What voltage are you at?

Technical Forum for the Porsche Macan
dangezza
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Joined: Fri Oct 16, 2020 8:35 pm

Post by dangezza »

Just trying to ascertain whether my battery is fine and if my 30 min drives every few days are keeping it topped up (or if I need a new battery or battery maintainer).

Turn the key, the voltage settles to 11.7V, with engine running it seems to be at 15V.

Never seen any low battery warning, but having only had the car 4 months (early 2019 model) I would think the battery should still be in decent shape.

I know from reading up there’s a few factors at play here including the weather which has been barely above 10C past few months and more recently closer to 0C, but at the same time don’t want a expensive battery replacement or alternator for that matter if I can avoid it.

davewf
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Joined: Thu Aug 14, 2014 9:35 pm

Post by davewf »

When it's at 15V it's charging, the car has an intelligent charger so it only charges when needed, hence sometimes you will only see 13V or so when driving. You will also notice on full charge the voltage will go up on overrun, thats the car recouping engery via the alternator, It must have minimal effect on fuel consumption but suppose every little helps.

Its hard to tell from the 11.7V as when you turn the key some load is applied, its best to test with a multimeter but I would say if you are seeing 11.7 V the battery needs a charge.

Mine is not too happy and even charging it once a week its not looking to heathy, but car is 4.5 years old so may be the battery but waiting for a bit longer until we are out of lockdown to see how it goes when the car is in more use.
bobajob
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Joined: Sun Jan 05, 2020 6:24 pm

Post by bobajob »

My battery currently shows 11.7v when I turn the ignition on> Checked at the battery with a multimeter and the actual voltage is 12.3 which is about 70% charged. Usual I'd be fine with this but with no prospect of using the car for the next couple of weeks I will put it on charge.

As a rule of thumb I always take the view that if the stop-start cuts in once the car has warmed up then battery is fine.
dangezza
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Post by dangezza »

Thanks, I do actually have a multimeter so will see what that shows up on the weekend. 11.7 was with engine off but at night so lights on, music playing, blower, guessing air suspension primed.

Start/stop rarely cuts in but then again I do have a tendency to press the sport button soon as the oil temp is above 70/80 with the obligatory beans given when oil temp hits 90 (As I tell the mrs I need to stretch it’s legs once a while so all the mechanical parts don’t seize up.) :lol:
bobajob
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Post by bobajob »

The 11.7 volts on the dash did concern me until I checked that battery. It is great that you can access so much information via the dash, oil temp and pressure voltage etc but I do think of them as worry gauges sometimes! I can get a bit paranoid about stuff and the information can fuel that! Probably the result of too many years driving old 1960s / 70s cars with a dash full of electro / mechanical gauges and dubious electrical and mechanical integrity.
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Guy
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Post by Guy »

I'd get hold of a CTEK and use it whatever the state of the battery, for piece of mind. I've used mine on several cars, mowers, motorbike; it's especially useful when some of these batteries don't get much use.
On-Track
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Post by On-Track »

It's interesting that some members are getting a different reading with a multimeter compared to the dashboard reading. When I've fully charged mine with the CTEK charger, the MFD voltage shows as 12.6V which is what CTEK say is the reference voltage for the charger.

If your MFD is showing 11.7V before starting the engine I would expect it to take more than a 30min run to fully charge the battery. As davewf says, unless you see 13.2-13.7V in the MFD when driving the battery is not fully charged. If you don't have a CTEK charger, I'd recommend getting one and topping the battery up every few weeks.
Peter

Current: 2020 Carmine Red GTS http://www.porsche-code.com/PMST9ZI9
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MikeM
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Post by MikeM »

Agree with OP’s 30 minutes not enough, invest in a CTEk and leave it plugged in it will also help prolong the life of your battery.
Previous Porsche’s
2008. 987 Boxster S Sport basalt
2012. 991 Carrera S aqua
2016. Macan Turbo volcano
Current
2020. Macan GTS crayon
2024. Macan GTS gentian sometime this year https://configurator.porsche.com/porsche-code/PR8H7WC6
dangezza
Posts: 130
Joined: Fri Oct 16, 2020 8:35 pm

Post by dangezza »

Sounds like a CTEK charger might be best practice, especially if I cut down to taking the car out once a week, will save a bit on fuel, just won’t be as fun. But if the impending result is a dud battery or worse than I suspect it’ll more than prove it’s worth.

I have a driveway with close access (<2M) to an external power supply. Any feedback on what is a good model to go for in such a scenario?
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Guy
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Post by Guy »

These are quite popular on the forum - as stated I have used extensively with no problems:



I have also bought one of these for a neighbour to use with his Morgan - it is much more basic but works well as a trickle charger, and you can buy similar accessories to the CTEK chargers:

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