12 volt battery indication - issue?

[K6CCC]

Sanity check since the manual does not really give much info.

If I turn the truck on into accessory mode, I immediately get a battery indicator light on the dash. That never clears until I either shut off the truck or turn it fully on. My understanding is that this is not normal. Been this way since day 1. Can someone confirm this?

Since I need to take the truck in for the upper control arm ball joint recall, if this is not normal, I will have them address this as well.

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[Heliian]

Totally normal, in accessory mode it only draws from the 12v.

 

[Maquis]

There is no reason to use accessory mode. At least I haven’t found one. Most EVs have no such thing.

 

[TaxmanHog]

My understanding is that this is not normal.

Normal, the HVB contactors are open in this mode and are not providing energy to the DC/DC charging inverter.

 

[MaintGrl]

Just like ICE, your running off of the 12v Battery....

 

[K6CCC]

Normal, the HVB contactors are open in this mode and are not providing energy to the DC/DC charging inverter.

Just like ICE, your running off of the 12v Battery....

I fully understand both of those. But that is not a "problem" as would be indicated by the dash light indication. As I said at the beginning, I recall reading here that what is normal is that at boot up the indication will display and it SHOULD then go out unless the 12V battery is in trouble. Mine never goes out while in accessory mode. Works fine when "On" and therefore the HVB is providing charge to the 12V system.

Guess I will ignore it.

 

[TaxmanHog]

I recall reading here that what is normal is that at boot up the indication will display and it SHOULD then go out unless the 12V battery is in trouble.

If that was said/written then it was a miss-statement, the lamp is a REMINDER that you're draining your LVB simple as that.

If it stays on while in RUN/READY TO DRIVE mode, then you've got an issue with the DC/DC charging system.

 

[K6CCC]

Got it.

 

[Adventureboy]

Totally normal, in accessory mode it only draws from the 12v.

Actually, the DC-to-DC converter will come on to supply 12v power from the HVB in Accessory mode. It supplies a maintenance voltage, so it won't draw down your 12v. The indicator light will still show while in Accessory mode. Initially, the software set accessory mode to draw only from the 12V batteries, but that caused too many issues with dead batteries. Thank goodness they fixed it.

 

[Jackdforme]

Actually, the DC-to-DC converter will come on to supply 12v power from the HVB in Accessory mode. It supplies a maintenance voltage, so it won't draw down your 12v. The indicator light will still show while in Accessory mode. Initially, the software set accessory mode to draw only from the 12V batteries, but that caused too many issues with dead batteries. Thank goodness they fixed it.

you sure about that? I ask because of all the battery issues (12v) on them.

 

[Kansan]

you sure about that? I ask because of all the battery issues (12v) on them.

On my 24 Flash, accessory mode charges the 12v. The red battery indicator stays on in accessory mode even though it’s charging the 12v.

 

[TaxmanHog]

For "Those who got an update" the operation might now allow accessory mode LVB charging / maintenance ................ IF you got the update on "OLD" Lightnings or that it's baked into the newest model years.

I'd like to see proof by model year, with & without the modified software.

 

[riggie]

every car I've ever had (including Volt's, Mach E and now the Lightning) when in accessory mode the battery and some other lights as well, are all illuminated...normal

 

[Adventureboy]

you sure about that? I ask because of all the battery issues (12v) on them.

100% sure. I've monitored it, and it kicks up to about 13.5 volts for my 2023 Lariat on Accessory mode. 14.8-15v when full ON.

 

[Jackdforme]

Now I feel better in a mild climate, leaving it in accessory w/windows open. thanks.

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