Brake Regen suddenly weak

[acdii]

On my way home last night, the car acted as though the battery was fully charged. Very little regen effect when braking. It was so bad my brake score was under 70%. It had the same feel the Camry had, which was the main reason I got rid of it. Normally as you press the brake the car will slow, and as you apply just a bit more you can feel the regen get stronger slowing the car. What happened last night, I press the pedal the car starts to slow, but the more pressure I apply the less the car slowed, until I had to use service brakes to slow down. A few times it was so bad the car nose dived to a stop.

 

This morning, everything was back to normal, in fact 99% score which is good for my daily drive, usually its around 96%(stupid lights at the bottom of hills that suddenly turn red.

[SteveB_TX]

In fact, you have now entered... The Twilight Zone! :)

[hybridbear]

On my way home last night, the car acted as though the battery was fully charged. Very little regen effect when braking. It was so bad my brake score was under 70%. It had the same feel the Camry had, which was the main reason I got rid of it. Normally as you press the brake the car will slow, and as you apply just a bit more you can feel the regen get stronger slowing the car. What happened last night, I press the pedal the car starts to slow, but the more pressure I apply the less the car slowed, until I had to use service brakes to slow down. A few times it was so bad the car nose dived to a stop.

 

This morning, everything was back to normal, in fact 99% score which is good for my daily drive, usually its around 96%(stupid lights at the bottom of hills that suddenly turn red.

How cold was it? Maybe your HVB was cold and thus the charge limit was lowered. Did you have a lower EV threshold on the Empower screen at the same time?

[Easy Rider]

What happened last night, I press the pedal the car starts to slow, but the more pressure I apply the less the car slowed, until I had to use service brakes to slow down.

YIKES !!! :drool:

 

If you mean that it was necessary to use the "emergency/parking" brake to actually stop, that is a BAD fault.

 

I think you should report it to your dealer ASAP, just incase they know something about that kind of failure.

It would make me REALLY nervous to keep driving it not knowing why it did that.

[hybridbear]

YIKES !!! :drool:

 

If you mean that it was necessary to use the "emergency/parking" brake to actually stop, that is a BAD fault.

 

I think you should report it to your dealer ASAP, just incase they know something about that kind of failure.

It would make me REALLY nervous to keep driving it not knowing why it did that.

Where does he say "emergency/parking brake"? I'd suggest that you go back and re-read the 1st post. You'll see then that your interpretation is incorrect.

[acdii]

Service brakes worked fine, it felt as if there was virtually no regen braking, such as when you have a fully charged HVB. Car was fully warmed up, and the EV was working properly, in fact I got over 40 MPG going home which is 2 MPG higher than I normally get, but the brake score was very low. It was just very disconcerting when expecting the car to slow with a certain amount of pressure and the car is not slowing. It was perfectly fine this morning though.

[lolder]

Was the HVB full? Do these cars re-condition the HVB?

[Easy Rider]

Service brakes worked fine,

Here's the problem for me.

I don't remember seeing the normal mechanical brakes referred to as "service brakes" before.

My problem, no doubt.

[acdii]

Technical term on a mechanic level. I was a mechanic for several years. There is the parking brake, mistakenly called emergency brake, dont know if anyone has tried to stop a car going 60 with one, lets just say, those little drum brakes behind the rotor, they dont last very long. Years ago when cars had drums in the rear, they could stop the car if enough pressure could be applied to the pedal.

 

Then there are the service brakes, the normal ones used to stop the car. In the trucking world, they are normally called service brake, then you have the emergency brakes. Service brakes work on air pressure, as long as you have 60 PSI and greater, you can stop, however if pressure drops below 60 PSI, the Emergency brakes kick on, the pressure switch on the dash pops releasing the hold back air pressure on the emergency side of the brake bellows, and a huge spring pushes down applying enough force to lock the wheels. There are 8 of these on a standard semi. If you look at the axle on the trailer you probably saw the double pancake actuators on them.

 

On our hybrids we have 3 braking systems as you are well aware, the standard brakes, the regenerative braking, and the parking brake. Regen works as long as there is sufficient "room" in the battery pack to put energy back into, When the pack reaches max capacity fewer and fewer amps can be recovered until the service brakes are applied.

 

However in my case, my battery levels were about 25% charged, so there should have been plenty of room to send amps to, but the regen was hardly doing anything.

 

Lolder, the 13+ doesn't appear to do a cycle refresh on the pack like the 10-12 models do. The Lion batteries work in a far different way then NiMh do and don't require a topping off, actually topping off Lion batteries is a bad thing. Over time NiMh lose teir capacity if used regularly to certain levels, so the 10-12 models would peak charge them until they were at max capacity. This refreshes them which allows them to last as long as they do. For those who have never driven the early FFH, the battery levels usually stay around the 50% mark when driving above 45 MPH, unlike the 13+ where they range is anywhere from barely reading to maxed out on the dash graph. The early FFH does go all the way full in city driving when you are braking often, but in normal suburban driving, it usually is around half charged. It is quite different to the Toyota systems, and took a little getting used to "is this normal" when I first got it, as I was used to large swings of battery levels in the Prius and Camry.

[GrySql]

Was the HVB full? Do these cars re-condition the HVB?

These cars use Cell Balancing instead of 'conditioning'.

 

Cell Balancing

Individual cells can deviate over the life of the high voltage battery. The purpose of cell balancing is to equalize the individual cell charges. By balancing the cells the high voltage battery maintains top efficiency. The BECM (Battery Energy Control Module) continuously monitors individual battery cell voltages and will perform balancing automatically only when required. When balancing is performed BECM discharges individual cells with the highest voltage to match the remaining cells.

[acdii]

I do the same thing with my LIFE, and Lipo batteries.

[hybridbear]

These cars use Cell Balancing instead of 'conditioning'.

 

Cell Balancing

Individual cells can deviate over the life of the high voltage battery. The purpose of cell balancing is to equalize the individual cell charges. By balancing the cells the high voltage battery maintains top efficiency. The BECM (Battery Energy Control Module) continuously monitors individual battery cell voltages and will perform balancing automatically only when required. When balancing is performed BECM discharges individual cells with the highest voltage to match the remaining cells.

Is this referring to the Energi or the Hybrid? I think the Energi does cell rebalancing when fully charged & left plugged in. That's what the Focus Electric does.

[Texasota]

These cars use Cell Balancing instead of 'conditioning'.

 

The 2014 (page 144) and 2015 (page 151) owner's manual does describe a periodic re-conditioning process that the battery undergoes shown below). But I suppose this could be a carry over from the pre-2013 Fusions and is possibly incorrect.

 

Note that this was previously discussed in this thread:

http://fordfusionhybridforum.com/topic/8335-hybrid-battery-reconditioning-service/?p=82511

 

 

Unique Hybrid Operating Characteristics

Your vehicle behaves differently compared to a non-hybrid. Here is a description of the major differences:

Battery: Your hybrid is equipped with a high voltage battery. A cool battery ensures battery life and provides the best possible performance. Your hybrid high voltage battery may periodically re-condition itself to ensure maximum efficiency. You may notice slight changes in driveability during this process, but it is an important part of your hybrid's high voltage battery optimization features.

Edited January 29, 2015 by Texasota

[GrySql]

 

The 2014 (page 144) and 2015 (page 151) owner's manual does describe a periodic re-conditioning process that the battery undergoes. But I suppose this could be a carry over from the pre-2013 Fusions and is possibly incorrect:

 

I'd bet that is text left over from the previous generation Hybrids. We've seen that happen many times in our OM's.

I'm just reading the Workshop Manual and we've found errors in that too.

Edited January 29, 2015 by GrySql

[GrySql]

Is this referring to the Energi or the Hybrid? I think the Energi does cell rebalancing when fully charged & left plugged in. That's what the Focus Electric does.

It's the same language for both HEV & PHEV sections. However, that does not necessarily make it correct or complete.

Edited January 29, 2015 by GrySql

[Texasota]

I'd bet that is text left over from the previous generation Hybrids. We've seen that happen many times in our OM's.

I'm just reading the Workshop Manual and we've seen errors in that too.

Maybe, but Hermans said he experienced it in his MKZ in this post:

 

http://fordfusionhybridforum.com/topic/8335-hybrid-battery-reconditioning-service/?p=83049

[GrySql]

Maybe, but Hermans said he experienced it in his MKZ in this post:

 

http://fordfusionhybridforum.com/topic/8335-hybrid-battery-reconditioning-service/?p=83049

Go figure, not a word can I find in the Workshop Manual about that type HVB event.

[hermans]

Not only the MKZh, but it happened recently in my FFH. The car would not go into EV mode and when I shut the car off the HVB was making noises. This was at just over 20K miles. The next time I drove the car all was well in hybrid land.

[GrySql]

Well, maybe what used to be called 'conditioning' with the older version is now called 'cell balancing' and the effect is the same.

I've never noticed anything like this in 36k miles but that is not conclusive by any means.

[acdii]

39000 miles on the car and not once did it have a non EV event. Just this weird thing with regen where it feels like when you have air in the lines. You can feel braking, but it is nothing like it should be. It is out of warranty now, so anytime it goes in is $200.

[hybridbear]

It is out of warranty now, so anytime it goes in is $200.

And this is why if we buy an ESP it will be $0 deductible. I don't want the internal conflict of not wanting to use the ESP because it'll involve money out of pocket after I spent thousands out of pocket to buy it.