Reviving an Old Car Battery

• 

  JIMB0 on 29/12/2019 - 13:48

  It will probably work ok for a while but I wouldn't rely too much on it.

• 

  Mechz on 29/12/2019 - 14:10

  +2

  A mechanic mate sent me this a few months ago;

  A brilliant young hippy genius (really,) i know introduced me to a terrific process for reclaiming tired batteries:

  Hook it to a load, like a 12V light, and run it stone, motherless flat. Then give it a touch more acid (not top-up with water,) to ensure the precipitates will dissolve. Then hook up a high-current charger the WRONG way - pos to neg etc - and charge the battery to full. (Might need to add a "normal" car battery to the circuit to buffer the load and stop the charger tripping.) Once fully charged, connect the load and run the battery stone flat again. Then charge at normal polarity and away you go.
  Done it to 2 of my cars and they're going strong after 7+ years.

  • 

    resisting the urge on 29/12/2019 - 16:05

    +1

    Any idea how much current a medium (say 80AH) battery will draw when run flat and reverse charged?

    Or are you maxing out the charger and hoping it doesn't overheat/cut out?

    Not sure the buffering battery should be connected for long, it could overload the cables. How big would they need to be? If you push it below 12V it will begin to grow sulfation on its plates also.

    • 

      uniqualz on 29/12/2019 - 16:28

      Yes, good questions, @Urge.. was thinking the same.

      • 

        resisting the urge on 29/12/2019 - 16:38

        +1

        Indeed. The law of diminishing returns means for every battery you part revive, another will be part worn, or a charger part burned… only a good test can tell!

  • 

    uniqualz on 29/12/2019 - 16:28

    Thanks @Mechz.. Incredible. As long as I don't blow my head off..

• 

  payless69 on 29/12/2019 - 14:33

  +1

  you are turning wine into water! Many ways to skin a cat. My NBN battery went beep so got a more affordable one than they recommend.
  Found of youtube a way to open the old one and yep it was dry but not because it was a bad battery. Idiots who designed the NBN backup box made the battery to sit vertical rather then the intended horizontal way it should be. A bit of membrane filtered water, a $2 charger and it it feels like born again. Makes a fun spark generator.
  Most cars could run on supercaps who would hold charge for about 14 days. Plenty of youtubes out there. $30 lipo packs can start dozens of cars but why go for the new if the old is cheaper?

  • 

    uniqualz on 29/12/2019 - 16:31

    +1

    Thanks Payless.. good points. Will youtube the supercaps - sounds amazing.

• 

  OzHunterNSW on 29/12/2019 - 14:42

  Have a look at your vehicles battery box. If you are able to install a larger battery, the I suggest steering clear of the smaller batteries and install a heavy duty.
  My Batteries were lasting 2y until I installed the larger battery… going on to 5 years now.

  • 

    resisting the urge on 29/12/2019 - 16:15

    Larger means heavier, higher initial cost, more fuel consumption.

    There are many factors involved, some others are:

    • Infrequent use will push a small battery below its usable range, so sulfation will occur faster.
    • If your car lives in a garage, or is otherwise warmer overnight, temps will be higher and allow the battery to last longer.
    • If your car draws a lot of current (max wipers, fax, lighting, other accessories) a larger battery and your alternator needs to be larger to prevent the system running out of power on a rainy night.

    Best way to get good life is to ensure your alternator is healthy and charging properly at all speeds, and that your engine starts easily so it is not stressed as hard each time you drive it

  • 

    uniqualz on 29/12/2019 - 16:34

    Thanks OzHunterNSW, yes, I do always push the limit to what size and CCA rating I can squeeze in, which of course helps heaps. But they still seem rubbish compared to batteries from years ago. I just presume it's the standard 'planned obsolescence' designed into modern day batteries, just like everything else these days. Maybe not though..

• 

  ShannonN on 29/12/2019 - 16:22

  +3

  in the old days we used to add a 1/2 t spoon of bi carb to each cell, after it stops fizzing top up water, seal (cap cells) overnight then un cap in morning, allow to vent then trickle charge 12 hrs. may work for you however if its down to nine volts probably 2 plates have buckled and for reliability get a new battery

  As you're on the Goldie ring Peter Goulding at big lttle batteries at Miami
  (2/43 Hillcrest Parade, Miami QLD 4220. Phone: 0414 777 662)
  Tell him Shannon referred you

  He has good traded batteries that are checked and 3 mths guarantee cheaper than going to a new one if you're selling the car etc

  • 

    uniqualz on 29/12/2019 - 16:36

    Thanks ShannonN.. yea.. at 9 volts, she doesn't look too good. Soon find out I guess.