How long should a battery last?

As per the title I just wondered how long you should reasonably expect a car battery to last for?

Cheers

John

Reply to
John
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Decent quality starter battery (not deep cycle) should last 5 to 7 years if:

Its never discharged deeply Its always charged right back up asgain with a sensible length drive Its never discharged even slightly (left lights on for 30 mins etc) and left Your alternator charges at the correct level for your battery (modern stuff

14.4 when running)

Or days to weeks if...

If you let it go flat ever (even once) especially if you leaver it that way or if you do it more than a few times. You do short winter trips. Your leave a modern car without a maintainance charger for a week or more often you drive an old car (13.8v) with a modern battery Your acessories outdo your alternator... You use a crappy cheap non logic controlled 3 or 4 stage charger.

And everything in between.

Reply to
Burgerman

I've left my 197 for a couple of weeks a couple of times. It's fine?

Reply to
DanB

The OE sealed for life battery in a new car always seems to last a lot longer than whatever you replace it with in my experience. The one in my Focus is still fine at just over 7 years old despite hardly ever getting a long enough run to keep it fully charged. I've had it go completely flat and had to put it on a charger a couple of times already due to most of its runs being the half mile to the local shops and back which in the winter doesn't even replace the starting current and the heated screens, fan blower etc to de-ice it on the driveway. Working from home all the time I sometimes only do 100 miles a month. By rights the battery should be buggered by now but apparently isn't.

The only other newish car I had with an OE battery was an Astra way back in

1983 and that battery was also still fine at 7 years old when the car got nicked. I did actually get it back and it sat for many more years on the drive until it rusted away because I couldn't get repair parts and the battery was still ok for ages. Exactly how long I can't now remember but at least 10 years or so.

On the other hand cheap replacement top-up type batteries might last only 2 or 3 years. I've bought several of those over the years on the old nails I used to run and rarely had one last very long. Definitely a false economy compared to an OE spec sealed for life one. I also suspect it has a lot to do with the fact that a new car has a new alternator, good wiring, an engine in good nick that doesn't need a lot of cranking to start and the battery stays well charged and in good condition. By the time the car is on its second battery all the ancilliary electricals are getting a bit shagged too which then hurts the battery life.

I'd therefore say that in a newish, well maintained car you'd be hoping to get up to 10 years from a quality OE spec battery in average UK temperatures. Very hot weather and very cold weather are both much harder on batteries than our temperate climate.

I'd be interested to know what's the longest life anyone has ever got out of an OE battery. I'd guess 15 years isn't unheard of. What kills them is mainly three things. Being undercharged, overcharged or not being topped up fully if applicable. Undercharging, or just letting them go too flat sulphates the plates up, overcharging boils off electrolyte and overheats the plates and not topping them up kills any exposed plate surface in very short order. Sealed for life batteries eliminate the latter cause and an alternator in good condition should prevent the first two.

Reply to
Dave Baker

Reasonably? Three years.

Realistically? Three to ten years.

Chris

Reply to
Chris Whelan

I had a Mk2 Astra 1.4 for 10 years and the original battery was absolutely fine all that time. I've had my Mk4 Astra 1.6 for 7 years and there's no sign of any battery problems. Both were/are sealed maintenance-free batteries.

Reply to
A.Clews

Nope you damaged it.

Reply to
Burgerman

All batteries dislike being discharged. Even Deep Cycle ones. A Deep cycle battery uses thick solid lead plates rather than a bit of "sponge lead". They are designed for 300 80 percent discharge cycles under controlled conditions. Or 1000s of 5 to 10 percent discharges. Or realistically half a dozen 95 percent cycles.

Starter batteries are much less happy with any kind of discharging. They use many thin plates coated in lead "sponge" so as to give huge starting currents. They dont like deep cycle use at all. You get about 1/4 as many cycles at say 50 percent discharge compared to a deep cycle one. They are designed to start a car which needs big current for a few secs and then get charged right back up again. Typically 3 to 5 percent discharged, maybe 10 max.

Your car discharges the battery when you dont drive it. All modern cars are worse than old ones with residual loads for remotes, clocks, computers un radios, central locking, injection system and imobilisers alarms etc. After a week the battery voltage will show you the level of dishcharge. Anything less than 12.7 to 12. 8v and your battery is being damaged. Maybe not much on some cars but its not kind. At anything less than "float" voltage (13.4 to 13. 7 usually) the battery sulphates and available capacity and starting current diminish. In older cars batteries could be left weeks without many problems since only a set of diodes leaking (negligible) and the batteries own natural self discharge (a couple of percent per day) happened.

Any decent battery on float charge or driven often and not flattened should live up to 10 years. Any decent battery that abused or allowed to park for long periods especially in modern cars or gets run flat will last an indeterminate time less than the ideal.

Buy a maplins solar charger!

Reply to
Burgerman

The mother of a friend of mine bought a Herald in 1966. The battery that was in it then lasted until 1987. They don't make 'em like they used to ...

Ian

Reply to
Ian

13 years in my dad's 1993 Audi 80. Only changed it for peace of mind but even then it was still going strong with no signs of slow cranking, but the car has always started first turn of the key. Still got it stored in the garage regularly kept charged for nostalgia.
Reply to
Redwood

In article , John writes

-for a cheap replacement battery: about a week longer than the guarantee period! LOL (how do the manufacturers of cheap batteries manage to be so accurate in their life estimates?)

Reply to
Chris Holford

Depends much on your definition of good though.

A starter battery with Capacity (not normally stated since you shouldnt be using its capacity) of say 50 Amp hour or 110 mins reserve and a CCA of 500 amps could be down to 1/3rd of that and still start your car!

So a good well looked after 9 year old battery may well start the car but its still way past its sell by...

Batteries used for telecom - big banks of pure lead plate weak acid deep cycle last the longest. Especially if they are kept on permenant float charge as they are. Even then they age chemically and lose capacity and are replaced after 7 to 10 years. They may work for 20 but that doesent mean they are still "good"...

Incidentally one reason modern maintainance free batteries dont last as well is that the very chemical changes required to make them maintainance free and not "gas" and therefore lose electrolyte also shorten theIr life.

Reply to
Burgerman

Average warranty return time.

Reply to
Burgerman

Nah.

Reply to
DanB

Yep! Only a bit! But all the "bits" are what kills them in the end!

Reply to
Burgerman

Luckily the battery for my Sierra only costs £23. At that price I could afford a new one every winter. Mine does sit regularly for a week at a time unused. Forgot about it recently and time just zoomed by and realised today it had been sitting there since June 28th. Turned over, but hardly and not enough to fire, so didn't try it once I realised. To be honest it was this thread that made me think how long it had been since I last started it. I checked the terminal voltage half an hour after cranking it and was spot on

12 volts.

I didn't realise modern cars had slightly higher voltage batteries. My car is designed for 13.8V not 14.4V and presume the battery is still the 13.8V type? My charger is modern though, but guess it doesn't make much difference in charging, even if it is designed for 14.4V batteries. Lidl charger BTW and very good it is too.

Graham

Reply to
Graham

State of Charge Voltage (measure after standing 12 hours or so)

12.7+ = 100% 12.45 = 75% - And as low as you want to go ever with a starter battery! 12.25 = 50% - Deep Cycle batteries only or damage! 12.10 = 25% damage... 11.95 = less than 5% remaining - Discharged and not well.

You get thousands of cycles at 10 percent. You get hundreds from deep cycle and tens from starter batteries at 50 percent You get 300 from GOOD deep cycle batteries at 80 percent discharge but 20 or so from starter batteries. You get tens of cycles at 95 percent discharged from good deep cycles. You get one or two if you are lucky with starter batteries.

Modern maintaintainance free batteries use slightly different chemistry so require a slightly higher charge voltage. Otherwise if you charged at say

13.8v it would take forever to recharge them fully as this is only .3 of a volt over the standard float / maintainance level.

Onthe other hand you are slightly overcharging them if on a very long trip. Swings and roundabouts.

Trucks are usually set a bit lower like 14v because of this.

Reply to
Burgerman

That is a very useful list of voltages. Especially on my campervan that has two batteries, one for leisure use (deep cycle) and huge one for the engine. Thanks for that. Very good info and saved it for future reference.

Graham

Reply to
Graham

I might have spoken too soon there. Out of curiosity I stuck the DVM on it and got a sparklingly non healthy 12.31 volts, equivalent to about 50% charged. It's been sat a couple of days mind and the last run it had of more than about 5 miles was three weeks ago. Anyway my poxy 30 year old 4 amp Halfords battery charger is now putting a feeble 13.8V and 1.5A into it on its highest setting so maybe in a week or three it'll be slightly more than half charged.

It might however be a good representation of how long a rather abused battery can last. As I say mine must be half discharged for most of its life given my lack of mileage.

Better news. After 15 minutes charging I'm up to 14.4V so maybe the little Halfords charger is still capable of doing the job. It's obviously taking a while for the internal resistance of the battery to drop. Amps down to 1.3 though so this will not be a quick operation.

I've also just reminded myself you DON'T measure amps with a DVM by putting it straight across the battery terminals. Ouch. Dickhead. Sparks and little gobs of hot lead flying. It's been sooo long since I've done this sort of thing. Amazingly the DVM still works on the amps setting with it connected into the charging circuit rather than across it. I thought I'd have fried every fuse inside it.

Reply to
Dave Baker

No worries. The exact voltages vary with battery type and make and temperature. And are only accurate if said battery has been disconnected from any car/system/charger for 12 hours or preferably a day.

12.7V plus = full charge refers only to a battery thats been stood 12 hours or more after charging. Otherwise you are only measuring a "surface charge". Some batteries have more or less of this. So just because a quickl test with a digital volt meter shows 13. something volts under the bonnet that doesent mean its actually fully charged.

If you start your car and it reads 14.4v (or very close) then you have no alternator worries. If you then stop it and measure battery voltage it wont tell you anything, you need to wait a long time.

I sell Optimas so have to know this stuff... Funny how almost all the ones returned as faulty are from leisure or race vehicles that only get used very occasionally. Or boats, leisure equipment, or similar... Almost never get a return on a standard regular driver.

Makes you wonder why manufacturers dont fit a 5 watt solar panel with 13.6v regulator chip (float/charge level) in the roof of all cars doesent it...

Reply to
Burgerman

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