Porsche Enthusiasts Club Forum

Yeah, my boot lock works the same.

A slow charge is better than a fast charge.

So, I've done some investigating today. Used the car last night so I knew it would start today. Showing 11.8v on the battery (bit low?), started fine, then showing 14.25v (alternator good) when running. Probably would not have started left for a day or two more.

Took the battery out and put it on my new charger to see that it was showing over 80% charged. Hmmm, voltage should be higher than than with over 80% charge you would think.

So, thinking what is causing drain (if battery not at fault, it may still be!) then I remember I have a something called a CAT III on my car, a little electrickery box that's connected to the chassis via electrode pads, it pumps ions or something through the chassis and is meant to stop/slow the rusting process. This has been on the car 10+ years and I have a history of needing a new battery every year or so, maybe this is the drain. I've never been convinced it makes the slightest bit of difference as I've still had to deal with rust! Anyway, I've always left it on doing its business!

So, this time I've disconnected it, I've deoxidised the battery terminals and clamps, and put it back in. Was showing 12.1v, then started it up and got my 14.25v showing again and ran it for a bit.

I then ran a "load" test, got the Mrs to crank the car while I checked the meter, didn't go below 10v, this would seem the battery is healthy? Not an expert but it's higher then the reading the bloke in the video got so happy enough with that. To be fair his car much more modern with more electrics, but anyway, time will tell.

So, I have an almost fully charged battery, I will be monitoring daily with my multi-meter and see what's what.

Stuart

Good luck with that. There's nothing like a drain to try and find.
I use a battery disconnect. It makes for easier crawling in the boot to connect and so simple to disconnect when say doing something electrical/electronic.

This one:

https://www.ebay.co.uk/itm/264539496409 ... R6KSqISQZQ

Item number: 264539496409

See how the checks go tomorrow, and the day after, and the day after!

That looks like a good bit of kit, probably order one.

If you do, give me a shout 'cos there's a very simple way to install it. I could send you a pic..

So car left for a day and a half after a short drive. Battery showing 11.83v, over 90% charged, turned over nice and fast and started no bother.

Should I be concerned at the battery showing less than 12v? It passed a load test with flying colours and showing 14.25v started and running. Green tick (good) illuminated on battery. It apparently can also show symbols for "recharge" and "replace". It is a Yuasa 5096, 80ah, which should be more than up to the task. Maybe about 18 months old.

What are you guys seeing across the battery after the car been left for a few days?

Stuart

How about I measure it tomorrow. I doubt I will drive it before Saturday, so I could measure it on Saturday morning. I can safely leave mine for 10 days with no starting issues. Longer than that, I tend to use that disconnect device anyway.

Thanks Rob, yeah that would be good to get a comparison.

When this battery was new I could leave it over a week and it was fine.

The cold snap may have had an impact. Do you want me to test tomorrow or leave it for as long as possible? Car is in the air getting TLC underneath so it won't be moving soon. I have located at least half a dozen potential rattles. I had to take off the front apron thingy. What a pig to re-install on your own.
...and whilst I was in there... An afternoon's job turned into 3 days and counting.

Ordered that pipe from the air intake hose to the alternator direct from Porsche Edinburgh. It's never had one. Always been missing. And: ordered stainless steel replacement fine pitch M5 0.8 thread screws for the air intake box. I never couldn't stand the sight of the old ones. Plus 2 x left hand thread bolts also in stainless steel for the alternator tension bar and power steering tension bar.

Never ending!

Please take a battery reading today and give me a baseline, then another on Fri/Sat if the car hasn't moved.

I installed the alternator air feed on mine a few years ago, it makes a difference, alternator performs better when cooler.

Stuart

12.28v at the battery. I haven't started it since Saturday. My multi-meter hasn't got a max and min function so as there is no one around, I can't do it till later.

Thanks!

Mine never dropped under 10v during cranking. I don't think I have a load issue, more like a quick discharge or low voltage issue. The thing is over 90% charged.

My battery today, after approx 24 hours since last start, showing 11.77v. Admittedly all I done yesterday was idle for 5/10 mins. Still spun up quick and started on the button, 14.3v showing across the battery with car running so charging from the alternator can defo be ruled out.

After switch off today, again 10 mins idling, 12.6v across the battery, slowly dropping as you'd expect. It's dropping back to 11.77v in 24 hours, whilst being 90% + charged, that is my issue. Points to a faulty battery imo.

https://carbatterygeek.co.uk/car-batter ... rt-uk-12v/

The chart shown on the link suggests a battery at 30% charge would show 11.8v. My battery is 90% charged showing 11.8v.

On the flip side, any time I've installed a brand new battery I've never seen anywhere near 12.6v, more like 12.2v.

It's also 2 degrees outside, this will also make the battery produce less juice.

I still think my battery is faulty!!

You need a proper discharge test. Phone around some local garages, there must be a few dozen within easy reach of you. Ask if they can give you a print out.
My 75ah Bosch was declared goosed when it seemed to be okay and it was showing 11.9v. I was surprised. I got a replacement under the Bosch 5 year warranty.

Yeah probably do.

I will call my garage again tomorrow and explain my findings, if this isn't enough I will try and get a local test done.