12v electric car battery charger

Discussion in 'Electricians' Talk' started by bond007, May 29, 2018.

  1. bond007

    bond007 Active Member


    THe charger has busted for this electric car battery.

    Apart from buying a new charger, any other way I can end up charging this 12V battery?


    Attached Files:

  2. Pollowick

    Pollowick Screwfix Select

    Pictures of the actual battery labels would be useful.
  3. bond007

    bond007 Active Member

    Doesnt have 1 to be honest, just a 12V electric car battery
  4. Get a jump start or a push and the alternator will charge it.
  5. bond007

    bond007 Active Member

    What kit would i use to jump start with ?
  6. A pair of jump leads from another car or a battery booster pack.
  7. Peter208

    Peter208 Active Member

    Polco, ( also sold as Torq )Smart Automatic Battery Charger. Does AMG batteries with Auto, or 2, 6 or 12amp.
    Also has a trickle charge, reverse polarity protection. B&Q used to stock and sell them
    Last edited: May 29, 2018
  8. Bob Rathbone

    Bob Rathbone Screwfix Select

    Just use any automatic car battery charger, must be automatic because the battery is a sealed gel type. Look on E Bay, 1 amp 12 volt chargers like the one that is bust are easy and cheap to get new.
  9. bond007

    bond007 Active Member


    Also i will connect the clamps to the black and red terminal? same as we do on a jump start
  10. bond007

    bond007 Active Member

    Also cant seem to find a 12v 2 pin charger, like the one i have attached in the picture.

    Can i change the input side connection to a single pin?
  11. MGW

    MGW Screwfix Select

    The battery charger states 12 volt 1 amp, however a 12 volt battery needs between 13.2 and 14.8 volt to charge, so there may be some switch mode unit inside the car which charges it, or the charger may be showing nominal figures, and actually does give out around 14 volt not 12.

    So the safe method is to directly charge the battery and not go through the cars circuit as you have no idea what that circuit really is.

    The battery seems to be a valve regulated lead acid, not gel as gel you can normally top up with water, the important thing with VRLA is not to over charge, so you need a battery charger designed for such a small battery.

    This advert for a VRLA gives physical size from that you will have a good idea of the size in Ah that yours is.

    Lidi did a battery charger designed for 1.2 Ah to 130 Ah maximum output 3.8A but under 14 Ah the maximum output is 0.8 amp which reduces to 0.1 amp as the voltage raises. At £14 likely the most cost effective method to replace old battery chargers.

    However depends how long it has been flat for, I found with two 7 Ah batteries out of a stair lift, I had to connect it in parallel with a much larger battery as the volts went over the 15 volt cut off point without doing that, higher quality chargers like the CTEK XS 0.8 may well cope with batteries in a worse state of care, but they are over twice the price, the CTEK MXS 3.8 is the equivalent to the Lidi one, clearly a better quality cheapest I could find is around £35 the spec says it will charge the battery with a lower start voltage to Lidi, but to my mind we know the Lidi charger works well with a good 7 Ah battery, so it may need so fiddling first time, but after that it is straight forward.

    Personally I would fit two spade connectors to battery connections and charge disconnected from the vehicle, just in case there as a protection zenor which could short circuit the charger.
  12. bond007

    bond007 Active Member

    Something like this ?

    http://www.lidl-service.com/cps/rde...eAttr=en&title=CAR BATTERY CHARGER ULG 3.8 B1
  13. MGW

    MGW Screwfix Select

  14. bond007

    bond007 Active Member

    SO with that I can charge a 6v and a 13v battery?

    Connect the clamps on the battery connectors?
  15. Bob Rathbone

    Bob Rathbone Screwfix Select

    Sorry I meant 'busted' as the asker said.
  16. Bob Rathbone

    Bob Rathbone Screwfix Select

    Cut the lead off the old charger and connect it to the new one, observing polarity, it's on the 12 volt side so no shock risk.
  17. Heat

    Heat Screwfix Select

    The CTEK or other other electronic chargers may fail to charge a really flat battery, but all you need is a basic charger to bring the battery charge up first, then revert to using the CTEK more advanced charger.
    The Lidl small electronic charger is also very good and only cost me about £14
  18. MGW

    MGW Screwfix Select

    Yes the Lidi charger will charge both 6 and 12 volt lead acid batteries, and it is designed for small batteries down to 1.2 Ah. Details are here the main point is a standard car battery charger will fry small batteries, it needs one designed for small batteries.

    What I find good with the Lidi battery charger is the sequence shows when battery is charged, and it can be safely left connected to battery for weeks.

    But I will admit it is a cheap copy of the Ctek MSX 3.8, not exactly the same, but for the motorcycle setting the 3A and 3.8A charge rates are not used, just two charge rates 0.8A and 0.1A and the charger alternates between them to vary charge rate, it seems this pulsing between 0.1 and 0.8 helps to charge a sulphated battery.
    Heat likes this.
  19. MGW

    MGW Screwfix Select

    There is a problem with this, we don't know what internal control is done with the car electronics, also the Lidi charger needs you to press a button to start the charge off.
  20. MGW

    MGW Screwfix Select

    With the Lidi the volts need to be between 3.8 and 15 volt. Getting a charger to start the process off could be dangerous, as when I monitored input to charger it stayed at 2W for days, then rocketed to 20W seems this is common, so very easy to return to find the battery has exploded. Better option is connect in series with another 12 volt battery, be it a car battery or as in my case the leisure battery off the caravan then charge both with Lidi charger, it took a very long time for the VRLA battery to start accepting a charge, around two weeks, before that point using the charger for both my 12 volt VRLA in parallel (they came off a stair lift) the charger would start charging at 0.8A but the voltage would hit 15 volt before the charge rate dropped to 0.1 amp.

    Once the two batteries in parallel would charge, i.e. dropped to 0.1 amp charge rate before 15 volt reached, it took 3 more days before they started to charge proper, and over around 2 hours the charge rate kept changing between 0.1 and 0.8 amp, at 14.4 volt charge rate dropped to 0.1 amp then at 12.8 it returned to 0.8 amp. Then I got around 6 hours at 0.8 amp then tailed off again dropping again to 0.1 amp.

    Where I had the advantage was I was using a MiHome energy monitor on the supply to charger so could see the graph of the charge rate.

    In spite of battery being left flat for so long, they both now will run my cool box used to load and test them. However I knew why the batteries were flat in the first place, my father-in-law had turned off the supply to chair lift, they were then left some 3 months until after his death before found and put on charge.

    Would be interesting to see how the Ctek does, but not interesting enough for me to buy one, I already have two Lidi chargers, don't need another.

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