A colleague here has brought the report concerning a battery explosion to my attention.(Maritime Feedback No 20). My company is a specialist battery supplier and has supplied the marine industry for many years. For marine applications we recommend the use of AGM batteries – absorbed glass mat or re-combination – as these will gas significantly less when charging compared to the “wet” batteries used by that unfortunate mariner. The charging process will cause hydrogen and oxygen to vaporise out of the sulphuric acid electrolyte. The AGM batteries are sealed, with a valve to release gases under more extreme conditions, whilst wet batteries require the loosening of the cell caps. Both hydrogen and oxygen are highly explosive, odourless and invisible and therefore most dangerous if not adequately vented. Unfortunately the AGM batteries are relatively expensive when compared with standard “wet” batteries but do have a good working life, and are maintenance-free, and therefore the actual cost of ownership over time is more favourably comparable. Used correctly, they can also be mounted on a side or end to fit tight compartments.