I have a Renault captur 2016 vehicle with start and stop capability, the battery is EFB 70Ah 720A, I couldn't start the engine with cables connected to another standard battery of another running vehicle, the battery is almost 3 years old, so I took it out and now I'm charging it at home I'm wondering if it's even possible to revive this battery?

I never had any problem with this battery before it was never totally depleted like this.

I'm using truecharge 20 charger microprocessor controlled by Xantrex and hopefully it would help and stop, I'm afraid it will get overcharged.

Any advice would be helpful...

  • Charge it for at least 12 hours then retest it.
    – Solar Mike
    Commented Apr 2, 2020 at 14:15
  • Welcome to Motor Vehicle Maintenance & Repair! Along with what Solar Mike stated, you might need to have a separate 12vdc source (a good battery) which gives the charger a source voltage to work from. Many battery chargers won't produce a charging voltage if it doesn't detect a voltage or if battery voltage is much lower than a standard battery would be. Just a thought before you decide the battery is completely dead and needs replaced. Commented Apr 2, 2020 at 14:37
  • So in order to give the charger that additional voltage source to work from I need to connect a good standard 12 volts car battery in parallel to the depleted one (EFB) on the charger output...?
    – Infidel
    Commented Apr 2, 2020 at 15:02
  • I have a voltmeter at home I can check if I got 12 volts on the depleted one, the charger is charging with 20 amps right now but it doesn't say to voltage.
    – Infidel
    Commented Apr 2, 2020 at 15:04
  • I have 14.4 volts, and I've noticed that the charging current is now at 16 amps, this charging current will probably decrease when the battery will reach its full capacity...?
    – Infidel
    Commented Apr 2, 2020 at 15:10

1 Answer 1


It worked I was able to charge the battery in order to start the vehicle this morning, hopefully it will not get me stranded somewhere in the next couple of days...

  • Discharged lead-acid batteries die of sulphation - lead sulphate is deposited on the electrodes; this is insoluble, insulating, and consumes both lead and acid as it is produced. I would expect this to happen to an extent over the course of a week, but evidently there’s a usable amount of battery capacity still left in your case. This is likely to shorten the life of the battery but you’re ok for now. If you ask a battery shop they may test it ( perhaps for free) so you know whether it’s still good or on its last legs.
    – Frog
    Commented Aug 26, 2021 at 20:11

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