For about a week, I could smell 'rotten egg gas' from under the bonnet, and could only smell it during the afternoon heat. - no smell at all in the morning.

Initially I thought it was the coolant, as I had to put a fair bit in.

I took the battery out and the smell went away.

Battery is my 2nd battery (not cranker) and was recently purchased brand new and was only installed about 2 weeks before it started smelling.

My ute's been sitting idol for a while and the battery's hooked up to my 2 x 120w solar panels on the roof.

In the viewing window on the top of the battery it's gone from a green colour to silver. Looking at the index, it says I should get the battery checked.

Any ideas on the problem?

TIA.