Charged Up
Posts: 59
Joined: Wed Aug 10, 2011 7:13 pm
Location: Virginia

Incredible Charge Times?

Mon Aug 27, 2012 12:45 pm

MFM does not show how much energy you put back into the battery during the charge, but if you look at how much energy you used since the last charge you can infer how much energy went back into the battery.

I had one instance where I had used 18kWh and another 17 kWh and the car recharged to 100% in 2:01 and 1:59 respectively. And yet in other instances the car has charged at rate that is more in line with times expected by a 6.6k kW charger.

Has anyone observed something similar to this? This would appear to be charging faster than the onboard 6.6kW charger would allow.

I'm thinking perhaps Ford does not have the battery balance the cells during each recharge which would shorten the charge time, but still can't understand what is going on here.

I wish it were true, but I'm skeptical.

I have the Schneider L2 30 amp charger, but that shouldn't matter.

Hoping to get a chance to monitor this and see exactly how much energy is being pulled from the wall.

Evocus
Posts: 39
Joined: Thu Jul 19, 2012 12:53 pm
Location: Southern California

Re: Incredible Charge Times?

Mon Aug 27, 2012 1:59 pm

I agree there are issues with MFM calculations. I have 1:59 or 2:00 respectively nearly every time I charge but something doesn't look right about it.

My typical usage is 55 miles round trip and my usage in MFM shows 6 & 7 KWh per trip (less going out and more coming back). That roughly matches 2 hours of charge time so I haven't thought too much about the precision of the 2 hour numbers, other than they look strange to my trained eye. I've also confirmed via SoCal Edison that I'm pulling the 6.6 kW only during the Midnight-2AM hourly time slots if I start charging exactly at Midnight. So Edison matches MFM pretty well for my daily usage, but not always when I change it up on the weekend.

For example, last night it started charging at 12:02 and MFM said it would take till 1:27 am to finish. The fully charged email from MFM came through at 1:18. However, MFM log reports that it started at 12:02 and ended at 12:02 with "less than a minute" charge time, even though it's now fully charged! If I do the math from the email time stamps, 1.25 hours * 6.6 kW it should have replaced about 8.25 kWh (assume slightly less because the end charge scenario will be lower than 6.6 kW). That fits what I used for my out and back trip for that day. So the MFM charge log was clearly wrong. MFM is likely just truncating something in the calculations resulting in losing extra minutes somewhere. I won't be able to check Edison until tomorrow, but I expect it will show the ~8 kWh used as it has before.

I also have the Schneider EVSE and the hour indicator bars on the unit will tell you if you go into the 3rd or 4th hour of charge, but that doesn't help with partial hours.

Perhaps you can also setup the email messaging and check the times as I have done. You will get the message that it's starting and that it's complete.

Bottom line, I believe it's pretty buggy right now and hopefully one or more of the 1000 engineers Ford has working on electrification is also working to fix annoyances like this.
2012 Ford Focus Electric White Platinum Tricoat Metallic (4 July 2012)
Schneider EV2430WS Level 2 EVSE

Charged Up
Posts: 59
Joined: Wed Aug 10, 2011 7:13 pm
Location: Virginia

Re: Incredible Charge Times?

Mon Aug 27, 2012 7:30 pm

Thanks for sharing that, and truncating times and energy used was one thought, or rounding errors.

But 18 kWh in 2:01? Just dividing 18 by 6.6 = 2.71. And that's best case scenario, as you point out the charger probably isn't putting out anywhere near 6.6 kW at the end of the cycle.

Really you would expect 3 hours at least to replace 18 kWh.

Trielectric
Posts: 30
Joined: Fri Aug 10, 2012 9:15 am
Location: SE North Carolina

Re: Incredible Charge Times?

Wed Aug 29, 2012 8:44 pm

I installed a reconditioned GE house meter(the revolving kind that used to be outside everyones house) inside my garage that supplys only my Leviton 32 car charger supply unit. I have watched the GE meter near the end of the charge and it definitely slows down for the last 15 minutes. I haven't paid much attention to the times required to charge the car back up to 100%. We drive the car variable amounts every day and sometimes the car will go on the charger 3 to 4 times a day. I drive pretty hard and my wife always runs the AC. So far it looks like I'm getting around 3 miles per KW, but still not enough history to say which side of 3 the average will fall. We pay right about 10 cents a KW to the power company, except that I have electrical solar panels on my Garage roof that are grid tied. I'll see if I can keep up with a charge to see how long it takes.

Trielectric
Posts: 30
Joined: Fri Aug 10, 2012 9:15 am
Location: SE North Carolina

Re: Incredible Charge Times?

Sat Sep 08, 2012 7:50 pm

Here are 2 recorded times of charging with my FFE.
....................Start info; Finish info; result
Time...............18:06........19:06........1hr
Miles left..........17............40............23miles charged
ACKW used......523.3.........530.3........7.0KW used
I stopped this charge to go to supper!
.
....................Start info; Finish info; result
Time...............21:06........23:01........1hr55minutes
Miles left..........32............66............34miles charged
ACKW used......531.0.........543.0........12.0KW used
AC KW meter was turning 17 RPM at beginning of charge.
AC KW meter was turning at 1 rev per 73seconds @22:55.
Charge stopped itself.
The 1st charge makes sense. The charger is rated for 6.6KWDC into the battery. The charger used 7KW AC to do this.
The second charge has a lot of time running the cooling system near the end of the charge and is not as efficient. My best guess.

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