Drivers with start-stop cars pay the price for choosing cheap batteries

Cheap batteries

Fit the wrong kind of battery to a start-stop car and you might be surprised at how quickly it fails

Drivers are paying more than they have to for replacement car batteries because they don’t realise that cars featuring eco technology need specialist equipment. Frequently, cheap batteries bought for start-stop cars then fail relatively swiftly because they aren’t up to the job they’ve been bought for. 

Nearly two thirds (60 per cent) of the cars sold in Europe now have either start-stop or energy recuperation technology. This is where the engine automatically shuts down when the car comes to a rest. It then fires up again as soon as the driver dips the clutch, or in an automatic, releases the foot brake. Start-stop is estimated to cut fuel use by between five and 10 per cent. Energy recuperation harvests the kinetic energy that’s usually wasted as a car slows down.

But in order for these smart technologies to work, cars need to have special batteries. These Absorbent Glass Mat (AGM) and Enhanced Flooded Batteries (EFB) last longer than regular lead acid cells. This is because they’re designed to retain sufficient charge to be strong enough to power a car’s various electrical systems such as the windscreen wipers, ventilation and sound system while the engine is turned off.

Spares company Euro Car Parts has reported a 100 per cent year-on-year increase over the first three months of 2016 in sales of AGM and EFB batteries. But it warned that some drivers ignore their car’s requirement for a special battery. Company CEO Martin Gray said: “It is no longer a case of any old battery will do. It’s about choosing the right battery. If you fit an incorrect battery to a car with start-stop, it might work initially but certain systems will soon begin to fail, starting with things like the radio, air con and electric windows, and then more vital systems, such as the start-stop function itself.”

Understandably, drivers are being tempted to choose cheaper batteries by the difference in price between regular and start-stop batteries. A battery for a Volkswagen Golf-size car without start-stop will cost £85 including a four-year guarantee, from motor retailer Halfords. However, an AGM battery for the same size car will cost £149. And it will cost around £15 more to fit an AGM battery compared to the less sophisticated sort. While the majority of batteries are guaranteed for four years and can go on to last between five and seven years, a regular battery that’s fitted to a car needing an AGM type may struggle to outlast its guarantee.

Find out if your car needs a special battery by looking in the handbook. This should give the exact specification of battery that it needs.

Read more about looking after your car’s battery

19 comments on “Drivers with start-stop cars pay the price for choosing cheap batteries

  1. Sam 18/04/2016 5:45 PM

    Nice comment about cheap batt why don’t you explain why are the batts going dead the real problem like short trips batt not getting charged due to short trips.

  2. John Grayson 17/11/2017 9:18 AM

    I let my start stop battery go flat for 4 weeks. AA started the car but the car cut out completely [twice] at speed [I was just short of going on a motorway!!!] Had to fit a new Ford battery under warranty. This new system could cause fatalities in the near future as batteries reach the end of their lives and cars cut out in the fast lane.

    • Scottie 15/01/2019 5:49 PM

      What’s a “fast lane”? I can do 85 mph on the inside lane of a smart motorway (4 wide) while others are pottering at 60 mph in the 3rd lane (overtaking).

      • Rick 12/04/2020 10:40 AM

        No you can’t the speed limit is 70. Not gonna argue about the idiots hogging overtaking lanes but driving like a prat to make your point will get you banned in swift order. Don’t forget the cameras that infest every inch of smart motorway.

      • Steve 28/02/2021 10:15 PM

        That’s illegal
        The speed limit is maximum 70mph for a reason

  3. John Grayson 19/11/2017 9:19 AM

    I have been told Ford Eco car alternators do not continuously charge [as per older car alternators used to] but ‘pulse charge’. In my case the battery was not giving any output so presumably when the alternator decided to have a rest then that is when the car cut out completely. Hope this problem is sorted before this type of alternator is used in a ‘driverless car’!
    I understand that I should not have set off with a duff battery but the AA engineer got the car started [just as we used to do in the olden days] and off I went.

    I should be grateful if someone could let me know what will happen as these type of batteries just get to the end of their lives and just get the car going only to find your car cuts out completely in the fast lane of a motorway.

    i.e. Has this ‘pulse charge’ system been fully tested to ensure the car keeps going with a duff battery.

  4. Rob 20/12/2017 9:32 AM

    I have stop go and been told that my battery needs replacing at a cost of £228 after just 5 years. As I almost never use the stop go I seem to be paying a very high price for eco tech which isn’t used. Previous cars have been sold with original battery at 10 years old. So this could cost me £400 over that lifetime which would buy me a lot of fuel. So much for ECO tech which costs a lot but doesn’t work or is excess to requirement.

    • Rob 03/10/2018 5:32 PM

      You don`t need one, if you don`t use stop/start a standard battery is fine,

    • Mr Edwards 15/12/2019 8:54 PM

      My ford focus ecobost battery has just failed after only three and a half years. I also do not use stop start function. I think it should be replaced for free or ford should contribute towards cost. All previous new fords purchased batteries have lasted between 6 and 10

    • Briilock 17/01/2024 10:42 PM

      Just get a good branded battery it’s all a load of rubbish, if it fails send it back under warranty!

  5. Jim Lo 02/04/2018 1:58 PM

    I am sitting outside our local motosave. Waiting for one of these special battery…at a cost of over £185..My ford focus is only over 2 years old and had its second service a month ago..At 24000 miles I should think the battery should last a bit longer…btw I always disable the auto stop funtion…..Mu last Focus battery managed 110000 miles on one battery over 8 years.New technology is useless and costs.

  6. Paula David 13/12/2018 6:44 AM

    I just bought a second hand car which I didn’t know had start stop. When I found out I found out it wasn’t working only had the car2 days when I broke down due to to the battery. When I called the RAC they tested the battery which they told me was the wrong battery for the car. They fitted a new one which cost a fortune but all electrics working fine now. Obviously the other battery just wasn’t up to the job long term. False economy buying a cheap battery if it’s only going to last a year. New battery is at least guaranteed for 3 years. If your buying a used car with start stop worth testing the battery to make sure it’s the right one and fit for purpose as it’s quite an expense when you’ve just bought the car and usually not covered by the warranty. Fortunately the dealer paid half for mine so not so bad.

  7. Rob 26/03/2019 3:43 PM

    It`s called a smart charging system, to get back to the old 14.2 continuous charging just disconnect the sensor on the negative rail of main starter battery, no more variable charging, always have a fully charged battery, can use any lead acid battery as in old days, gets rid of stop/start, no need to have battery coded as the EMU does not know what battery is installed or it`s condition because sensor is disconnected, no EML light on dash and because of no stop start standard battery will last longer than any agm with stop start. The fuel gains with these system in place is marginal, try it, if not happy plug sensor it back in.

    • brian lockyer 17/01/2024 10:44 PM


  8. Sam G 27/03/2019 12:43 PM

    When you disconnect the sensor it will bring a fault.
    battery life span is about 3 years they do last longer all they need to do is go for a longer drive then park the car up over night and the system will read battery life again and it’s not a good idea to use different battery’s As the control units won’t like it and can damage other components.

  9. Graeme 08/07/2019 11:10 AM

    My BMW branded Start Stop AGM battery has failed at just over two years old.

    I’m told these batteries need to be used daily – cant leave the car used for days at a time.

  10. David Williams 23/09/2019 3:08 PM

    Do you really need a stop start battery when you never use the stop start function ?

  11. Mac 27/12/2019 5:02 PM

    AGM a complete waste of money, I had a standard sealed batt on a VW 14 years AGM 3 years. fitted a standard batt disconnect the sensor on the Negative pole so the Alternator gives a constant charge instead of a pulsing charge and you are back to old school no stop start no warning lights.

  12. Peter K 28/01/2023 11:08 AM

    My five and a half year old Skoda Yeti needs a new battery. Dealer quote is over £300 for a new battery.
    I have been offered cheaper, £180, by a well-known tyre and brakes company, but they do not electronically match (adapt or code) a new battery to the car. I am therefore going to accept the dealer quote. I am baffled by the new science.

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