Pouring boiling water over car battery- safe?

Dunno how you do it Conor. You give a perfectly reasonable answer and get shot down in flames for your answer. Mebbe the cage drivers know instinctively what you drive LOL. I would add one proviso, don't try this with the battery in situ on a beemer with the battery in the back, or a Mercedes Vito with the battery under the drivers seat. Most cars with an engine compartment battery will be fine, the battery sits on a corner with drain holes under it that exit to the ground. If you are silly enough to buy a car with a battery in the engine compartment, but with drain holes that mysteriously spread through the body, it serves you right.

That seems unlikely.

I would dearly like to know what is so mystical about this white powder that it can only be removed with a ritual involving boiling water.

I'm rather baffled as to why it would be a bad idea though.

Isn't that what you're doing just now?

Tipping water into places you can't see where it might hang around a while can't be a good thing, especially if you're washing acid down with it. God knows the things rust well enough without help.

The world will not end, I grant, but the seeming pointlessness of it is what gets me.

Done Retching - anal retentive extraordinaire.............................................................. ...Funny how the name Buchan sounds like someone being sick eh? especially in a Scots accent.

Yes dear. I don't understand what you said but I'm sure it was very clever.

Funny thing to say with a name like Stuart.

extraordinaire..............................................................

very rententive, what if I was a Stewart then? But as I said, a Scots accent helps........

Stuart Gray wrote

I always used to pour (almost) boiling water to clean up battery terminals, then smear them with vaseline, but I don't remember seeing any white powder around the terminals of my last few cars.

I thought it was a 'thing of the past'.

Oi! Leave it!

Stuart Sharp

I haven't either but then, like you, I bother to grease the terminals.

Years of practice...

It gets rid of all of it quickly and if you use enough it flushes it away. You then get a smidgen of vaseline/grease and coat the terminals. Saves getting out spanners, trying to remember radio codes and fighting the car alarm PLUS you can also get the missus to make a brew at the same time :-)