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So, I'm loading my bay boat to chase little fish on Saturday. My neighbor two houses over is working on his B35 as he can't get the sb motor to start. I wave, he waves and kneels down on the deck and reaches into the battery compartment, I turn around and the explosion occured. Turned around, see him bail onto his dock amid smoke, acid, whatnot.

Hurry over, water hose in the eyes for a good 15 minutes. Other neighbor calls 911. Being a small canal community, everyone comes a runnin. Long story short, he's ok, refuses transport to hospital. A couple of cuts, lost hearing in right ear, bp was a million over 100. But otherwise, shaken not stirred.

Post mortem as I cleaned his boat of the acid was he was jumping from the Port to SB battery to kick it over. Why does this explosion occur? I was told a layer of hydrogen builds up on the top of the battery with the cooler weather we've been having. Any truth to that? Anyway to avoid this in the future. He was lucky, he had battery plastic imbedded in his coaming pads and eyebrow bimini.

I have heard of lead acid batteries exploding, most likely due to hydrogen being released during the normal charge/discharge cycles, but never heard of cool weather being responsible for generating higher than normal amounts of it.

Safety is one of the reasons I went to sealed AGM batteries when I redid my 12 volt supply system last year.

Battery explosions are common, mostly, to wet cell batteries...

A battery explosion is caused by the misuse or malfunction of a battery, such as attempting to recharge a primary (non-rechargeable) battery, or short circuiting a battery. With car/boat batteries, explosions are most likely to occur when a short circuit generates very large currents. In addition, car/boat batteries liberate hydrogen when they are overcharged (because of electrolysis of the water in the electrolyte). Normally the amount of overcharging is very small, as is the amount of explosive gas developed, and the gas dissipates quickly. However, when "jumping" a car/boat battery, the high current can cause the rapid release of large volumes of hydrogen, which can be ignited by a nearby spark (for example, when removing the jumper cables).

When a battery is recharged at an excessive rate, an explosive gas mixture of hydrogen and oxygen may be produced faster than it can escape from within the walls of the battery, leading to pressure build-up and the possibility of the battery case bursting. In extreme cases, the battery acid may spray violently from the casing of the battery and cause injury. Overcharging—that is, attempting to charge a battery beyond its electrical capacity—can also lead to a battery explosion, leakage, or irreversible damage to the battery. It may also cause damage to the charger or device in which the overcharged battery is later used. Additionally, disposing of a battery in fire may cause an explosion as steam builds up within the sealed case of the battery.

Avoidance includes good ventilation to the batteries, proper charging systems, good maintenance, and leave the jumper cables in the trunk of the car... Wire the batteries either through battery switches or a soleniod to allow for paralleling.

I had a battery explode on a 46' Bertram about 20 years ago. Happened when I tried cranking the engine. No real harm done because the batteries were in a closed and dedicated compartment under the cockpit deck. Just a real ugly mess to clean up. The fault was old batteries that the top plates were bulging on.

I don't know if temperature has any bearing on the situation...

Best percaution? Switch to glass mat batteries...

Every car owner's manual I've had for the last 30 years all require the same procedure for jumping batteries:

Positive of good battery to positive of battery being jumped,
Negative of good battery to ground of chassis.

The last connection brings the danger of spark, and you want it a good distance away from from the battery. My BMW even goes so far as to put the battery in the trunk and provide jumper terminals in the engine compartment. My 1970 Mustang manual actually suggest touching bumpers if possible. (For you youngsters: yes, there once was a time when bumpers were bare steel and grounded, instead of plastic).

If your neighbor had grounded the negative cable to the engine, there's a good chance this wouldn't have happened.

Cheers!

John

AGM!!!!!!!!!!!!

BCBertie wrote:Every car owner's manual I've had for the last 30 years all require the same procedure for jumping batteries:

Positive of good battery to positive of battery being jumped,
Negative of good battery to ground of chassis.

The last connection brings the danger of spark, and you want it a good distance away from from the battery. My BMW even goes so far as to put the battery in the trunk and provide jumper terminals in the engine compartment. My 1970 Mustang manual actually suggest touching bumpers if possible. (For you youngsters: yes, there once was a time when bumpers were bare steel and grounded, instead of plastic).

If your neighbor had grounded the negative cable to the engine, there's a good chance this wouldn't have happened.

Cheers!

John

I knew that was the procedure for a real long time...I've even done it that way on occasion. Never knew why. Thanks for that explanation. I'm sure I'll be doing any jumping that way from now forward.

Carl

I've had two lead acid batteries blow up on me, one in an old Ford wagon and it blew the hood up, and the other one blew up in my face when I hooked a charger up to it in a mud boat. Both were low on water and that makes them gas off real bad. Hydrogen is what makes the space shuttle go bang......

UV

Tom,

I have experienced three battery explosions. Two on the old bertram and one car battery. All three explosions occurred while attempting to crank the engine. Turn the ignition switch and boom!!!!. Luckily the boat explosions occurred at the dock.

Garry