50 firefighters are tackling a blaze at G&P Batteries on Willenhall Road, Walsall.
ITV News Central has been told by eyewitnesses that a number of loud explosions could be heard at the plant.
It is the second time this year a fire has broken out at the factory - the previous one on 14 January saw 60 firefighters in attendance.
More top news
A cold and mostly dry day, with wintry showers becoming more confined to coasts. Brisk winds, especially near coasts.
A mostly dry day with sunny spells. Wintry showers from late afternoon in the west and north, perhaps falling as snow to lower levels.
Isolated wintry showers perhaps giving further, mainly slight, snow accumulations inland.