I have an 81' Hunter 30. It has two batteries. One has exploded, and one will not hold a charge. This happened over the winter. The positive terminal wire connections on the battery that exploded are either burned or melted. I am plannning on using my multi-meter to test for continuity between all positive and negetive wires before I put new batteries in the boat. Is there anything else I should check/do?
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Jim Maroldo
Wow!
Fred, you haven't mentioned any of the conditions that were present over the winter. May we assume that you had a charger running during this time? Was the lead going from the charger to the battery fused? I cannot imagine a battery exploding all by itself; there would have to have been either a large current going in, or a dead short circuit (i.e.: something with heavy wire that won't pop like a fuse, like your starter motor?). Jim Maroldo Ocean Gate, NJ
Fred, you haven't mentioned any of the conditions that were present over the winter. May we assume that you had a charger running during this time? Was the lead going from the charger to the battery fused? I cannot imagine a battery exploding all by itself; there would have to have been either a large current going in, or a dead short circuit (i.e.: something with heavy wire that won't pop like a fuse, like your starter motor?). Jim Maroldo Ocean Gate, NJ
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Jim S
Re:Battery exploded! What should I check?
Fred, When a battery explodes it usually is caused by a very low resistance high current connection from the positive to the negative terminals, commonly referred to as a "dead short" It could be mechanical, (like dropping the proverbial crescent wrench right across the terminals) or it could be a good soaking of water on the top of a battery that had a film of dried battery electrolyte on it. Since the terminal of the exploded battery got hot enough to melt, it's not likely that a short in a component wired with 12 AWG wire or smaller would have caused the trouble, also my '76 Hunter 30 has 10-20 amp circuit breakers on all the loads that (at least by design) should trip open way before a terminal could melt. If you've added any hard wired loads or devices (especially with heavy gage wire like an inverter or a battery A/B switch) I'd inspect all that wiring for shorts not only with your ohm meter but with your eyes and hands. If you don't find any smoking gun shorts, and all your testing shows high resistance from positive to negative, just to make yourself comfortable you could gang up 8 d-cells in series and hook them up before you put in the $120+ of new batteries. If those don't peter out immediately but they can light up a cabin light or two, whatever short you had is gone. Jim
Fred, When a battery explodes it usually is caused by a very low resistance high current connection from the positive to the negative terminals, commonly referred to as a "dead short" It could be mechanical, (like dropping the proverbial crescent wrench right across the terminals) or it could be a good soaking of water on the top of a battery that had a film of dried battery electrolyte on it. Since the terminal of the exploded battery got hot enough to melt, it's not likely that a short in a component wired with 12 AWG wire or smaller would have caused the trouble, also my '76 Hunter 30 has 10-20 amp circuit breakers on all the loads that (at least by design) should trip open way before a terminal could melt. If you've added any hard wired loads or devices (especially with heavy gage wire like an inverter or a battery A/B switch) I'd inspect all that wiring for shorts not only with your ohm meter but with your eyes and hands. If you don't find any smoking gun shorts, and all your testing shows high resistance from positive to negative, just to make yourself comfortable you could gang up 8 d-cells in series and hook them up before you put in the $120+ of new batteries. If those don't peter out immediately but they can light up a cabin light or two, whatever short you had is gone. Jim
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Geof Tillotson
Or a spark of some sort....
You didn't mention what type of battery you had that exploded, but if they are the older flooded type of batteries they create hydrogen and oxygen when they are being charged. Since they often aren't closed cell, they vent these gases to the space around the batteries. If this is the case, even a 4% hydrogen concentration is enough to cause an explosion if there is a spark present. Think about the zepellins that were hydrogen filled, you get the picture? When I was younger, I did some work with a prevention of blindness group and they showed videos of folks who were trying to charge car batteries that exploded, showering them with sulfuric acid, not a pretty site, and a common cause of blindness and disfigurment. Things have gotten better over the years, and you don't hear about it happening as much now. Anyway, check to see if this might have been a contributor to problem. Sparks on boats are not a good thing. If you can isolate them you won't be surprisedd in the future. Also, you do need to ventilate flooded cell batteries as a matter of course. Geof
You didn't mention what type of battery you had that exploded, but if they are the older flooded type of batteries they create hydrogen and oxygen when they are being charged. Since they often aren't closed cell, they vent these gases to the space around the batteries. If this is the case, even a 4% hydrogen concentration is enough to cause an explosion if there is a spark present. Think about the zepellins that were hydrogen filled, you get the picture? When I was younger, I did some work with a prevention of blindness group and they showed videos of folks who were trying to charge car batteries that exploded, showering them with sulfuric acid, not a pretty site, and a common cause of blindness and disfigurment. Things have gotten better over the years, and you don't hear about it happening as much now. Anyway, check to see if this might have been a contributor to problem. Sparks on boats are not a good thing. If you can isolate them you won't be surprisedd in the future. Also, you do need to ventilate flooded cell batteries as a matter of course. Geof
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Jim Wallace
Winterizing batteries
To prevent this from happening in the future, always disconnect the wiring connections when storing batteries for any length of time. Leaving them connected in the winter can cause the batteries to freeze, expand and burst. At the very least, disconnect the ground.
To prevent this from happening in the future, always disconnect the wiring connections when storing batteries for any length of time. Leaving them connected in the winter can cause the batteries to freeze, expand and burst. At the very least, disconnect the ground.
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Fred G
More details and Thanks
The batteries were in the boat when I bought it (Dec 2000). I had a charger hooked up to dock power to keep the batteries topped off. The batteries were in boxes, and that helped contain the mess a lot. The battery that exploded was clean with no water or buildup on it. The battery boxes have covers and hold down straps on them. They could have frozen, but I keep a heating element in the boat as well and it was working properly. Thank you for all of your suggestions.
The batteries were in the boat when I bought it (Dec 2000). I had a charger hooked up to dock power to keep the batteries topped off. The batteries were in boxes, and that helped contain the mess a lot. The battery that exploded was clean with no water or buildup on it. The battery boxes have covers and hold down straps on them. They could have frozen, but I keep a heating element in the boat as well and it was working properly. Thank you for all of your suggestions.
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Steve
Charger?
You might check the charger. It could have cooked the batteries or be placing too much voltage in them. That generates heat as well as the exposive gas.
You might check the charger. It could have cooked the batteries or be placing too much voltage in them. That generates heat as well as the exposive gas.
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Paul Akers
Happened to me
That once happened to me. I had hard-wired a cigarette lighter (accessory) plug to my house batteries. The connector on the end of the wire parted. The charger was running. What I figured was that the batteries were gassing from the charger and the spark set it all off. One battery split and the casing shattered. Another battery was bulging. The other 2 were dead. I had to buy 4 new batteries. I had acid in the bilge and everything on board that was plastic was discolored. This was in the summertime while I was away from the boat. A bittersweet smell permeated the whole interior and it took a couple of months to get rid of the smell.
That once happened to me. I had hard-wired a cigarette lighter (accessory) plug to my house batteries. The connector on the end of the wire parted. The charger was running. What I figured was that the batteries were gassing from the charger and the spark set it all off. One battery split and the casing shattered. Another battery was bulging. The other 2 were dead. I had to buy 4 new batteries. I had acid in the bilge and everything on board that was plastic was discolored. This was in the summertime while I was away from the boat. A bittersweet smell permeated the whole interior and it took a couple of months to get rid of the smell.
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Stan
Battery Short??
I have seen a large fork truck battery with an internal short heat up and ultimately explode. All wiring was disconnected but it didn't stop the meltdown.
I have seen a large fork truck battery with an internal short heat up and ultimately explode. All wiring was disconnected but it didn't stop the meltdown.
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Peter Brennan
Benn there, done that
I will bet it was an internal short in one of the batteries that caused a steam -- not hydrogen -- explosion. Far worse than a hydrogen pop from a gassing battery. That the other battery will not hold a charge would indicate these units were not in the best of shape despite over winter charging. Did you apply a load just before it blew? I had three batteries which I knew were not great and was planning to replace them. They had refused to hold a charge the previous fall after being mistreated by the yard where the boat had been laid up for engine work for several months. Everything was fine until I goosed the engine and its high-output alternator. Then Blam! Blam! Blam! Everything in the boat is and was fused and breakered, even the lighter sockets. But no fuses can protect against an internal short, possibly caused by bulged plates or debris at the bottom of the cells. And of course the acid in the cells turns to instant steam, utterly shattering the cases and spewing acid everywhere. Also caused a fire. The fire extinguisher powder, all fifty pounds of it, helped neutralize the acid. Repairs cost $34,000. These included, long after the fact, replacing the wood backing plate on a through hull, which had been turned to punk by acid and alkali. You got off easy. Next time, make sure the batteries are fully charged and then disconnect them totally for the winter. Charged batteries won't freeze in any reasonable climate and good ones lose surpringly little charge from self discharge. Mine (new Rolls) came in at 12.5 volts after four months.
I will bet it was an internal short in one of the batteries that caused a steam -- not hydrogen -- explosion. Far worse than a hydrogen pop from a gassing battery. That the other battery will not hold a charge would indicate these units were not in the best of shape despite over winter charging. Did you apply a load just before it blew? I had three batteries which I knew were not great and was planning to replace them. They had refused to hold a charge the previous fall after being mistreated by the yard where the boat had been laid up for engine work for several months. Everything was fine until I goosed the engine and its high-output alternator. Then Blam! Blam! Blam! Everything in the boat is and was fused and breakered, even the lighter sockets. But no fuses can protect against an internal short, possibly caused by bulged plates or debris at the bottom of the cells. And of course the acid in the cells turns to instant steam, utterly shattering the cases and spewing acid everywhere. Also caused a fire. The fire extinguisher powder, all fifty pounds of it, helped neutralize the acid. Repairs cost $34,000. These included, long after the fact, replacing the wood backing plate on a through hull, which had been turned to punk by acid and alkali. You got off easy. Next time, make sure the batteries are fully charged and then disconnect them totally for the winter. Charged batteries won't freeze in any reasonable climate and good ones lose surpringly little charge from self discharge. Mine (new Rolls) came in at 12.5 volts after four months.
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Greg aboard "BlueBerry"
...and if there was no water
in the batteries, that would cause the meltdown you described. Leaving a charger on over a long period of time, without constantly replenishing the water, will at least fry, and if in an enclosed space, detonate the built up gases.
in the batteries, that would cause the meltdown you described. Leaving a charger on over a long period of time, without constantly replenishing the water, will at least fry, and if in an enclosed space, detonate the built up gases.
past discussions indicate
Fred: Past discussions on this subject indicate that fully charged batteries will NOT freeze. I think that you batteries were being overcharged and where NOT be refreshed with water. My suggestion is to get a smart charger (Statpower/Xantrex 20/40 Plus). Others that have had these charges indicate that they do not boil your batteries. They seldom need to add water. These charges also have the benefit of being able to charge Flooded, AGM or Gels (in case you want to change to a different type now or in the future).
Fred: Past discussions on this subject indicate that fully charged batteries will NOT freeze. I think that you batteries were being overcharged and where NOT be refreshed with water. My suggestion is to get a smart charger (Statpower/Xantrex 20/40 Plus). Others that have had these charges indicate that they do not boil your batteries. They seldom need to add water. These charges also have the benefit of being able to charge Flooded, AGM or Gels (in case you want to change to a different type now or in the future).
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R.W.Landau
My guess
I agree with Jim S that it was due to a large currant load. Here is my theory. If your batteries were not full charged, the plates may have silted enough that one of them shorted out. The other battery provided more power to support the short , the battery heated up and exploded. The drained battery froze and is now worthless also. r.w.landau
I agree with Jim S that it was due to a large currant load. Here is my theory. If your batteries were not full charged, the plates may have silted enough that one of them shorted out. The other battery provided more power to support the short , the battery heated up and exploded. The drained battery froze and is now worthless also. r.w.landau
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Fred G
Thanks guys!
I appreciate all of you educating me on what the possible causes were. I feel somewhat relieved that most of yor comments stem from the batteries and charger and not the rest of the electrical system. I can tell you that I never checked or added water to the batteries (I will now!). I will see if I can replace the charger as well. Aside from testing all positive and negetive battery connections for continuity, and replacing the burned connectors, should I check anything else and how should I do it?
I appreciate all of you educating me on what the possible causes were. I feel somewhat relieved that most of yor comments stem from the batteries and charger and not the rest of the electrical system. I can tell you that I never checked or added water to the batteries (I will now!). I will see if I can replace the charger as well. Aside from testing all positive and negetive battery connections for continuity, and replacing the burned connectors, should I check anything else and how should I do it?
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Mark
wintering batteries
IMHO the best thing a person could do for his/her batteries in the winter would be to put them somewhere where they will not freeze (like a basement), make sure the case is clean so that the juice will not leak down the dirt to ground, and put on a trickle charger made for that purpose. Next best thing is to put a trickle charge on each batt. every 30 days. A batt. left alone will lose about 2% of its charge every month. If it freezes, it's probably ruined. By the way, cement floors do not drain the charge from a battery-but the dirt on the case acts like a conductor.
IMHO the best thing a person could do for his/her batteries in the winter would be to put them somewhere where they will not freeze (like a basement), make sure the case is clean so that the juice will not leak down the dirt to ground, and put on a trickle charger made for that purpose. Next best thing is to put a trickle charge on each batt. every 30 days. A batt. left alone will lose about 2% of its charge every month. If it freezes, it's probably ruined. By the way, cement floors do not drain the charge from a battery-but the dirt on the case acts like a conductor.
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Pete Albright
Parallel batteries need fusing
I know this is not the usual method used, but any batteries installed in parallel should have _individual_ fusing for each battery. This will prevent a fault in one battery from shorting out the others in the bank. The bigger the battery bank, the more important this becomes. Peter Brennan's $34,000 example of what can happen is all the proof anyone should need.
I know this is not the usual method used, but any batteries installed in parallel should have _individual_ fusing for each battery. This will prevent a fault in one battery from shorting out the others in the bank. The bigger the battery bank, the more important this becomes. Peter Brennan's $34,000 example of what can happen is all the proof anyone should need.
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Peter Brennan
How big a fuse
Very good point about individual fuses for the batteries. The high-output charging circuit does have a big fuse but that does not protect against an internal short. The windlass circuit has a 100 amp circuit breaker. I supose you would run the postive battery cable through a high amp fuse or breaker before it connected to any switch or anything at all and cut the battery completely out of the system if it had an internal short. Any thoughts?
Very good point about individual fuses for the batteries. The high-output charging circuit does have a big fuse but that does not protect against an internal short. The windlass circuit has a 100 amp circuit breaker. I supose you would run the postive battery cable through a high amp fuse or breaker before it connected to any switch or anything at all and cut the battery completely out of the system if it had an internal short. Any thoughts?
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Pete Albright
Fuse Sizes
Per ABYC you shpould have fuses sized based on the main battery cable size. This fuse can be installed after you parallel the batteries. To protect each battery in the bank, you would fuse each battery, again based on the cable size. example: (battery +) to (2/0 cable) to (300 amp fuse) to (2/0 cable) to (battery switch) to (2/0 cable) to (main positive bus bar). If the cables are paralleled before the main bus bar, then another fuse should be installed, unless theparalleled cable can carry the combined load.
Per ABYC you shpould have fuses sized based on the main battery cable size. This fuse can be installed after you parallel the batteries. To protect each battery in the bank, you would fuse each battery, again based on the cable size. example: (battery +) to (2/0 cable) to (300 amp fuse) to (2/0 cable) to (battery switch) to (2/0 cable) to (main positive bus bar). If the cables are paralleled before the main bus bar, then another fuse should be installed, unless theparalleled cable can carry the combined load.
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Forrest Clark
Thermal Runaway
I believe that you may have had a battery in thermal runaway. Thermal Runaway is when the internal temperature of the battery increases at a faster rate than it can dissipate heat. This can occur during charging and as such the charging current increases as the heat increases.I have seen this happen to a bank of 36 2v 1900ah gel cells. There was no acid on anything but lots of oxidation and some corrosion mostly on electronic circuit boards. This was a large battery with alot of electrolyte. The remedy was to decrease the charging voltage slightly. You may want to check the voltage from your charger to be certain that it is not malfunctioning.
I believe that you may have had a battery in thermal runaway. Thermal Runaway is when the internal temperature of the battery increases at a faster rate than it can dissipate heat. This can occur during charging and as such the charging current increases as the heat increases.I have seen this happen to a bank of 36 2v 1900ah gel cells. There was no acid on anything but lots of oxidation and some corrosion mostly on electronic circuit boards. This was a large battery with alot of electrolyte. The remedy was to decrease the charging voltage slightly. You may want to check the voltage from your charger to be certain that it is not malfunctioning.
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