Porsche Macan Forum banner
41 - 60 of 582 Posts

· Registered
Joined
·
3,735 Posts
... where do you think the MFD comes up with that number -- 12.1, 11.9, pick a number, any number -- when you turn the key to the accessory position?...
I had thought exactly as you currently think. A way to measure your battery voltage. After my test, I now think it is something else. I know it is not even close to accurate.

It will be interesting for MF members to check their MFD reading, with ignition ON but, car not started & post their V reading.

Perhaps it is some type of artifact not meant to be used hence, Not listed in the owner's manual?

Have you noticed when you use a multimeter to test voltage for anything....b4 you connect the leads to whatever you're testing, your reading is not "0" but a small, ever changing voltage? I recall reading somewhere that it was measuring atmospheric voltage or 'floating input'. Also read it was capacitive coupling but, that may be when you connect 1 lead or probe but b4 you connect the 2nd one.

If this was the source of the MFD reading b4 you start the car, I'd expect the reading to be a fraction of 1 volt & Not
12V. If the Car's computer was capable of reading battery voltage...why would Porsche hide that fact?
 

· Registered
Joined
·
2,583 Posts
Performed Science Experiment

Okay, sportsfans, I spent some time with this last night and this morning.

First, I cobbed up some long leads for one of my multimeters. I used some extension leads with SAE connectors that I had lying around in my miscellaneous electrical box, snipped off the pointy probes from a multimeter* so I wouldn't have to deal with them, and used a couple of Posi-Locks. Here's what that looked like:



* (Don't wince at my butchering the probe leads. This is a Harbor Freight cheapie (7 Function Digital Multimeter), and as a consequence of HF's offering them gratis, with coupon and any purchase over the years -- I'd get some cable ties or a roll of electrical tape, as there's a store about two miles away -- I have accumulated a couple dozen of these:



Besides having spares, I give them away to an experimentally inclined 12-year-old who lives next door, whenever he breaks one.)

Okay, back to the experiment.

I did that wire-stripping, etc., last night. I also did some trial runs of different methodologies last night, without starting the car, which probably didn't do the battery any favors, but c'est la vie.

In any event, I finalized(?) my test runs this morning, and here's the sequence of what I did:

1) Hooked the meter up to the jumper posts under the hood, and turned the meter on.

2) Carried the hooked up meter Into the car, mounted it with a vent-phone-holder next to the MFD, turned the ignition to the Accessory position, and observed for a while.

3) Opened the garage door with the HomeLink button (at c. the 43-second mark).

4) Started the engine, and closed the car door. (I had hoped to compare the MFD's alternator output readings with the multi-meter, but the MFD display just showed that the hood was open, and, unlike the door, I didn't want to close the hood on the leads. Oh, well. If this is really important to someone, I leave it as an exercise for the reader.)

5) Turned off the engine, all the way.

6) Put the ignition in the Accessory position again, and observed some more.

7) Got out of the car, and watched the meter, while the inside lights, taillights, etc., went out.

Some background notes:

A) This was done with our '18 S, which is now c. 27 months post delivery, and has 37,000-something miles on it. And because it's our daily driver, it's never been on a charger.

(I have a couple of PulseTech Xtremes -- XC100-P Xtreme Charge 12V Battery Maintenance Charger Desulfator -- for my motorcycles, etc. I've used them on our Camry, and it's probably time that I put one on the Macan, if it will be unused for a day or so. BTW, PulseTech talks a good game -- desulfation and suchlike -- on its web site. They have no switches to set, but I don't know whether that's because they're really sophisticated, and so figure out a battery's needs by themselves, or not really sophisticated, using a one-size-fits-all approach. They seem to do an excellent job vis-a-vis the bikes and my riding lawnmower.)

B) As I said, that HF meter is probably a far cry from a $200 Fluke or something like that, but I can't find the specs anywhere. They seem to work fine to me, yield repeatable results, and so forth.

Also, there has to be some voltage drop across my long-lead fabrication. Each lead is about eight feet, from meter to alligator clip, of, I think, segments of 14- to 18-gauge wire.

The Results:

If you have two minutes and fifteen seconds to spare, here's an expurgated video of those sequences I described above:


(If the embeddedness doesn't work, because of some security conflicts, or pop-up blockers, etc., you can just put vimeo.com/388249756 into your browser's URL field.)

Some observations on that:

- The under-hood-only battery reading could be a little higher, certainly. As I said, maybe it's time to let a PulseTech have its way with the battery for a day or so (it took about that long on the Camry, every year or so; on my smaller motorcycle batteries, I plug in after coming home from a ride, and it takes about 10 - 15 minutes to go to its float state).

- The MFD reading does change during the testing, dropping down 0.1 VDC at times. Thus, for instance, it doesn't just take a single snapshot of the battery when you use the Accessory position. Instead, it seems to be an active readout.

- Further, the MFD seems to read roughly 0.3 VDC higher than the meter, and they seem to move in sync. As I say, those leads were long, and also I don't know the accuracy specs of the meter. By the way, you may notice that I had the meter set to its 0 - 20 VDC scale, i.e., it was optimized for this test.

That's my story. You may have your own interpretation of all this, certainly, but to me it indicates that the MFD voltage display, with the ignition in the Accessory position, is actively displaying the battery's voltage output more or less in real time.

That's all I got.
 

· Registered
Joined
·
32 Posts
Just bought a CTEK MUS4.3 to charge up my 2020 S, which mode should I use? Snow flake or regular battery mode?
I connect it directly to the charging posts under the hood. When I selected battery mode, stage 4 lights up, when I used Snow flake mode, stage 6 lights up.
I experienced the same thing with a new Ctek MUS4.3 Test & Charge. The problem is you need to have both Regular Battery and Snowflake selected (lit) at the same time. Press mode until you get to Regular Battery but keep pressing Mode (don't lift) until the Snowflake lamp lights. It's not explained what the charger is doing with just the Snowflake lamp lit. The user manual is not very clear on this.
 

· Registered
Joined
·
4,531 Posts
I was reading this thread and maybe I am not following the issue that is being addressed here. I have a 15 S with 44k miles so I don't drive that much. My office is less than 10 miles from my house so many times I don't have a chance to warm the car enough. I live in MN and we get temperatures of -30F sometimes and below 0F for a good 4 months/year every single day. My point here is that not a single time I had any issues with the battery meaning I always turned the car and the car started immediately. I did replace the battery after 4.5 years but because my SA said it was running low although I never experience any issues. I simply followed his recommendation. Thus, why are you guys buying all these stuff to charge the battery? Are you experiencing issues way sooner than expected?
 

· Registered
Joined
·
32 Posts
I was reading this thread and maybe I am not following the issue that is being addressed here. I have a 15 S with 44k miles so I don't drive that much. My office is less than 10 miles from my house so many times I don't have a chance to warm the car enough. I live in MN and we get temperatures of -30F sometimes and below 0F for a good 4 months/year every single day. My point here is that not a single time I had any issues with the battery meaning I always turned the car and the car started immediately. I did replace the battery after 4.5 years but because my SA said it was running low although I never experience any issues. I simply followed his recommendation. Thus, why are you guys buying all these stuff to charge the battery? Are you experiencing issues way sooner than expected?
As outlined in the original post, Porsche's new car warranty implies that a battery maintainer be used on cars driven less than 6000 miles per year. Since your car is out of warranty it's not as much an issue. I haven't owned my Macan (2018) long enough to experience a failing battery but if it fails during the warranty period I want to have satisfied Porsche's requirements.
I do have a 16 year old Mercedes that has exhibited problems as the battery ages. Even though the car starts fine other issues would pop up, like the headlight leveling system getting out of whack and sensors throwing false malfunction messages, etc. Also using a maintainer extends battery life.
 

· Registered
Joined
·
4,531 Posts
As outlined in the original post, Porsche's new car warranty implies that a battery maintainer be used on cars driven less than 6000 miles per year. Since your car is out of warranty it's not as much an issue. I haven't owned my Macan (2018) long enough to experience a failing battery but if it fails during the warranty period I want to have satisfied Porsche's requirements.
I do have a 16 year old Mercedes that has exhibited problems as the battery ages. Even though the car starts fine other issues would pop up, like the headlight leveling system getting out of whack and sensors throwing false malfunction messages, etc. Also using a maintainer extends battery life.
Got it. I am just surprised many folks would drive the Macan less than 6k miles per year.
 

· Premium Member
Joined
·
7,168 Posts
Who has a relatively new Macan with a new battery? Just turn the key to accessory (turn on accessory but not crank the engine) to see if the battery voltage display shows around 12.1v.

My 5-year old battery shows 12.1v.
 

· Registered
Joined
·
1,752 Posts
Got it. I am just surprised many folks would drive the Macan less than 6k miles per year.
Just bought my macan a week before Christmas. For the first few weeks after I bought it most of my trips were short, less than 5 miles And some days I Huhhhhh( did not use it at all. Occasionally I started getting low battery messages in the MFD. I was familiar the use of Battery Tenders on motorcycles and other vehicles not used frequently and how it can extend the life of the batteries. Expecting that a new battery for a Macan would not be cheap, my interest in chargers was peaked.
 

· Administrator
Joined
·
11,990 Posts
Discussion Starter · #50 ·
...AGM batteries are not designed to be charged by an alternator in a car, rather the alternator is strong enough to maintain the charge but not charge it,
This was a post from two years ago in another thread. Anyone else know anything about this? Is it true the alternator cannot increase the charge of the battery but only maintain what exists, presuming you drive the minimum 6,000 miles/year? I never heard nor read this anywhere before.

If true, it explains the need to throw the battery on a charger once in a while.
 

· Registered
Joined
·
32 Posts
This was a post from two years ago in another thread. Anyone else know anything about this? Is it true the alternator cannot increase the charge of the battery but only maintain what exists, presuming you drive the minimum 6,000 miles/year? I never heard nor read this anywhere before.

If true, it explains the need to throw the battery on a charger once in a while.
This from the Optima website:
 

· Premium Member
Joined
·
7,168 Posts
Does that mean if the resting battery voltage is above 12v there is no need to use a tender to charge a battery?
 

· Premium Member
Joined
·
757 Posts
My second Porsche was a Boxster S. I had a company car so I didn't drive the Boxster very much. The battery died. Because I didn't keep the Boxster on a charger Porsche refused to honor any kind of warranty. Now I drive my Macan more.
 

· Registered
Joined
·
3,735 Posts
Does that mean if the resting battery voltage is above 12v there is no need to use a tender to charge a battery?
12V = < 50% charged. Not at all good.

Text Line Font Number Parallel
 

· Registered
Joined
·
3,735 Posts
Performed Science Experiment...
...First, I cobbed up some long leads for one of my multimeters. I used some extension leads with SAE connectors that I had lying around in my miscellaneous electrical box, snipped off the pointy probes from a multimeter* so I wouldn't have to deal with them, and used a couple of Posi-Locks. Here's what that looked like:
...
Thanks for doing this.

Would you please do this quick and easy test?
1) Again use your long lead MM to check battery voltage @ the under hood jump start terminals & then disconnect it.
2) Get your standard (short lead) MM & recheck V.
Are the readings the same?

If so, you proved that the long leads did not adversely affect the accuracy of your MM.

Your MM readings seem to show that your Macan battery is only ~ 30% charged! (See my posted voltage chart above)

Will a 92Ah battery @ only 30% charge still starts the Porsche Macan? IDK. If you MM readings are correct the answer is YES!
Surprising.

I have charged my Macan battery measured with MM @ under hood battery terminals to 100% several times & recently to 95% charged.

The idea that "My battery is fine" or "Never gave me any trouble" based on the fact that it has always started the car, while a common sentiment, is not really an indication of battery health. I'm sure every stranded motorist with a dead battery thought just that... until it failed to start the car.

I think the reason so many Macan owners are interested in this thread about charging & replacing the Macan battery is many of us do not wish to pay Porsche $700-$800 to replace our batteries when they fail bc we think it is a rip off when a great AGM battery of = or > specs can be purchased for $150-$300.
 
  • Like
Reactions: JoeInBucks

· Premium Member
Joined
·
7,168 Posts

· Administrator
Joined
·
11,990 Posts
Discussion Starter · #57 ·
This from the Optima website:
Thats says it can't recharge from dead. The post above says that can't charge the battery all, just maintain it. I can believe that if its winter, a short trip, heater on, heated seats on, lights on, that the alternator takes a certain amount of time to just get back the energy to recover from starting and might not have enough time to charge further. But I don't see that, if given enough running time, it can't raise the state of the battery to a full charge.

This problem does not seem to happen with other car makers cars to the same extent. Whats going on.
 

· Registered
Joined
·
2,583 Posts
Thanks for doing this.

Would you please do this quick and easy test?
1) Again use your long lead MM to check battery voltage @ the under hood jump start terminals & then disconnect it.
2) Get your standard (short lead) MM & recheck V.
Are the readings the same?

If so, you proved that the long leads did not adversely affect the accuracy of your MM.

Your MM readings seem to show that your Macan battery is only ~ 30% charged! (See my posted voltage chart above)

Will a 92Ah battery @ only 30% charge still starts the Porsche Macan? IDK. If you MM readings are correct the answer is YES!
Surprising.

I have charged my Macan battery measured with MM @ under hood battery terminals to 100% several times & recently to 95% charged.

The idea that "My battery is fine" or "Never gave me any trouble" based on the fact that it has always started the car, while a common sentiment, is not really an indication of battery health. I'm sure every stranded motorist with a dead battery thought just that... until it failed to start the car.

I think the reason so many Macan owners are interested in this thread about charging & replacing the Macan battery is many of us do not wish to pay Porsche $700-$800 to replace our batteries when they fail bc we think it is a rip off when a great AGM battery of = or > specs can be purchased for $150-$300.
Nag, nag, nag. Actually, it's a good thing you had me do this, because it reinforces my overall conclusion in post # 43, above.

Okay, no videos today, just some pics. Here's what I did this morning, a few minutes ago:

1) Opened the door, unlatched the hood, waited for all the lights to go out, and hooked up the meter, with my 8' leads, to the jumper posts:



The reading was c. 12.1 VDC.

Yesterday's reading was c. 11.8 (see video), but as I noted yesterday I had been playing around with testing methodologies the night before and that morning, and perhaps all the lighting action, steering wheel adjustments, etc., had not done the battery any favors.

2) Switched to the leads (c. 3') that come with these multimeters:





This bumped the reading up to c. 12.2, i.e., I gained about 0.1 VDC by dropping 5' of lead length.

3) Swapped in a "new" multimeter.

I had to dip into my stash of "new" multimeters this morning (all of which are actually several years old), in order to get a fresh set of factory pointy-probe leads for the test above. Recall that I cut off the probes of the other leads yesterday.

So, as long as I had opened that package, I decided to check out a second meter, and used my purpose-built 8' leads with it:





And lo and behold, this second meter reads c. 12.5, i.e., about 0.3 VDC higher than the meter I used yesterday!

That's particularly relevant because recall that I noted yesterday, with respect to the in-car comparison with the MFD, the meter was reading about 0.3 VDC lower than the MFD's display.

4) Next, I carried the new meter into the car, turned on the Accessory position, and did today's MFD-vs-meter comparison:



The meter was jumping around a bit, but was basically reading c. 0.1 VDC lower than the MFD readout. And if you add another 0.1 VDC -- the result of using shorter leads; see step 2, above -- than there would be spot-on agreement.

Note also that both readouts are c. 0.4 - 0.5 lower than the underhood reading. As @jzwu noted (post #51, above), the battery is now under load, what with the dash and overhead lights on, etc., so that makes sense.

The bottom line of all this is that, IMO, it further confirms that you get a real reading -- minus half a volt or so, because of the "under load" situation -- when you get in the car, turn the ignition to Accessory, and check out the relevant MFD display.

5) Last, I discovered in the packaging, after getting out a "new" meter, that there is a spec section in the included paperwork:



The relevant info is that in the range we're talking about, the alleged accuracy is "1%±2D." I'm not an engineer or spec writer, but I think that means that the meter, in our 12 VDC realm, is accurate to ±0.1 V ... ± the last two digits. At least, I think that's what "2D" means. Put together, that's about a whole volt. (In my defense, note that I use meters almost exclusively for motorcycle electrical farkles, and all I'm really interested in is whether I made a valid connection, did I hook up a relay with the correct lugs, that sort of thing ... as opposed to caring about actual voltages.)

If this second meter is more a reflection of reality than the first meter, it also means that my 2+ year-old battery is in the 80 - 90% state-of-charge range, per the post by @iconoclast (#55, above).

That's today's report.
 

· Premium Member
Joined
·
7,168 Posts
So the MFD showing of battery voltage at 12v and above means the battery is good.
 
41 - 60 of 582 Posts
Top