Re: Deep cycle battery boils dry
Lots of good info has been posted here. First, you do not remove the caps except to maintain the battery, i.e. add water or check the electrolyte. Do not remove them when changing or discharging. As JRJ mentioned, there is off-gassing during charging/discharging. The battery is basically using energy (electricity) to separate the water (H2O) molecules. Oxygen comes off, and hydrogen comes off. Neither gas is harmful to breath in limited amounts but the hydrogen is extremely unstable and can explode.<br /><br />Another component of the off-gassing is the batterys soup itself. It is basically sulfuric acid (H2SO4). Some of those molecules are carried out intact, alive and well. H2SO4 is very corrosive and not something you should be breathing. The caps on a flooded battery are designed to allow the battery guts to breath as needed during normal use so you dont need to remove them.<br /><br />A 12v battery is really six 2v batteries in series, housed in a plastic box. Since you cant check the voltage of each 2v cell individually with a voltmeter, a hydrometer is needed to very the status of individual 2v cells. A voltmeter can be used (and is easier) to check the whole, 12v package. See the values Walleyehed posted above. It is a lot easier to start with a fresh battery and a voltmeter. Hydrometers are something you definitely needed for the feeding and care of high-end batteries. You will know when you get your hands on one of those critters because each 2v cell is removable (replaceable)...and one 12v battery can cost about as much as a brand new 15hp outboard motor.<br /><br />I am a fan of hydrometers but I discourage the use of the cheap units with floating balls inside. Of all the hydrometers on the planet those are the least accurate. For about $20-$25 you can get a calibrated hydrometer on-line from a winemaking supplier. Winemakers use them to gauge the volume of alcohol in the wine as it ferments. The specific gravity of wine is similar to battery acid. Note: you do not have wine in your battery
do not drink the batterys acid! A hydrometer will tell you if there is a bad 2v cell but there is nothing you can do about...you will need to replace all six of the 2v cells, i.e. get a new battery, so you might as well just use a voltmeter.<br /><br /><br />
Quality hydrometer here. <br /><br />Overcharging a battery does not necessarily need to be detrimental to the battery. It depends on how much soup evaporated, how long the lead plates were exposed, and how much of the lead plates were lost to the overcharge. Fwiw, controlled overcharging is the method used to resurrect dead batteries. The overcharging current reverses the effects of sulfur crystals that normally/naturally develop on the lead plates. Desirable overcharging is called equalizing. Undesirable overcharging is called yucky-bad. And just to let you know, having removed those caps could have prevented the battery from exploding during the yucky-bad overcharging. Left uncontrolled, the batterys soup could have dropped to a level that permitted arcing to occur inside the battery and that arcing could have detonated the hydrogen gas in the battery, had the caps still been on it. Having only one electron, hydrogen is the lightest atom. It wants to float away similar to helium.<br /><br />What to do? Regardless of any battery you have or get, as everyone above has pointed out, you have charger problems that need to be addressed. I would add distilled water to the cells of that battery, charge it, then load test it. If it passes, it works so use it. If it doesnt pass the load test you can try replacing the electrolyte, charging, load test again. Otherwise, toss the battery and start anew with a battery, a voltmeter, and a decent, smart charger.<br /><br />Good luck
and welcome to the board!
