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The battery on my Volvo keeps dying. How should I determine and fix the problem?

I have a 1996 Volvo 850 GTL Wagon.  We drive it infrequently, averaging 2 trips per week.  If it isn't driven in 10 - 14 days, the battery will invariably be dead, and I'll need to jump start it, or charge it with a trickle charger overnight.  

At first, I thought the battery was worn out even though it was wasn't quite to the end of its warranty period.  I replaced it, but this didn't solve the problem.

Next, I thought our typically short trips weren't allowing the battery to fully charge, so I specifically changed my driving habits and used the trickle charger to top up the battery on a regular basis.  After doing this, the battery would measure in the 12.3 to 12.6 V range, but after two weeks without driving would be again be dead, measuring in the 11 V or lower range.  Even after needing a jump-start, the battery will start the car again after just 5 minutes of driving.

I've measured the steady-state current draw from the battery after the car has been off for several minutes to several hours using both a clamp-on style ammeter (<0.1 amps; lowest the clamp-on could measure) and an inline current meter between the negative terminal and the negative terminal's clamp (40 mA). 40 mA seems reasonable from what I can find online, and shouldn't be enough to drain the battery over 2 weeks.  

So, I have an 11-month old battery that won't hold a charge for two weeks, and I'm fairly confident there's no abnormal current draws from the car.  Should I replace the battery again and hope for the best?  Is there any truth (and references!) to claims that a lead-acid battery once drained too low can never recover?

Updated with new information for the various suggestions below:
After fully charging the battery, I disconnected it for 48 hours.  It remained at 12.6 volts over the entire period, and when I reconnected it, easily started the car.

I don't suspect the alternator:  When the car is running, 5-6 amps flows into the battery and the voltage on the battery is 13.6 V; and if I drive the car once or twice a week, the battery never dies. 

I do suspect something with the keyless remote.  I stopped using my keyless remote years ago because I found it too bulky to carry around -- I lock and unlock the car using the key in the door.  Christy still uses her keyless remote.  Recently, she was the last one to drive the car before we went out of town for 10 days.  When we got back, I was positive the battery would be dead, but it started the car without a problem.  So, I ran the experiment of leaving the car unlocked, locked with the key, and locked with the keyless remote.  After a few days, the battery would be dead when locked with they key, but not when locked with the keyless remote or left unlocked.  Frustratingly, I've checked the current draw in all three configurations, and it's 40 mA in each case (and stays that way for several minutes). 

For now, I have a solution that keeps the battery from dying if I don't regularly drive the car, but I'd still like to understand what is going on.

Updated with solution 2010-09-02
At the car's next regular service, the shop recognized the problem.  On cars of this type and age, the crimp on the positive terminal can fail turning the positive wire to the battery into a resistor rather than a wire.  This is diagnosed by measuring the charging voltage on the battery and giggling the wire (it will jump around, and not remain at the required 13.8 V), and by noticing that the wire itself is hot.  Volvo recently released a fix for this, and previously the shop had to remove the entire wiring harness, at great expense, to fix it. 

So, my battery was never getting fully charged, and I've selected the best answer from among the suggestions that my measured charging voltage was too low.   

smalin3 years ago
In my opinion you have following possible problems: 1. Voltage on battery during drive should be around 14.2V (13.6 is not enough). - suggests to check charging unit. 2. Charging current should be around 40A even higher for new battery. - suggests dead battery. 3. If battery is 11 moth old by accident 1 cell can be broken. Take it to the shop where you bought it and ask to check it (if still on guarantee). 4. replace battery with other (from a friend) and see what happens.
ewilhelm (author)  smalin3 years ago
Low charging voltage turns out to be the correct answer!

See my updated info in the original question.
marjone3 years ago
You may need to remove the lamp assembly or some trim panels to gain access to the defective tail light bulb.
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juzerhusain3 years ago
keep your battery out of cercket or open one wire of battery
awesume3 years ago
Have you tried getting a new battery
shortw3 years ago
At idle and/or  throttle you should have about 14.5 volts. With or without load like lights it should be about the same.
Check your belts, if you have V-belts check for a glazed/ shiny belt ( on side of belt) this will make the belt to slip on higher RPM. Replace if belt is glazed.
Check your belt tension.
Check amp output on alternator, idle and no light, no fan, no air conditioner, no heater it should be about 20 Amps.
Check amp on battery, it is normal to be 5-10 amps, it depends how low the battery is. On very low batteries the amperage could be higher. But if the battery starting to charge the amperage will start to go down after a while if the capacity of the battery increases.
Check for corrosion on the battery post, take the battery connectors off and clean them with a wire brush or sand paper.
Check your Minus wire for corrosion on each end leading from the battery post connector , it will be grounded on the engine, transmission, alternator or bracket ( take the bolts off and clean it).
Also you should have a smaller ground wire that goes from the battery post connector to the fender Check at the fender for corrosion. Or you may have a ground wire that goes from the engine block or transmition to the frame or body, check that for corrosion .
If you have a external voltage regulator, that could be bad also, but that is not to common.
The next 2 things may be checked at the parts store for free. ( autozone, advance auto, etc.)
Have the battery checked, a bad cell in the battery could make the battery have the proper voltage, but the battery could lack on amperage.
Have the alternator checked, a bad alternator could have the proper voltage but could lack on amperage or it could lack on voltage or could lack on voltage and amperage.
Make sure your Engine RPM is right on idle.
13.6 volts is low. The voltage has to be higher so the battery can charge proper.
Check if the voltage goes up if you increase your engine RPM.

Hiyadudez3 years ago
Get a new car.
abadfart3 years ago
have the alternator checked
Hmm I (in UK) have a V70 2002 vintage, my wifes car, and it recently started doing the same sort thing. Loosing charge and refusing to start. I was going to change the battery but out of curiosity I read the manual. I know this is cheating but hey! I was surprised to find the battery needs watering. I thought modern car batteries were maintainance free, most of my other cars have been, even our lawn mower is, but not our Volvo. In the 5 years we've had it I didn't do this but it is serviced when it needs it and may be they did it. Anyway I checked and one of the cells was quite low, to the plates, and one blelow where it should have been so I topped it up with de-ionised water as reccomended and charged it (again). That was three weeks back and it has behaved perfectly since. Not sure how long a battery should last but this one seems to be performing now its had a drink. Take care.
seabananers3 years ago
o dont know any thing about cars but baterrie could be leaking
framistan4 years ago
LOTS of things can cause dead battery. Loose alt-belt, phantom loads, corroded terminals, CORRODED GROUND-TERMINALS BOLTED TO CHASSIS.... and things others have already suggested. One thing I would do is attach a VOLT METER to the battery so I could constantly monitor the battery as i drive. The battery should have a reasonable charge on it up about 12volts then when car is started... the voltage should be a couple volts HIGHER. A voltmeter constantly monitoring will help you troubleshoot the problem i think.
s1mp13m4n4 years ago
I am going through a similar situation on my 16 year old car. I am performing what is called a paracitic load test on the car. What this does is helps you narrow down where the draw is coming from and which circut is causing your battery to be drained when the car sits. Here are the basics of what to do: get a testlight (continuity tester) from Walmart $3 remove the repetitive battery cable from the battery and do not let it touch the battery connect the clip of the testlight to the negative battery cable touch the pin like tip of the test light to the negative battery post if the light comes on inside the testlight then you have a paracitic draw now one at a time remove a fuse from the fusebox inside the car, check the testlight if the light is still lit replace the fuse and remove another do this until the light goes out when it does you have found your circut with the issue now you must find through a book, friend, repair shop, owners manual which items are powered by the circut you just found causing the problem this procedure gets you in the ball park of where the problem is, once you get that far then you test each circut in which the fuse allows power to. It takes time, but costs nothing to diagnose.
substantially my idea, except I'd point out that he has a multimeter. No need for a test light. 40 mA seems reasonable to me too. Two weeks of that draw only totals 15 watt/hours I'd measure current with all the fuses out and by the DC negative terminal method. If you have no current, add back fuses one at a time until you can isolate the current. Figure out what drains what. Is it possible that you detect 40 mA just after being shut off, but there's higher drains later? Is your hood by any chance shorting the battery terminals? That would give you 40 mA drain when the hood was open, and a higher drain when the hood was closed.
Is your hood by any chance shorting the battery terminals? - - - - - Why are the line breaks I add to my comment to improve readability being stripped out?
crasch484 years ago
i have a similar problem and installed a battery disconnect switch i purchased at harbor fright for $10.
omnibot4 years ago
From experience I'd say you have something that draws power from the battery when the car is not in use, you may also have wornout brushes on the generator. I'd suggest installing a mainswitch and completely disengaging the battery between drives.
Measure the charging current from the alternator with the engine running. (but make sure your leads can't come loose, as things could get nasty....)
NachoMahma4 years ago
.  When locked using the remote, is there an indicator (usually in the middle of the top of the dash) that comes on? Or was there an indicator that came on? My first guess is that the indicator has gone bad and is pulling too much current. The indicator is probably pulsed every minute or two, so you are probably missing the high-current pulse (or it is too short for your meter to catch).
. Oops! I read that backwards didn't I. hmmmmm doesn't make any sense to me, either.
Check that the terminal volts on the battery rises to 13.6 V when charging. If it isn't you've got a dead alternator.

Steve
ewilhelm (author)  steveastrouk4 years ago
When the car is on, current flows into the battery, and the voltage on the battery is 13.6. I've updated my question with more information.
NachoMahma4 years ago
.  The battery should be reading close to 12.6V (6 cells x 2.1V/cell) when fully charged. Since you are getting that, I suspect you have a load that is discharging the battery, even though you weren't able to measure it.
.  Disconnect the ground terminal of the battery the next time you plan on being parked for a few days (make sure the battery is fully charged first). If the battery stays charged, you need to start looking for excess load when key is off (you can usually do this by pulling fuses while watching your ammeter and looking for a sudden drop).
.  If battery discharges when disconnected, the battery is bad.
.
.  Yes, deep discharging a lead-acid battery can damage it. Modern batteries are less prone to this problem, but they are by no means immune.
ewilhelm (author)  NachoMahma4 years ago
Battery stays charged when left unconnected. I've posted more information in my original question.
PKM NachoMahma4 years ago
This sounds like a good "divide and conquer" approach. Determining whether the battery discharges while not connected to the car should show you which half of the system the problem is in (battery or car).  Just make sure you have the code to reset the stereo if it has theft prevention that will kick in if disconnected from the battery (my dad's old car had that).

If the problem is in the car but is an intermittent fault, go and read Zen And The Art Of Motorcycle Maintenance if you haven't already, that's the best primer for intermittent fault finding I can think of :)
ewilhelm (author)  PKM4 years ago
The first time the battery died, I called the repair shop where the car was most recently worked on, and they gave me the radio code. 

It's 1333 by the way! 
starphire PKM4 years ago
I like NachoMahma's approach too, though it might be more conclusive to (also) disconnect the battery when the car will be parked for a longer time - a week or two - and see what its state of charge is.  Further, the disconnected battery can instead be connected to a dummy load - a ~300 Ohm, 1/2 Watt or larger resistor across the terminals would give a steady 40 mA draw to simulate the expected load from the car.  Or if you want to speed up the experiment, see what happens to the voltage after a 10 Watt load is connected to the battery over a 12-24 hour period.

I also wonder about the possibility of an intermittent fault here, so maybe calibrating the battery's capacity against expectations isn't a bad way to eliminate that question.

But I'm guessing the newer battery has already lost some of its original capacity from general inactivity and accumulated time in a lower state of charge.  That's just speaking from experience, and knowing that this sort of usage pattern is what deep cycle batteries were made for surviving over the long term, whereas car battery electrode design assumes they'll almost always be topped off. 

Perhaps a DIY solar battery charger project would prevent this problem in the future. :)
ewilhelm (author)  NachoMahma4 years ago
I've disconnected the battery, and charged it for 24 hours.  I'll leave it disconnected and measure the voltage over a few days.  This is a great suggestion, and I don't know why I didn't do this before posting the question!  
acidbass4 years ago
hmm it sounds like the alternator is screwed
airsofter14 years ago
I suggest buying a 1.8 watt solar trickle charger/ maintainer off amazon or someplace like that. Just leave it plugged in cigarette outlet. It won't overcharge the battery becuase of the low output. Good luck.
RelientOwl4 years ago
Ask a mechanic or somebody smart in things like this!
Goodhart4 years ago
I hate it that they seal batteries and yet don't make them last much longer. 

There is one thing that will drain a battery quickly even if it is not hooked up to anything at all......it's the plates of the battery. 

A short internally, normally causes this.  Sometimes there is too much build up from short charges and discharges and two plates (or more) will short out. 

With a battery that is not sealed, this was easy to check.   You'd get an acide specific gravity tester (a small glass tube with some colored balls inside) and suck up some of the acid....the number of balls floating told you if the cell was charged or not.....a shorted cell, will read discharged or at least MORE discharged then the others.
.  Gee, you're getting old. heehee  Car batteries _do_ last much longer than they used to. Back in The Good Old Days an automotive battery would likely be worn out after two years (especially if you lived in a colder climate). Not unusual to get four or more years out of one nowadays. Considering the conditions they operate under (heat and vibration, in particular), I'm amazed that any of them last more than a month. :)
.
.  If the OP's battery goes dead while disconnected from the car, that will all but prove your shorted (sulfated) cell(s) theory.
In the Good ole days, someone that knew how to care for a battery didn't have much trouble unless their regulator stuck closed and boiled all the fluid out of the battery.  I had bought a 1968 or '69 VW bug with the original battery in it,  in 1977 and had it for two more years.
Now, it is impossible to do any "caring" of batteries (thus eliminating harm done by those that didn't care)

I  suppose they do last longer now a days, but I have only ever had to replace one battery that I can remember in my life (although, back then, the cars didn't last so long, as I was buying them @ 15+ years old most of the time)
 
IanKelley4 years ago
It's been said before, but I had the exact same problem a few years ago with my car (and it was about the same age as yours) and the problem was with the alternator.  Specifically the alternator belt was too loose. Check the alternator voltage and see what it's at. (it should be between 13-14 volts or so) If it's too high or too low then you've found your culprit.
rich_moe4 years ago
OK, Here's my $0.02 worth...
,
Being as it is a 1996 model, and you have changed the most likely cause of the problem  (to some, anyway), I'm going to go through some likely scenarios. 

1. - Dirt buildup at the alternator where the wire comes out of the alternator.  Sometimes, dirt mixed with the natural by-products of use can "bridge" the wire to ground, causing an unusually high discharge/low charge rate.

2. - Have you checked the battery terminals for corrosion? Corrosion causes lack of continuity and can lead to a charging system to not be up to nominal output.  Also, do not neglect to check the ground points, as electricity needs to have a return path (but we all know this already, didn't we?). Ground points are sometimes not easy to see, and can easily be forgotten. Add to that the possibility of corroded wires INTERNAL to the sheathing that you see outside the wires. Check all points where there are heavy gauge wire connected to bolts, terminals, and the starter motor.

3. - Have the fusible links checked in the high-amperage lines, as sometimes they tend to not carry the full load (charge) to the system if they have  been run to almost rated capacity time after time. How, you ask? Well, the starter is a high-amperage motor with a large current draw. Add to that lights, signals, air conditioning, electric cooling fan, radio, blower motor, etc., and you can picture a wire getting really hot...

4. - Any memory-hold items in the circuits (radio, GPS, etc.) can cause a drain on a battery as well. Perhaps not as much as you think, but still enough to drain a battery after a while. Especially after it not being fully charged. See item No. 2.

5. The fuse block may have dust/dirt/corrosion buildup. The relays may be stuck in the on position draining current through the coils. Have you had problems recently with another / other electrical circuit in the car?

These are some of the quick and dirty items that I can think of off the top of my head, but YMMV depending on what is really going on. This is just some of the armchair quarterbacking from the masses.

Good Luck, Eric.
rickharris4 years ago
Your car is using electricity even when your not driving it.

Check the interior light and the boot and under the hood light actually go off when your parked.

Disconnect the battery lead when not in use 9 does it still go flat in a few weeks.

A fully charged lead acid battery should retain that charge for months with no drain on it.

A "dead" battery can generally be re-lifed however this calls for some special charging equipment - a battery shop should be able to do this for you.

Ogver time or under heavy discharge or deep discharge (under 10.6 volts) a batter is subject to sulphating of the plates which makes it unusable, this can be reversed but calls for a special charging system - see comment above.
Culturespy4 years ago
 This sounds exactly like the problems I have been having with my motorcycle. I don't ride it much and have neglected to keep my battery on a tender. I'm on battery number three now. 

I took my old one(s) in to batteries plus and they knew almost immediately what was going on. If you don't keep a charge on car/motorcycle batteries they can go bad. They will often even take a charge but not be able to hold it for more than a few days. I don't know the chemistry behind it but that's what the battery experts had to say. 

Also, I have a solar cell I got from a VW dealership that is used for the sole purpose of keeping car batteries charged during shipping from the factory to the dealerships. Dealerships were spending too much money replacing batteries that once drained too low had to be replaced. Seems polychristaline solar chargers with integral charge controllers to keep from overcharging the batteries. 

They are considered "disposable" so the consumer rarely if ever sees them. They have a much shorter life than the more expensive monocrystaline cells we see in most applications. 

Here's a link to the manufacturer of the solar charging units that explains what I just said but with far more eloquence. 

www.icpsolar.com/markets/industrial.html
lemonie4 years ago
Have the thing fully charged with an appropriate car-battery charger, then see how well it lasts.
I'm thinking of a charge-problem like others.

L
V-Man7374 years ago
I wouldn't say never recover... But there is a reason they make "deep cycle" batteries (in contrast to what is probably in your vehicle). Automotive batteries are made to perform the way we usually (ab)use them -- sucking a tiny bit of current to start the engine, then charging it back up to overflowing as long as the engine is running. Draining it too low will cause excessive chemical reactions inside the battery that will impair its future capacity.

I once had a problem with my vehicle identical to what you describe. In my case, it turned out that the trunk was improperly latching, causing the trunk light to remain on at all times. Once I fixed the trunk latch, the problem went away.
Honus4 years ago
If you're trickle charging it there's still got to be some drain somewhere. After a quick search I found that if your car has a SAS secondary air system, there is a relay for the air pump it is mounted low on the left front of the car. The relay gets wet and corrodes and shorts out, causing a drain. Another thing to look at is the electric cooling fan, the relay for that top of radiator and at times they cause the fan to come on while unattended. A bad alternator/regulator can cause a drain as well.

Having had similar problems on previous cars I've owned I'm inclined to believe it's the alternator/regulator.

By any chance do you have a Bentley manual? They pay for themselves real quick!

trebuchet034 years ago
If your quiescent current is 40mA - it doesn't seem to be a discharge problem. This sounds like a charging problem....


What's the voltage and current while running? Current is going into the battery, right? To me, this sounds like an alternator (or associated componentry) that isn't outputting quite enough current or the voltage is too low and the battery is never getting a full charge (and slowly sulfating).

What is the battery voltage while under load with the car off? If you've got a big power resistor in the lab - throw it on there and remeasure... Or just turn on your high beams (that's about 100+ watts :p). Does the voltage drop significantly? If yes, your battery charge is pretty low.... Fully recharge, and test again - if the voltage drops significantly again - the battery capacity has been damaged from not being fully charged.

Pb Acid batteries are great - but leave them uncharged (or not fully charged) and they slowly sulfate... Overcharge and they gas off. This is why a failed alternator typically takes the battery with it (unless the alternator failed suddenly)
Re-design4 years ago
First thought is that if the battery has been discharged once the it's capacity is much less than it was before the discharge.  It had been my experience that once a battery discharges it is never the same again.

Are the cables clean and tight?

Driving once a week or once in two weeks should be enough to keep the battery charged if the charging system is good, the car starts reasonably easy and there are no extra drains on the battery.

Have your alt. checked for free at pep boys or somewhere like that.

Charge the battery fully then disconnect the ground cable, leave it for two weeks the reconnect the cable and see if it's dead.  If it is then the battery is bad.  It should hold a charge for months if disconnected.  If it is not discharged then there is too much drain in the off position.  You could install a disconnect switch but it's a hassle to turn it off and on each time us use the car.

You could run a test by disconnecting one fuse at a time until you find out which circuit is causing the trouble, then working on the items that are on that circuit.

It's hard to isolate a problem like that.  I once had a Chev. Monza that I really liked but did the same thing except it only took 3 days.  Worked on that car for 6 months.  Never did fix it so I just traded it in on something else and made it someone elses problem.
seandogue4 years ago
one of two likely causes.

1) something isn't being turned off when the vehicle is disengaged (key off and out). you can check by pulling the battery cable, then use a current meter attached to the now open terminal and the other end attached to the cable.

2) your charging system is failing. A bad diode in the alternator could be the cause, or the regulation circuit could be faulty. Finally, check the drive for the alternator to see if it's slipping.

Other than those, I'm not sure.