Preparation Before Your 12 Volt Battery Dies

[skyagade]

My 12v battery just died....and I mean completely died! So dead that I couldn't even use my portable jumper to start the car. I had to use regular jumper cables connected to my other car battery, but I had a heck of time trying to connect to car's positive terminal under the hood; there is very little space between for the humongous cable clamps. But eventually forced into space to connect and start the car. I guess that why Murphy says "Standard jumper cables are not needed ..." because current draw of a starter motor doesn't exist, thus heavier gauge jumper cables aren't needed?

[Fezbearer]

Thats a great idea. I'm going to tie a cord to the release this weekend.

[TomPauls]

During this Wuhan virus shut-in, I wanted to pull the car out and make sure the tires were pumped. Car was totally dead. So - how to open the rear hatch? (2015 Energi). I found you may hook up a low-power 12V source to the red covered terminal under the hood (+) to a charger. Mine outputs 2A, which is very safe. I’ll let it run for a while, as the battery only had 3.5V on it. Then the hatch can open. You can then hook up a high-current charger to the battery in the rear.

 

Takeaway - If the car is not operated regularly, like mine wasn’t - for a month, keep measuring the battery voltage under the hood. Also, keep one of those low-capacity jump modules handy to operate the 12V electrics. I’m also working with the Ford service dept. to see if our car has the fatal power draw anomalie. If that battery is allowed to discharge significantly, you will ruin it. Those lead/acid batteries need to be kept at full charge to maximize their life. Mine will have to he replaced, obviously.

Edited April 15, 2020 at 07:46 PM by TomPauls
Better wording.,

[murphy]

Connect a small rope to the emergency trunk open handle.  Fold down the right rear seat back and attach the other end of the rope to the seat back latch bar.

 

Use emergency key to open driver's door.  It's inside of the key fob.  Open right rear door.  Fold down the seat back.  Pull the rope.  Trunk is now open.

 

That is one of the reasons that my car has an AGM 12 volt battery.

[jsamp]

 

Yes, the phantom drain issue is well known on the Energi.  It seems to be worse on certain years and/or with certain firmware versions.  1 month of no use is almost guaranteed to wind up with a dead 12V battery.

 

Worth keeping a jump module handy, or using a trickle charger for long periods of no driving.

Edited April 15, 2020 at 10:28 PM by jsamp

[muzicman61]

During the virus conditions I make sure i go every Sunday and get donuts, smokes and pickup any prescriptions i need.  That typically will use most my battery.  Then I charge.  So far no problems with my 12v being dead or drained.

[Shannon]

On 5/4/2017 at 1:59 PM, shaggy314 said:

 

I wonder if all it'd take is a 12vt lantern battery to throw the breaker for the HVB...

 

Contest Idea ... Smallest battery used to jump your Energi.

 

Gonna get me a couple of these and keep in the glove box ...

 

[Chango99]

2013 owner here. Moved from Sunny San Diego to Upstate NY a few years ago which then started giving me battery troubles. I went from mild weather, 40 mile each way commutes to less than a mile, a lot of sitting since I just walked my commute most of the time, winters with low temps.

 

I had to eventually replace my battery once at a ford dealership, but still suffer 2 years later, every winter. It dies in less than a week. The voltage after a jumpstart is still "healthy" right now though. 

 

 

Some tips and things I noticed over the years

• Tie a rope to the trunk handle and bring it to your rear seat, like others have mentioned
• Your 12V needs to be functioning for your HVB to be charged. Why? Because physics. 
  • When your HVB is fully charged, then your 12V is allowed to charge.
    • Thus, if you leave your car plugged in using your charging cable, your car battery should theoretically be able to be topped off
• If you are locked out with car not functioning, the driver door handle can be opened basically using your key to pry it open. A piece of plastic pops off. That kind of chipped/break off a piece with cold weather
• Your battery is in your trunk. The hood has connections to it but if you can access your trunk, use that, it's an easier terminal to use
• The older units had I think a deprecated 3G antenna or something that got deprecated. It's used with MyFordMobile and other remote connections for your car. Anyway, how I understand it is that, with less towers to ping, it was constantly reaching out and thus draining the battery. They had a recall for an update and I noticed an improvement. So if you got the notice, get that updated to what I believe is the 4G model now.
• I still don't know how the 12V outlets in the car work. I have a dash cam that sometimes auto shuts off when I turn the car off, and sometimes it just stays on. I notice the camera one when I check my car like an hour later. I would have thought power to those ports would be killed but I'm not sure. I do see my voltmeter drops voltage immediately after I power off, but not completely. 
• I got a car alarm notification to my phone from MyFordMobile somehow when I got into my car with a dead 12V battery... so the cell unit in the car was still powered but the rest of the car wasn't.

 

Hope that helps. I know this forum goes months/years with people not replying but people use this as reference so I'll put in my 2c

 

 

[murphy]

The car came with a 2G modem.  When 2G went away Ford upgraded it to 3G for free. I don't know if it had to still be in warranty.

I doubt they will do anything when 3G goes away.  It shouldn't be long since my cell phone is now on 5G.

 

The 12 volt outlets turn off after 70 minutes if the 12 volt battery has a good charge.  If it is low they shut off immediately.

 

Without 12 volts available the HVB is isolated from the car by two contactors.

 

With the advent of Covid-19 my car sits in my garage most of the time.  I have a smart battery charger connected to the terminals under the hood to keep the 12 volt battery from dying.  All of the always on microprocessors in the car put a constant load on the 12 volt battery.

 

Once the the HVB is fully charged the 12 volt battery is then charged. When that turns off it will never turn back on since there is no load on the HVB to draw it down.

That is why I have a battery charger connected to the 12 volt battery.

 

Welcome to the cold weather.  I get about 10 miles out of my battery when it is below freezing.

 

[Ffe]

So, once charging is complete, it won't periodically trickle charge the hv or 12v batt?  Is that correct?

 

What if I disconnect and reconnect the EV plug.  Will that restart the cycle?

 

If so, I imagine I can use a home automation relay to cut power to the charger station and reapply power once a day when its load has been low for a couple hours.

 

Maybe other folks on quarantine could leave their Energi connected to it's normal charger port and if they have a 'smart charger station' they could schedule it to disconnect and reconnect power at a certain time of day and that would keep their 12v topped up too.

 

I don't like the idea of having two cables from car to house.  I'd much sooner find a way to tap into the 120/240 lines coming from the Plug in connector (once warranty is up of course) and find a 12v trickle charger that could automatically handle 100-250vAC.  (That's not an uncommon spec for electronic switching power supplies anyway)

 

I also envision making my own jump start cable out of 12 ga wire and leaving it connected to the under-hood terminals.  Perhaps use o-ring terminals andnuts on that end for a better connection, and a removable positive clip to reduce chance of a short under the hood.  Coil it all up and velcro tie it to the hood wherever there's space.   Maybe I could use a cig lighter outlet and plug as a disconnect for the clamps, and then I also have an extendable 12v outlet outside the car to use with air pump or another accessory in a pinch.

 

Actually, I have always kept a little 12v emergency light in my trunk, and its got the cig plug and also clamps, so it could be my clamp on the donor car.  That light itself might be small enough to stow under the hood too.

 

Then I would keep a real jumper cable in the back to jump someone else' car off my battery if i needed to.

 

Skinny cables to jumpstart the Energi, big cables to jumpstart anyone else' car.

 

[murphy]

It will not restart.  Once the HVB is fully charged the contactors , 2 of them, open and the HVB is completely disconnected from the car.  There is nothing to cause it to lose charge.

If the EVSE contactor is not closed there is no voltage available to the car.  The car will not ask the EVSE to turn on if the HVB is fully charged.

[Ffe]

Interesting!  Does self-discharge not happen on HVBs?  Or so negligibly that it's just not accounted for?  half a percent per day?  or less?

 

Even a 12v lead acid battery on the shelf long enough will loose charge, I thought.

[theterminator93]

Oh, they all self discharge - it's something that's improved over the many years of battery technology evolution but it's still present in every type of battery cell to varying degrees. The rate of self discharge depends on SOC, temperature, specific battery chemistry and aging. Some battery control/monitor electronics are better at showing the charge loss than others but generally, the newer the battery, the more predictable the SOC after being left unused/unmaintained for a period of time will be.

 

Generally speaking, you can assume a Li-ion pack will self discharge 1-2% per month. I would think that the BECM is "smart" enough to constantly monitor battery voltage to show the actual SOC after an extended period of non-use, but it's possible (I have not observed this, so someone please correct me if you have information to the contrary) that the BECM only "remembers" the SOC when it the car was last charging or powered up. In this case, if the car is left off for a month or two and not charged (with the 12V battery on a tender to prevent it from dying, since there is a constant load on it with the car off), the car would think the HVB is at the same SOC as it was when it was last used, giving a falsely high reading at startup or when reconnecting the EVSE for a top-off charge by not taking into account the self-charge over that period.

 

Li-ion batteries and lead-acid batteries will both die permanently if the cell voltage drops too low, but for different reasons. Lead acid batteries last longest at a full charge but Li-ion batteries last longest at low states of charge, with only periodic charge boosts to make up for the self discharge.

[Ffe]

That is great to read!  My last car, an Prius from 2010 had NiMH and I was used to it dropping 15-20% overnight or during a work day.  Not that it was meant for extended EV driving anyway, but it always irked me that the offramp and down-hill regeneration from highway to house was 'wasted' before morning came around.  I'd daydreamed about finding a house with an uphill offramp and higher altitude a couple times.....  all offramp's ought to be uphill for that matter.

 

2%/month is small enough to me to just ignore! 

Edited March 13, 2021 at 01:26 AM by Ffe