Tom and Ray settle a bet but not in reader's favor

Dear Tom and Ray:

Please help me settle a bet with my father-in-law ... the winner will buy the loser his next battery.

My father-in-law claims that even though car batteries may be marked ?maintenance-free,? if the battery has vent caps you can pry off, you should do so, and check and ? when necessary ? refill the electrolyte levels as needed.

I say no, that modern car batteries do not require checking electrolyte levels, and that by prying off the vent caps, you actually could cause some harm to a maintenance-free battery.

Can you help settle our bet?

~ Michael

Ray: We can but you?re not going to like the settlement, Michael.

Tom: Back in the 1970s, battery manufacturers switched over to calcium lead plates because they seriously reduced out-gassing.

Ray: Out-gassing, aside from being a byproduct of eating a beef-cheese chorizo burrito, is when the fluid inside the battery heats up and ?boils off.? It's similar to what happens when water boils and gives off vapor ? eventually, you run out of water.

Tom: Because calcium lead grids reduced out-gassing significantly, and all but eliminated the need to add water to the battery cells, these batteries were called ?maintenance-free.?

Ray: But they don?t eliminate out-gassing completely. And if the engine compartment is subject to extremely high temperatures, even a maintenance-free battery can lose fluid.

Tom: With maintenance-free batteries, out-gassing is most likely to happen in areas of the country that get extremely hot in the summer, or where cars are in constant stop-and-go conditions and their engine compartments get up to very high temperatures.

Ray: Most people will never need to add water to their maintenance-free batteries. In fact, the vast majority of batteries don?t even allow you to check the fluid levels anymore.

But if your maintenance-free battery does have removable caps, there certainly is no harm in removing them and adding water if the fluid happens to be low.

Tom: It's not a regular maintenance item, like it was 20 or 30 years ago, Michael. But you owe your pop-in-law his next battery. If you?re really lucky, his next battery will be for his flashlight.

Sponsored by George's Friendly Auto Service.