Will 2015 cmax energi run as ice only if the HVB were to go bad?

[dpowell7299]

I was curious if anyone knew if the cmax would just run as ICE if the high voltage pack were to go bad (or if I pulled it to replace the individual cells)

 

anyone know?

 

Don

[homestead]

Depends on the failure mode.  If the pack goes lower and lower as time goes on it should still work fine on gas with shorter and shorter distances on battery.

Also some people have the energi model and for various reasons never bother to charge the battery.

It will still run fine as gas only.  Not as efficient as the hybrid but still good mpg's.

 

What is wrong with your battery pack?

[stolenmoment]

The HVB is what runs the two electric motors that conspire to start the ICE and to get ICE torque to the wheels, remember?  The 12v battery is just for the accessories and the power relay that lets juice out of the HVB.  If the HVB is totally dead,  your car is bricked.  But there's a long way to go from "can't run on battery for long" and "not enough battery to start the ICE".

[garageman402]

On 5/28/2024 at 12:51 PM, stolenmoment said:

The HVB is what runs the two electric motors that conspire to start the ICE and to get ICE torque to the wheels, remember?  The 12v battery is just for the accessories and the power relay that lets juice out of the HVB.  If the HVB is totally dead,  your car is bricked.  But there's a long way to go from "can't run on battery for long" and "not enough battery to start the ICE".

 So there's no conventional "starter" to start the ICE? I just acquired a 2014 Energi from my sister-in-law who, sadly, cannot drive anymore, & I'm learning more & more about this car. So, what, basically does the 12v battery do? It has regular starter sized cables coming off it, why would it need those large cables if there's no starter? Would a deep cycle battery be a better choice for this application? From reading this forum, there is no alternator to keep the 12v charged? So there's a DC-DC trickle charger that runs when the car is on. Does it also charge when it's plugged in? I've also noticed you can't use EV later if the battery has no miles left on it. Also it automatically uses the EV at "idle" & take offs, then switches to ICE. ICE shuts off when coasting too.

 

 My sis-in-law never plugged it in, she drove it in hybrid mode all the time & she had problems with the 12v right from the start, now I know why. She bought it in 2017 with 22k miles, when I got it had 33k, lol. She always took it to the dealer for service, oil change every 6 months, all the recalls, & I see a fairly new Motorcraft 12v battery in there. In later years, the only time it ran was to the pharmacy & back. When I first got it, we drove home (50 miles) at night, mainly using ICE but not really running it hard. One day after picking up my 6 year old granddaughter, we got on the main road & she said "you gotta go fast grandpa", so I pushed it a little harder. OMG, the smokescreen I left behind me, I looked like a skywriter! It dissipated for the most part but could see a little lingering smoke. I thought I blew something up, got it home, checked the oil, full & very clean. I can just assume I blew out the water built up in the exhaust from all those years of putting around town. I did that again, got a little bit of vapor blowing out. Since then we have taken a fairly long trip using ICE only (EV later mode), no more skywriting, lol.

 

 What is the second battery gauge for? I notice when the charge goes out of the HVB, another battery monitor appears, is that "hybrid" mode? Does it only regenerate while braking or will it charge while coasting? On our long trip I went down a steep grade for a few miles, riding the brake pedal lightly all the way down. Got 3 miles worth of charge out of that! At the bottom I pulled over to feel the brake rotors, the rear ones were cold, actually cold, the fronts were barely warm, you could hold you hand on it. So riding the brake pedal will engage the generator in the transmission, & only apply the brake when you push down more? If I put the transmission in "Low" will that increase the charging, or am I losing out by not riding the brake?

 

 I know, so many questions! I realize this thread is almost one year old, thanks for any help (advice) you can give this newbie!

 

 

[cr08]

I may miss some questions, but will try to cover everything:

 

There's no conventional engine starter on either the hybrid or Energi models. The engine is cranked by the starter/generator motor in the transmission as part of the hybrid system and is directly powered by the HVB. The 12v battery is just used to wake up the various computer modules and activates the HVB contactors so it can take over. But it still needs beefy cables as it still has other sizable 12v loads no different than a traditional ICE only vehicle plus additional unique 12v loads like the electric power steering, electric water pump, etc.. The DC-DC converter takes place of a traditional alternator, converting power from the HVB down to the 12-14v to charge the 12v battery and provide running power to all the 12v systems. It is capable of providing up to ~140 amps of power and is programmed to behave like a traditional alternator in many respects. It runs at all times when the vehicle is running even when the engine is off. Much like an ICE only vehicle, the 12v battery should be able to be sufficiently maintained under normal driving conditions, even without plugging in, as long as you don't drive super short trips constantly.

 

The HVB is able to be charged in a number of ways: Via plugging it in for Energi models or via regen braking or the engine directly charging it while cruising. Regen can happen while actively braking, coasting, or using cruise control/hill descent control. Any time you see the upper arrow on the gauge in the cluster (I am not sure if the 2014 models still had this. Ford removed it in some later model years), charge is going back in. HVB charge level does not impact the DC-DC converter in any significant fashion that I am aware of.

 

For Energi models while plugged in and the HVB is charging, the onboard charger, separate from the DC-DC, will provide a minimal amount of 12v support to keep the car awake during the process. Once the HVB is completely charged, it will top up the 12v battery before putting the vehicle to sleep completely. No further 12v battery maintaining will be done in this state until the vehicle is woken up again (ie: Locking/unlocking, opening a door, etc. when everything begins to light up inside)

 

The 'second battery gauge' is simply showing the hybrid portion of the battery charge. There's only one single HVB and it is software segmented between of the plug-in charge and the depleted hybrid only operation. Once the plug-in charge is depleted and that second gauge shows, it will fluctuate up and down normally as it is driven and normal charge/discharge cycles happen of the HVB. When in this depleted charge mode, the 'EV Auto' mode you're stuck in behaves the same as EV Later.

 

The brake pedal is specifically designed in these vehicles that under light application it does not put pressure on the friction brakes but engages regen at various levels depending on pedal pressure. The further the pedal is applied, you start physically applying friction brakes as well. Low gear just engages extra off-pedal regen. Unlike an ICE only vehicle, it will not affect how the vehicle operates while accelerating. It should NOT be conflated with one pedal driving for a few reasons. It will not bring you to a complete stop on its own. Regen effect will start to taper off down under 5-10mph. Also the brake lights will only activate with the brake pedal applied.

 

Using cruise control and hill descent control (The button on the left side of the gearshift) will also apply regen in their own way. Cruise control will maintain speed via deceleration as well as acceleration. Under decel it will focus on regen as much as possible and has methods to bring in full ICE based engine braking and the friction brakes if needed. Hill descent control will try to keep you from gaining speed downhill with no throttle/brake applied, even without cruise set. Similarly, it will use regen as much as possible.

Edited Monday at 03:11 AM by cr08

[garageman402]

14 hours ago, cr08 said:

Using cruise control and hill descent control (The button on the left side of the gearshift) will also apply regen in their own way. Cruise control will maintain speed via deceleration as well as acceleration. Under decel it will focus on regen as much as possible and has methods to bring in full ICE based engine braking and the friction brakes if needed. Hill descent control will try to keep you from gaining speed downhill with no throttle/brake applied, even without cruise set. Similarly, it will use regen as much as possible.

That's what that button is for! So I can use that button to hold the speed on a downhill while increasing regen without using the brake pedal? Would shifting to "Low" have the same effect? Will hill descent control disengage upon stepping on the throttle?

 

14 hours ago, cr08 said:

The brake pedal is specifically designed in these vehicles that under light application it does not put pressure on the friction brakes but engages regen at various levels depending on pedal pressure. The further the pedal is applied, you start physically applying friction brakes as well. Low gear just engages extra off-pedal regen. Unlike an ICE only vehicle, it will not affect how the vehicle operates while accelerating. It should NOT be conflated with one pedal driving for a few reasons. It will not bring you to a complete stop on its own. Regen effect will start to taper off down under 5-10mph. Also the brake lights will only activate with the brake pedal applied.

 

Is there any way to tell when the friction brakes start applying?

 

14 hours ago, cr08 said:

For Energi models while plugged in and the HVB is charging, the onboard charger, separate from the DC-DC, will provide a minimal amount of 12v support to keep the car awake during the process. Once the HVB is completely charged, it will top up the 12v battery before putting the vehicle to sleep completely. No further 12v battery maintaining will be done in this state until the vehicle is woken up again (ie: Locking/unlocking, opening a door, etc. when everything begins to light up inside)

I have noticed the light on the 120v charger stops blinking showing full charge but if I leave it plugged in, it will start blinking again, is that from the DC-DC charging the 12v? I have had it plugged in now for over 24 hours & the light has remained solid. I presume the 12v is now fully charged as well.

 

14 hours ago, cr08 said:

Much like an ICE only vehicle, the 12v battery should be able to be sufficiently maintained under normal driving conditions, even without plugging in, as long as you don't drive super short trips constantly.

I think my sis-in-law drove super short trips a lot. In addition to her never plugging it in, I think that contributed to the 12v battery's demise. Now I know how to keep it topped up!

 

14 hours ago, cr08 said:

Any time you see the upper arrow on the gauge in the cluster (I am not sure if the 2014 models still had this. Ford removed it in some later model years), charge is going back in.

Yes, the 2014 has this, along with a line that rises & falls showing charge & discharge. Using the cruise control makes the green ECO light come on, will that provide more regen than manually trying to maintain constant speed?

 

 

One other question I have. There is an indicator on the lower right corner of the radio control panel just below & to the right of the volume/tuning knob. There is a symbol associated with this in the shape of a lock, sometimes the yellow light is on, sometimes off. What is this indicator? It looks like a button, but it does not depress.

 

 Thanks for all your answers, I really appreciate the help!! This is quite a learning curve.

Edited Monday at 05:14 PM by garageman402
Clarify last question in first line.

[stolenmoment]

Shifting into Low doesn't try to keep a constant speed, the hill descent control does.  Personally, I'd rather keep it in L and manage the speed with the accelerator pedal.

 

I *think* that the loopy arrow over the battery display on the left screen is only shown when friction braking is applied, but I'm not sure about that.

 

When you plug the charger back in, the car wakes up and checks stuff; it will go back to sleep when it's satisfied.

 

The indicator on the lower right lights when the doors are locked.  Yes, it should be a button, but it isn't.

 

I consider it a bug that the car doesn't keep the 12v battery topped up when plugged in.  If I'm going to leave my car undriven for long periods, or in cold snaps like this, I use the fob to start it occasionally, just to try to take care of the 12v.

 

I suspect that they used those beefy cables to attach the battery because that wouldn't require a special part.

 

At the end of each trip, the left screen briefly shows per-trip stats, including how much regen you get; I typically get about 20%.

 

Folklore indicates that the high-voltage battery will last longer if you keep acceleration low, and use EV Later if you're going over 45mph.  My 2013 Energi still has 20 miles in the HVB, so I tend to believe that.  I use EV Later whenever I'm going farther than one exit on the highway, or when there are hills to be climbed; my town is sliced by a highway, it's damned convenient to use it to get to the other side of town, and I'll use the HVB for that distance.