Despite a lot of advances in battery technology, lead acid batteries are still used in many applications due to cost and their ability to provide a lot of surge current. But they don’t last forever. However, [AvE] shows that in some cases a failed battery can be restored with — of all things — epsom salts. If it makes you feel funny to use the stuff grandpa soaks in when he has a backache, you can call it magnesium sulfate.
You can find a complete explanation in the video below (which includes [AvE’s] very colorful language), but fundamentally, the magnesium sulfate dissolves lead sulfate build-up on the battery plates. The fix is usually temporary because this build-up occurs with other failure mechanisms like plate material shedding and collecting at the bottom of the battery. Obviously, epsom salt can’t repair damaged plates or do any other magic cure.
We really enjoyed that [AvE] tore open a battery to show the plates and what was really happening inside. He also explains why the epsom salt might help.
We were surprised that he poured the salt directly into the battery. We were always taught to heat up some distilled water and saturate it with the epsom salt. Then you’d filter out any solid left and pour the water/salt mixture in until it couldn’t take any more.
Not only does this not always work, but it also doesn’t work instantly. We’ve heard of batteries treated with epsom salt or caustic soda reviving after several weeks. However, even if you don’t want to restore a battery with salt, there’s plenty of interesting battery facts and lore in the video that you’ll find interesting.
Everyone loves to point out how just about any project could have used a 555. That chip can charge your battery after you repair it. This isn’t the first time we’ve contemplated salting a battery, by the way. On the other hand, you can make a peculiar battery out of molten salt.