Member Since: 19 Feb 2015
Location: Ploiesti
Posts: 65
Alternator broken?
Hi,
With the cold weather these days I have programmed the FBH to start every morning before leaving to work, but, on several occasions I have found a message on the display saying that the battery level is low and I need to start the engine.
With the engine started, radio on, HVAC on full power and front and rear windows heating on as well as the headlights on high beam, the battery voltage shows 11.8 - 12.0 v. Closing everything and leaving only the HVAC on Auto and the radio on, will show a battery voltage of 14.8 v.
Does this mean the alternator is on its way out?
Thanks.
Cosmin
31st Dec 2017 1:48 pm
Narpy
Member Since: 18 Jul 2011
Location: Stockport
Posts: 7830
Stick a multi meter across the battery when the engine is running and see what you get.
If you're relying on the onboard diagnostic screen they are not very reliable.Mods:
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31st Dec 2017 2:05 pm
cos192000
Member Since: 19 Feb 2015
Location: Ploiesti
Posts: 65
These values were indeed found with a professional multi-meter on the battery with the engine running.
Checked the same with the IIDTool and the values were not far off.
31st Dec 2017 2:24 pm
Narpy
Member Since: 18 Jul 2011
Location: Stockport
Posts: 7830
In that case, your alternator is paggered.
If it let's go completely it might take your battery with it so be warned.Mods:
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Wing Mirror Indicator Repeaters.
Long Roof Rails
Make your own Narpy grill thread
I'm not scared, I'm outta here.
31st Dec 2017 5:01 pm
robpenrose
Member Since: 12 Jan 2016
Location: Surrey / SW London
Posts: 2136
After my recent ordeal with a failed alternator, I would say get it changed ASAP at your convience! If you don’t, It’s bound to pack up when you most need the car.
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31st Dec 2017 5:05 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Re: Alternator broken?
cos192000 wrote:
Hi,
With the cold weather these days I have programmed the FBH to start every morning before leaving to work, but, on several occasions I have found a message on the display saying that the battery level is low and I need to start the engine.
With the engine started, radio on, HVAC on full power and front and rear windows heating on as well as the headlights on high beam, the battery voltage shows 11.8 - 12.0 v. Closing everything and leaving only the HVAC on Auto and the radio on, will show a battery voltage of 14.8 v.
Does this mean the alternator is on its way out?
Thanks.
Cosmin
Thats pretty much what mine does from a frozen cold start, with all three de ice buttons switched on, running the volts are only just above 12 with everything on as I scrape the screen, within 30 secs or so still on idle its all systems go as the voltage ramps up, climbs much faster if I just drive it ie not to much ice nut enough to justify all three buttons lit up.
3 years its been like this.
I reckon most do it but as most people dont have a constant volt gauge running they are none the wiser.
I only do 5 mile commutes so alternator pretty much runs at 15.1 volts all the time.
31st Dec 2017 5:33 pm
cos192000
Member Since: 19 Feb 2015
Location: Ploiesti
Posts: 65
So you're saying the 11.8 v in those conditions is normal and the alternator is working as it should?
Thanks,
Cosmin
31st Dec 2017 5:49 pm
Davethegeo
Member Since: 01 Oct 2015
Location: Edinburgh
Posts: 879
Mine behaves similarly. On a frosty morning with Max Defrost, heated seats and all, the plug in cigarette lighter voltometer struggles to show above 12V even when driving. Albeit on slow urban roads. Once the front heated screen switches off and the engine is warmer and smoother and happier then I get an indicated 14.8V.
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31st Dec 2017 5:55 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
cos192000 wrote:
So you're saying the 11.8 v in those conditions is normal and the alternator is working as it should?
Thanks,
Cosmin
Im not saying its correct but mine has done it for 3 years with no issues and I aint changing the alt yet
Like I said above very few people run a volt meter so if you mention volts the only time people may check their alt output is if they have another problem, ie starting issues
I run the same volt meter in another 2 cars and a boat, all very basis compared to the D3 but all weak volts wise when on a cold start with low revs.
The cheapo cig lighter volt meters are handy guides to whats going on, yes I know they are not 100 percent accurate but we are not after accurate we are after bench marks we can rely on.
What would be interesting to know iw what the power draw is with all the heated screens and hevac on full chat actually is plus of course the normal power required to run the car in the first place?
31st Dec 2017 6:26 pm
Jubbly
Member Since: 20 Nov 2016
Location: Stourbridge
Posts: 401
Mines the same, with all the heaters on and lights, it's 11.8v, however after a 50 mile commute it's at 12.7-12.8 for the rest of the day, so I think my battery and alternator are working fine.
It's just down to the draw on the car in cold conditions.Jaguar I-Pace HSE imminent.
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1st Jan 2018 12:48 pm
cos192000
Member Since: 19 Feb 2015
Location: Ploiesti
Posts: 65
Hi & Happy New Year!
Thank you all for your answers.
I had another go today with the IIDTool and this time I've logged the progress. Indeed after 105 seconds it went from 12.0 v to 13.5 v and it stayed there for another 135 seconds. After that it went all the way to 14.8 v where it remained till the end of the test.
All the heaters and consumers were on till the end of the test so I don't really understand why the voltage initially drops and gradually returns to a normal value but it seems indeed this is the way it works. Also I don't have an explanation for why the battery gets low from time to time but for now I'll exclude the alternator. Hopefully I will not come to regret it later on
Thanks,
Cosmin
1st Jan 2018 1:52 pm
Jubbly
Member Since: 20 Nov 2016
Location: Stourbridge
Posts: 401
Don’t forget you will also have glow plugs operating at startup in cold conditions, especially if the heater hasn’t been running.Jaguar I-Pace HSE imminent.
Gone HSE with Flappy Paddles. IID BT tool. RLD Spare Protector, Altox GPS.
1st Jan 2018 1:55 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72784
^^^^^^^ That's pretty much what mine does. Though sometimes on long drives it does drop down to a low voltage, like 11.7v, where it can stay for the rest of the drive and is regardless what I switch on or off. I've stopped being paranoid about it, for now.
1st Jan 2018 1:56 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
cos192000 wrote:
Hi & Happy New Year!
Thank you all for your answers.
I had another go today with the IIDTool and this time I've logged the progress. Indeed after 105 seconds it went from 12.0 v to 13.5 v and it stayed there for another 135 seconds. After that it went all the way to 14.8 v where it remained till the end of the test.
All the heaters and consumers were on till the end of the test so I don't really understand why the voltage initially drops and gradually returns to a normal value but it seems indeed this is the way it works. Also I don't have an explanation for why the battery gets low from time to time but for now I'll exclude the alternator. Hopefully I will not come to regret it later on
Thanks,
Cosmin
Iirc rough rule of thumb is you need to drive the car for at least 15/20 minutes plus to put back what starting it took from the battery.
It is a smart alt and I think is ecu controlled and the ecu can cut power off to non essential stuff when voltage is low.
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