percentage charge...

[fjpod]

Does anybody have hard facts on the SOC of our batteries vs. the dashboard indicator? IOW when we show 100% charge, is the battery really at 100% or as some have suggested, it might really be 80% to protect it. And is there a similar protection on the low end?

On another forum, it has been stated that the Leaf and Tesla don't "protect" the battery. that you can actually charge and discharge the battery fully. And the PiP and Volt have protections built in.

 

[NeilBlanchard]

I think that the Leaf uses ~95% of the total capacity. I think that it's meter is using ~22.8kWh (95% of 24kWh) as the 100% charge? They recommend that you regularly charge it to 90% and only go to 100% when you really need to.

 

[tonymil]

The Miev Handbook says simply that charging is complete when the charging indicator light turns off. I'm going by the theory that if we were supposed to charge to less than 100% then Mitsubishi would have told us. Like others here, I guess I'll be the guinea pig who charges almost every day and who charges until complete.

 

[Don]

I don't have any 'hard facts' . . . . This is all my perception, so it could be 100% wrong as I've not (yet) tested anything

I believe our charging system charges the pack to 100%. I *think* it charges with a constant current up to a certain pack voltage and then maintains that voltage with decreasing current for the last hour or so to the end of the charge - This will be easy enough check with a wattmeter . . . . I just haven't left mine connected during the final hour or so of a charge to see how the current tapers off, but I know the charging cable cools off* as the charge nears it's end, so I suspect it's because it's drawing less current. I also *think* this is pretty much the standard way to put a 100% charge on a lithium battery. Once the charge current tapers off to a certain number it cancels the charge, the car tells the relays in the EVSE open and it's all done

*I have the EVSE Upgrade installed in my OEM charger and on 120 VAC it pulls 12.5 amps and that makes the cable get fairly warm and it does cool down over the last hour or so

Don

 

[jjlink]

Here is a sample of how it tappers off:


i-MiEV Charge Intterupt by JJLINK, on Flickr
Ignore the odd spikes, its caused by other items in the house.

I don't have any 'hard facts' . . . . This is all my perception, so it could be 100% wrong as I've not (yet) tested anything

I believe our charging system charges the pack to 100%. I *think* it charges with a constant current up to a certain pack voltage and then maintains that voltage with decreasing current for the last hour or so to the end of the charge - This will be easy enough check with a wattmeter . . . . I just haven't left mine connected during the final hour or so of a charge to see how the current tapers off, but I know the charging cable cools off* as the charge nears it's end, so I suspect it's because it's drawing less current. I also *think* this is pretty much the standard way to put a 100% charge on a lithium battery. Once the charge current tapers off to a certain number it cancels the charge, the car tells the relays in the EVSE open and it's all done

*I have the EVSE Upgrade installed in my OEM charger and on 120 VAC it pulls 12.5 amps and that makes the cable get fairly warm and it does cool down over the last hour or so

Don

 

[jennrod12]

Jjlink,

At what time was the charge completed, on that graph? 5:30am? 6am?

Thanks,

Jenn

 

[jjlink]

Jjlink,

At what time was the charge completed, on that graph? 5:30am? 6am?

Thanks,

Jenn

Here is one from last Saturday which looks to be 4:55am end time. The overall chart follows that chart.


455 by JJLINK, on Flickr


455all by JJLINK, on Flickr

The saw tooth is most likely my refrigerator cycling on and off.

 

[jennrod12]

Nice - thanks for the charts!

Jenn

 

[marlon]

I've been charging with a kill a watt. To my surprise, the charging has been almost completely linear right to the point where is shuts off. It must be computer controlled. As far as I know, batteries, like capacators and inductors should charge with an exponential decay. However, this sure makes estimating charging time easy.
However, I don't understand why the graphs posted by you folks look different than mine. There appears to be a slow down approaching full charge. Are the cars programed differently or do we have different meters?

Any thoughts?

Marlon

 

[EVMOTO]

yes, it's a computer controlled charging process.

It is taken into account the actual voltage of the battery (315 - 365 V), the voltage of the power outlet (100-230 V, CHAdeMO 400V), the maximum charging current (16A AC, 125 A DC) and the temperature of the on-board charger (AC-DC converter).

Is the battery entirely empty (315 V = 5.5% SOC) shall be charged at first with a clearly defined current (A), in the second part with a defined voltage (V) The charge is terminated at 365 V with houshold outlets. With CHAdeMO outlets charching is stopped when 80% of 16.280 kWh are charged.
At the end of the charging current is reduced. At 100V, the reduction is fast, at 230 V it takes about 1 hour.
https://picasaweb.google.com/lh/photo/8mJYH7rB6m3G63ra_u0_mEQmPRJ1QbYZrDrT9lQJxZI?feat=directlink
The voltage of the 88 battery cells is controlled by the MiEV Computer between max 4.147 V and min 3.579 V.

More Details you can find here on page 59 and 60:
http://www.mitsubishi-motors.com/jp/spirit/technology/technical_review/pdf/technical_review_2008.pdf

The max and min limits of battery charge are given by the battery producer YUASA based on hundred of tests in the years 1995 to 2008
http://www.gs-yuasa.com/us/technic/vol5/pdf/05_1_021.pdf

Mitsubishi implemented these limits in the MiEV-computer. The driver has neither influence nor closely knowlegde about this because there are no accurate meters for the real state (A, V, Ah) of the battery. For the driver, it is sufficient to see the approximate charge level of the battery and the estimated range. The charging process works automatically without any user intervention.
With the Mitsubishi service unit MUT-3, the exact values can be displayed.

 

[garygid]

The LEAF protects the charging and discharging process
so that no cell (96 cell-pairs) gets too high, or too low,
and that the cells stay within a "usable" range of the
"real SOC", which is 95% SOC when filled to 100% usable.

Filling to 80% usable (80% "real SOC") is the other charging
option given by Nissan, which many use whenever they
do not expect to travel very far the next day.

When charging with Chademo, and starting below 50%,
the LEAF stops the charging at 80%. When starting
(or re-srarting) the charging above 50%, the LEAF
will continue charging (at decreasing currents, controlled
by the LEAF's internal charging controller) until "full".

So, the LEAF certainly tries to protect all the 96 cell pairs.

 

[jray3]

I've been charging with a kill a watt. To my surprise, the charging has been almost completely linear right to the point where is shuts off.

Any thoughts?

Marlon

Marlon, I assume you're charging with only the Panasonic Level 1 unit at about 960 Watts. At that low a charge rate, there's much less reason to taper down.
For those of us using Level II and want an 80% charge option for better battery life, I want a timer option better than the remote delay, which requires a mental calculation every time one plugs in (oh horror :shock: ), plus the risk of an uncharged car when unplanned travel needs arise. In short, I want a relay that will disconnect the charger when the charge rate tapers down after bulk charging is complete. That seems a good compromise for daily use to maximize both battery life and vehicle utility, and is built into EV conversion chargers like the Manzanita Micro PFC series. (One should still do an occasional full recharge for balancing purposes.)

Any ideas on implementing such control? I'm picturing an offboard relay in a box that opens when current detected drops below a certain level, and resets upon J1772 disconnect. It would also need a microswitch to disable this feature, and the pause in charging that has been documented by others could create false stops...

 

[Don]

Jay,

You sound like someone who might be interested in playing around with the Open EVSE project - You can program it yourself do all sorts of things, *if* you're a programmer type. I'm not, so mine uses the standard code that Chris provided - That allows me to set whatever charge current I like (in steps between 6A and 20A) on both L1 and L2. I have no doubt it could be programmed to do what you want . . . . to shut off at some point when the current draw begins to taper off. I've been lobbying them to add some timer features to the code, but the Leaf guys there seem to have lost interest in any more programming for the 'basic' model like I built. Most of the effort these days seems to be making it into a 75 amp EVSE for the Tesla's which come equipped with dual 10Kw chargers

At any rate, it's an enjoyable build - You can make pretty much anything of it you'd like and it doesn't cost a lot compared to similar commercially available units. I have less than $400 in mine

Don

 

[garygid]

The OpenEVSE project, extended by "goldserve" has added a Real
Time Clock (RTC) with backup battery to the project, with the 1.6.2
version of the firmware adding RTC support, and charging Timers
to the firmware. See this thread:

http://www.mynissanleaf.com/viewtopic.php?f=26&t=11064&sid=3e4105ee5c7797dd129cefe2d7f1a478

The main OpenEVSE thread is long:

http://www.mynissanleaf.com/viewtopic.php?f=26&t=6546&sid=3e4105ee5c7797dd129cefe2d7f1a478

 

[jray3]

Jay,
You sound like someone who might be interested in playing around with the Open EVSE project -
Don

Thanks Don- I even look like a geek too, but have somehow managed to muddle through life without soldering skills thus far... However, you've sparked a thought! I've been using an analog glass dome utility meter mounted on a little box to log my EV charging, and have been itching to rebuild it onto a real 'spider box' that has all the common outlets. Since I already added the J1772 inlet on my Karmann Ghia EV and have the Leviton J1772 30 amp cable (feeding that car in 'dumb' mode at home and with the Manzanita "Smart Box" adaptor in the wild), I've already got the most expensive part of Open EVSE taken care of.
http://www.manzanitamicro.com/products?page=shop.product_details&flypage=garden_flypage.tpl&product_id=112&category_id=41Plus
The only shortcoming of the Manzanita Smart Box thus far is that it can't shake hands with my SPX-brand EVSE. No problems yet with Blink, Chargepoint, SemaConnect..

So, an Open EVSE Spider Box is now on the project list!