Parasitic draw - What are the more common culprits?
 

Dear all,

History:
Bought the car from a previous owner, car's fine, no major issues, but the battery died within the week. Previous owner told me at the point of sale that he did not drive it much, few times out of the year. So I figured a dead battery wouldn't be unusual. So I replaced it with a new one. This is my weekend car, and I drive it only on weekends. So it stays parked for ~4-5 days consecutively.

Fast forward to ~3 months of ownership. I recently came back from a 2 weeks trip to find my new battery is dead as well. So I suspect there's a parasitic draw somewhere. Took it to an alarm installation shop because I thought it would be my Viper alarm. Negative. They pulled fuses for ~1 hour and half and they cannot find the source of the draw. They're good people and definitely not one to scam customers. Shop owner has a S2000 himself and he's a little bamboozled. He asked me to check the forums and look to see the usual suspects for parasitic draw for this car. (He hasn't had electrical issue, so he can't be sure).

So, with an AP1, what are some of the usual suspects for parasitic draw? Thanks!

P.S. - I don't think it's an alternator problem. Otherwise, this new battery wouldn't be functional ~3months into it. Thanks!

How much is your parasitic draw, car locked and unlocked?

The shop forgot to tell me about the actual draw, and I believe they checked locked/unlocked as well. They even pulled the Viper alarm and switched into another one, results were the same.

I'll get a multi-meter and start going through the fuses myself. Kind of expensive to pay for them by the hour to do it. I can report the voltage next week when it stops raining.

Well its good to know for sure if there really is a problem with an excessive current draw.
You need to connect your multimeter in series to measure current (A not V), if you are unsure about this check some youtube videos or similar.
If you do it wrong your meter will blow up, do not turn the ignition on either as that will most likely blow the fuse in your meter.

They have confirmed an excessive draw, and it's definitely higher than average draw. The rain has stopped, I'll give it another 30minutes or so for the humidity in the air to subside first before going out there.

@flanders and everyone else

So, bought a multi-meter and I read up on how to use it, and what are the acceptable figures:

Interstate branded Costco battery 1 week old on my Mazdaspeed 3 - CAR OFF
https://cimg7.ibsrv.net/gimg/www.s2k...f4369b5172.jpg

Interstate branded Costco battery ~3 months old on my S2000, recharged at O'Reilly ~1 week ago - car OFF
https://cimg9.ibsrv.net/gimg/www.s2k...b8549fa17e.jpg

Interstate branded Costco questionable battery on S2000 - car ON, Looks like the alternator is working fine.
https://cimg1.ibsrv.net/gimg/www.s2k...7f8e42649d.jpg

Interstate branded Costco questionable battery on S2000 - car ON, everything ON (headlights, fan, AC, stereo, dome lights, etc)
https://cimg0.ibsrv.net/gimg/www.s2k...4fe35f3739.jpg

Interstate branded Costco questionable battery on S2000 - car OFF, ~44 - 45 milliamps. Seems within acceptable range?
https://cimg2.ibsrv.net/gimg/www.s2k...f28a2361c4.jpg



What is the typical car off drain on an AP1 S2000? Everywhere I read, ~50 milliamps is the upper limit of the acceptable range.

Lastly, I think I just got a bad battery from Costco. It's barely at 12.0 volts after sitting overnight.

Any thoughts from you experts? Thank you!

*NOTE*
That Interstate branded Costco battery on my Mazdaspeed 3 is only 1 week old and it's only sitting at 12.5 volts, that's kind of low for a brand new battery, right?

Yeah, compare the battery's voltage after just turning the car off, after a good, long drive or when fully charged. Then, in the morning --- after sitting overnight. If you have considerable drop, you'll need to pull fuse-by-fuse to find the culprit. Like this video.

But I'm only drawing ~45milliamps, and that's nearly identical to my Mazdaspeed 3 (whose battery died due to age, and the previously replaced battery started the car after the same 2 weeks I went on a vacation).

But a 12.00 v when the car is off isn't a healthy battery, right?

45mA is acceptable, mine is a bit lower than that like 30-38mA.
So unless you have something that randomly ups the parasitic drain it looks like your battery is bad.
Make sure it's fully charged then go somewhere where you can have it tested.
Otherwise a cheap test you could do yourself is to measure the voltage when you are trying to start the car.
There will be some voltage drop like maybe down to 10V but if it's much lower its a good sign the battery is bad.

Then I'll need a 2nd set of eyes to watch the multimeter for me, will update again next weekend.

Also, this questionable battery was recently fully charged by O'Reily about a week ago. So, this is fairly close to its tip top shape.