When is the 12 volt battery being charged?

I did some testing the 12 volt battery in the FFE.
When the vehicle is on the battery voltage measured 14.6 volts with 0.8 amps charging the battery. With the car off for about 5 minute the battery voltage dropped to 12.77 volts with 0.5 amps load on the battery. I check the battery after 15 minutes the battery measured 12.69 volts and load of 0.2 amps.

Using the level 2 charger the battery was at 13.4 volts after about 10 minutes. Once the charging was complete the battery voltage was at 12.81volts with a 0.2 amp load.

Using a level 1 charging cord the battery voltage was at 13.40 volts after about 10 minutes. Once charging was complete the battery was at 12.75 volts with about 0.2 amps load.

From this testing we can see that whenever charging is occurring the battery is being charged at a lower rate than when the car is switched on.
The load on the battery seems to be about a constant 0.2 amps when the car is parked. I did use a DC clamp on current probe so the accuracy is not very good at low current levels. I would estimate the current draw when the car is off at about 0.1 to 0.2 amps. Most likely the BXT-67R 390 12 volt battery is rated at 40 ah. Since this would exhaust the battery in 8 to 16 days we may assume that the current draw must be less than 0.1 amps, in order to last 30 days. The FFE may go into a deeper sleep mode in order to save the battery, when not in use for extended periods.
I would recommend using the BXT-96R as a replacement because it has a higher Amp Hour rating. I don’t know if this battery is a direct drop in replacement.

Thanks for posting the results of your testing. It would be nice to know if it goes into a deeper sleep mode after a while.

jeffand said:

Using the level 2 charger the battery was at 13.4 volts after about 10 minutes. Once the charging was complete the battery voltage was at 12.81volts with a 0.2 amp load.

Using a level 1 charging cord the battery voltage was at 13.40 volts after about 10 minutes. Once charging was complete the battery was at 12.75 volts with about 0.2 amps load

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What did the voltage go to between the 13.4 after 10 minutes and the completion of the charge?

It's kept it at a constant 13.4 volts for the remainder of the charge cycle.
It seems that the 13.4 volt is what float charger will use. This provides a small trickle current to the battery. This is a constant voltage level that would not damage the battery, or allow the battery to be discharged.

My early 2013 FFE has the BXT-67R 390 battery.

Which 12 volt battery is in you FFE the BXT-67R 390 or the BXT-96R?
The number can be found under the black battery cover.

jeffand said:

Which 12 volt battery is in you FFE the BXT-67R 390 or the BXT-96R?
The number can be found under the black battery cover.

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I have the 67R 390. I wonder what the difference is?

BTW, you mentioned the battery cover. I was looking at the motor a few days after I got the FFE, and I noticed that at the bottom of the radiator (where the belts would usually be), there was a piece of plastic sitting there. I dug it out and realized it was a battery cover. Someone didn't snap it back on after removing it.

Jeffand the worst happened today. Sorry I didn't take voltage readings.

On 110V charging, the 2014 car finished 100% charge around midnight on Friday. Didn't try to drive the car until Monday early afternoon. Guess what, the battery was completely 100% dead. I got a brief, shutting down because the 12V battery is low, and then the dashboard when totally black. Tried charging the 12V battery for 2 hours on a charger, didn't do any good. Tow truck showed up, the clown in the tow truck tried to jump start it with his battery pack - used up all the charge in his pack. The lights flashed a bunch, the dash flickered on and off, but it wouldn't start. Had it towed to my dealer this early evening.

Good news, the loaner is a Ford Energi. So I'm not out gas for a loaner.

By the way, if anybody knows where to complain about Ford Roadside assistance, I'm all in. Wow that was the worst service I've ever seen.

Oh, clearly the 12V battery does not charge when the car is plugged into 110V. That I can guarantee.

It provides a float voltage to the battery for both level 1 and 2 charging. It should slowly bring the battery voltage up to 13.4 volts. If your car is not doing this then some thing is wrong with either the dc supply, or some thing is loading it down.
I was wondering if i could get my hands on the electrical prints for the car. It seems to me that owners that do experiance issues the 12 battery may not be caused by the same problem. Some have problems only after driving the car for a while. This could be caused by the DC to DC converter not charging the battery from the high voltage pack. Others are having issues when the car is parked over night. This could be caused by a power drain from some system when the car is parked. A sticking relay in the power box would be an example. Others have problems when charging the car. This could be caused by not having the float voltage applied to the battery. But these are all guesses at this point. I need more information to determine a root cause.

Good thinking Jeffand. Probably many different causes. Got a call from the dealer and the problem appears to be a tough fix. The car started after they jumped it. After sitting for a while it wouldn't start. Jumped it again and it started. Then left it for a while and it would start. Then it wouldn't start again. The service manager needed to go so I didn't get to ask if the battery was in good shape. I'm assuming that was the first thing they checked for a bad battery.

More to come I'm sure.

The service tech should check the battery voltage. It should go up when the vehicle is powered up. 14.0 volts or more. When charging the battery voltage over time should climb to 13.4 volts. A clamp onDC current probe could be used to measure charge current.

Oh man, this is not good. Got the car back on Friday. The answer was, it's just a fluke, we must have left something on in the car and that's why the battery died. They left the car sit for 48 hours and it started right up, no problems.

So I got the car home, promptly plugged it in to 110V. It charged in 30 minutes. We didn't drive the car Saturday. This morning, Sunday, I went out to start it - AHHHHHHHH Battery low, shutting down message on the touchscreen. All dead again.

So this afternoon I checked the battery voltage before I put on the charger (I will try not to go throught that disaster called Ford Roadside Assistance again). Well the voltage read 3.75 Volts. Yeah, the meter was on DC and I had it hooked up correctly.

When I plugged in the 12V charger, the front marker lights flashed a bit, then a bunch of relays made noise, about the kind of noise the car makes when you plug it into the charger. And then all the lights went dead. It appears the car has decided the battery is really dead and it doesn't want to deal with the 12V charger.

So Monday it goes back to the dealer. I hope I can get it to run.

I'll wait until they figure out what is wrong - software, part, or whatever and they can point to a real fix. Then I will ask for a new battery. Going to fully dead twice is a really bad idea.

When the battery voltage on the 12 volt battery drops below 10.5 volts damage is being done to the battery plates. The longer the voltage is left in this dischaged state the greater the damage. The battery should be checked for storage capacity. My guess is the battery has significant damage done to it. If the battery is replaced this problem may come back because the real cause was not found. If seems to me that when the car is powered down not every thing is turning off. This could be caused by a relay contact not opening when the car is turned off. To diagnose this problem they will need to measure the battery current draw, and verify that all the systems are shutting down. By installing a DC volt meter in the 12 volt power socket located in the center arm rest you can monitor the battery voltage while driving.

I got the car back on Friday. The dealer applied the programming change described in the technical service bulletin 13-9-19 (I think unplugged quoted from sippycups). They kept the car two days fully charged and plugged into 110V. The car started, no problems with the 12V battery. Go figure, it was just that simple. I haven't driven the car a lot since the repair.

If in fact it is fixed, we'll talk about a new battery.

I went on a three week trip and left my FFE plugged into my level 2 charger. When I came back, the high voltage battery was fully charged and the 12V battery was dead. I assume this is because the car does not detect when the 12V battery needs charging, and will not charge it from the level 2 charger when it is low. So once the high voltage battery finished charging the 12V battery drained continuously until it died.

However, once I was able to get even a little charge into the 12V battery so that I could turn the car on (I was getting a 12V battery low warning), I went for a 15 minute drive and the 12V battery was charged significantly during that ride. I assumed it was charged from the high voltage battery during the ride. I supposed it could have been charged solely from regenerative braking, but I don't recall braking much during the ride. Am I correct that the car charges the 12V battery from the high voltage battery when turned on?

Gatorman82 said:

Am I correct that the car charges the 12V battery from the high voltage battery when turned on?

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Yes.

The 12V battery is not (directly) charged from regenerative braking.

With my FFE, the voltage across the 12V battery measures about 12.5V when the car is off, 13.5V when the car is plugged in, and 14.5V when the car is on. This suggests that the 12V battery is being moderately charged when the car is plugged in, and definitely when the car is on.

You know when I had my Chevy volt if it was parked more than 3 days then it went into deep sleep. Meaning that the cellular portion (OnStar) would not work. They said that was to save the battery. Now on our FFEs does anyone know how long the cellular portion stays active when the car is parked? I know mine has sat for 48+ hours and I could still communicate with it thru MFM. This could be the problem with battery drain. Because other than that there really is nothing else on or ( running ) that I can think of once the HV battery is charged. Thoughts?

WattsUp said:

Gatorman82 said:

Am I correct that the car charges the 12V battery from the high voltage battery when turned on?

Click to expand...

Yes.

The 12V battery is not (directly) charged from regenerative braking.

With my FFE, the voltage across the 12V battery measures about 12.5V when the car is off, 13.5V when the car is plugged in, and 14.5V when the car is on. This suggests that the 12V battery is being moderately charged when the car is plugged in, and definitely when the car is on.

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What this tells me is that it could be a problem to only drive short distances every day. The car will not be on long to charge the 12V battery, the charger will not be on long to charge the high voltage battery, and the 12V battery will sit and drain slowly the rest of the time. Unfortunately, this is often my driving profile.

Gatorman82 said:

WattsUp said:

With my FFE, the voltage across the 12V battery measures about 12.5V when the car is off, 13.5V when the car is plugged in, and 14.5V when the car is on. This suggests that the 12V battery is being moderately charged when the car is plugged in, and definitely when the car is on.

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What this tells me is that it could be a problem to only drive short distances every day. The car will not be on long to charge the 12V battery, the charger will not be on long to charge the high voltage battery, and the 12V battery will sit and drain slowly the rest of the time. Unfortunately, this is often my driving profile.

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Fwiw, my FFE is my daily driver and my commute is about 12 miles each way. Is that short? I do often drive it more than that on weekends.

I've had my FFE since January 2013 and (knock on lithium) have never had any 12V battery issues or an SSN incident.

My 2012 FFE went into service just about 11 months ago and is now 20,000 miles experienced...

I have had a low battery warning a couple of times, but nothing tell tale. This weekend the BXT 67r 390 is clearly a dead player. It was suspect that it could recover relatively quickly from a 12v charger, however it dropped below 10v in about an hour.

I also noticed my charge voltage is only about 12.66v on the level 2 charger, so I must be having charging system issues as well.

Taking to the shop asap.

This is the first problem I have had with the car, and just googling the battery type gives me concern of widespread issues with the battery in use.

LJ

My commute is 7 miles each way. But the car does fine with that. It died over Thanksgiving weekend, and I think it is because I was only using it occasionally for short trips to the grocery store (< 0.25 miles). This is the third time it has died on me (I've had it since July 2012) after sitting unused for a while, and I'm speculating the battery has been damaged by that.

I'm thinking about getting a third party battery that is rated very highly by Consumer Reports for capacity and long life. My experience in the past with Motorcraft batteries is that they don't last very long. I can't think of any reason a third party battery would be a problem, and should minimize the headaches of having to deal with the 12V drain issue. Does anyone disagree?

Gatorman82 said:

I'm thinking about getting a third party battery that is rated very highly by Consumer Reports for capacity and long life. My experience in the past with Motorcraft batteries is that they don't last very long. I can't think of any reason a third party battery would be a problem, and should minimize the headaches of having to deal with the 12V drain issue. Does anyone disagree?

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My only thought is that you may want to consider a deep cycle RV/Marine battery. The FFE doesn't really have to crank a starter and thus doesn't really need a typical automotive battery (which is designed to deliver a ton of current in a very short amount of time and don't like to be discharged). Deep cycle batteries, on the other hand, are designed to be discharged a bit more (and slower).

Just my $0.02.