Thanks Maris, interesting observation from you about the white bits; I concur.
I waited and waited for the quite small window whereby the recessed writing on the front panels were still in shadow, but the edges were in sunlight and therefore highlighting the writing.
It was a surprisingly small time slot, around 5-10 minutes. After that, the shadows in the writing started to blend in with the face of the panel.
I did this last week and with today being our longest day of the year with 14:47 of daylight, I have another, "white on white" subject to photograph this afternoon. I have around a two week window for this house, it is facing almost due south and only early in the morning and late in the afternoon is the light right. I have been ready to do this for all of last week, but the weather, either high wind, clouds or extreme heat, have made it not worth doing.
By the way, the batteries are actually called Zcells, I just made the title to reflect the way we pronounce the letter, Z.
It is a Qld company who do these, with base manufacture now in Thailand with finishing in Qld. They were originally wholly manufactured in Qld, then base manufacturing was done in Mexico to reduce costs, probably with the USA market in mind.