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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

#241

Post by bonestamp2 »

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…

> The second told me it's normal for the battery to die if you don't drive it for 3 days

No, this is not normal. When the cars are manufactured, they often sit for more than 3 days just to get on a train for delivery. During transport they often sit for more than 3 days.

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

#242

Post by cwillu »

MaKey wrote: post #207
jessaustin wrote: post #144

Earlier quoted context omitted.

It would take someone more skilled than I, or with better tools, to check current in a fuse box without removing fuses. Maybe I should watch that guy and get better...

AFAIK the fuses have contact points you can use to measure the current.

You can check continuity across the contact points, but measuring a 75mA current via the voltage drop across a 0.0034ohm resistance (give or take) means reading 0.2mV, which is… borderline for a consumer multimeter.

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

#243

Post by bonestamp2 »

KingMachiavelli wrote: post #134

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 act…

Cutting the power is easy, the hard part is for the car to know when/how to reconnect power when the driver wants to start the vehicle. I guess with a physical ignition switch, the mechanical motion of the tumbler could reconnect power. But, most cars don't have ignition tumblers anymore.

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

#244

Post by bonestamp2 »

fullstop wrote: post #145

"Fixed" in the same way I can "fix" a stuck key on a keyboard by physically removing it. They've circumvented the problem but are left with less than what they originally had.

Ya, keyless entry/start is a huge convenience. I'd be mad if I had to disable those features to use my car.

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

#245

Post by bonestamp2 »

aftbit wrote: post #158

I have a parasitic draw on my 2004 Honda Civic back in college. All the mechanics I went to wanted to sell me a battery or alternator. I finally bought a meter with a 10A current limit and tested every fuse each time I parked. It turned out to be an issue with the magnetic AC clutch, so I drove it for 2 more years with the fuse for that component removed.

In hindsight, you could have put a relay on that circuit that was powered by some other circuit... so it only connected the AC clutch circuit when the vehicle was on.

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

#246

Post by rconti »

kccqzy wrote: post #7
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'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?

I try to keep my cars on trickle chargers (Noco Genius 5 in my case) when not driven regularly, because regularly killing $300 AGM batteries gets expensive.

That said, I'd expect most cars should be able to manage, say, 2-3 months. It's when I exceed 4 months with some regularity that battery life starts getting sketchy.

If you're driving the car every weekend, I'd expect that should be plenty. Note that fancier cars with more electronic features don't do well when only driven short distances. If you only drive 2-3 miles at a time, you might be discharging the battery faster than you're charging it.

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

#247

Post by rconti »

yurishimo wrote: post #236
chrisdhal wrote: post #121

Earlier quoted context omitted.

My wife drives about once a week, probably less on average. She has a 2013 Honda CR-V, only 15,000 miles on it. We live in Minnesota, so have cold temps, but the car in a garage. The car always starts. We've replaced the battery once just due to longevity. Every 3 days? No way.

15k miles on a 2013 CR-V? Enjoy the last car you'll ever own! I assume you know this, but some of the maintenance items for that car are 8 years I think; worth checking the manual to find out!

Tires should be first on the list!

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

#248

Post by jakestl »

sixstringtheory wrote: post #152

Hah. I’ve replaced the battery in our Subaru Outback on average once per year, which is way too high for this environmental minded person. I just went out last night to grab something from the car and it was making a loud electrical whirring noise. I had driven it several hours prior, no idea how long it had been going. I recorded a video and it is clearly audible. I started it and turned it off again, and the noise…

Same here, 2018. Last battery replacement was 6 months, let's see how long this one lasts.

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

#249

Post by hutzlibu »

Freedom2 wrote: post #153
aidos wrote: post #147

Earlier quoted context omitted.

“path of least resistance” is very fitting.

Definitely a cool, new term! Thanks to the GP for introducing it to my lexicon.

You also might enjoy this joke then:

https://i.pinimg.com/originals/a4/c5/bb/a4c5bbd867b819a687ea...

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

#250

Post by acapybara »

jopsen wrote: post #219
nickff wrote: post #62

Earlier quoted context omitted.

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?

> 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? Imagine opening a computer software support business where you bring in your old proprietary binary programs that you got from who knows where, and the business is to fix bugs you've found. Maybe some really big enterprises would pay for that sort of thing. But I doubt it would be feasible f…

That actually sounds like a great business idea.

Bug Hunters

Extremely valuable service. I bet there'd be a lot of demand.

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