dead battery - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Lil bastard · 03-22-2008, 06:52 PM

No! Never use a load tester on the charger - you'll blow them both!

But, I still suspect the battery. Even if only a year old, there are lots of reasons a battery can fail prematurely. Manufacturing defect, hitting a pothole and breaking/cracking the plates, alternator output too high and so on.

Have the battery load tested. Test the battery with a multimeter when it's not hooked up s/b no more than 13.2volts. Hook battery back up and run car, this time when you connect the DMM leads to the battery terminals, you should see 13.8-14.2 volts, if more, the alternator diodes have probably failed and this is cooking your battery.

986chris · 03-23-2008, 04:53 PM

dealer put a new alt. when I bought the car 08-07. warranty company did a service call before issuing policy. thats how I got the new alt. & bat. Any advice on a meter, good one, make and model? Will the load test measure amps or is it a different test.

Lil bastard · 03-23-2008, 09:06 PM

No a load tester will not measure Amps that's an ameter. But for a DMM (digital Multimeter), if you're a homeowner or such, it pays to buy a good one.

Once you have it, you'll be amazed at how much you use it. There are several good brands out there. My preference is Fluke they make several models and are a well respected brand.

Mine also has a temp probe in it and that's a nice feature to have. I've used mine on everything from household wiring to my lawnmower. I figure it's saved me more than 10 X the cost over the years, not to mention hours of frustration trying to chase down electrical issues.

For a Shade Tree guy, I think the load tester I linked is perfectly acceptable. These things can range up to $400, but there's just no justification to spend that much if you''re not making your living with it. Expect to pay around $100 for a quality DMM with good features - Temp probe, audible continuity, auto adjustment (AC/DC and range), though they can be had for as little as $10.

The $10 one will suffice for a lot of people. I have been wrenching on cars since I was 13, so for me, I always looked at my tools as an investment and bought good ones. Other people's priorities are different and that's OK too.

986chris · 03-25-2008, 02:45 AM

our tool philosiphy matches. so i could use a dmm as a tire pyrometer too? which i was getting ready to buy.

Lil bastard · 03-25-2008, 06:56 AM

Quote:

Originally Posted by 986chris

our tool philosiphy matches. so i could use a dmm as a tire pyrometer too? which i was getting ready to buy.

Well, I never thought of that, but I don't see why not. It may not be as accurate as an IR Pyrometer, but then again, you're not driving the GP at Monaco either - lol. It'd be interesting to test the DMM against a Pyrometer and see how the two differ.

If you find you need more accuracy than that, you can always get a pyrometer. But I suspect you'll use a DMM much more.