Battery not holding charge

Discussion in 'Car and Van Talk' started by Tipptop, Apr 19, 2020.

  1. Tipptop

    Tipptop Member


    The battery in my son’s focus doesn’t hold charge if left idle for around three days. It has had to be jump started on about 10 occasions in the last year. After jumping and recharging by driving for an hour I disconnected the battery completely and measured the voltage across terminals as 12.8 initially which dropped to about 12.2 over the next few days. I reconnected and the car started no problem but did not take it for a drive. Tried to start the next day but failed. I’m more than happy to replace the battery but is there any other reason that this might be happening other than a failing battery?

  2. spannerw

    spannerw Screwfix Select

    How old is the battery? Any guarantee on it? If as you say you disconnected the battery and it lost charge then I would change it.
  3. Tipptop

    Tipptop Member

    Battery is four years old. The car has done substantial mileage since then but often with extended periods of inaction. Better to replace it then.

    many thanks
  4. rogerk101

    rogerk101 Screwfix Select

    I would be horrified if a battery only lasted me 4 years. Mine usually last 10 years. Only once one lasted me 8 years, but that was because I left the car unused and uncharged for one harsh winter in the Alps.
    If the battery is used regularly (e.g. minimum of one 10km trip per month), then the battery should last 10 years. If you do have to leave it over winter without any use, then buy a trickle charger (like a CTEK) and leave it trickle charging over winter. If you don't do this and we have a harsh winter, you will take years off the battery life.
    If you do end up buying a CTEK or similar smart charger, then you can try using it to recondition your current battery. Sometimes this can work and will give you a few years more on a battery that you would otherwise have chucked out. (I did this for my sister-in-law, and she's still using the 'dud' but reconditioned battery 3 years later.)
    Heat likes this.
  5. Tipptop

    Tipptop Member

    I have a car battery charger somewhere so I’ll give that a go first. Thanks
  6. dray

    dray Active Member

    Seems short life to me also, are you sure that there is not a glove box/or boot light staying on, or some other drain like dashcam etc. The other thing is some cars(not sure about focus) don't actually shut all electrics down until locked so perhaps a chance the radio is staying on if left unlocked in garage?
  7. techie

    techie Screwfix Select

    If the battery is disconnected and the voltage falls as you mention, then the battery is end of life and needs replacement.
    The term “12 volt battery” is a little miss-leading in that fully charged the voltage would be 13 volts plus. At 12 volts its almost fully discharged.
    Time for a new battery but don't buy and cheap as chips carp as it won’t last.
    Also check the charge voltage when car engine is running, it should be 14 + volts.
  8. quasar9

    quasar9 Screwfix Select

    Car batteries by design are not deep discharge types and if it’s been run down flat and left like that for any length of time, it damages them and over a few cycles of full discharge, it starts to lose capacity. There are so called special chArgers that claim to revive these by use of special waveform but I doubt if they actually work. Best swap for a new and quality product and do not allow full discharge. Check for current drain when the car is locked and if possible use a trickle charger.
  9. Heat

    Heat Screwfix Select

    The CTEK small smart charger is excellent for charging the battery fully. Also will refurb the battery and can add a few years of life to it apparently.
    Ordinary battery chargers only charge a battery to perhaps 3/4 full charge and cut off.
    Note that if a battery is very low in charge, the electronic smart chargers will not begin to charge the battery unless you use an ordinary charger to bring the charge level up first
  10. Tipptop

    Tipptop Member

    Thanks for all the input. I’ll let ye know how I get on.
  11. Wayners

    Wayners Screwfix Select

    Buy a 12V Car Battery Monitor bluetooth BM2 Voltage Meter Battery Tester Analyzer. About £25. Will tell you if it's being drained or if it's not charging. I found out my crank voltage was too low because starter motor was playing up. Pulled so much from battery when starting it killed it. Easy fit with free phone app.
  12. MGW

    MGW Screwfix Select

    I was rather surprised on how long it takes to charge a battery, the problem is the sulphur on the plates gets hard, and it takes time to convert it back into sulphuric acid, they is not quick method, it takes time.

    So with a battery left for over a year, in theory this battery is now useless, but I thought nothing tried, nothing gained, so thought I would try to recharge it.
    First problem was no volts so charger will not work, so had to cheat, and I used a 7 Ah VRLA is parallel with the 90 Ah flooded battery so that the charger would work, I also plugged the charger into an energy monitor that was linked to the PC so I could see what happens.

    So the Lidi Smart charger 3.8 amp first charges the 7 AH and then just sits there doing nothing, or so it seems, at 14.4 volts the charger switches off, and at 12.8 volts it switches back on again, so it would switch on for a few seconds volts hit 14.4 and it switches off staying at 12.9 volt for a long time then another pulse as it drops to 12.8 volt.

    After two weeks it started to charge, it would only charge at 0.8 amp with Lidi charger without some one pressing buttons, so it took over 5 days to charge, at first it was pulsing on/off as it would not even take 0.8 amp, then flat line, and then again pulsing on/off as it finished the charge, it was another week before it stopped pulsing, so in all that battery was on charge for a month.

    So battery was for caravan not car, however it worked the motor mover without a problem, and seemed not the worse for being allowed to sulphate. But any battery can part sulphate, so to get it back to A1 condition it likely needs charging for a month, clearly with a smart charger or it would dry out being on charge for that long, but it is the time that matters not the voltage hitting 13.8 volt.

    In the main a fully charged battery left for 1 hour or more not being charged will show 12.8 volt or more. If it shows less than 12.8 volt after being off charge for a couple of hours, then it was never fully recharged. OK my battery was rather an extreme case, I did the same with two 7 Ah batteries off a stair lift which had not been used for ages, and same result, nothing for a week, then they seemed A1 again.

    I now charge my cars for a week at a time, moving from car to car, except for the Jaguar as it says charging with external charger can unset the engine management monitoring of the battery, and anyway it sends a message to wife's phone if it needs charging, so she can start car from phone to recharge battery. So I don't charge the Jag battery, but do charge the rest.
  13. rogerk101

    rogerk101 Screwfix Select

    MGW, I've managed to restore a battery that was stone cold flat (0V) over a winter, but it couldn't be done with a smart charger initially. I had to use either another fully charged battery or a dumb charger first to get enough charge into it before the smart charger would work. It seemed that all the battery needed was around 5V, so even connecting it to another battery in another car for an hour is usually good enough to get the 'dead' battery up to 5V. Once it was at 5V, the smart charger can do its thing. I set my CTEK charger into recondition mode and left it for a day or so and it was fine. That 'dead' battery has now been working flawlessly for the last 3 years.
  14. MGW

    MGW Screwfix Select

    The Ctek is 12 volt only, so has some advantages over the Lidi ULGD 3.8 but also some disadvantages, the Ctek will auto restart after a power cut I am told, and will return to full 3.8 amp output, but does not have a built in volt meter, and will not do 6 volt. So Lidi lower limit is 3.8 volt and upper limit is 15 volt, above 15 volt it assumes the leads have been removed and switches off.

    Below 7.5 volt it assumes a 6 volt battery is connected, so again it will not charge to over 7.3 volt. The Lidi charger does work well, and since it charges at a constant current you can easy work out how many Ah it has tried to put into the battery.

    This post reminded me, and I have just put the 120 Ah battery of the Kia Sorento on charge, never had a problem with that car, but these are unusual times, last time used 106 mile round trip to old house and back dropping off trailer for son to load for me, he is buying my old house, that was 20th March easy to remember it was his birthday.

    So just 5 minutes at 3.8A and it dropped to 3A, so 68 watt dropped to 55 watt input to the charger. charge21-4-20.jpg So this is the graph so far, you can see the short 68 watt charge under Tuesday, having done it before I expect to get some thing like this Car_battery_recharge5.jpg likely I will need to remove charger tonight as sockets are outside and it may rain, and continue tomorrow, Lidi now do a 5 amp version, but since it switched down after 5 minutes would not make much difference, as said it is time that matters, the one I did earlier shows 5 days at 2 watt, so 2/12 = 1.7 amp, I know the charger does 0.1, 0.8. 3, and 3.8 amp so really 0.8 amp but the PC does not show mantissa. I know in fullness of time it will drop to 0.1 amp and with large batteries how ever long I leave it it will not drop to zero, with small 7 Ah and 12 Ah batteries VRLA it does drop to zero.

    Without the Energenie energy monitor I would not know what the charger is doing, and I have realised even when charger says fully charged it is still taking a small charge even a week latter, so with Honda Jazz a single extension lead will reach, so often I leave it on charge for 4 or 5 days, it was dad's old car and getting on a bit now, still original battery 04 plate, and I used it before lock down to drive to station less than one mile, so it never gets a good run, so once a month battery goes on charge.

    I do like the Ctek charger range, however I don't like the price, the Ctek M25 is perfect to charge a caravan battery on site, but £250 is a bit steep and the Ctek D250SE is again perfect for car to caravan battery charging, again it is the £250 price tag which is off putting. Even the MXS 3.8 which is basic same as Lidi is £56.50 and Lidi one was around £14, think you can see why I selected Lidi.
  15. Bob Rathbone

    Bob Rathbone Screwfix Select

    The issue is either the battery is self discharging or the car has a fault leading to excessive quiescent current draw when the car is parked. The easy way to decide is to run the car , go shopping or a drive to charge the battery, then when you get home, disconnect the cattery negative. Leave the car for 3 of 4 days and re connect the battery and start the car. If it starts, the issue is the car, maybe the hands free phone unit or radio, if it does not start, fit a new battery.
  16. MGW

    MGW Screwfix Select

    April 19th was during lock down, today there are less problems, I am wary today about disconnecting a car battery, the Ford Focus came out in 1998 and there have been four generations, I don't know how it progressed but it is likely radio codes will need re-entering or computers resetting when the battery is disconnected, I know the Jaguar which was at one point linked to Ford battery changes need the computer updating.

    I know @Tipptop says he has already disconnected the battery so clearly he has no problem, but by now one hopes he has solved the problem. I know the Jaguar XE my wife has sends a text message to her mobile phone if battery is getting below a safe level advising her to start the engine, not my car so I have not got it linked to my phone, but as far as understand she can start it from the phone.

    She did have a battery problem, and the fact that once changed the problem never returned seems to show it was the battery, but the old one is still used in the caravan with no problem. Which includes running the motor mover which is a fair load.

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