Charging timer: start time based on END time?

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Jimmydreams

Jimmydreams

Well-known member
Joined
Apr 23, 2010
Messages
1,500
Location
Oceanside, Ca.
I was told this is possible by someone in the EVP, but don't want to try it out when I need to car for work.

I was told that you can tell the car that you want 80 or 100% charge accomplished by a certain time and the car would use that end time as the designator for when to START charging. IOW, tell the car "be at 100% by 5:30am" and the car will figure out exactly when to start charging to make that happen. This maximizes the super-off peak times for overnight charging.

I'm GUESSING that is you use the charge timer and set an END time but not a start time that it might work this way....

I'll try it this weekend, but anyone braver than myself want to try it before then and report back what happens???
 
Jimmydreams said:
I was told that you can tell the car that you want 80 or 100% charge accomplished by a certain time and the car would use that end time as the designator for when to START charging.
Click to expand...

I think Brian (at PN) told us the same thing. The only hitch would be whether the car's estimate of time to charge is accurate - it seems that it overestimates that time, and you wouldn't want that skew to trick the car into starting before super-off-peak if it didn't really need to. So if you're going to do this persistently, it might be better to stick with explicit start and stop bounding super-off-peak and making manual adjustments if/when you have knowledge that it's not going to get to where you need it on a given day...?

We're not on TOU so I can play around with it when I get a chance. Of course I haven't even managed to take any pictures of the car yet, so I'm not sure when that will be.
 
And I hope it takes into account any pre-heat/pre-cool you want in addition. If you activate that remotely after charging has already started then the car won't reach the goal ... just keep that in mind.
 
Jimmydreams said:
I was told this is possible by someone in the EVP, but don't want to try it out when I need to car for work.

I was told that you can tell the car that you want 80 or 100% charge accomplished by a certain time and the car would use that end time as the designator for when to START charging. IOW, tell the car "be at 100% by 5:30am" and the car will figure out exactly when to start charging to make that happen. This maximizes the super-off peak times for overnight charging.

I'm GUESSING that is you use the charge timer and set an END time but not a start time that it might work this way....

I'll try it this weekend, but anyone braver than myself want to try it before then and report back what happens???
Click to expand...
JimmyD,

I tried it SUN night (MON morning) with my Fluke 289 DVM with i410 amp clamp when my leaf was already charged to 80% SOC and got some a very funny recordings. I set it to end at 0500, 100%, with no start time. It did "fill it up" to 100% but it was weird. It did not do what I would have done. The car indicated it needed 2.5 hrs of charge so naturally I thought (I don't know why I thought this) that it would wait 'till the last possible time to start in order to finish at 100% at 0500 hrs; my preset end time. I was thinking since the time 'till charge reported by the LEAF is in 30 minute increments it might add half an hour for good measure and say it would take 3 hrs to "fill 'er up." Nope. It started at 0030, stayed at 15a for about 75 min, did some strange dance for the next 21 minutes, stopped, sent me a 12 of 12 bars charged email and 54 minutes later it came up to 13a momentarily and did that same strange dance down to turn off 5 minutes later at 0306 hrs and sent me another 12 of 12 bars charged email and stopped. Weird but obviously Nissan has something up their sleeve.

Here is the pdf of the view.

http://dl.dropbox.com/u/15670224/leafme_End_Charge_Recording_2011_0110.pdf

I'll give it another try at some point to confirm my observation. Last night I went back to the "start at 0000 hrs" with 24 non-eco miles showing on the display and set the end time to 0700 knowing it would fill before then. I got the full email at 0449 hrs.

Malcolm :geek:
 
VERY interesting, Malcolm!! Let me know if you try it again. I'll try the same thing for Friday morning (my day off) and see what happens.
 
Years ago I was told that an analogy for a smart charging system is like pouring a can of Coke into a glass. You pour and it foams up. It settles down and you pour some more. You continue to do this with less and less pour until the glass is full. This analogy is only conceptual it's not at all what's really going on chemically inside the battery pack.
 
ENIAC said:
Years ago I was told that an analogy for a smart charging system is like pouring a can of Coke into a glass. You pour and it foams up. It settles down and you pour some more. You continue to do this with less and less pour until the glass is full. This analogy is only conceptual it's not at all what's really going on chemically inside the battery pack.
Click to expand...

Are you saying the Leaf runs on coke? Holy %&#$!!! :lol:

If the battery pack gets babied or takes a deeper charge (somehow) by stopping and starting, great. So long as it's at 100% by the time I get in and go. :mrgreen:
 
Looks like it's charging to full then tapering down and stopping, and then at the last minute topping off to be sure it's fully charged and to make up for any loss from setting.
 
leafme said:
<snip>
I tried it SUN night (MON morning) with my Fluke 289 DVM with i410 amp clamp when my leaf was already charged to 80% SOC and got some a very funny recordings. <snip>

Here is the pdf of the view.

http://dl.dropbox.com/u/15670224/leafme_End_Charge_Recording_2011_0110.pdf

Malcolm :geek:
Click to expand...
Excellent work Malcolm!

You've captured the view of 'constant current / constant voltage' lithium charging from 'behind' the charger - I haven't seen it presented that way before - thank you!

Here's a chart - the black trace is charge current. Look familiar? :D

CCCV.jpg


The service manual doesn't give a deep look into how the car balances individual cells in the pack, but it does show that balancing is part of the process. There appears to be a capability to move energy from higher voltage cells to lower voltage cells. The manual suggests that balancing occurs later in charging - top balancing - when the cell is in its 'constant voltage' stage.

It's too early to know for me to say for sure, but it's possible that the second activation (about 10 minutes?) is part of the top-up after cell energy is shuttled around.

Very cool!
Andy
:geek: :lol:
 
Ok, so last night I set the charge timer to charge to 100% and set an END TIME only. I got that extra charge 'bump' after the initial EVSE cutoff:

Screenshot2011-01-13at52501AM.png

The EVSE came on at 9pm and charged full bore until 1:50, where it began the slow dropoff until 2:20am when it stopped completely. The EVSE came of again at 3:00am and gave me another bump of charge until 3:10am. I believe I had the end timer set to 4:30am, but I'll have to check.

I woke up to this:

Screenshot2011-01-13at52556AM.png

A new record high for available miles!!

I will check this weekend if similar 'charge bumps' occur during regular timer start and end times. More on this as I gather info.
 
smkettner said:
I wonder if that last bump is an equalization charge of some sort.
Click to expand...

I'm thinking that it is. But I haven't looked at my TED data for a regular, 100% no-charge timer charge to see if there is the same EQ bump. I'll look at that in the next few days as well.

Between all of us here, we're going to figure out how to tweek this car for max performance in fairly short order. :cool:

I'd love to be a fly on the wall inside Nissan when their tech guys/gals read all this. We're covering probably about 80% the same ground they did, with a few "We never thought of THAT!" thrown in. :lol: (plus a bit of "We never thought they'd EVER figure that out!!")
 
Jimmydreams said:
I'd love to be a fly on the wall inside Nissan when their tech guys/gals read all this. We're covering probably about 80% the same ground they did, with a few "We never thought of THAT!" thrown in. :lol: (plus a bit of "We never thought they'd EVER figure that out!!")
Click to expand...

+1.
 
Jimmy and Malcolm - you've got some good toys!

I can see those Nissan folks now:

:geek: :geek: :ugeek:
popcorn.gif
:geek: :shock: :ugeek:


:lol:
 
I suspect that Nissan's "equilization" (higher voltage cells "feeding" lower voltage cells??) is being done during the 40-minute "Off" time.

Is there ANY current (perhaps only one or two amps) flowing during this time?

Then, the final "top up".

After filling 100%, try a 1 mile drive, then plug in to charge again, and show us that current-flow graph, please.
 
Jimmydreams said:
smkettner said:
I wonder if that last bump is an equalization charge of some sort.
Click to expand...

I'm thinking that it is. But I haven't looked at my TED data for a regular, 100% no-charge timer charge to see if there is the same EQ bump. I'll look at that in the next few days as well.
Click to expand...

Interesting results. It will be interesting to see what happens during a manual charge event, or an event with a Start AND End time.

I would like to take advantage of the Super Off Peak rates (12-5AM) and I'm not sure that only setting an End time will accomplish this. You said that you set the End time to 4:30AM, and it began charging at 9:00PM. But it actually finished (after its power up blip) at 3:10AM. I'm wondering why it finsished 1h and 20m before the programmed End time? I assumed that if an End time was programmed (e.g. 5AM) the charge cycle would begin at the lastest time that would result in completion at, or about, 5AM.
 
Frank said:
Interesting results. It will be interesting to see what happens during a manual charge event, or an event with a Start AND End time.

I would like to take advantage of the Super Off Peak rates (12-5AM) and I'm not sure that only setting an End time will accomplish this. You said that you set the End time to 4:30AM, and it began charging at 9:00PM. But it actually finished (after its power up blip) at 3:10AM. I'm wondering why it finsished 1h and 20m before the programmed End time? I assumed that if an End time was programmed (e.g. 5AM) the charge cycle would begin at the lastest time that would result in completion at, or about, 5AM.
Click to expand...

If the charger is choosing it's start time based on it's end time, there are some fudge factors it will take into consideration. It has to allow for deviations during the charge, account for the 'EQ bump' (which this morning was 1 full hour after the main drop-off), etc. So a lot of experimentation will need to be done to sort out the start times.

I too would like to use super off peak hours. Ideally, I'd like the charger timer to be set up so that you could input your rate periods and assign them a charging order. IOW, tell the car "here are super off-peak times, (use this block most often), off-peak times (use this second) and peak rate block (use this as little as possible). That wouldn't be hard to do at all. that way, the car could decide how best to charge and still be ready when you say you'll need it. Let's see if we can't lobby Nissan to make that change.
 

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