Battery Testing

[RWebb]

If I go to a parts store (e.g. AutoZone) and have them test my battery using one of those handheld things, how accurate are they?

I thought I had a bad battery (Optima) but 2 different places used their testers on it and said it was good...

Any possibility at all that it would test good and then have some sort of intermittent fault?

[Oh Haha]

It could but I think you probably have another issue.

Are you having a battery drain problem or no start?

[brads911sc]

The Sears Auto Center tester is good in my opinion... Not sure what Autozone uses.

[RWebb]

it was a no start - 2x

worked fine with jumper cables and another car

BTW - the testers used were a Midtronix (sp?) and an AuoMeter 220 - I think it said 200s...

[86 911 Targa]

Originally Posted by RWebb

it was a no start - 2x

worked fine with jumper cables and another car

BTW - the testers used were a Midtronix (sp?) and an AuoMeter 220 - I think it said 200s...

It's "Bentley" time.

Check your parasitic drain, and if not a sealed battery-water level.

Next check the alternator output.

As per the previous post, Sears does all of those things very well.

Good luck,

Gerry

[RWebb]

it is clearly not parasitic drain - not only is nothing on the car when stopped except a clock, but this happened after 1/2 hr of high speed driving and a 15 minute stop

with a jump start, it started right up, then I drove for 20 min. and stopped again - it would not restart right afterwards

with all the problems reported with Optima batteries in the last 10 years, I keep wondering if it is something in the Optima...

The alternaotr & Vreg. were completely rebuilt and tested just a few years ago...

[pwd72s]

Hey guys, Buy a Sept. '10 issue of HOT ROD. Page 74, article title: "A current Affair"...It explains how to bring an AGM (absorbed Glass Mat) battery back from the dead. Both Optima and Odyssey are AGM batteries. If they suffer a parasitic drain or sit long enough to get a low enough voltage, they "won't take a charge" because many conventional battery chargers can't "read" the battery to send the current.

Here's the simple trick: "When an AMG won't charge by ordinary means, simply connect a second well charged battery (12.4 volts or greater) in parallel with the "dead" unit. Positive to positive-negative to negative, then connect the charger to the pair. This will in effect trick the charger into delivering the necessary current to the discharged battery. Optima advises that normal charging should be limited to 10 amps..." -Hot Rod

Seems to me Randy partially solved his optima's charging problem when he jumped...but he simply didn't leave his optima hooked to the charged battery long enough to be efficitve.

Buy the Sept. HOT ROD. This tech bit alone makes it worth the cover price...people who worship only Porsche can ignore all the other articles, right?

[Oh Haha]

Cool tech tip, Paul.

Just last evening I re-read my 1001 tech tips book made by Hot Rod (Wayne Scraba is the author) back in the 90's.

[86 911 Targa]

Originally Posted by RWebb

it is clearly not parasitic drain - not only is nothing on the car when stopped except a clock, but this happened after 1/2 hr of high speed driving and a 15 minute stop

with a jump start, it started right up, then I drove for 20 min. and stopped again - it would not restart right afterwards

with all the problems reported with Optima batteries in the last 10 years, I keep wondering if it is something in the Optima...

The alternaotr & Vreg. were completely rebuilt and tested just a few years ago...

As per the previous post-Try Sears.

[RWebb]

not confident in the car to get to Sears; also not sure what Sears can do that the others could not if I take just the battery over

paul - thx, but I've done that before -- the main problem is that I keep this thing on a maintainer religiously & there is no reason it should have gone dead or need to be brought back

after the two episodes, I put it on a charger @ 2 amp feed for 2 days; let it sit for 4 days un-connected and then had the 2 shops test it; as noted both said it tested good, not even marginal

hence the thoughts re an intermittent internal problem...

[pwd72s]

Have you done a voltage check with the battery in the car when you're in "no start" mode? That might tell us something...

[86 911 Targa]

Originally Posted by pwd72s

Have you done a voltage check with the battery in the car when you're in "no start" mode? That might tell us something...

+1

A static voltage check, then another while cranking would tell us a lot.

[wdfifteen]

I've never encountered an intermittent battery problem. I'm not saying it isn't possible, but comparing the complexity of a battery to the complexity of the rest of the starting system it seems more likely that the problem is elsewhere.
Do you have another vehicle to swap batteries with? That would give the definitive answer.

[RWebb]

static voltage check = fine

also fine as part of the 2 tests done at parts stores

have not done a test while cranking - hard to do alone but may try tomorrow

[pwd72s]

Originally Posted by RWebb

static voltage check = fine

also fine as part of the 2 tests done at parts stores

have not done a test while cranking - hard to do alone but may try tomorrow

Easy to do...if you have a cigarette lighter plug in...just connect your multimeter to the leads of a male pulg in...read the voltage with the unit resting on your passenger seat..

Since Porsche is so "quality" that they don't feel a need for a voltmeter...the above is a handy way to check out your electrics as you drive..a good way to spot if your alternator/regulator are working as they should.

[E Sully]

Could it be an intermittant starter problem? Ground strap or connector corrosion?

[brads911sc]

have someone follow you. drive to sears... have them hook up your car to their machine. it will test the battery under load, the voltage reg, starter, alternator, look for drain, all of the things everyone mentioned. they will charge you $15 and they are using commercial grade equipment and sell more batteries than probably any single vendor in the country. The Diehard Platinum comes in our stock size, is basically a rebadged optima/AMG battery. The whole process will take 30 minutes. That is what Id do as a start.

[86 911 Targa]

Originally Posted by brads911sc

have someone follow you. Drive to sears... Have them hook up your car to their machine. It will test the battery under load, the voltage reg, starter, alternator, look for drain, all of the things everyone mentioed. They will charge you $15 and they are using commercial grade equipment and sell more batteries than probably any single vendor in the country. The diehard platinum comes in our stock size, is basically a rebadged optima/amg battery. The whole process will take 30 minutes. That is what id do as a start.

+++++++++++++++++++++1.

[brads911sc]

They will even give you handy print out that shows all the specs and actuals. At least they did when I took mine there. No need to reinvent the wheel on this one. Sounds like a bad battery to me. Batteries will routinly act like this when they are going bad... its not an all or none with most battery failures.

[brads911sc]

The other option is to buy a new battery (if more than 5 years old - definitely), install it, and then drive it into Sears for the test to make sure everything is working. Seriously, it is just too hard to do the load testing, regulator testing with and without a load, etc, when you are working on the car yourself with a $30 ampmeter/voltmeter.