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I fixed a parasitic drain on my car in 408 days

davidmuller.github.io

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Re: I fixed a parasitic drain on my car in 408 days

#131

Post by bityard »

jessaustin wrote: post #123
lylejantzi3rd wrote: post #96

Earlier quoted context omitted.

That's a great idea. I can't believe I didn't think of that. Thanks!

Pulling fuses is a pretty reliable way to find the relevant fuse in the first place. If the battery doesn't run down while a particular group of fuses is pulled, the one you want to pull is in that group. Start with half the fuses, then narrow down. You might have to reprogram your radio channels...

I can recommend searching for "South Main Auto parasitic draw" on YouTube. The guy is a genius at electrical troubleshooting.

His strategy isn't to pull fuses, it's to set the car sit for at least 30 minutes or so (with key off) and then check each fuse with a multimeter to see which has current on it, and then check everything on that circuit. Arm yourself with schematics and wiring diagrams, otherwise it'll end up being something of a wild goose chase.

(The idea being if you start pulling fuses, you can "reset" various computers in the car, which may show up as a false positive. It can take up to 30 minutes or so for all the various computers in a car to all go to sleep, although it's usually only a few minutes for most cars.)

Re: I fixed a parasitic drain on my car in 408 days

#132

Post by ChuckNorris89 »

stocknoob wrote: post #12
kccqzy wrote: post #7

Earlier 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?

Or disconnect the battery (you’ll have to reset the clock, etc., which is annoying).

Not great advice.

Most new-ish cars also store the dinamic engine calibration data in ECU RAM so if you disconnect the battery you can find your engine running harsher next time. So are the values of the headlights auto leveling system and other stuff.

You're also risking to reset the radio/media unit security code (on cars that aren't too new but also not super old), which if you got the car second hand and the former owner didn't save the piece of paper it came with and give it to you, tough luck unlocking it.

Re: I fixed a parasitic drain on my car in 408 days

#133

Post by explaininjs »

overthrow wrote: post #3

Well 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…

In the military, the folks tasked with Mechanical maintenance of vehicles are an entirely different branch with different training, infra, etc than those tasked with Electrical maintenance of vehicles. Perhaps we need a similar dichotomy on the civilian side.

Re: I fixed a parasitic drain on my car in 408 days

#134

Post by KingMachiavelli »

I've never understood why cars don't just cut power before the battery is too low to start. If that's too complicated then just have an option to cut all power after X hours of non-running time.

I bet the old popular theft of car radio is a root cause; cars needed to stay running to keep the alarm active and power the radio continuously so it wouldn't require the unlock code every time you start the vehicle.

It's actually pretty impressive how much power even a 200mA draw at 12V is over a few days; it's about 58 Watt-hours or 3.5 iPhone batteries per day.

Re: I fixed a parasitic drain on my car in 408 days

#135

Post by nuancebydefault »

falcolas wrote: post #125
nuancebydefault wrote: post #99

Once you find the fuse that passes the highest current, why not just place a switch button in series with it? Turn it off when exiting the car. Add an LED to show when it is on.

Personally, I'd go for a relay on a non-problematic circuit. But I also get why you might just leave it disconnected - if it's pulling a few more amps with no clear cause, what is going to go wrong with it next, and what vital system will it take with it?

Oh a relay that goes on after you turned the key would be very handy. It is rather easy to find a point where there's only a voltage present after/while starting.

Of course, when the array controlled circuit would be vital for entering or starting, this would not be an option.

Re: I fixed a parasitic drain on my car in 408 days

#136

Post by EricE »

tsgagnon wrote: post #117
ambicapter wrote: post #83

Earlier quoted context omitted.

"You will own nothing and you will be happy"

This must be the new astroturfing attack against concepts like public transportation. I've seen this phrase pop up too frequently at this point for it to be organic.

The simple may see it as astroturfing, others see it as an observation by those paying attention. I'm now living in a house I own without a mortgage because 20 years ago I bought a house and didn't rent. Utilities and property taxes are my only expenses. Yes, there is maintenance but if you don't think that's also factored into rent you are beyond delusional. Landlords aren't going to lose money out of the goodness of their hearts. I haven't had a car payment in over a decade because I take care of my stuff. The car goes in the garage; I don't fill my garage with a bunch of useless stuff I will likely never touch again (or pay someone else to store it!). Common sense stuff like the above, sadly, isn't common sense any more - so hence pithy phrases like own nothing and like it. A modern day emperor has no clothes, if you will.

Re: I fixed a parasitic drain on my car in 408 days

#137

Post by amtamt »

bityard wrote: post #126
overthrow wrote: post #3

Well 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 seems like mechanics really don't like digging into the electrical part of the car. That is certainly correct. Troubleshooting electrical issues takes a different set of skills than most mechanics are trained to deal with. Most mechanics are so busy that throwing parts at a problem is the best way to deal with issues where the cause isn't readily apparent. It's not worth their time to really dig into a difficult…

This sounds like a majority of software engineers (and their direct managers) asking to add more CPU and RAM, when software is slow, instead of analysing a problem.

I guess mechanic's time is more valuable than parts.

Re: I fixed a parasitic drain on my car in 408 days

#139

Post by legitimayzer »

overthrow wrote: post #3

Well 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 seems like mechanics really don't like digging into the electrical part of the car.

this is like saying that computer programmers don't like digging into the proprietary and binary blobs from other vendors.

I am trying to say it's not fair to blame mechanics because even if they want to dig into the electronics, the car manufacturers take active measures to prevent 'random mechanics' from digging around.

I suppose there are many rational and reasonable way to justify why this is so; probably all having some form of "because safety" and "because IP of vendors".

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