Slowing down/braking issues while at 100% charge

[SnBGC]

Care to elaborate? I know Ford builds a bigger buffer into its battery management to prevent drivers running their high-voltage batteries down to zero charge.

The other thing I've noticed is that the MME takes driving habits into account when calculating range to a far greater extent than my Tesla. That must be why my MME seems to estimate my real-world range more accurately than the Tesla. Aside from gradual battery degradation, the Tesla's range estimate never seems to change by much no matter how I drive. The MME estimated range seems to be a lot more realistic than the Tesla's range estimate.

The larger buffer serves several purposes. In fact, 100% displayed varies day to day compared to kWh to empty. Something Ford does for a couple of reasons.

In short, it is almost impossible for the Ford to be operated in a way that compromises the battery and HV system where it is quite easy with the Tesla system. I think I read on another thread recently where someone posted their Tesla had 14% deg after only 35k miles. I am at 34,500 now and measured deg is 1.5% ish. The test routine said less than 5% which is the lowest reading it can calculate apparently.

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[Mach-Lee]

The steering wheel shaking like that would almost have to be due to warped or contaminated rotors. At 100% it's probably using the mechanical brakes when you lift off the pedal instead of regen. Put it in neutral and then use the brake pedal, see how that feels. Putting it in neutral will disable regen.

Note: Mach-E braking system can apply mechanical brakes at any time regardless of brake pedal use. Pedal will not move either when its applying. Likewise pressing the brake pedal does not guarantee mechanical brake application unless you are in neutral.

 

[mamejunkie]

The steering wheel shaking like that would almost have to be due to warped or contaminated rotors. At 100% it's probably using the mechanical brakes when you lift off the pedal instead of regen. Put it in neutral and then use the brake pedal, see how that feels. Putting it in neutral will disable regen.

Can you explain, I'm not sure what you mean by putting it in neutral? Can't drive in neutral. So if car is stop and I hit the brakes, how can I tell if anything is wrong?

What I've done is turned off 1PD and use the brakes. Is that using mechanical brakes? If so, it feels fine. Smooth and steering wheel doesn't shake.

 

[Mach-Lee]

Can you explain, I'm not sure what you mean by putting it in neutral? Can't drive in neutral. So if car is stop and I hit the brakes, how can I tell if anything is wrong?

What I've done is turned off 1PD and use the brakes. Is that using mechanical brakes? If so, it feels fine. Smooth and steering wheel doesn't shake.

Accelerate to 40+ MPH in D, turn shift dial to N, apply brakes. No, disabling 1PD does not mean it will use mechanical brakes, it will still use regen when you press the brake pedal.

 

[DaMeatMan]

I just recently noticed this since I changed the max charge to 100% for a trip I took. (Normally set to 85%) Using 1PD and when I lift my feet to slow down or stop, the brakes seems to 'shudder'. Not sure how best to describe it but like someone tapping on the brakes. It is not a smooth deceleration. Also, seems to happen only when the battery is at or near 100%. Like the software is setup to not use regen and op for the friction brakes. Once I drive a few miles and get it down a little, its okay. Tested it a few times and seems to behave the same. Anyone else experience this?

It's possible that because your at 100% the vehicle is not using regen as it has nowhere to store that energy, as a result It's very likely your braking almost exclusively with traditional friction brakes and your front rotors are either warped or have bits of pad stuck to them. You might not normally feel this since you usually drive with 1PD, so the sensation of using only friction brakes would likely be quite different and noticeable, particularly if rotors are warped or not smooth.

My MME gets steering shutter like that when I break hard and I'm using friction brakes. There was a TSB released early on that some vehicles may run into this situation as a result of pad material sticking to the rotors. I haven't take my vehicle in yet to address this, but will do so soon. You may want to as well.

 

[mamejunkie]

@DaMeatMan Thanks for the info. My visual inspection of the brakes looks fine without any major crap sticking to it. I will try take it into another dealership. Don't trust the service quality of the one I took in for the recall work.

 

[woody]

1) The current maximum charge is only 90% (at 100%). You still have 10% of the battery to store
2) Therefor it sounds like some other issue
3) If you could charge to 100%, then you would be unable to regenerately brake until you first run the battery down a bit ( as in the Bolt, etc.)
4) My MME regeneratively brakes at "100%" without your described problem

Hope they solve and correct

 

[hawkeye3point1]

Wasn't there some discussion about regen and the Mach-E at 100% from the woman that heads it up?

Yes, recalled this also. It was in this thread.

https://www.macheforum.com/site/thr...om-donna-dickson-mach-e-chief-engineer.15492/

Copied from first post:
One of the reasons to avoid charging above 90% (unless you need the range) has to do with the car's ability to leverage regenerative braking. When the battery is at (or near) 100%, it is harder to push electrons into it. As a result, the regenerative braking is less efficient with a full battery and you'll see a lower miles/kWh rating (particularly in stop & go driving when regen is really useful.)

Not sure it explains the behavior observed by the OP, but the fact that it only happens with the HVB @ 100% implies some relation.

My experience with reduced regen force when the HVB is stone cold, was just a lack of decel. with no other symptom, fyi.

 

[SnBGC]

Yes, recalled this also. It was in this thread.

https://www.macheforum.com/site/thr...om-donna-dickson-mach-e-chief-engineer.15492/

Copied from first post:
One of the reasons to avoid charging above 90% (unless you need the range) has to do with the car's ability to leverage regenerative braking. When the battery is at (or near) 100%, it is harder to push electrons into it. As a result, the regenerative braking is less efficient with a full battery and you'll see a lower miles/kWh rating (particularly in stop & go driving when regen is really useful.)

Not sure it explains the behavior observed by the OP, but the fact that it only happens with the HVB @ 100% implies some relation.

My experience with reduced regen force when the HVB is stone cold, was just a lack of decel. with no other symptom, fyi.

It is worth noting that statement merely says that harvesting energy via regen is less efficient when the battery is at a higher state of charge. It still works, but more waste heat is created compared to a lower state of charge (all else being equal). In order to transfer energy to the battery then the source voltage must be higher than the battery voltage. When the HVB is at higher states of charge, the voltage is higher as well.

 

[Jimrpa]

The larger buffer serves several purposes. In fact, 100% displayed varies day to day compared to kWh to empty. Something Ford does for a couple of reasons.

In short, it is almost impossible for the Ford to be operated in a way that compromises the battery and HV system where it is quite easy with the Tesla system. I think I read on another thread recently where someone posted their Tesla had 14% deg after only 35k miles. I am at 34,500 now and measured deg is 1.5% ish. The test routine said less than 5% which is the lowest reading it can calculate apparently.

Where is “kWh to empty” presented? I thought the car only displayed an estimated range (the beloved GOM)

 

[SnBGC]

Where is “kWh to empty” presented? I thought the car only displayed an estimated range (the beloved GOM)

You will need a scan tool to access the PIDs.

 

[Jimrpa]

You will need a scan tool to access the PIDs.

Thanks. I was hoping they might be easily available.

 

[mamejunkie]

Took the car back in to the dealership and it was the rotors that needed rework just like the service bulletin. Only thing now is they are not sure what will be covered since the normal warranty for the brakes are 12 months and I'm at the 14 month mark.

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