car battery

As more and more electrical gadgets got loaded into the cars (esp. the newer models), the life span of car battery just getting shorter and now they are designed to last for about 3 or 4 years at most.

If the type that you are using is still the one that you can open the top and refill, all you can put/add is distilled water. Do not put any chemical in coz that will mess up the ionization "line up". Keep in mind the battery recharge itself by ion exchange, recharge is just reverse the process. If you put other chemicals in, the reverse process cannot be completed in this case.

You can recharge it by using a recharger to run it overnight and speed up the recharge process. But my experience told me that your battery can only recharge only once or twice at most within its service life. Since nowadays all batteries got a warranty for 7 years, if it die sooner, you will be partically refunded on a pro-rated basis (manufacturers can recycle them) anyway.

Normal life 3 to 4 years.

If you found liquid level low, you can refill it with Distrilled Water to the level marked HIGH. No other chemical nor battery liquid is needed.

You can run the engin while adding distrilled water, or at least run the engin for a few minutes before adding, because water will dilute the battery.

After water added, run a few more minutes to re-charge the battery.

In fact, you need not re-charge it manually. Your enginer got a Dynamo built-in to re-charge the battery while your engin is on.