux a month for charging. It's actually cheaper for me to charge at home.
 

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30c per day over 3 years is around $120
So, you work 133 days a year. That's awesome!

And yes, I agree with others here. This effort is a trivial pursuit. Just drive the dang car!

Of course, if I had 232 days off a year, I'd probably do trivial stuff as well.
 

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I'm jealous. I have to work 177 days per year.
 

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I'm jealous. I have to work 177 days per year.
This year, I will have driven to work 111 days and work from home 98. 209 or so total this year. Some of those are on-call and weekends though, so, it's not all that lovely. Good thing is that on-call and weekends are in the work-from-home category.

I could use a work charger so that my miles would be 100% electric. If I drove a Bolt instead of an ELR...

However, I wouldn't spend brain power trying to maximize a few kWh.
 

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In order to maximize the use of the free charging my work offers I would like to be able to have some control over the charging at home and can't quite get my head around it.

I have a 240 Level 2 at home.

I charge to full at work and typically get home with around 15-20 miles and 4 bars of battery left.

I leave home at 6am.

I would like to do the math to figure out what delayed start time to use in order to add about 15 miles of charge.

I am thinking that it charges about 10 miles per hour.

So to charge the fill 30-35 would take 3.5 hours, to charge the 15 I want would take 1.5 ? (this is a question :)

So I want to start charging at 4:30 to get the 15 miles and add another 2 to the theoretical full.

So I think I want to set "Ready by 8am"

Does this make sense? Am I overlooking something?
I think there are too many 'abouts' and guesses involved for you to get as precise an answer as you want. Just plug in for a couple of hours and go with that.
 

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How is it an inordinate amount of effort? I spent around 5 minutes thinking about it, and 1 minute writing this post. Then another 30 seconds to set the timer on the car? Plus it's a challenge I kind of enjoyed trying to figure out.
Because life is unpredictable and you'll have to made ad hoc adjustments. For example, one day you might need to make a stop or go to a medical appointment before work. If you need more range then you'll have to figure out how to change the charging schedule on that day. So it just doesn't seem paying for a few more kWh is worth the effort.

In any event, I confirmed how to set the timers if you want to do it this way.
 

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I totally get it. We have free workplace charging as well. Between my morning charge and my post-lunchtime errands charging, I'm using 18 KW of charge a day according to the charger readout. I'll use even more as it gets colder. I'm getting a value of ~$400 / year of free charging. It has become a game to minimize charging at home. I use delayed charging as a safety to make sure I have enough charge to make it back to work on days when I run errands or take a detour on the way home. Getting it "right" has been trial and error and requires tuning as the weather changes. The catch is remembering to double-pump after lunch to ensure I charge before leaving. I look at it as a variation of hypermiling, and a fun low-cost game. There is a fellow Volt owner who is doing the same thing, but for some reason the Leaf owner only plugs in once every couple of weeks.
 

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I play the same game but have too much variation on the SOC each day due to errands and weather. Getting an approximate time is good enough and much less stress.

Also, I find my delayed start finishes about 30 minutes before the set time which should not play into your calculation but could be a factor for others.
 

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Great input, thanks :cool: You took more time answering this than the thought I have put into it. Employer provides free charging as a benefit why not use it? Perhaps you should give up a little pay if it's not important to you. 30c per day over 3 years is around $120 - if you just want to send me a check for that amount then I won't bother.





How is it an inordinate amount of effort? I spent around 5 minutes thinking about it, and 1 minute writing this post. Then another 30 seconds to set the timer on the car? Plus it's a challenge I kind of enjoyed trying to figure out.
Maybe you should also consider to save that 30 cents or whatever you're shaving the margin of charge you have for unanticipated detours, temperature variation of range performance, emergencies... If you miscalculate you end up burning gas. For some that's a bigger deal. Playing this sort a game is mostly harmless though, so whatever works for you.
 

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I agree with those who suggest leaving yourself a margin. I drive 3 miles to work, down a significant hill (that can add anywhere from 4-9 miles to range), and I can tell you that weather and traffic create wide fluctuations in how much range is left when I get home.

I've had the car over 3 years and share the view that even if you get to work with 5-10 miles range left, it's better than missing even once or twice and having the gas engine kick on.
 

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I believe when someone asks a straightforward question, either answer it or don't answer it. Editorializing and questioning someone's motivations seems petty. Everyone has their own motivation for what they do; shouldn't have to be put down for asking a question.
 

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I believe when someone asks a straightforward question, either answer it or don't answer it. Editorializing and questioning someone's motivations seems petty. Everyone has their own motivation for what they do; shouldn't have to be put down for asking a question.
So what's the straightforward answer?

IMHO the straightforward answer is there are a number of variables that make it impractical to 100% predict getting to work with nearly zero charge. Who is likely to just do that math for the OP? You can't entirely predict traffic, and weather conditions.

Worrying about a couple of KWhr. extra charge at home doesn't seem reasonable. If I'm already getting free charging at work how much effort is it worth to scrounge another $120/year out of my employer?
 

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Maybe you can push on the parameter - how can I slow the charging down overnight to get me there and to some value that will increase my battery cycles life by......how much.....
LiIon @ batteryuniversity, etc
:)
 
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