This process is basically meant to refurbish the batteries even when they are totally discharged or dead. One of the main objectives is to get rid of the sulphation developed on it. This is done by letting in some additives and then letting them rest for some time that leads to the breaking down of the sulphation off the plate. This process also causes the battery to be charged properly in its full capacity and increases its life expectancy.
Charging does not solve the purpose of breaking down the sulphation. Hence even if you recharge them, reconditioning them is advisable. With some requisite tools, it can be done at home.
Accumulation of lead sulfate crystals on the lead plates hampers the performance of the batteries obstructing electrical charge running through them. Reconditioning ensures that this accumulation is removed.
A desulfator and a battery having the voltage between 6 to 10 amp is a good option. In this process, you have to connect the batteries with the desulfator and the charger. You will have to charge it till the specific gravity is displayed as anywhere between 1.250 and 1.300.
Specific gravity can be measured with the help of a hydrometer. In case you don't have that, voltage will have to be checked. Keep the charger switched on and note the voltage. Ideally, it should show more than 15 volts. This procedure takes overall 24 hours. Check the voltage and then turn off the charger, in case it displays more than 11 volts. Then let it run for around 12 hours after connecting it to the desulfator. Then again turn the charger on and let it run for 12 hours more. Continue this, till the battery gets in the ideal range of voltage and specific gravity.
You can use these units on any lead acid battery. In case you are skeptical about doing this yourself, you can get it done from a professional or you can trade yours for reconditioned ones, rather than buying new ones.