Not just for highly computerized cars, I have a 97 Ranger where literally everything is manual and I don't even have a dome light anymore. There's a parasitic drain I can't quite figure out so I just make sure to start it every once in a while. Since I'm a year round bike commuter the truck can sit around for a long time, especially in winter when there's no house and garden projects. I've considered adding a manual battery disconnect, the only thing I'd lose are the pre-programmed radio stations.
I fixed a parasitic drain on my car in 408 days
81–90 of 515 posts
Re: I fixed a parasitic drain on my car in 408 days
#82South Main Auto has an excellent youtube channel with various parasitic draw videos. For those struggling, it's a good watch.
Here's one such: https://www.youtube.com/watch?v=qDqlG5bRq8k
Re: I fixed a parasitic drain on my car in 408 days
#83Earlier quoted context omitted.
> it's normal for the battery to die if you don't drive it for 3 days I've heard this nonsense a couple times now. I was incredulous at first but everyone seems to say this. What are anyone's suggestions for a weekend-only car? (I bike to work so I don't need a car on weekdays.) Trickle charge the car battery on weekdays?
You should see if there are carshare options around you. Even if you’re spending $50/weekend (which is a fair amount of driving — Communauto is as low as $3/hr), that’s still quite a bit cheaper than owning a depreciating asset with lifetime maintenance costs (not to even mention insurance and fuel).
"You will own nothing and you will be happy"
Re: I fixed a parasitic drain on my car in 408 days
#84Earlier quoted context omitted.
>there's three gazillions of wires My old math teacher would deduct points for not listing the units.
My former English teacher would question why the age of your math teacher is relevant in this post.
Who said anything about the age of their old math teacher? You've got to learn old math and new math, presumably with different teachers.
Re: I fixed a parasitic drain on my car in 408 days
#85Earlier quoted context omitted.
Really nonsense. It's true it might be more common due to all the additional modules and computers cars have now. If one goes crazy, it might drain your battery. But this is only in case of a failure. Edit: cold weather can accelerate that. If it's 'weekend only', battery should be no problem. If sometimes you leave it a couple months unused, that might be a problem. Depending on how ready you would like to be when y…
> Edit: cold weather can accelerate that. My Honda HRV dies anytime it gets below -7C. Outside, inside, driven a bunch a day or two before -- once it's cold that battery taps out. Probably a vampire drain but I suspect it's just a small battery. My old 2013 Mazda 3 starts in -25C without fail.
Could be a weak starter (and or the combination of that, a weak battery and maybe even bad ground straps).
Re: I fixed a parasitic drain on my car in 408 days
#86Earlier quoted context omitted.
> It seems like mechanics really don't like digging into the electrical part of the car... Tell me about it. I'm in a similar boat. My audi a4 has had a parasitic draw for the past 10 years. My mechanic didn't want to take the time to address it because that sort of thing takes a serious amount of time and he's always backed up. I got out my fluke and narrowed the cause to what I believe is the comfort control unit.…
The problem with specializing in these issues is that most customers will be dissatisfied when you charge them thousands of dollars to reset a minor module on their car. How many hours of shop time are you willing to pay for with no guarantee of a solution, and very few (if any) parts replaced?
Dude's been tending his issue for a decade, I bet he'd have at least those like him as a customer. In a metro he might have a pretty lucrative business. On the other hand in the metro there is probably someone who already does this work, but they are very hard to find!
Re: I fixed a parasitic drain on my car in 408 days
#87Well this is timely. I have a parasitic draw on my NC Miata. The first mechanic just replaced the battery. The second told me it's normal for the battery to die if you don't drive it for 3 days (because "cars have computers now"). It seems like mechanics really don't like digging into the electrical part of the car... but these days that encompasses more and more of what can go wrong. Without time to dig into it myse…
> it's normal for the battery to die if you don't drive it for 3 days I've heard this nonsense a couple times now. I was incredulous at first but everyone seems to say this. What are anyone's suggestions for a weekend-only car? (I bike to work so I don't need a car on weekdays.) Trickle charge the car battery on weekdays?
Yeah, if a mechanic told me having the battery die in 3 days was normal, I'd stop going to that mechanic.
Re: I fixed a parasitic drain on my car in 408 days
#88Well this is timely. I have a parasitic draw on my NC Miata. The first mechanic just replaced the battery. The second told me it's normal for the battery to die if you don't drive it for 3 days (because "cars have computers now"). It seems like mechanics really don't like digging into the electrical part of the car... but these days that encompasses more and more of what can go wrong. Without time to dig into it myse…
I saw this on the Gears and Gasoline Youtube channel: https://youtu.be/XgOowUWbCdk?t=628 -- looks like a lot of work to trace a parasitic drain.
Re: I fixed a parasitic drain on my car in 408 days
#89I found that my old (1997) Range Rover would flatten its battery after being parked outside my house over a weekend. If I didn't drive it for two or three days, it would be too flat to start.
It turns out that the BECM (body ECU) wakes up from sleep if it hears anything coming in from the RF keyfob receiver, on 433.92MHz, a standard ISM frequency. If it's not a valid fob code (and there is a surprisingly complex rolling code sequence) it'll go back to sleep after 20 minutes or so.
The oil tank gauge for my central heating had a remote sensor that... yup. Transmitted on 433.920MHz, of course.
The aerial for the keyfob is on the rear right corner of the vehicle, the oil tank for the heating was on the left-hand side of the driveway right at the back of the house, so when I backed into my driveway it was right beside the receiver.
I managed to do just fine with popping the lid off the oil tank once a month and looking inside to see how much fuel was left, having taken the battery out of the tank sender.
Re: I fixed a parasitic drain on my car in 408 days
#90I used to be a computer engineer working on embedded systems for automobiles. Quiescent current is what the normal proper draw is called for these systems when the car is off. We worked very hard getting these numbers in spec but it was hard to catch everything especially in this case where the issue is probably due to software missing the sleep state for that module. This could be from bad code or your CAN/LIN bus i…
> This could be from bad code or your CAN/LIN bus is messed up in your car. If the car had been operational for years and years, why would bad code crop its head now?
Some counter finally overflowed. And now the new value is less than the old one, which breaks something, etc, etc.