Question: Voltage meter

[GravelRash 62]

Owned the GT for about 3 weeks. Driving up the M6 yesterday and I had to pull up fairly sharpish and during this series of events I noticed that my voltage gauge fluctates between 12 and 14 volts.

I then proceed to spend the next 100ish miles doing some testing.

66 Plate, Pro model, so it's the electronic display of the Water, Oil and Voltage that I'm watching.

• Lights off (not auto), CC off, holds mostly at ~14.1, with occasional drops down to around ~13.5. No significant rev changes on my part.
• Lights off (not auto), CC at 70mph, holds mostly at ~14.1, with rare drops down to around ~13.5.
• Pulling into a service station, stop rolling, voltage drops to 12 and comes straight back up to 14.1
• Off the M6 and making progress down some A roads, holds mostly at 14.1, with a few drops to 13.5, and one two occasions, 12
• About 90 minutes later, up to temperature, lights on, no CC, holds at 14.1 constantly

I've not owned a car with a volt-meter before, but is it supposed to be this variable? I've not seen any other problems with the car and it's just ticked over to 5K miles, so I don't think it's age related.

 

Cheers

[Ade 517]

It regulates voltage depending on state of charge of the battery. 13.5 is a bit low. Mine runs at 14.5 until it drops to 13.8-14v when battery is charged. Turn the stereo on a crank it and it goes back up to 14.5v after a little while. I do have an AGM aftermarket battery though.

 

Sent from my SM-G935F using Tapatalk

 

 

[Tareim 343]

do you have air con on? if so I'm guessing the drop in voltage is probably when the ac compressor kicks in

[Ade 517]

45 minutes ago, Tareim said:

do you have air con on? if so I'm guessing the drop in voltage is probably when the ac compressor kicks in

The air con doesn't directly load the alternator as it is belt driven. At idle where voltage regulation is a bit pants, sure if the ac causes revs to move but not at a few k rpms steady state on the motorway. 

[Kodename47 446]

MY17 may regulate different to earlier models for improved efficiency.

[Tareim 343]

just seen this come up on facebook, might be of some use once more replies come in however 1st response would suggest its normal

https://www.facebook.com/groups/FRSBRZGT86Enthusiasts/permalink/587433098047736/

[GravelRash 62]

On 24/08/2017 at 10:59 PM, Tareim said:

just seen this come up on facebook, might be of some use once more replies come in however 1st response would suggest its normal

https://www.facebook.com/groups/FRSBRZGT86Enthusiasts/permalink/587433098047736/

Thank you for the link. I don't use Facebook so I can't see the thread, but can someone summarise what it says?

[GravelRash 62]

Went out for a drive last night and observed the following:

 

Warmed up, coming onto the M67, accelerating up to speed, voltage pegged at 12v. No electrics other than dashcamera. Stayed at 12v for a while even when holding at speed.

Heading over Woodhead, traffic, mixture of 5 and 6 gear, 30-45 ish speed, varying, voltage mainly around 12v, blipping upwards occasionally.

After a few hours with some friends, heading back over Snake, lights on, radio on, heated seats on etc (it was cold!), 14v never moved.

 

I think this is normal. There's no indication that the car is suffering and I've not spotted anything that I'm doing to trigger it. From doing some additional reading it also appears that I've got a MY17 car, not the last of the older model. Is there a way to absolutely confirm this? VIN number or something?

 

Back to the voltage I'm going to ask Toyota. If they reply (Daddy T never respond when asking questions about the Supra) I'll update this thread.

 

Edited September 1, 2017 by GravelRash
I can't type.

[Tareim 343]

23 minutes ago, GravelRash said:

I think this is normal. There's no indication that the car is suffering and I've not spotted anything that I'm doing to trigger it. From doing some additional reading it also appears that I've got a MY17 car, not the last of the older model. Is there a way to absolutely confirm this? VIN number or something?

 

you've definitely got the MY17 car as the previous gen didn't have the volt meter etc. and there never was a pro model in the prev gen

as for the facebook video it appears to have been removed however when I first saw it the responses were that it was normal for it to dip down in voltage

[GravelRash 62]

5 minutes ago, Tareim said:

you've definitely got the MY17 car as the previous gen didn't have the volt meter etc. and there never was a pro model in the prev gen

 

Awesome. thank you. I feel such a newb about this car. The perils of a spur of the moment purchase. The dealer mentioned Toyota were sending them the new model so I assumed it was the older one.

[GravelRash 62]

On 01/09/2017 at 8:33 AM, GravelRash said:

Back to the voltage I'm going to ask Toyota. If they reply (Daddy T never respond when asking questions about the Supra) I'll update this thread.

After a little conversation with Toyota UK they confirmed my suspicion that they are as useful as a chocolate teapot. The end of the conversation was to send the 86 in for a warranty check 

 

Some more observations are it appears to be related to the HVAC and Lights. Various combinations can be fiddled with to get the variance. As I can now almost produce this at will I'm 99% that this is normal.