System Off to Preserve Battery

[NightHawk]

No they didn't have to order anything. All they do is hook up the computer and send the fix over.

So its simply a software/firmware patch or update any Ford Electric-Certified dealer service dept should easily be able to do if you give them the TSB number?

 

[studio460]

Yes. They'll look up the TSB in their service database, and it will likely tell them to flash the ECM with version XX.XX of the car's firmware. This should take only about a minute to do. But, this "fix" a bit worrisome for two reasons: First, both of our cars are recent enough production-line models (I think mine was built 8 August 2014) to have already been been flashed with the most current firmware version. Second, if the "patch" isn't already included in the current firmware release, why not?

 

[studio460]

[FYI: I'm currently charging on L1 at home, but by Saturday, I should have my Bosch L2 charger installed. I did leave the car plugged in for 24 hours straight last weekend, but then later that night I unplugged it. By the morning, it lost several percent of its charge, so I had planned to always keep it connected at home from that point on. Perhaps, HB's suggestion of simply dis-/re-connecting the car once every 24-hour period solves the problem also.]

 

[studio460]

I've ordered this nifty 12v accessory port gadget from amazon today to easily monitor the 12v battery voltage inside the car without lifting the hood or using a regular multimeter. Then I'll know if I'm ok each day and if I need to do an external 12v battery charge if its ever getting down too far:

http://www.amazon.com/gp/product/B0092KVYGI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Cool find! Only $6.99!!! I'm ordering one for myself tonight!

 

[NightHawk]

Cool find! Only $6.99!!! I'm ordering one for myself tonight!

Or order from the vendor I chose 3rd down in the list (lowest price order) in New Jersey - only $4.81
There are several other similar models you can see linked at amazon.
One model is like this but adds a 2.1A USB charging port, costs twice as much, but could be useful if you want another USB.

 

[studio460]

Thanks, but I'm just glad that vendor ships with Amazon Prime. I was reading the reviews for the product--they're all over the place, from "very accurate" to off by 0.3V. Now, of course I got side-tracked looking at the cool-looking, panel-mount versions at Amazon.

 

[GladeStorm]

I bought a nifty device like that for about the same reason. What you will find is that the cigarette lighter times-out after a period (about a half hour?). This was discussed in an earlier thread.

For a lead-acid battery 12.7V is considered 100% SOC.

The normal parasitic drain on the 12V battery isn't that bad (unless there is a fault or something is left on). The Owners manual doesn't suggest disconnecting the 12V battery unless storing for extended period (30 days). Last summer I went out of town for about 3 weeks (leaving the car unplugged); I didn't measure the voltage when I got back, but had no issues.

 

[NightHawk]

I'm measured 12.9-13.0V after a full charge with external Sears battery charger.
It will go down slightly after 24 hours if you don't turn on anything (lights,etc) and leave the car in OFF mode without the charger plugged in; about 12.8V
However if I open a door and the lights go on for a short time, after that the voltage drops to 12.5V and then goes back up to 12.7V or so quickly. My Sears premium charger displayed the SOC at that point as 75% where it was over 90% before. I don't know if that much drop after such a small load for a minute is indicative the battery is now a little weak due to it getting excessively discharged last weekend due to the unknown FFE issue that does that?

But it at least it looks like it is staying above the level that the car will start up if I don't leave the charger plugged in and have the car in OFF mode for a few days, assuming the battery was fully charged before that. So monitoring the 12v battery voltage daily should help catch a problem before it goes down to far.

I will probably try to get the Ford dealer to try to do that TSB fix in a week or two and possibly exchange the battery too.
The dealer's general manager just emailed me a "thanks for purchasing your Ford Focus Electric" email today and mentioned if I wasn't completely satisfied to contact him directly...

 

[NightHawk]

After about 36 hours since I fully charged my FFE's 12v battery with an external Sears battery charger and leaving the car in OFF mode without the charger plugged in the voltage was about 12.8V
I just tried plugging in the 110v EVSE (current HV battery level is 98%) and the 12v battery voltage knocked down to 12.4V and stayed there even after I unplugged; there were no obvious loads like lights on (the car was still OFF).

My Kill-A-Watt device measured the EVSE taking about 0.45A@110V, 15W (30% PF) while it was plugged in - I'm still unclear what this low power mode is (the EVSE green charging light blinking) compared to not charging at all with 1W (EVSE green charging light off) and full charging mode at 1170W (EVSE green charging light blinking).

In any case the 12v battery was definitely being discharged when I plugged in the 110v charger EVSE with the HV battery state nearly full (98%) compared to when its not plugged in and the car is in the OFF state. This doesn't seem right - when the EVSE is plugged the car should never cause a discharge of the 12v battery when it could instead charge it from external power! I hope that is what the TSB patch/update fixes and would be an easy way to test/verify the fix by replicating that test.

 

[davideos]

- when the EVSE is plugged the car should never cause a discharge of the 12v battery when it could instead charge it from external power!

I'm not sure that is necessarily true. My guess is that the FFE is a much more complicated system. I don't know the system either, but I think the charging circuit runs off of the 12V battery. It is likely that there is only one DC to DC converter...and that is from the High Voltage battery to the 12V battery. This DC to DC converter or "charging circuit" may only kick in when the certain voltage thresholds are hit.

Just a theory; but to understand the system better, someone would need to put a data logger on the 12V battery and monitor it under various conditions. I've done some monitoring myself and I do know that it does change when the state of the car doesn't.

Regards.

 

[NightHawk]

Cool find! Only $6.99!!! I'm ordering one for myself tonight!

My plug in voltmeter accessory arrived in the mail today and it works great!
I verified its voltage reading was accurate, as it matched that of my regular multimeter.
I can now monitor the FFE's 12V battery voltage without raising the hood now just plug it into the interior 12V socket.
I'm getting 12.6V typically right after opening the door and the interior lights come on.
It can build back up to 12.9V after an hour or so with everything off.
If I turn on ACC mode it measures 13.4V or so and in ready to drive mode goes up to 14.4V or so, charging mode.
I found the 12V socket power eventually turns off if the car is in OFF mode, but it takes awhile not just a couple of minutes.

I plan to check the 12v level daily even if I am not driving the car that day from now on.

 

[studio460]

I think a neat mod would be to mount a hardwired, panel-mount voltmeter display on to the top of the dash (e.g., above the VIN, facing outside), so it's visible through the windshield. So, at a glance (at least at night), from outside of the car, you could confirm its voltage.

 

[jmueller065]

For an experiment: Program a go time with the HVAC off and measure the battery voltage at that time or about 30 seconds before it (my guess would be that its in the 14V range).

 

[Lmengoli]

Left 240 volt ESVE connected for 40 hours
Car would not start and accessories dead
Message on blank screen "system off to preserve battery"
This refers to 12 volt battery not EV battery
Voltage of 12 volt battery was 9.0 volts by voltmeter
Connected focus 12 volt battery to good battery in my other car (jumper cables)
Charged for only a minute or two
System came back up and voltage on 12 volt battery quickly to 14 volts
Seems to me this should not happen (especially on Sat am with a 7:00 tee time)

 

[NightHawk]

Left 240 volt ESVE connected for 40 hours
Car would not start and accessories dead
Message on blank screen "system off to preserve battery"
This refers to 12 volt battery not EV battery
Voltage of 12 volt battery was 9.0 volts by voltmeter
Connected focus 12 volt battery to good battery in my other car (jumper cables)
Charged for only a minute or two
System came back up and voltage on 12 volt battery quickly to 14 volts
Seems to me this should not happen (especially on Sat am with a 7:00 tee time)

yep that happened to me early on too.
I learned to not leave the car plugged into the EVSE for long after its reach a full charge.
I think it didn't happen for me if I use "Value Charge" mode though, but I still unplug it in less than 12 hours after a full charge anyway.
For the past several months I use an accessory plug in voltmeter to always be aware of the 12v level in order to catch it early before the car won't start, but its never gotten below about 11.8V at anytime since then for me.
I also keep a small portable 12v battery jumper unit (uses a Li-On battery pack) for an emergency quick 12v charge/jump but haven't needed it yet.

 

[Lmengoli]

I had same problem - system off to preserve battery
HV battery fully charged but car would not start
Able to start with jumper cables but 12volt battery would not hold charge
12 volt Battery replaced under warranty
2 years and 15,000 miles