"Full Accessory Mode" vs starting vehicle... ?

[LightningCanuckNB]

I am trying to sort out in the Lightning (and perhaps Ford EVs in general) what "Full Accessory Mode" actually is.

In an ICE vehicle, when you turn on Full Accessory Mode, the car runs everything except the engine including all the HVAC, windows, etc. It is different from the basic "Accessory Mode" which usually only powers 12 sockets, and the entertainment system, and on some vehicles windows. A red indicator light in the dash lights up as well to tell you you're burning the 12V battery hard when you do this.

"Full Accessory Mode" in the Lightning, does the same.Everything turns on. Except... in the Lightning, the heat and AC works in the HVAC, since it is electrical. In fact, *EVERYTHING* works. I can only see two differences between this mode and fully "starting" the vehicle.

a) You can't drive the car.
b) The same red indicator light that ICE vehicles have lights up.

I am trying to figure out... is the HV battery attached when in "Full Accessory Mode", or is everything - including the HVAC and heat etc - running just off the puny 12V battery? Because if that is the case.... why would anyone ever want to do that in an EV?

Why does this mode even exist???

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[RickLightning]

Good question. You should never use it IMO, since it provides no value except to drain the 12v battery.

Everything runs off the 12v battery regardless of the mode, except things that only run off the HVB battery like the motors.

 

[LightningCanuckNB]

Good question. You should never use it IMO, since it provides no value except to drain the 12v battery.

Everything runs off the 12v battery regardless of the mode, except things that only run off the HVB battery like the motors.

This is exactly what I thought was the case... which leaves me to question why Ford would ever even include this mode at all. It serves zero purpose except to put wear on your battery, and create a potential for it to strand you. It is not like an ICE car where the battery will charge "for free" next time you drive... it is just going to charge from the HV battery and it will all be a wash.. so why would anyone ever want to do this?

 

[invertedspear]

In fact, *EVERYTHING* works.

I can't speak to the heat, but I can assure you that the AC does not work when in "Full accessory mode" The fan blows but there's no chill. Annoys my wife as there's no easy way for a passenger to reach over and press the brake pedal so that the AC can be on.

 

[jimfigler]

This is exactly what I thought was the case... which leaves me to question why Ford would ever even include this mode at all. It serves zero purpose except to put wear on your battery, and create a potential for it to strand you. It is not like an ICE car where the battery will charge "for free" next time you drive... it is just going to charge from the HV battery and it will all be a wash.. so why would anyone ever want to do this?

I can't believe heat is running off the 12v in accessory mode. Seems like a few minutes would drain that 12v if it was supplying juice to the heater.

 

[mr.Magoo]

Everything runs off the 12v battery regardless of the mode, except things that only run off the HVB battery like the motors.

Just like it's cold outside, unless it is not - everything runs off the LVB battery unless it runs off the HVB

 

[mr.Magoo]

I can't believe heat is running off the 12v in accessory mode. Seems like a few minutes would drain that 12v if it was supplying juice to the heater.

Fans, the servos that direct airflow, etc. runs off the 12V battery.
The heater element (that warms up the "coolant" both for the battery and cabin) runs off the HVB. (it's around 9-10kW in size)

 

[LightningCanuckNB]

I can't believe heat is running off the 12v in accessory mode. Seems like a few minutes would drain that 12v if it was supplying juice to the heater.

It runs all the heated seats and steering wheel etc as well.

 

[Heliian]

What's wrong with having a 12v accessory mode?

It's essentially the same as an ice truck. Except, when you're charging.

 

[RickLightning]

What's wrong with having a 12v accessory mode?

It's essentially the same as an ice truck. Except, when you're charging.

Name one benefit of using the Accessory mode on the Lightning, vs. simply starting the truck.

In a gas truck, the benefit is running the accessories off of the battery and not wasting gas. What's the benefit on the Lightning?

 

[Heliian]

Name one benefit

The hvb contactors are open, no drive possible if you're working on it or showing it off.

When you're charging, it is essentially in accessory mode, no drive but heat available.

You can power the truck if the hvb fails. There's enough power in the 12v to get it into tow mode.

Rolling up or down windows without putting it in drive mode.

It's essentially the same as a gas version except for the wasting gas part.

Could they have designed an automatic one press on, one press off? Sure, but it's not about being radically different, it's an f150.

Personally I don't mind the acc. mode. Going completely the opposite direction, one manufacturer has or has proposed that just getting in with the fob should power it all up, no button to start.

 

[LightningCanuckNB]

Name one benefit of using the Accessory mode on the Lightning, vs. simply starting the truck.

In a gas truck, the benefit is running the accessories off of the battery and not wasting gas. What's the benefit on the Lightning?

Agree... this feels like a holdover from ICE that makes absolutely zero sense. I doubt this exists on a Tesla or Rivian. Accessory mode makes some sense, "Full Accessory Mode" does not.

 

[LightningCanuckNB]

The hvb contactors are open, no drive possible if you're working on it or showing it off.

When you're charging, it is essentially in accessory mode, no drive but heat available.

You can power the truck if the hvb fails. There's enough power in the 12v to get it into tow mode.

Rolling up or down windows without putting it in drive mode.

It's essentially the same as a gas version except for the wasting gas part.

Could they have designed an automatic one press on, one press off? Sure, but it's not about being radically different, it's an f150.

Personally I don't mind the acc. mode. Going completely the opposite direction, one manufacturer has or has proposed that just getting in with the fob should power it all up, no button to start.

I think you're missing the fact that there are three modes

- Accessory mode
- "Full accessory mode"
- Drive mode

No one is debating the first. It is the second one that is a pointless mode. "Rolling up and down the windows" is something that many cars allow in the first mode, if Ford disables it that is a Ford decision.

"You can power the truck if the hvb fails There's enough power in the 12v to get it into tow mode."

That has nothing at all to do with this discussion. You can't shift out of park in either accessory mode so you can't tow or move the vehicle at all in these modes. You need to turn the truck on, see the HVB error, and get it to shift out of park. I don't know how to do that but I guarantee It has nothing to do with accessory mode.

 

[Heliian]

That has nothing at all to do with this discussion. You can't shift out of park in either accessory mode so you can't tow in these modes. You need to turn the truck on, see the HVB error, and get it to shift out of park. I don't know how to do that but I guarantee It has nothing to do with accessory mode.

The owners manual is a great tool that no owner should be without.

 

[LightningCanuckNB]

The owners manual is a great tool that no owner should be without.

What does any of that have to do with this discussion???!?

Where is "Full Accessory Mode" mentioned anywhere in that document?

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