How long should a car battery last?

Stoke

derrick wrote: »

I have used this vehicle and previous battery without problems for over 5 years, the only difference is this rubbish battery.

What are "parasitic discharges? To my knowledge I have none.

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You know? Remote central locking? Radio? Clocks? Fag lighters.

Anything which can cause it to discharge is a parasitic discharge. However some things cause it to happen more than others.

AdrianC

derrick wrote: »

What are "parasitic discharges? To my knowledge I have none.

Discharges that are going on while the vehicle's parked - and you definitely will have. The question is whether they're acceptable or not.

They include remote locking, alarm, stereo memory, other ECUs. Disconnect the battery -ve terminal, and connect a multimeter on a current setting between the terminal and clamp. You'll have an initial spike, but once the alarm's been reset and everything's finished any self-testing, you'll drop down to a figure that should be small fractions of an amp.

If they're higher than that, then something's consuming current - that might include an interior light that's not going out, or it might include an ECU that's not being properly powered-down.

derrick

AdrianC wrote: »

When did the charging voltage drop from the usual 14.4v to the 13.5v you're seeing now?

I don't know as I have not needed to check until 2 weeks ago.

.Anyway that is the alternator charging, so what has that got to do with battery not holding a charge from full, surely it just takes longer to charge via the alternator.

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AdrianC

derrick wrote: »

I don't know as I have not needed to check until 2 weeks ago.

Exactly my point.

Anyway that is the alternator charging, so what has that got to do with battery not holding a charge from full, surely it just takes longer to charge via the alternator.

You're using the car infrequently. Is it always being used for long trips? Forgive me for assuming, but a 20yo Carina E that's garaged for weeks at a time suggests a certain demographic - and that demographic is not normally undertaking long trips. So the battery may well never be being fully charged. The charge rate depends on the difference between the battery resting voltage and the charge voltage - so going from 14.4v/12.5v to 13.5v/12.5v makes a VERY big difference to the speed of charging. At that charge voltage, the battery is probably never being fully charged, even on relatively long journeys.

Sort the charging before blaming the battery. Even then, with infrequent use, you are always going to have a shorter life from a battery, especially if your use is then shorter journeys.

derrick

AdrianC wrote: »

Discharges that are going on while the vehicle's parked - and you definitely will have. The question is whether they're acceptable or not.

They include remote locking, alarm, stereo memory, other ECUs. Disconnect the battery -ve terminal, and connect a multimeter on a current setting between the terminal and clamp. You'll have an initial spike, but once the alarm's been reset and everything's finished any self-testing, you'll drop down to a figure that should be small fractions of an amp.

If they're higher than that, then something's consuming current - that might include an interior light that's not going out, or it might include an ECU that's not being properly powered-down.

Those small things should not flatten the battery in 2 weeks, it had never done that in over 7 years with the same scenario.

I will try that disconnection idea tomorrow.

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derrick

AdrianC wrote: »

Exactly my point.


You're using the car infrequently. Is it always being used for long trips? Forgive me for assuming, but a 20yo Carina E that's garaged for weeks at a time suggests a certain demographic - and that demographic is not normally undertaking long trips. So the battery may well never be being fully charged. The charge rate depends on the difference between the battery resting voltage and the charge voltage - so going from 14.4v/12.5v to 13.5v/12.5v makes a VERY big difference to the speed of charging. At that charge voltage, the battery is probably never being fully charged, even on relatively long journeys.

Sort the charging before blaming the battery. Even then, with infrequent use, you are always going to have a shorter life from a battery, especially if your use is then shorter journeys.

I have been charging it via a charger every 4-5 weeks, stop making assumptions.

Irrespective of use it is this battery that has caused the problem, I have owned the car for 13 years, this is the second battery I have fitted, no problems with the first replacement that lasted at least 5 years with the same use of car.

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AdrianC

derrick wrote: »

no problems with the first replacement that lasted at least 5 years with the same use of car.

...but almost certainly without the current charging system problems. SORT THAT FIRST.

derrick

AdrianC wrote: »

...but almost certainly without the current charging system problems. SORT THAT FIRST.

But still an average 4-5 weeks charge via a battery charger! So no change there then!

Bottom line a 2 year old battery should not fail.

If nothing constructive to offer don't reply!

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AdrianC

derrick wrote: »

If nothing constructive to offer don't reply!

<shrug> I'm very sorry if the answers fail to reinforce your preconceptions. But don't blame me when sorting the symptom fails to sort the problem, because you've not addressed the cause of the problem.

Strider590

They put a 2 year warranty on these for a reason, they expect minimum 2 years worth of use. They certainly won't over engineer a battery to last much longer if it doesn't need to.

Lead acid batteries are constantly being damaged if they are not kept at 100% charge, no car charges it's battery to 100% because those last 10% of charge take a lot longer than charging from 80% to 90%, several hours in fact. So short journeys and low mileage can very easily wipe out a new battery in 2 years.

Now as for the charging system, true you should be seeing 14.4v with the engine running and if you don't then you have some expensive issues to fix.