A bang of a story...
There was a large Bang! Or was a it a pow! Actually it was more of a BOOM! Surely the largest explosion I have ever been in close proximity to.
I was shocked, dismayed and in pain. I had been on my hands and knees on the #2 engine hatch. Reaching in the open #3 hatch. I was manually trying to get my old 6.5kw Kohler generator to start. The explosion was a complete surprise! The next thing I knew, I found myself on flat on my back. My ears were ringing and I was cradling my right arm, it hurt and was all a tingle. I said a very bad word and did a quick inventory of all my extremities. Though the skin on my arm was buzzing at about the same rate as my ears, I could see no obvious damage. I still had all my fingers and they all seemed to still work ok. There was pain in my elbow, forearm and shoulder, but they worked as well.
All good news. Rolling over onto my stomach I crawled over and peeked over into the center compartment. My mind was racing. What was I going to see? All the while I was asking myself "What in the hell could that have been?" I thought I had taken all the safety precautions. There was no Smoke. Good. No fire. Even better... The explosion was so loud I thought it may have blown a hole in the boat! I stared intensely at the bottom of the boat. Waiting for the little puddle of rain water in the bilge to grow. Thank God for U.S.Industries Steel. I could detect no leaking of water. My next thought was that the battery for the generator may have blown up. My eyes scanned all over the battery next to the generator. It was there all right and still completely intact!? There was no sign of bloating, leakage or cracks of any kind. It was at this point that I realized I should not be able to view the battery at all. It's supposed to be in a marine rated battery box and strapped down to the mounting board? That's when I finally focused on all the debris scattered all about the engine compartment. Small pieces of the heavy black plastic battery box were everywhere! It would appear that the battery box had blown completely off of the battery! "What the Hell?" Then I found the clue that put everything into place. I spotted a small scorch mark on the negative battery terminal. It was still very hot. I took the negative lead and wiggled it. Yep, it was loose! Too loose. Surely the cause of the explosion.
After some thought, here's how I think the unexpected explosion came about. The generator was cold and didn't want to start so it cranked a bit long before it finally started, depleting the battery. Once started the generator will put a heavy recovery charge on its cranking battery. As I was having cut_off relay problems with the generator, it would run only 30 seconds or so, then the breaker would pop and cut the engine. The pop out breaker had an adjustment screw so I would make small adjustments, reset the breaker and hit the switch. The generator would run another short bit and kick off again. I did this four or five times, standing in the engine compartment, right next to the battery box I might add. By this time the battery must have been out-gassing hydrogen from the heavy charging. All the while the multiple starting's were heating up the loose ground connection on the battery terminal. The last time the generator started it ran for almost a full minute. Long enough for me to crawl out of the engine compartment. Long enough for the battery to out gas a fair amount of hydrogen. When the breaker failed again, I was on deck. I knelt down on the #2 hatch and reached over to make my last adjustment and push the button... The negative battery lead must have sparked inside the battery box... Hydrogen Boom! I was lucky in about a hundred different ways. I very well could have been still in the compartment at the time of explosion! Lacerated by sharp plastic. Or sunk my boat! My wife tells me I have an angel on my shoulder and I think she may be right. Suspected culprit. Now I have heard of batteries blowing up, falling apart and catching on fire. But I have never heard of a battery box blowing off of the battery! Ever! Till now. On the battery terminals I was using was a wing nut adapter' It was the wing nut' connector that came loose. Had I used a bolt on type with a locking washer I would not be out a nice West Marine battery box and a big fat bruise on my forearm. Take it from me, go and inspect all your battery terminals. Make sure you have the right size wires and your connections are tight! You may not be as lucky as me! Safe boating to all...
Mike Wolfe "The River Queen Refit" December 2003.
One of the larger pieces!