Instructables
Picture of Car Battery Goes Dead after A Few Days
This is my 2012 Hyundai Sonata. I did not drive it for ten days. When I returned home, the battery was dead. I have never had that experience on any car ever I drove.

This Instructable applies to my car, but with all of the modern electronics running in the background on today's automobiles, your car may have this problem, too. This Instructable tells about the solution to my problem, but may be helpful with a similar problem on your car, too. 

Materials needed for this Instructable--none

Tools:
  • Multi-meter with an ammeter scale capable of reading up to about three amps.
  • 8 mm socket wrench and ratchet
  • Spring clamp for connecting a small alligator clip to the battery post

Step 1: How much is the current draw?

Picture of How much is the current draw?
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I disconnected the negative (-) battery cable and connected my multi-meter between the cable and the battery post. (Check to be certain it is safe to do this on your car. I was reading the manual for another new vehicle and it seems some things need to be reset if the battery is ever disconnected.) The meter was set to measure DC amperes. Check the terminals on your meter to be certain you have the leads connected properly for the scale on the dial. The leads plug into the meter at different terminals for a current reading than they do for a voltage or a resistance reading.

With everything "off," the doors closed for a few minutes so all dome lights have gone "off," and the key removed; there is a current draw of 470 milliamps, or nearly half of an amp. At a recent visit to the nearest dealership for routine warranty service I asked about this. I was told that is normal. If I am concerned, I should connect a trickle charger when I will leave the car unattended for more than a week.  See the second photo. This is a battery conditioner we bought a few years ago for another purpose. I could mount it in the engine compartment and connect an extension cord to it when we will be gone for more than a week.

My question of the dealership was, "What do I do if I need to leave the car in an airport parking garage for a couple of weeks?" There are no electrical outlets in the parking stalls at any airport garage I know. 
 
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Prosia609 months ago

Dear Phil B,
Thanks for your info.
Personally I think that your car is Azera/Grandeur codename:HG not a Sonata!
Please be informed that even if you park your car for 2-3 days(not such a long time like in the airport as you said), this symptom will happens.
Yes you are right. that current is so much.
But based on my experience, your Instrument Cluster is leaky. Reason is that if you pull out Memory1 fuse(which feed up cluster as well) where is in the passenger compartment fuse box, mentiend dark current would drop to half.
So, I recommend you to replace your cluster with a healthy one.
And after that tell the dealer to do variant coding for it.(if not, the language will be in Korean not English).
Regards,

Phil B (author)  Prosia608 months ago

Thank you for your comment. I can assure you my car is a Sonata. I have left my car unused for a few days and the battery still started the car. I read on a Hyundai owner's forum that owners of some models had problems with a depleted battery that was traced to a design flaw in the car's radio. I did not find anyone complaining of an abnormal electrical drain in the instrument cluster. From what I have read, newer cars have a lot of functions governed by the car's computer that run continuously in the background, even when the car is not running, so that a heavier current drain is normal. The dealership did check my battery and charging system. Those are normal.

pourboy1 year ago
2000 Corvette (30mpg BTW) started doing this 2 years ago, never have been able to track down the cause, so I bought a knife switch disconnect to put on the battery, which works great.

Google for
car battery knife switch disconnect
Phil B (author)  pourboy1 year ago
A knife switch would be a good alternative if some feature like I described is not built into the car. There would be an investment of time and money.
iceng1 year ago
A new thought on this lost memory fiasco matter.

There may be a collusion between  Hyundai and the battery mfg to perhaps sell more of something.
Phil B (author)  iceng1 year ago
My theory is that Hyundai wants to sell its roadside assistance service, which carries a subscription fee after an initial "free" period. My wife signed us up for AAA a couple of years ago. (My preference was always to do preventative maintenance and to carry a few tools. That approach has worked for me over more than four decades, even with some older high-mileage cars.) When the Hyundai salesman asked if I wanted Hyundai's roadside assistance service, I said we already have AAA, a GPS, and we have cell phones. He agreed we were well-covered without Hyundai's service. But, consider the response I got from Hyundai of America. Instead of warning owners about the memory fuse as a preventive measure, they want to talk about enrolling in their roadside assistance service.
iceng Phil B1 year ago
Very informative, just another greedy company.

The switch idea sounds good too.
ironsmiter2 years ago
sad. this is just really really sad.
On my old beater car, I start it up, and run it for a while every MONTH.
and not because the battery will go flat, but to keep the moving parts loose and lubed.
As for battery drain, once I found the grounded short, and fixed it... the only way the battery is even partially drained(much less dead) after a week is if I left the parking lights on(dead battery in ~22 hours). So... your brand new car drains the battery 7 times slower than my 15 year old car with the lights left on. I think we found a problem

and flat in a week? REALLY? The SO's 2010 Ford escape has around a 45mA draw when parked and off. I think there's something fishy at that particular dealer. Or maybe it's just that particular car model?


I think, as a stop-gap measure, I would seriously have to consider replacing that fuse with a toggle switch. Seems SO much easier.
So weird that for 1 week worth of storage they make you disconnect the audio and lighting, just so you'll be able to start the car when you get back. Is there room under the hood to run a dual-battery set-up?
Phil B (author)  ironsmiter2 years ago
The rate at which current is drawn from the battery is a surprise that was not mentioned when I was purchasing the car after doing a lot of comparisons with several other models, some of which also had some surprises. For example, I strongly considered a VW Passat TDI, but there were two nasty surprises I discovered on it. The engine requires seven gallons of auto grade urea every 10,000 miles to keep nitrous oxides in the exhaust low, and auto grade urea costs around $7 a gallon or more. The other surprise was the high-tech DSG transmission used in those cars is supposed to have $800 in service every 40,000 miles. If a home mechanic wants to attempt this service, a $125 kit is necessary. The advertising brochures do not mention those things.

As much of an unpleasant surprise the potential dead battery is, I am glad to know there is a relatively quick disconnect in the form of this memory fuse. At least there is a way for me to leave the car unattended for several weeks without needing to call for someone with jumper cables or a tow. My main pain now is wondering why the dealer did not seem to know about this.

The space under the hood is full. I first looked for a place to mount the battery conditioner pictured in step 1 and struggled with that. There is definitely not enough space for a second battery. As for a toggle switch, I would need to get behind a fuse panel mounted low in the dashboard and then find the right wires.

As I mentioned, owners of several makes and models are having problems with batteries that go down in a few days. Not all appear to be design problems, but faulty components. But, a big question for me concerns my friend who has had two of these cars. He says he has left them for more than a week and the battery was fine when he returned. My dealer ran a detailed diagnostic process on the battery and charging system and found everything as it should be. That does not answer the question of a faulty component downstream that is sucking juice. A few years ago the Hyundai Azera had a faulty radio that easily shorted to ground and caused dead batteries.

Right now I am assuming I may simply be dealing with a new reality.
One thing that comes to mind as I read this discussion is the delar's experience with cars on his lot. Do they go out and start every car once a week? Maybe- to shuffle them around for display purposes.....

At the dealership where I work (non-Hyundai), I know for sure there are cars that sit for more than a week without being started.

Not to be panning Hyundai here, I just am a little suprised that the dealerships seem never to have run across this problem in the operation of their car lots.

Phil B (author)  Scanner21 year ago
I had the opportunity to go to The SEMA Show in Las Vegas in early November. There I stopped at the Hyundai booth and talked with a test engineer. He was very sympathetic and did not blow me off as I had expected he might. He did say the dealer have cars on their lots for a time, as well as dealing with cars arriving from a distribution point. The memory fuse is for dealers to use in order to keep fresh batteries in cars on the lot. He also said turnover is a big problem at dealerships and it is difficult to keep the right information in the heads of everyone who should know certain things. I did also talk to a friend who once trained to be a Hyundai salesman, but now works in a Toyota service department. He thought Hyundai's policy on all of this is quite humorous. I do not know what Toyota does, but they apparently do not have these problems. He did say his sales training at Hyundai mentioned nothing about the memory fuse. Thanks for looking and for your comments.
iceng2 years ago
So, I gather the intelligent dome light + control is always sucking 470ma...

What an outlandish design fiasco ##!!@@??..................

Most EEs can design a  self turn-off that draws No further power and
a restart magnetic reed switch that needs no power to activate a uP...

A
Phil B (author)  iceng2 years ago
The yellow plastic fuse holder encases a 10 A and a 15 A fuse. The 10 A fuse is marked "Room" on the fuse identification chart and seems to control the dome lights and dashboard lights plus whatever else. The 15 A fuse is identified as the "Audio" fuse. I removed the 10 A fuse from the yellow holder and inserted it alone into its socket. The current draw was 330 milliamps. So, I figure the audio circuitry draws 140 milliamps when in a state of rest. When I open and close the door so that the dome lights are on, as well as the dashboard lighting, the current draw shoots up to 2.99 amps. until the dome lights, etc. shut off in a couple of minutes. 470 milliamps is the constant draw with both fuses in place. The dealer claims the computer circuitry draws the nearly half of an amp. in current.
iceng Phil B2 years ago
OMG ( Oh My Goodness ) That suggests that at the airport parking lot
your car alarm will be non-operative !

A
Phil B (author)  iceng2 years ago
I am not sure about the alarm. It could be inactive. I am more concerned about not being able to start the car. I tend to buy and drive cars that are seldom stolen, and I do not leave valuables in plain view.
As a brainstorming idea- you could leave a charged jump pack in the trunk for when you return....
Phil B (author)  Scanner21 year ago
That certainly is an option. I think a jump pack is about $100. I expect it would become one of those things like a spare tire. Everyone knows they need to be kept aired, or, in the case of the jump pack, charged; but, no one gives it much thought until it is needed in full working order. Since posting this I have left the car twice for ten days or slightly more each time. I pulled the memory fuse each time and the car started just fine when I returned.

Also, I talked with a neighbor who drives a Mercedes station wagon. He has the same battery drain on his car.
jolshefsky2 years ago
That's 6 watts draw with the car off which is astonishing. If you wanted to keep the battery topped up with a solar charger, you'd need 6 watts * 24 hours = 144 watt-hours of energy each day, and if you get an average of 4 hours of noon-power sun (the low-side of average for northern climates). That means you'd need a 36-watt solar panel which would cost close to $150. Yeesh.

I once had a problem with my old Buick Roadmaster wagon where the battery would get low fast. One of the interior lights was left on: there was the door switch and the dome-switch which would turn all of them on, but also 2 map lights, 2 rear-passenger lights, and 2 cargo lights each with individual switches at the light. It was the dim one behind the driver seat which I never happened to see. Too bad it's not as simple as one of those!
Phil B (author)  jolshefsky2 years ago
In the last few days I have been doing a few Internet searches with a string like "car battery goes dead in a few days." From the hits I am seeing, it appears automotive electronics industry wide are moving toward on-board computer systems that draw more current than we were raised to think a car should. Certainly, some of those who post are looking for help identifying and fixing a defect, like a bad battery cell or an unexpected short or a faulty diode in the charging system. But, many are simply running into the reality that some cars draw up to 600 milliamps when everything is thought to be "off." For example, Ford now has a "keep alive" fuse comparable to Hyundai's "memory fuse."

By the way, I did pull down the back seats so I could see if the trunk light was "on" and I opened the glove compartment a crack to make sure its light was not "on." Neither was malfunctioning.

About four years ago I read "Physics for Future Presidents" by Richard Muller and recommend it highly. Solar cells are expensive and not very efficient. A rider in good condition puts out energy comparable to a solar cell array powering an experimental electric vehicle. You might do as well by driving a small alternator from a stationary bicycle.

Thank you for looking and for commenting.
To go on a tangent about solar ...

I installed a system on my roof — 4KW — which had a real cost of US$23,000 but I got a New York State credit and had to pay $16,000 out of pocket, and I will be getting $9,000 in tax credits, so my cost was more like $7,000. It's estimated to produce about 4,000 KWH per year for 25 years.

One thing to consider is the actual cost of electricity. I'm paying about $0.08/KWH, so the solar system produces $320 in electricity each year ($8,000 in 25 years). But I also pay $25/month just to be "on the grid" — the connection fees and such. In 25 years, that works out to $7,500. So if I were to go off-grid with this system (not a totally fair comparison), I'm up to saving $15,500. In remote locations, it often makes sense to go solar before you even hook to the grid: purchasing and installing the cable to connect to the grid is often many thousands of dollars.

The other thing that changes the game is independent electricity production. If everyone could produce their own electricity, there wouldn't be a need for centralized power plants and the massive distribution network that entails — mostly all that copper, telephone poles, and long-distance transmission lines. It's easy to nitpick the details (would a maintenance vehicle really be removed from service if individuals would require it anyway) but I think you can see how it would be radically different.

I don't know if it works out dollar-for-dollar or pollution-for-pollution or material-for-material, but it's certainly something that is a plausible alternative.
Phil B (author)  jolshefsky2 years ago
Government subsidies mean other taxpayers who do not benefit from someone's solar installation must pick up the expense. Alternative power sources need to work on their own as a thoroughly practical solution without subsidy by other taxpayers who derive no benefit themselves and without ideological commitments to an environmental philosophy to prop them up.
Solyndra any one!
Phil B (author)  SicknTwisted2 years ago
This would be a good time for me to explain a little about Richard Muller's book "Physics for Future Presidents" and why I recommended it in a response to a comment. Muller is a very popular physics lecturer at UC Berkely. The book was written before the 2008 elections in the USA as an open letter of sorts to whomever would become the President, because he would be called upon to make weighty decisions on numerous matters from energy to environment to defense, all of which would be aided by a sound basic scientific knowledge. The problem is that all of us think we know things we really do not know. Because we have wrong information we make wrong choices. Muller's book explains how things really work, what is true and not true, in several important fields. The book is apolitical completely.
Alas, all things [in the U.S.] work on government subsidies.

E.g. do you think the grid is self-sustaining?
Bill WW Phil B2 years ago
"Solar cells are expensive and not very efficient".

Boy, isn't that the truth! Have to be better ways of capturing solar energy.

Solar PV cells are 10% - 15% efficient. But if you just want to heat water directly from solar energy, effiency is easily 50%.

Phil B (author)  Bill WW2 years ago
Thanks, Bill. I marvel at all of the things transistors do, and yet, they are basically made from sand. It makes me wonder what else is under our feet that could do similar wonders, if only we knew what to do with it.
Phil B (author) 2 years ago
I made this update to the text of the Instructable on a car battery going dead or flat in a little over a week. I am posting it as a comment, too, so those who have already seen the Instructable and commented on it will be aware of the update information.

UPDATE: October 9, 2012-- A friend who owns a 2013 Sonata spoke with his dealer in a different state and city. He did not let the dealer know he is aware of the memory fuse. He asked about the battery going down in a short time. The dealer said new cars of all makes and models have so many electronics items running in the background, even when everything is "off," that the battery on newer cars will go down fairly quickly. When my friend asked what to do, the dealer advised buying a trickle charger. Then my friend asked what he should do if he needs to leave his car at an airport lot for a few weeks. He got only a blank stare from the dealer and no answer. Then my friend led the dealer a bit and asked if there would be any kind of fuse that could be pulled to reduce the current draw. The dealer said he did not know of any!
Nice job!
This made me think, that the maker of the car should have maybe hidden a (vacation) switch....
Phil B (author)  SlickSqueegie2 years ago
Thanks.
stroland2 years ago
Thanks Phil. Good info.
Phil B (author)  stroland2 years ago
Thank you. Thanks for looking.
Ray-l-l2 years ago
My wife's 2008 Santa Fe has the same issue. Her previous car was a 2001 Santa Fe. It could be left off weeks at a time with no battery drain issues. Some time in between appears to be when Hyundai made some electrical changes.
Good info about the fuses.
Phil B (author)  Ray-l-l2 years ago
Ray,

I feel guilty doing an Instructable on information that is in the owner's manual, but I would wager most owners are not aware of that memory fuse disconnect. It seems good to do an Instructable that will later show up in an Internet search by frustrated owners who are trying to figure out what in the world is happening with their vehicle. I have to say I very much like the car and have no intention of trading it. (I recently brought two pieces of concrete reinforcement bar home from Lowe's inside the car and each was ten feet long.) I assume you will check your wife's car to see if it has one of these disconnect fuses. I would be curious to know what you find. If you get the chance, ask some questions of your dealer and let us know what you were told about this fuse disconnect.
rimar20002 years ago
WOW, this is very annoying. Car vendors ignore MANY THINGS about cars. Basically, they do not care about anything but sell, sell, sell.
Phil B (author)  rimar20002 years ago
It might be interesting for people who read this to check the actual current draw on their newer cars. I expect part of the problem is that we expect our cars to have ever more features. I remember when no one had air conditioning, power windows, cruise control, and adjustable seats. Now we assume every new car will have those things.
knife1412 years ago
Wow! A half amp seems like a huge draw. I wonder if other auto brands pull anywhere near this much.
Phil B (author)  knife1412 years ago
If you do an Internet search for "car battery dead after a few days" you will turn up a number of incidents in various brands. The dealer for my car claims the computer system runs 24/7 whether the engine in running or not and says this is a normal draw. The dealer also claims the maker (Hyundai) put out a TSB so dealers could warn owners not to leave the car unattended for more than a week without a trickle charger on the battery. That is all I know up to this point.
Strange, I remember that excact same thing happening to my uncles Hyundi.
Phil B (author)  PotatoCoffee2 years ago
What year and what model does/did he have? What did he do to solve the problem? Did his dealer tell him this is normal? Please share this with him. It could be a big relief to him.

Thanks for looking and for commenting so soon.
Sorry, I think he had the 2011 model, I'm no car wiz and they look rather simalar. He has gotten rid of it now and has switched to Mazda. Sorry I thought it was the same. All the best.
PotatoCoffee
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