On the topic of batteries

[Phil Crader]

Today, at Pardee (a great fishery, by the way ), I heard a LOUD noise from the back of the boat. I asked my buddy, "What was that?", and he had no idea. When I stepped on the trolling motor, it had almost no power. Took a look in the bilge to see if something had come undone and noticed that one of the trolling motor batteries had EXPLODED. On one of the batteries, the tops of the cells were blown off and laying on the other side of the bilge, and the front and top sides of the battery were totally blown out like a bomb had gone off.

I have no idea what caused this, but did notice that this morning the light for that battery on my Dual Pro Sportsmans Edition was flashing red. I unplugged the boat and plugged it back in after 30 minutes and it resumed charging. I guess it was trying to tell me there was a problem with the battery.

Has anyone else had this problem? If so, was it the battery or the charger that was at fault? I bought a new battery at Pardee Marina today so I could finish the day. I'm hoping this was a problem with my old battery, and not related to the charger. I would appreciate any feedback. Thanks

[NaCl]

Phil,

If a battery is low on water, explosive gases build up inside the battery during recharging. Any spark (including one created by an internal load between dry plates) can cause the gasses to ignite. The battery explodes and acid gets all over the place.

It sounds like your charger was trying to warn you about a low water level in the battery during charging. This hot time of year, its easy for a battery to lose a lot of water during recharging. That is normal, however, if your charger is "overcharging" it will actually cause the battery to be low on water.

At this point, you need to have the charger checked for proper charging voltage and for its "trickle charge" circuit. If the charger tests out okay, then the problem was lack of maintenance by the battery owner...failure to keep the water levels up.

Here's the actual section out of the Interstate FAQ website:

"14.3. MYTH: A battery will explode.

True! Charging a wet lead-acid battery naturally produces hydrogen and oxygen gasses as electrolysis of the water occurs and needs to occur in well ventilated areas. While spark retarding vent caps help prevent external battery explosions, sparks occur when jumping, connecting or disconnecting charger or battery cables and ignite the gas causing an explosion. From the U.S. Department of Energy, DOE-HDBK-1084-95, "Precautions must be routinely practiced to prevent explosions from ignition of the flammable gas mixture of hydrogen and oxygen formed during overcharge of lead-acid cells. The maximum rate of formation is 0.42 L of hydrogen and 0.21 L of oxygen per ampere-hour overcharge at standard temperature and pressure. The gas mixture is explosive when hydrogen in air exceeds 4% by volume." Less common internal explosions usually occur while starting the engine or using the battery and normally just blow the filler caps or cover off the battery and splatter electrolyte all over the engine compartment or battery box.

The most probable cause of internal battery explosions are from a combination of low electrolyte levels below the plates in the battery, a low resistance bridge is formed between or across the top of the plates, and a build up of hydrogen gas in the cell. The low resistive bridge is called "treeing" between the positive and negative plates. When current flows in the battery, a spark occurs and ignites the residual gas in one or more of the cells. A second possible cause is a manufacturing defect in the weld of one of the plate connecting straps causing a spark igniting the residual gas. Another source of internal battery explosions are caused from direct electrical shorts across the battery's terminals. The battery rapidly over heats form the high current and can explode. The largest number of internal battery explosions occur in hot climates due to the loss of water while starting the engine. Most internal battery explosions could have been prevented if the plates were always covered with electrolyte. Please see Section 3 for more information on preventive maintenance.

A less common form of internal battery explosion occurs when a dead short is applied across the battery terminals or the battery is in a fire.

[Source: Popular Mechanics]

Periodic preventive maintenance (Please see Section 3.), working on batteries in well-ventilated areas, or using sealed AGM (Ca/Ca) or Gel Cell (Ca/Ca) type batteries can significantly reduce the possibility of battery explosions. To neutralize residual battery acid, be sure to thoroughly wash the engine compartment and the back of the hood with a solution of one-pound baking soda (bicarbonate of soda) to one gallon of warm water and rinse thoroughly with water."

Phil, until you get your charger checked out, just use it like a "manual" unit. Plug it in for a few hours when you get home and then unplug it until you're ready to go fishing again.

.....NaCl

ps Might want to throw a bunch of baking soda into your bilge to neutralize the acid. I carry a box of baking soda in my emergency bag in my boat for this reason on the water.

[Phil Crader]

Thanks for the good info, Dean. I went out to the garage this morning to check the batteries and the same bank on the charger is blinking red. I've unplugged it. I'll get the charger checked out.