Is it possible to make the car battery last 'forever'?

Uxb1

If the OP is genuinely interested in understanding why Lead-acid/gel batteries don't last forever then they can look up sulfation and shedding plus that the typical charging profile from the car's usage and the charging rate control (or lack of it)  is probably not best suited to prolonging their life (over charging/undercharging/over depletion).

AdrianC

Anyway, let's turn the question round a bit...

Why so fixated on making the battery last forever? It's a cheap consumable. All but the very largest wet lead-acid batteries can be bought for about £60-70 from top-notch brands, and are quick and easy to fit. Regard it as a routine consumable...  At the first sign of it giving a bit of gyp, just get over the whole "Ohnoes! It's only done X years...!" and replace it. It's cheap preventative maintenance.

Grumpy_chap

AdrianC said:

Anyway, let's turn the question round a bit...

Why so fixated on making the battery last forever? It's a cheap consumable. All but the very largest wet lead-acid batteries can be bought for about £60-70 from top-notch brands, and are quick and easy to fit. Regard it as a routine consumable...  At the first sign of it giving a bit of gyp, just get over the whole "Ohnoes! It's only done X years...!" and replace it. It's cheap preventative maintenance.

That makes sense, though I have never thought of the battery in that way.  

I am currently stretching the life of a deceased battery, you've convinced me to just do it.

AdrianC

It's the price of a tank of fuel, or one tyre, or a set of front pads, or a brake fluid change...

Or about three sets of wiper blades - and we all replace those annually, which is about their effective life, don't we...?

Compared to the average PCP, it's about 750 miles excess mileage charge... 40% of the annual VED on a car that was new in the last few years, or a month and a half's VED if it was over £40k list.

It's cheap.

Grumpy_chap

It absolutely is, Adrian, I just truly never thought of it like that.

It is odd how we are conditioned to think that some things should last forever, whereas others we are happy to accept as disposable and it is not simply financial value that influences that conditioning of thought.

I have always thought it inconsistent the number of threads on here with people wondering what to do at the end of a 3-4 year PCP deal on a car, but then other threads in other areas of the forum where people have a TV, washing machine, etc that failed after 5 or 6 years and the author seeking to make some kind of a claim under the product not lasting a reasonable life-time.  That is a triumph for automotive marketing to condition us all into thinking that £20k plus products are "disposable" versus the marketing for washing machines that focus on durability as desirable.

princeofpounds

Battery on one of my cars just gave up the ghost recently. Was about 11 years old. Even when 'fully' charged it struggled to produce enough current to turn the engine over for ignition. I had it replaced as part of a pre-MOT service and the thing that surprised me was that not only did it start right away, but the engine (diesel) actually ran much better in normal operation as well. I didn't realise how much the car had been limping around the last year or so.

All chemical batteries degrade through repeated charging cycles, unfortunately. It's pretty much a law of physics although the chemical mechanisms involved vary between battery chemistries. 

AdrianC

princeofpounds said:

...the thing that surprised me was that not only did it start right away, but the engine (diesel) actually ran much better in normal operation as well. I didn't realise how much the car had been limping around the last year or so.

Once the alternator is producing charge, the battery does nothing. What's far more likely is that simply "rebooting" cleared stored settings and codes from the ECU.

tedted

batteries on modern cars do a lot more than you realize,all sorts of problems crop up

A_Lert

I replaced my 04 plate's battery earlier this year, I think it might have been the original. I was having electrical glitches, the speedo or/and rev counter going haywire intermittently. And then one day it wouldn't start for no obvious reason. Since the new battery was fitted, no problems so far.

I don't know how much battery degradation depends on mileage versus time. My car's old but it's only done about 40,000 miles. (And I flattened the old battery from leaving lights on a couple of times, which I know is bad for it.)

Yes, a new battery is 'cheap', but it's not the only replaceable item on a car. It can all add up.

AdrianC

A_Lert said:

I replaced my 04 plate's battery earlier this year
...
My car's old but it's only done about 40,000 miles.

Low use can be one of the worst things for a car. Averaging 2,500 miles/year - 50 miles/week - over its entire life suggests it's rarely got properly warmed up. Cold engine, low speed, short journey use is far more wearing than long motorway runs.