Yes. The battery exploded
Which is why I’m keeping bicarbonate of soda next to my batteries from now on
A friend of mine recently went to help another boater whose domestic batteries weren’t holding their charge.
It was a substantial lead-acid battery bank - around 500Ah - but it was going flat overnight. My friend has spent decades working with batteries, so he arrived with a battery tester to find out what was going on.
The batteries were isolated and he began disconnecting them so they could be tested individually.
As he removed one small cable from a terminal, there was the tiniest spark.
Then the battery exploded.
The top blew apart, sending pieces of the casing upwards. Fortunately, he wasn’t directly over it. The engine-room doors were open and most of the electrolyte remained inside the battery.
Even so, his ears rang for several days. A T-shirt he’d been wearing subsequently developed tiny holes where droplets of sulphuric acid had landed on the cotton.
His immediate thought was the battery acid.
He quickly got himself to clean water and drenched himself, then went back to deal with the area around the battery.
What he hadn’t known was that the batteries had been on charge for several hours before he arrived and had only recently been disconnected from the charger. A failing lead-acid battery can give off hydrogen while charging. A tiny spark can be enough to ignite it.
There was another clue.
The boat’s sophisticated intelligent charger had refused to charge the failing batteries. Assuming the charger was the problem, a cheap standalone charger had been bought instead - and that had been charging them before my friend arrived.
As he put it afterwards, it was a classic case of the holes in the Swiss cheese lining up.
He also admitted something rather important. In his professional life, working on batteries meant proper protective equipment. On a friend’s boat, doing a quick favour, he hadn’t taken the same precautions.
So this isn’t a story about somebody who knew nothing about batteries.
It’s a story about somebody who knew a great deal about them.
Moral of the story
If you have lead-acid batteries aboard - including sealed ones - treat them with respect. Wear suitable protective gloves and proper eye protection before working on them, and make sure the area is well ventilated.
And keep some bicarbonate of soda near your battery bank. It can be used to neutralise small spills of battery electrolyte on surfaces before the area is cleaned and rinsed with water.
If you suspect battery acid has reached your skin or eyes, however, forget the bicarbonate - flush the affected area immediately with plenty of clean water.
Because sometimes all it takes is the tiniest spark.