# car batteries - why do they still suck? **URL:** \ **Category:** Factual Questions\ **Created:** [August 31, 2011, 4:51pm UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761 "2011-08-31T16:51:12Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [August 31, 2011, 11:04pm UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/21 "2011-08-31T23:04:28Z")
> [@Max\_Torque](#): > > Tell me about it. Car batteries are a favorite target of drug users and general thieves hereabouts. They steal them and sell them to the local scrap dealer who knows they’re all criminals, but never asks questions. Pain in our collective asses. A partial solution to that: here in Minnesota, we passed a law requiring scrap dealers to get valid state ID from each seller, and to keep a copy of that in their records. If the dealer doesn’t get ID, accepts an invalid ID, or fails to keep a copy of the ID, they can be charged with a crime, like any other fence. This has helped to reduce this kind of stuff. Previously, we had some thieves saw off the arms & head of a bronze sculpture in a park, and take them to a scrap dealer, who bought them – no questions asked! ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [September 1, 2011, 12:06am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/22 "2011-09-01T00:06:14Z")
Most batteries are sealed today…so you never add water or do anything (except keep the terminals clean). But in years past, car mags used to carry ads for mysterious additives (VX-70?), that were supposed to magically resurrect dead batteries-were these things basically snake oil? I had my OEM battery fail last November-I came out of a store, and the engine wouldnot turn over-no hint of a problem. I sallped in a WalMart battery, and no problems since. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [September 1, 2011, 12:55am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/23 "2011-09-01T00:55:29Z")
> [@Kiwi\_Fruit](#): > > Exactly. I’ve just replaced the original battery in my car. 5 years old and it went from being perfectly fine to dead overnight. Past experience tells me don’t bother recharging even partially ‘dead’ ones because they’ll just fail again very soon, and when it will cause lots of inconvenience. > [@flano1](#): > > perzackerly! > > modern batteries just die. no warning. This. Modern batteries ain’t like 10-20 years ago. The don’t run down, then recharge, drive another year, etc. When they die, they’re dead. Get used to it. ---
**Author:** ![Romeo\_and\_Whatsherface](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@Romeo\_and\_Whatsherface](https://boards.straightdope.com/u/Romeo_and_Whatsherface)\ **Post date:** [September 1, 2011, 1:07am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/24 "2011-09-01T01:07:03Z")
Would it be a good idea to just pop in a new battery as the old one nears the five year mark, or would it be wasteful? Is there a practical reason why vehicle batteries can’t be manufactured to indicate somehow that they were running out of juice? It would sure save headaches. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [September 1, 2011, 2:08am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/25 "2011-09-01T02:08:48Z")
It would be wasteful. I’ve had plenty of batteries last more than 5 years. The main practical reason you can’t have one that indicates how much use it has left in it is cost. You can however take the battery to ye ol local auto parts store and have it tested. Many places will test it for free since if it tests bad, it’s an instant sale for them. ---
**Author:** ![obbn](https://avatars.discourse-cdn.com/v4/letter/o/d6d6ee/32.png) [@obbn](https://boards.straightdope.com/u/obbn)\ **Post date:** [September 1, 2011, 2:36am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/26 "2011-09-01T02:36:08Z")
> [@Romeo\_and\_Whatsherface](#): > > Would it be a good idea to just pop in a new battery as the old one nears the five year mark, or would it be wasteful? Is there a practical reason why vehicle batteries can’t be manufactured to indicate somehow that they were running out of juice? It would sure save headaches. There is a practical way. Your instrument cluster should have a voltage gage. When you turn the key to the ACC position it will read the voltage from the battery. Not an exact measurment for sure, but should give you an indication of the health of the battery. Once the car is running the alternator is charging the battery so the gauge wouldn’t give you the reading from the battery alone. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [September 1, 2011, 2:40am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/27 "2011-09-01T02:40:53Z")
> [@Romeo\_and\_Whatsherface](#): > > Would it be a good idea to just pop in a new battery as the old one nears the five year mark, or would it be wasteful? Is there a practical reason why vehicle batteries can’t be manufactured to indicate somehow that they were running out of juice? It would sure save headaches. the only practical thing they can do is what some already do; e.g. put a hydrometer in one of the cells. It gives you a rough idea of the state of charge by showing how much of the electrolyte is sulfuric acid vs. how much is stuck on the plates as lead sulfate. the problem is that it only shows one of the six cells, and it can’t indicate shorted/broken/bad plates or any other failure mode. ---
**Author:** ![Romeo\_and\_Whatsherface](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@Romeo\_and\_Whatsherface](https://boards.straightdope.com/u/Romeo_and_Whatsherface)\ **Post date:** [September 1, 2011, 4:14pm UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/28 "2011-09-01T16:14:26Z")
Thank you for the helpful info! ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [September 2, 2011, 12:08am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/29 "2011-09-02T00:08:20Z")
> [@Romeo\_and\_Whatsherface](#): > > Would it be a good idea to just pop in a new battery as the old one nears the five year mark, or would it be wasteful? Is there a practical reason why vehicle batteries can’t be manufactured to indicate somehow that they were running out of juice? It would sure save headaches. > [@engineer\_comp\_geek](#): > > It would be wasteful. I’ve had plenty of batteries last more than 5 years. I disagree. Of course, it all depends on how much money you have and how much your time is worth vs. inconvenience. If a new battery for your car costs $100, then you’re talking $20/year to own a battery. If you made it through five years, get a new battery. Sure, if it make it through another year, then you wasted about $20. If it doesn’t, and you’re getting ready to go somewhere(work, trip, anything) and your battery is dead, it only cost you $20 to not have to have a hour or two of your time wasted. I’ll take the $20 option every time. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 2, 2011, 4:30am UTC](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761/30 "2011-09-02T04:30:36Z")
> [@yabob](#): > > I’ve become convinced that the manufacturers all put crappy batteries in cars as original equipment, probably to save money. Upmarket and economy marques alike. I’ve seen this scenario several times: > > 1 - buy new car. > 2 - battery craps out in 1 - 2 years. > 3 - replace with battery from auto parts store. > 4 - replacement lasts until car is sold. > > Batteries, of course, are generally not covered under new car warranties. So back about 10 years ago, Volvo used one battery supplier for both new and replacement batteries. The OE battery was molded in White plastic, the replacements were black. I had technicians swear that the white batteries were shit, and the black ones were awesome. Same battery. Also with Volvo the battery is covered by the 4 year 50,000 mile warranty so there was no advantage to putting in a battery that only lasts 1 or 2 years. > [@Stink Fish Pot](#): > > This was a maintenance free battery, and it was a brand new battery in a two year old car. > > Now, the one thing I did do was leave the battery connected and it sat for an extended period of time this summer. This was not planned, but just worked out that way. Perhaps this was the reason for the battery draining. Still, I would think that a battery that is just keeping the car in a non-running state, where the drain on the battery would be minimal, it seems rather surprising that it died. Completely. Drained out. > > Question. If I want to avoid this in the future, which terminal should I remove from the battery while the car sits? The positive, the negative, or both? > > Thanks New cars have a fair sized parasitic draw (things that use power while the key is off) All the on-board computers, radios, alarms all consume power. Depending on the car 2 months could put even a new battery down. BMW had a law suit a number of years ago, customer did not drive his car but about 1X a week, after Og knows how many batteries going dead, he asked for a buy back. BMW took him to court, they lost BIG time. > [@filmore](#): > > Are you in the South? It’s been really, really hot this year. I’ve heard that heat can kill a battery. I’m not sure why. Heat kills batteries. The kicker is the damage often does not show up until the weather is cold. The hotter the environment the battery lives in, the shorter its life. > [@engineer\_comp\_geek](#): > > I suspect that a lot of car manufacturers these days are putting in very lightweight and cheap batteries, partly to save cost and partly to save weight. Maybe one of our resident car expert dopers can chime in and say how often they see newer batteries fail compared to replacement batteries. Can’t speak for all car makers, but Volvo doesn’t do this > [@](#): > > Cars vary, but in general I think modern cars do tend the drain the battery a lot faster when turned off than an older car. You’ve got some power being drained to keep your radio from losing its memory, and the car’s engine computer also has to take some power to retain its settings as well. If the car has a wireless remote for the alarm or just to unlock the doors then that takes some power as well. > > In my experience, most cars will go a couple of weeks without being started with no problem. After that, it depends on the car. Some will kill the battery after a couple of weeks, some will last a couple of months before killing the battery. Every computer in the car draws some power as does the alarm. Car makers work very hard to minimize parasitic draw, but it is a huge issue. There is a constant battle inside the car companies with the battery guys not wanting any draws, and everybody else wanting their widget to get some power with the key off. > [@](#): > > I think most folks disconnect the positive, but it really doesn’t matter. You can disconnect either one. Unless you are working on an OLD British car, always disconnect the negative (ground) or run the risk of getting an impromptu lesson in arc welding when your wrench touches some piece of metal in the car. See post #14 > [@](#): > > As was already mentioned, you can also use a plug in battery tender. > > Depending on how long the car is going to sit, you may want to add some fuel stabilizer to the gas tank and put the car up on jack stands so that the tires don’t develop flat spots. Good ideas > [@obbn](#): > > There is a practical way. Your instrument cluster should have a voltage gage. When you turn the key to the ACC position it will read the voltage from the battery. Not an exact measurment for sure, but should give you an indication of the health of the battery. Once the car is running the alternator is charging the battery so the gauge wouldn’t give you the reading from the battery alone. This is incorrect. First off most cars don’t have a voltmeter in the dash. Secondly if you turn the key to accessory you have already turned on a bunch of the computers, so you are not reading the unloaded voltage of the battery. Finally, a reading of the charging voltage of the battery will give you an excellent idea of the state of charge of the battery, the problem is, I have never seen a voltmeter installed in a car that had anywhere near the accuracy needed to tell what the state of charge is. A DVOM will tell you with the state of charge in a second. > [@jz78817](#): > > the only practical thing they can do is what some already do; e.g. put a hydrometer in one of the cells. It gives you a rough idea of the state of charge by showing how much of the electrolyte is sulfuric acid vs. how much is stuck on the plates as lead sulfate. > > the problem is that it only shows one of the six cells, and it can’t indicate shorted/broken/bad plates or any other failure mode. It is much easier, faster, and less messy to measure the open circuit voltage of the battery. That will tell you everything a hydrometer will tell you with one exception. A hydrometer will tell you which cell is dead, the DVOM will only tell you there is a dead cell, but then again who cares which cell it is, if there is a dead cell, the battery is a goner. Getting back to the OP, the damage to the battery might have been done on the dealer’s lot, before he bought the car. If the car sat for a couple of months or more with no maintenance on the battery it might have been discharged and lost a fair amount of its life when he bought the car. [Previous page](https://boards.straightdope.com/t/car-batteries-why-do-they-still-suck/594761.md?page=1)