12 volt battery state in acc mode

[Twilloo]

Does the traction battery charge the 12 volt battery while in accessory mode? thanks

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[generaltso]

Does the traction battery charge the 12 volt battery while in accessory mode? thanks

No. Go into full Ready mode if you're planning to leave it on for a bit.

 

[louibluey]

Does the traction battery charge the 12 volt battery while in accessory mode? thanks

Yes. Acc mode has an odd charge rule. Seemingly by time, no matter what the initial soc state is, it runs the DC/DC converter for about 24 minutes, then that's it.

Not a good strategy, but if you are only using it for a short time, it should be charging for 0.4 hour anyway (unplugged, I think plugged in too, wow, I need to start a chart).

Obviously just what I have observed so far on my FE (several times now for acc mode), just one point of data FWIW.

Here is one example, the Dunkin Donuts parking lot question

Here is a more recent example, The DC/DC converter was on until that last ramp, after that now well known period of about 24 minutes (0.4 hours) in Aux mode. I finally went to AUX mode unplugged as a known way to run the battery down to get some comparison of soc well below 90%.

I always write Aux mode, when I mean Acc, not sure why.

 

[generaltso]

Yes. Acc mode has an odd charge rule. Seemingly by time, no matter what the initial soc state is, it runs the DC/DC converter for about 24 minutes, then that's it.

Not a good strategy, but if you are only using it for a short time, it should be charging for 0.4 hour anyway (unplugged, I think plugged in too, wow, I need to start a chart).

Obviously just what I have observed so far on my FE (several times now for acc mode), just one point of data FWIW.

Hmm, I only tested it once but didn’t see the DC/DC converter kick on at all when I just went into ACC mode. Maybe that behavior changed with one of the module updates. I guess I’ll need to try it again.

But I can’t think of a scenario when ACC mode would be a better choice than Ready mode.

 

[louibluey]

Hmm, I only tested it once but didn’t see the DC/DC converter kick on at all when I just went into ACC mode. Maybe that behavior changed with one of the module updates. I guess I’ll need to try it again.

But I can’t think of a scenario when ACC mode would be a better choice than Ready mode.

Agree as to strategy, not really sure when acc mode is the best plan (although I prefer it in a parking lot eating a donut, but even now that I know how it works, the red battery symbol makes me nervous).

Mine has always charged LVB for 24 minutes since day one, I don't think it was an update. It took me months to find someone to do that first 12V update, not until July or so.

 

[RockwallRick]

If voltage levels over 14 indicate charging then I would have to say that charging definitely occurs while in accessory mode. I don’t know how long it lasts since I usually don’t stay in acc mode very long?

 

[SnBGC]

We probably need to know if the LVB gets charged in ACC mode while off plug, on plug and in schedule and on plug outside charge schedule.

I suspect the LVB may not get charged in the third choice.

 

[louibluey]

If voltage levels over 14 indicate charging then I would have to say that charging definitely occurs while in accessory mode. I don’t know how long it lasts since I usually don’t stay in acc mode very long?

Anything over 13.4 V is DC/DC converter on and charging.

 

[louibluey]

We probably need to know of the LVB gets charged in ACC mode while off plug, on plug and in schedule and on plug outside charge schedule.

I suspect the LVB may not get charged in the third choice.

I'm willing to do the tests, but I do not completely understand the third choice?

 

[RockwallRick]

I'm willing to do the tests, but I do not completely understand the third choice?

I was off plug when I observed charging in ACC mode.

 

[chrisGT]

I checked Carscanner with Aux mode and LVB voltage was 13.5v. This is less than the 15v when the car is On. I am not sure if 13.5 is enough to charge the LVB. I left it on for a while and it did not increase the SoC of the LVB.
After I turned the car on the LVB SoC staring going up about 1% every 5 minutes.

Btw when the car is on, if you open a door then the voltage drops to 13.5v as well, so don't leave the car on with any door open if you want to charge the LVB.

 

[Twilloo]

I checked Carscanner with Aux mode and LVB voltage was 13.5v. This is less than the 15v when the car is On. I am not sure if 13.5 is enough to charge the LVB. I left it on for a while and it did not increase the SoC of the LVB.
After I turned the car on the LVB SoC staring going up about 1% every 5 minutes.

Btw when the car is on, if you open a door then the voltage drops to 13.5v as well, so don't leave the car on with any door open if you want to charge the LVB.

I have heard several remarks about what is considered good 12 volt sitting voltage. My car has sit in the garage at temp of 58 for about a day and a half and with everything off and I take the voltage at the terminals in the frunk I get 12.35. Is that ok or not? thanks

 

[chrisGT]

I have heard several remarks about what is considered good 12 volt sitting voltage. My car has sit in the garage at temp of 58 for about a day and a half and with everything off and I take the voltage at the terminals in the frunk I get 12.35. Is that ok or not? thanks

That seems ok to me as resting voltage. My post was for voltage while the car is On and the DC converter sends power from the HVB to the LVB. I have noticed if you remote start the car or if it is on but you open a door the voltage is 13.5v but if you are driving (or idle without open the door) it is 15v. At 15v it charges the LVB much faster than at 13.5v.
This is just a note for those people who leave the car on to charge the LVB. Yes it charges it but way slower than actual driving.

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