Boy do I need the Brain Trust about now... Wrench question

[john70t]

Originally Posted by drew1

Sometimes ohming between disconeted battery terminals as things are switched on can find a draw.

(just a note of caution: Do not use Ohm function on a live circuit or the meter will let out extra lucas smoke.)

[Icemaster]

Any accessories installed like a dash-cam that's wired hot?

[jyl]

Useful thread. I replaced battery on my son’s Jeep XJ and new battery was dead as a doornail the next day :-( Put it on a charger this morning, going to investigate tonight. old car so hopefully the search won’t be too hard.

[ramonesfreak]

Originally Posted by Icemaster

Any accessories installed like a dash-cam that's wired hot?

I was gonna suggest this as I have to remember to turn mine off…but the camera would be obvious to you

Less obvious would be a laser jammer. Seems highly unlikely but confirm there is no laser jammer installed up front behind the grill….or even a custom install radar detector. Long shot, I know…

[drew1]

Originally Posted by john70t

(just a note of caution: Do not use Ohm function on a live circuit or the meter will let out extra lucas smoke.)

should be no live circuit with battery terminals disconneted.

[deanp]

I don't know what the charging system is like on a 2014 TDI Beetle - but I had a Mini Countryman, it ate through a couple of batteries in a short time. Would seemingly be OK, drive fine, then parking and nothing, then just dead. As it turned out it had a negative battery cable with what Mini/BMW called an IBS -Intelligent Battery Sensor that told the car when to charge the battery. I replaced the negative cable and all was good. Does the Beetle have something in the charging system like that?

[WPOZZZ]

Does it have power seats?

[blucille]

My newer cars all have to be reset via OBD scan tool when replacing the battery. Especially when you have something funky with the previous battery.

It seems these AGM batteries have a specific charge cycle depending on the age of the battery. And it seems any OBD tool can reset the battery charging to compensate for a new battery.

[pwd72s]

Originally Posted by blucille

My newer cars all have to be reset via OBD scan tool when replacing the battery. Especially when you have something funky with the previous battery.

It seems these AGM batteries have a specific charge cycle depending on the age of the battery. And it seems any OBD tool can reset the battery charging to compensate for a new battery.

Could it be something as simple as that? Hmmm. Nobody's mentioned the need to use a memory saver when changing a battery yet..

[drew1]

Originally Posted by blucille

My newer cars all have to be reset via OBD scan tool when replacing the battery. Especially when you have something funky with the previous battery.

It seems these AGM batteries have a specific charge cycle depending on the age of the battery. And it seems any OBD tool can reset the battery charging to compensate for a new battery.

Good to know, thanks for posting.

Running AGM battery in my old truck. No issues yet but I'm thinking about when present battery goes in wife's 2007 Infinity, replacing with an AGM.

Seems like the dealer that scanned for LWJ would have done the reset.

One thing I found out on running AGM batteries, if one goes dead it needs a charger that can go into desulfating mode (hope I can can it right) before doing the charge or the charge will not hold.

Hope LWJ is getting his daughter's car fixed.

[Seahawk]

Originally Posted by LWJ

Going out to measure now.

Great ideas all! Thanks!

[fastfredracing]

I find parasitic drains are often one of the most difficult things to diagnose . Sometimes, I get lucky and uncover them in an hour or so, but there have been times, where I am led down the rabbit hole and just cannot devote that kind of shop time when there are 5 more cars out in the lot waiting for service .

Here is what I would do. Remove the battery . Slide a newer toyota or honda under the battery , and roll on . Just kidding, but best of luck with that one . Larger drains. like in your case are usually easier to find .

[john70t]

^that was funny. www.givesendgo.john70tkeyboard

[LWJ]

So we are in the very long and not obvious stage!

After the car sat with 0.01 draw for a day and didn’t drop much voltage, I had daughter come pick it up.

I told her to clean it. She did. Yay!

I showed her how to measure voltage and write it down. She did. Yay again!

She mentioned error lights and said the voltage dropped to 12.45. I told her to come over to swap out the car yesterday. She shows up.

Charging at 14.3 v
Initial voltage 12.79
Voltage after 2 min load test with high beams 12.59

I called this a good result and sent her on her way with instructions to measure it today and let me know.

So. The mystery continues…

[john70t]

Get something like this, and see when it's dropping. Turn the motor with EngineOffKeyOff and maybe one spot in the alternator has a short. Move the mirrors and seats and windows. Open and shut doors and hood and glovebox. Wiggle the wiring harness. Operate radio. Move keys away and close. Yell "president bomb allahu akbar" into OnStar. Roll the car and maybe wheel sensor is shorted. Turn on lights.

Something is triggering the battery draw. Just need to recreate it.

https://www.amazon.com/Cigarette-Lighter-Voltage-Digital-Voltmeter/dp/B00UCEAKYU

[LWJ]

^^^wheel sensor???

Maybe this! It does show low tire pressure randomly. Tire pressure is fine.

Would a wonky transmitter do this?

What a great bunch of geniuses you all are.

[rockfan4]

I don't think that year Volkswagen had tire sensors, it just counts the revs using the abs system, and if it counts too many one one wheel compared to the others, it lights the light. To reset a baseline, set the tires to the proper pressure, then press and hold the TPMS reset button, it should be in the glovebox. Hold it until the car "dings".

I changed the rear tires on my Jetta and didn't reset. Everything was fine until I took a trip out of town, about an hour into the trip the car dinged and lit the light, stopped at a gas station and checked all four tires, no issues. The new tires must have been just different enough to trip the system, but it took a long time to do it.

[LWJ]

^^^There are Tire pressure sensors. One or more has failed. A clue. Perhaps.

[john70t]

Most of those should be "off" with the key off. Maybe even weird ECU activity. It is odd.
Still, remember the KeepItSimpleStupid and loose battery plates (bolted down tight?) or something simple like a visor light switch.
Make a checklist and go through everything one at a time.
There is a puzzle to figure out. You'll be an expert when it's all over.

Always wanted a Fluke DVOM but they are pricey. The other yellow brand
Inline ammeter with a peak hold and a recall history graph function display would really help find the trigger.
https://reviews.chicagotribune.com/reviews/best-multimeters Top rated is only ~$20

[LWJ]

^^^That is cool! I need that multimeter gizmo.