Battery Life

diver110diver110 Member Posts: 67
edited March 2014 in BMW
I very recentlyl bought a 2000 540i (the car was placed in service in 10/99). It appears to have the orginal battery, making it almost four years old. There appears to be a coding to it. If a green dot appears in a window it is fine. A black dot means charge. A yellow dot means replace. Assumnig I am looking at the right thing, the window has a black dot. I gather BMW puts the battery in the back to keep it away from engine heat and give it longer life. Should I replace the battery? What kind of life do people generally get from their batteries? Thanks.


  • bretfrazbretfraz Member Posts: 2,021
    There's no sense in tempting fate here. Have a new one installed ASAP.

    4 yrs isn't bad for a battery but everyone's experience is different so there's no real accurate gauge of battery life.
  • kinleykinley Member Posts: 854
    94 Towncar, 106,000 original battery

     95 T Bird, 66,000 original battery
  • swschradswschrad Member Posts: 2,171
    there is apparently enough anti-theft in the radio, and enough computer interlock elsewhere, that just pulling a battery out, taking it to the store, bringing back a new one and installing it leads to nasty results... mostly the radio asks for a security code you don't have, I seem to remember some have claimed other issues, like starting trouble.

    this is one thing you should be able to avoid if you have the dealer change it out, they should be cognizant of the issues.

    but you should figure out what your security codes are on radios, etc. and write them down now, while you can. see the dealer if you can't find the instructions.


    although it appears I don't have similar issues in my detroilet iron at first research, I am going to whip up a standby voltage regardless before I hook up my trailer brake controller direct to the battery. this will consist of a 12v gel cell hooked through a lighter plug to keep the radio, etc. memories alive while I fool around with the post connectors.

    there are "radio save" kits of a lighter plug and a 9-volt battery clip in auto parts stores. but if you have a hood, trunk, or door light on while you are changing that battery out, the 9v job will be dead in seconds. your general 1.5 CP bulb draws something just over an amp, so I figure a 6 AH battery from one of my computer UPS systems will do just fine.
  • jc1973jc1973 Member Posts: 63
  • alcanalcan Member Posts: 2,550
    96 Riviera, 66,000 miles, original battery.
  • nippononlynippononly Member Posts: 12,555
    last year (owned since new) 6 years old, 115K miles, original battery.

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    Depends on the car, battery placement and what the car's accessories need, too. A big car with lots of accessories in a very hot or very cold climate might tax a battery a lot more than the "average" car. Also, cars like Saab that put the battery next to the turbo (duh!), well, every two years was more than enough. Mayby a GEL battery in the trunk could go 8 years.

    Case in point---my Benz battery is over 5 years old, works fine day in and day out, but when I took it up to snow country it could not crank beyond 30 seconds (in 10 second bursts). So for 95% of my use it was good but for that 5% is was useless.

    I think 4+ years is a good time to switch out the battery if you MUST have absolute reliability under all conditions.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    Glad you said that, Shifty! I was fixin' to say something to the effect that here in Colorado, I can't hardly keep batteries for "extended" lengths of time. I suspect it has to do with the temperature extremes, and other factors as well. What I hate is my own tendency to push my (battery) luck, and pay for it royally in hardship!
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    It's interesting to note that extreme HEAT also hurts battery life. I've read that battery life sayh in Phoenix would be less than say in San Francisco (unless of course they STEAL your battery in SF, but that's another thread.)
  • cutehumorcutehumor Member Posts: 137
    my autozone battery lasted 4 yrs and 3 months and 47k miles. Here in Memphis, the summer temps get up to 95+ heat index of 110 F
  • swschradswschrad Member Posts: 2,171
    the arizona dealers take out and ship back the OEM batteries, and put in ones with good old filler caps, so the extra evaporation can be dealt with.

    I've got a couple phoenix-area transfers in the office, but have not asked them to raise their hoods yet to verify this... ;)
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    And it DO sound a little far fetched, even if Consumer Reports said it. »:o]
  • kinleykinley Member Posts: 854
    One is 9 years old and the other 8. When thirsty, give em a drink.
  • armtdmarmtdm Member Posts: 2,057
    For under $75 99% of the time it is not worth the hassle to leave it in and be stranded somewhere and have to buy one under duress. Just replace it every 4 or so years.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    It's one of those items on a car that isn't worth "stretching". Unlike some components, a battery is so critical to a car's function that without one you are basically sitting in a huge flower box. (unless of course you drive a diesel, then you don't need a battery as long as you never shut the engine off).
  • swschradswschrad Member Posts: 2,171
    somebody posted a few weeks ago that today's electronic regulators will die right now if the battery is disconnected. which could take the alternator down, depending on the type of failure.

    sure a far cry from chrysler's introduction of the alternator, in which they took the battery out of a test car, and drove it coast to coast to coast to show the alternator provided more power than anything before.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    So just exactly how do all of us experts rate the batteries? Which brand or brands is/are best? Given the chance to buy the brand of your choice, what is it and why?
  • armtdmarmtdm Member Posts: 2,057
    The Optima gel batteries are the best, can be placed upside down if necessary but way overpriced and the waranty is no better then the top of the line of the same brand, non gel.

    For me an AC Delco maint free (no caps/plugs to check level etc) and if no Delco available for engine then the best top of the line (non gel) highest CCA one I can find that fits the case at Advance Auto or Auto Zone . Go for the warranty (by that I mean the replacement free part of the warranty) the prorated portion is worthless. So a 2 year replacement free 4 year prorated is better then a 1 year replacement free with 5 year prorated.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    I too have had very good results with AC Delco batteries, and they seem to be available for most everything. I understand that Interstate may be pretty durable. Most anything made by Exide is a good, quality grade of battery as well.
  • cutehumorcutehumor Member Posts: 137
    It was a good price only 29.99 plus tax. It's the standard with 1 year free replacement. My car is 11 years old so i don't know if a 5 year battery is worth the investment. lol
    otoh, the battery is made by Johnson controls which also makes the interstate batteries. I was thinking that maybe it might be a good deal.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    Are all the Walmart Everstart batteries made by Johnson Control? Thanks for this tip. I agree that this is a big plus for the Walmart line.
  • haspelbeinhaspelbein Member Posts: 227
    ...took the 7.5-year-old battery out of my E-Class. (Yes, take out the rear bench, disconnect the venting hose, give yourself a hernia...)

    Amazingly enough, Sears sells a replacement battery that matches the CCAs and dimensions of the OEM battery for $99. It also has a pro-rated warranty up to 7 years. It makes me wonder if they really expect it to last that long.

    My original battery surely did. It still started the car reliably, but the voltage would sometimes dip during starts, resetting the clock.

    Anyhow, the new battery worked out great, and resetting the radio anti-theft is something that most owners of German cars are used to.
  • swschradswschrad Member Posts: 2,171
    the lifetime they really expect the thing to have is around the non-pro-rated free replacement period. you should see something over a 5 to 10 percent failure rate shortly after that. most non-trash batteries should go 2 to 3 years in a car with a good charger and regulator that isn't crashing across obstacle courses.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    I would agree, swschrad , to the degree that the manufacturers seem to be getting rather optimistic/deceptive with their longevity designations on automotive batteries. I think your running a bit to the pessimistic side to imply or state that a battery is only good for the non-prorated period.
  • swschradswschrad Member Posts: 2,171
    except the infant mortality for batteries dropped in shipment and the like. when that free period is over, they are starting to see claims. but the distribution is probably the (in)famous bell curve of statistics, and there should be few claims for an additional year or two, and then they start rolling in at increasing rates.

    my personal uninformed opinion, based on no particular access to industry data at all, is that any battery that doesn't last at least 3 years without abuse (bad alternator or regulator, off-road racing, jumping across the cornrow furrows, running it dry, etc.) is one that I will never buy again.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    ...of that attitude. I have had a new car battery go out on me right after the 3rd year. On the other hand, I've run a few way past the end point set by the warranty. I hope to just once buy a battery before the death of its predecessor!
  • haspelbeinhaspelbein Member Posts: 227
    Now I should really read up on my warranty. So far, my batteries have lasted far longer than 3 years. (Not that the last three years in California have been very hard on them.)
    Both the ones in my truck and my convertible are slowly approaching their 7th year of service.
  • 528iben528iben Member Posts: 1
    Not sure where other people bought there batteries, but I just bought one for my 1998 528i from the dealer for $218.00. Checked Sears and other stores first but none carried the battery that’s in the car (840 volts). The largest I could find was 805 volts.

    See my post “528i Starting Problems”. The new battery, so far seems to have resolved my 6 month random no start problem which several BMW dealers could not and did not even thing of the battery. The battery was the original that came with the car.
  • andre1969andre1969 Member Posts: 25,317
    I've actually done that a few times with my Mopars...pull the battery out while the car's running, and then drive it. Don't ask me why, exactly, I did it...looking back I can't remember! I never tried it with my DeSoto though. That car uses a generator. Would it not make it without the battery?

    Were Chrysler alternators better than GM alternators, back in the day? I know that Mopar went to alternators before GM, but what about when GM finally switched to them?
  • swschradswschrad Member Posts: 2,171
    that's cold cranking amps, not volts, on the batteries. not even the hybrids use 800-volt stacks.

    a generator car would stop dead because you have to turn the armature (basically the same thing as an alternator rotor) within a magnetic field to generate electricity. both alternators and generators use a field coil to set up that magnetic field instead of pounds of permanent magnets; cheaper, lighter, smaller, and lasts longer.

    generator fields were always energized from the battery, thus, take the battery off, no magnetism, no voltage... nothing to commutate for spark coil primaries, so no spark... you walk.

    old-style alternators, like the original Motorola ones that Chrysler introduced, had a mechanical relay voltage regulator that allowed the battery to energize the fields through a resistor, or allowed the rotor's wye-coil to energize the fields through a diode module... with the higher output to the battery going through larger diodes. so the original Motorola alternators could indeed self-excite just enough at idle to keep operating once started.

    doesn't work that way today, the battery is at minimum a reference voltage for solid-state regulators that control output by adjusting the current in the field coil. my big Ford alternator even has a lead from the engine computer to cut alternator output if you whack the accelerator hard and the engine needs to shed some auxiliary power beyond the a/c compressor to try and deliver. you pull the battery cable on a modern charging system and you will get an ugly and dangerous spark along with hundreds of dollars of charging system damage.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    You've already bought the extremely expensive dealership-supplied battery, so it will be little solace to tell you, you could've bought a decent aftermarket brand for say 20-25% of what you paid the dealer. That 805 ampere hour battery you found was arguably quite large enough for the job at hand.
  • andre1969andre1969 Member Posts: 25,317
    a few months ago, I changed the battery on my Granddad's '94 Taurus. When I put the new one in, everything kept its memory, even the clock and the station presets! Last time he had a new battery before that, he had the dealer put it in, and I think they charged something ridiculous like $150! Said they had to "reprogram the computer"!

    Swschrad, thanks for the rundown on alternators, batteries, (and bears ;-) Interesting info. Good to know, too...I wouldn't have known that you can't pull a battery out of a modern car without doing some real damage. Although in the case of my Intrepid, the thing's so buried it's not like it's a 30-second yank-job, anyway!
  • haspelbeinhaspelbein Member Posts: 227
    You said:

    "you pull the battery cable on a modern charging system and you will get an ugly and dangerous spark along with hundreds of dollars of charging system damage."

    But that is only on a running engine/active charging system, right ? If the alternator is not running, there would not be enough energy in a static field to cause that kind of damage, from my point of view.

    Otherwise all those manuals asking me to disconnect my battery before doing any electrical work on my car would have been seriously wrong.
  • swschradswschrad Member Posts: 2,171
    I read the poster's question as, "I can do this with old stuff when running, how about the new stuff?" answer to that is good luck, friend, be ready for a parts run in the beater.

    you are completely correct that if the system is not in use, pulling the battery cable(s) off only affects things like computer eraseable memory and so on, and should not be breaking flows of current and removing reference voltages/currents from operating systems that need 'em.
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    I have heard that when a battery goes out, and you pretty much know you need to go get a new one, it could be wise (in terms of saving potential damage from occurring, I guess) to leave the vehicle and not run it on the (say) partially shorted or otherwise almost dead and gone battery. For clarification: Often you can use cables and get a vehicle running via jumping from a good car battery, then pull off the jumper cables and keep the idle high in the car and drive it some distance to get a new battery. Is that a no-no?
  • swschradswschrad Member Posts: 2,171
    what's happening, in a nutshell, is that in the old days, the regulators were chatter-down relays... the alternator generated something like 16 or 18 volts. 12 volt batteries don't like this, they evaporate out all the water, crystallize the plates, and become hot paperweights. the extra hydrogen and oxygen disassociated from water become an explosion hazard. all these pieces could come together to cause an explosion or battery fire if you haven't been living right. both are evil, evil.

    the regulators let through a tad bit of the 16 volts, then click open their relay contacts as coils heated up, and then the battery was fed with something like 10 volts until the coils cooled down again, and higher voltage hit. the battery as a voltage damper masked this action, and you appeared to have anything from 12 to 16 volts, depending on how you bent the relay contacts to introduce a mechanical delay in the process.

    those regulators could stick and either overcharge or undercharge the battery, but with nothing to damage, really, it was possible to run on 'em if you didn't have large current loads with the battery off. remember, we didn't have computer control on the 1961 mopars for anything, and computers tend to do things like melt and die instantly if they are fed overvoltage.

    what happens now in a regulator is you have a solid-state IC and transistor system -- you have a reference voltage generated off the battery by an IC that biases the operation of a current amplifier stage (pass transistor) or equivalent output circuit in a triac or IGFET. the reference voltage is part of a comparator, in which this is checked against the output of the alternator. if the reference voltage is higher, that means the alternator is low, and more current is allowed to the field, creating more voltage. if Vr is lower than the alternator, the alternator is cut back by reducing the current in the field winding.

    and if Vr from the battery suddenly disappears, you go out of range. what happens depends now on what choices the designer made. if the designer of this car's regulator decided that there would be no extraordinary measures to try and recover from what might be a dirty connection, the field will be cut below the point at which you generate electricity, and you stop dead.

    if the designer decided they would try and "punch through" a spot of corrosion at a battery connection that could have caused loss of Vr, the bias on the pass transistor (triac, IGFET, whatever) would be radically modified, and the last gasp of power from the collapsing magnetic field in the alternator would basically be cut through. you "spike the field," which is probably already spiking, to try and weld through the problem in the battery leads.

    physics predicts that as the magnetic field dies in a coil, and the steady (saturated) field collapses, this magnetic field collapsing will in itself cause a spike voltage. the collapsing field cuts across the coil wires and provides a magnetic analog to the engine's rotation usually used to cut the field with the windings of the rotor, generating voltage. the spike from a collapsing field is often higher than the steady voltage the rotor makes cutting a steady field.

    / late edit / oh, yes, the little detail about the field "should already be spiking" due to collapsing voltage. this means if the variables are aligned in the wrong way, even if your design of the regulator doesn't cut the spike through, you can still generate an overvoltage spike in a "coast to stop" system that can damage electronics. almost forgot that point. / end edit /

    there should be "snubber" diodes to short out the spike in the wrong, anti-polarity direction, which is why you are advised to never try and "polarize" an alternator by shorting the thing briefly on installation... something you had to do on a generator. whether or not the snubbers are damaged by peak reverse voltage over their limits, there will be a big spike positive.

    big spikes positive with solid-state electronics punch through the silicon's structures and kill stuff.

    so there is quite enough likelihood that pulling the battery from a running alternator system nowadays is going to be ugly that I am not going there on a bet. the Belchfire Motors alternator for 2001 might have been designed to just quit if you do this, but the 2002 supplier might have had another idea altogether. and I'm not going to be the test agency for these parts, particularly as the costs keep rising for the things :-D

    lest anybody say it's idiotic to put a zap into an open circuit and anybody who does it is a thug on drugs... the telephone system, from DC to daylight, on every service, is built with a "sealing current" flow that does the exact same thing. this is done because corrosion at the connection points has shut down lines since the 3-wire days. "sealing current" flows as the 48 volt battery is interrupted, and that usually has an arc-welder effect to cut through the crud at one or many points of the wire/connector mating point and restores the circuit. the end effect to a voice user is crackle or hiss, and to a data circuit is a shot of spikes that causes a loss of nail-up information between ends, taking the circuit down for transmission until the two ends nail-up a new logical connection on the wire.

    MORAL: if your battery is a paperweight, copy the numbers off the label or out of the manual, and whistle up a cab, bus, or neighbor to ride down to Parts Is We and get another one that way.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    These little devices that keep all your computer memory and radio codes intact while you switch batteries?
  • alcanalcan Member Posts: 2,550
    I make them from odds and ends. They work fine when I remember to use them. LOL.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    I guess you don't need much power, just some dinky 12v power supply?

    Well, what's the worst case scenario if you pull out your old battery without anticipating radio codes, computer issues, etc.?
  • fleetwoodsimcafleetwoodsimca Member Posts: 1,518
    Thanks for #37. I picked up a lot of understanding that makes me cringe a bit at where we are at in newer cars. I "lost" a battery a year ago in a McDonald's parking lot. A good samaritan jumper cabled me. I had a hard time driving the ten blocks needed to get a new battery, but that was all it took to get my 1996 Chrysler Concorde 3.5L V6 back up to "perfect." Was I just lucky? (:o]
  • swschradswschrad Member Posts: 2,171
    the radio helper they sell at CSK just takes a 9v transistor battery. if you have a door light in your car, by the time you shut the door, you have killed the 9v battery, they can't provide any current. and that is something like $15.

    get a fuseholder, a power plug for the lighter socket, and a gel cell from your batteries plus or similar outfit that is good for 4 AH or more, and you have enough hold current to get past the fifteen overhead and courtesy lights that come on when you open the door on something like my friend Exploder.

    in the case of my car, I would just lose the radio settings, and the engine computer would just hunt and fiddle around for 30 seconds to a minute after I make my first start until it gets the idle profile restored. not worth worrying about, except I am an electronics tech head, so I will do it when I finally get my trailer control power wired.

    in the case of a european car, you best be on good relations with your dealer, they will probably have to help you recover your radio from "enter code" hell.
  • swschradswschrad Member Posts: 2,171
    if you hadn't run the battery up over 10 volts on idle, either his or yours, and had it hold, you were getting blanks in some of the slots in your computer and it had fallen into limp mode. at that, you may have been lucky, they need exactly the voltage they want and none other.

    but it worked out. I must aploogize, when I first read your #36, I thought you were saying disconnect the bad battery after jumping the car to life and had visions of unpleasantness. re-reading, you were just talking about taking the jumpers off. that is still legal and permitted in all jurisdictions ;) but if the battery remains low under that action, you're hanging very heavily off the five weak cells without any help from the dead one. leave the lights off and the thumper-bumper 'o' rap off while driving to the parts house so the little action in the bad battery is used for what you need.
  • tbonertboner Member Posts: 402
    Remember, you are going to put that in the cig lighter before you disconnect the old one.

    But you do make a good point about lights, so if you have an underhood light or trunk light, make sure the bulbs are removed before you proceed.

    But the 9V should work.

  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    Why can't I just take a motorcycle battery trickle charger < one amp and hook that to the battery cables and then remove the cables?
  • swschradswschrad Member Posts: 2,171
    there is no filtering of the rectified DC on a charger... a wet cell battery is a dang sight more efficient filter than any capacitor.

    however, if you are SURE you can use those clamps without interfering with taking off and putting on the cables, an electrolytic in the range from 1000-2200 uF should suffice to make DC, not DC with high ripple.

    measure the voltage on a testbench with a single 914 bulb as load first, though... if it's above 14 volts with capacitor added by a toggle switch, you may risk the electronic geegaws, although as a safety measure in design, they should tolerate 16.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,482
    Okay, what if I hook up a motorcycle battery to the car's battery cables and then remove them?
  • haspelbeinhaspelbein Member Posts: 227
    You said:

    "[...] in the case of a european car, you best be on good relations with your dealer, they will probably have to help you recover your radio from "enter code" hell."

    Strange, but in all my european cars (BMW, Benz) the code was on a little check card that came with the manual. It takes me less than a minute to punch it in. If you have misplaced it, a simple call or e-mail to the dealer will do.

    It's probably better to get familiar with it anyhow. I'm not comfortable working on my car unless I have disconnected the battery. (No spark, no fried electronics when opening/closing electrical connections.)
  • swschradswschrad Member Posts: 2,171
    that probably won't turn the starter under load, but otherwise will hold loads.

    I didn't check the size of the fuse in my 6 AH hold battery that I hooked to a lighter plug for volatile RAM maintenance yesterday, turns out I had a 2 amp in there. popped the back hatch for another tool and the courtesy lamps blew it. oh, well, all I really had to reset was the climate control out of it, and that's two buttons. your results may vary... if the wiring on your lighter cord can handle it, use a 10 or 15 amp fuse just in case.

    a motorcycle battery should have more oomph than 6 AH for sure, I'd guess maybe 30 to 40 for most of 'em, and that's plenty of hold battery for a day or more on your eraseable settings.
  • stubborn1stubborn1 Member Posts: 85
    I have one of those cheap wanna be jumper cable type device that plugs into the cigarette lighter of each vehicle. It was one of those Christmas gifts that you give the pretend smile and say how you always needed one.

    It is supposed to be able to jump a dead battery in about 10 minutes of connection time. I have never tried it out because I have jumper cables and they would be faster.

    Would a device like this be enough to hold the charge while one replaces the battery? Our GM car has a radio with the "theftlock" feature. I don't have the code for the radio and want to avoid hassle when swapping the battery.
  • swschradswschrad Member Posts: 2,171
    it should hold the settings of the radio nicely. in practice, as you can see from my post above, even the best laid plans can go belly up in the pop of a fuse. do NOT overfuse to correct this, fires are no fun.

    this would be a good time to determine and write down what the activation process is for that radio, and staple it in the owners manual radio section.

    as for replacing jumper cables... well... let's just say I have my doubts. the little geegaw might do the job if the glove box light was on for two days and ran the battery down, 10 minutes is more than a mite optimistic. but if there is a fundamental problem like a dead cell or the battery is just beat and done with, the lighter plug jumper won't do diddly for you.
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