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Came back to the boat in the marina after three days away and discovered that the "fit and forget" (Numax/Electroquest) battery charger is going full belt, fan on, with a smell of cooking coming from the engine bay where the batteries are. Switched it off immediately, opened up the engine bay and the middle of 3 (ancient, Numax 110Ah)  very warm to the touch.

 

I know these batteries are shot, and replacements are ordered, but they won't arrive before I have to move the boat tomorrow. So what should I do?

 

risk running with the batteries as they are?
disconnect just the dodgy one?
disconnect all for the run (and will the alternator mind that)?

 

Any timely advice would be welcome.

 

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40 minutes ago, Capnbob said:

 

 

I know these batteries are shot, and replacements are ordered, but they won't arrive before I have to move the boat tomorrow. So what should I do?

 

 

Disconnect the batteries . Go and buy another new cheap starter battery or borrow one from a friend or take the battery out of your car and use that.

Edited by MartynG
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1 minute ago, Boater Sam said:

Don't disconnect your car battery, modern ones don't like it !!!!

Found that with the Daughter In laws Renault.

 

Starting was getting sluggish so decided to get a new battery.

For some reason decided to look at the owners manual to get the correct size/shape and noted that it said "take to dealer to change battery", I thought I can change a battery, but just on the off chance called our local garage (who does all our breakdowns MOTs etc) and he confirmed that unless the Management System was plugged into a diagnostic machine and retained voltage it would be seriously damaged / wiped.

 

The other way was to jiggle about with jump leads trying to keep the battery terminals attached to another car battery, whilst disconnecting from the Renault, lifting out and replacing the battery - decided that it was too risky, losing a croc-clip meant expensive repairs.

 

Took it into our local garage who provided the battery and did the job for the same price as I could source the battery.

 

Technology - moving forward - making life easier ?????

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A mate of mine - not sure which car - used the cigar lighter socket to connect to a second battery, keeps the system powered up whilst changing the main battery.  Needed the ignition Key in position 1 to connect up the socket.

 

Edited by Chewbacka
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1 minute ago, Chewbacka said:

A mate of mine - not sure which car - used the cigar lighter socket to connect to a second battery, keeps the system powered up whilst changing the main battery.  Needed the ignition Key in position 1 to connect up the socket.

 

Clever.

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12 minutes ago, Alan de Enfield said:

Clever.

Just looked on Amazon and you can buy a 12v unit to keep car systems powered up when battery changing using either the cigar socket or the obd connector.  

 

Added - spell checker twice ‘corrected’ obd, third time lucky.

Edited by Chewbacka
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I would immediately disconnect the hot battery  as it is unsafe, then charge the good batteries for an hour or two in case the bad battery has discharched them.  Then disconnect both batteries from the boat and each other and leave for an hour and then measure the voltage of each battery.  Reconnect if voltage is at least 12v.  If less than 12v the battery is no good.  Then fully recharge the good battery/ies

Edited by Chewbacka
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18 minutes ago, Chewbacka said:

I would immediately disconnect the hot battery  as it is unsafe, then charge the good batteries for an hour or two in case the bad battery has discharched them.  Then disconnect both batteries from the boat and each other and leave for an hour and then measure the voltage of each battery.  Reconnect if voltage is at least 12v.  If less than 12v the battery is no good.  Then fully recharge the good battery/ies

 

 

Yes by way of explanation, the hot battery has probably shorted inside and this lowers the voltage. The other two in parallel will then have heavily discharged themselves through the faulty battery making it hot. Disconnect the faulty one from the bank and the others will probably recover after disconnection and a good re-charge. 

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8 minutes ago, Mike the Boilerman said:

 

 

Yes by way of explanation, the hot battery has probably shorted inside and this lowers the voltage. The other two in parallel will then have heavily discharged themselves through the faulty battery making it hot. Disconnect the faulty one from the bank and the others will probably recover after disconnection and a good re-charge. 

This is not my own experience at all.

 

If the charger was working hard, (as suggested) it is highly likely that the voltage across all the batteries remained at 13 volts plus.

It will have tried hard to charge the failed battery, (hence the heat), but that is unlikely to have pulled down the others.

I reckon that even with the charger turned off, but with all batteries still connected, that the voltage across all three may not be particularly low.  Certainly that was what happened to me, though my bank was  5 batteries, not 3, so any ill effects from the failed one would get spread across more "not failed" ones.

Get the failed one out - you are unlikely to have immediate problems with the two remaining, although of course where one has gone, either of the others may chose to follow eventually.

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One small point. Do please be careful when removing the battery. We had one blow up once at work without warning having been checked quite recently. It literaly blew the casing to pieces like a big hand grenade.

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2 minutes ago, mrsmelly said:

One small point. Do please be careful when removing the battery. We had one blow up once at work without warning having been checked quite recently. It literaly blew the casing to pieces like a big hand grenade.

And you couldn't have mentioned this 4 hrs ago:)

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2 hours ago, mrsmelly said:

One small point. Do please be careful when removing the battery. We had one blow up once at work without warning having been checked quite recently. It literaly blew the casing to pieces like a big hand grenade.

Yes,

 

Fair warning.

 

The overheating battery will almost cerainly have been emitting large amounts of hydrogen.  It would be a good idea to have everything turned off for a while to let this disperse, before you try disconnecting anything.  Probably the biggest risk to the battery ending up in bits might be a spark whilst there is still a potentially explosive hydrogen/oxygen mix hanging about.

  • Greenie 2
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2 hours ago, alan_fincher said:

Yes,

 

Fair warning.

 

The overheating battery will almost cerainly have been emitting large amounts of hydrogen.  It would be a good idea to have everything turned off for a while to let this disperse, before you try disconnecting anything.  Probably the biggest risk to the battery ending up in bits might be a spark whilst there is still a potentially explosive hydrogen/oxygen mix hanging about.

 

We 'found' one of ours was shorted out in the middle of the night when the CO alarm went off.
Battery was 'untouchably' hot so I reckon we were very close to an explosion.

Disconnected it from the bank, ran the bilge blowers for an hour.

Went back to bed when it was cooled down.

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Well, I left the engine bay open for 3 hours to disperse the hydrogen, and nothing's been connected since. And, to be fair, it was the charger that claimed to be fit and forget, not the batteries.

 

The grenade reference is a bit terrifying, insn't it? Battery was warm mercifully, not untouchable, so I hope that means some tolerance left. Not that it matters, I'll be binning them soon. I have a part delivery from Tayna now, just waiting for battery 3 which, apparently, DHL lost in transit. Just hope all the cables swap smoothly over from old to new.

 

BTW, vaseline or not on the terminals?

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3 minutes ago, Capnbob said:

Well, I left the engine bay open for 3 hours to disperse the hydrogen, and nothing's been connected since. And, to be fair, it was the charger that claimed to be fit and forget, not the batteries.

 

The grenade reference is a bit terrifying, insn't it? Battery was warm mercifully, not untouchable, so I hope that means some tolerance left. Not that it matters, I'll be binning them soon. I have a part delivery from Tayna now, just waiting for battery 3 which, apparently, DHL lost in transit. Just hope all the cables swap smoothly over from old to new.

 

BTW, vaseline or not on the terminals?

The battery can and did go with a bang. It would probably have been lethal if any of us had been near it when it went of. The very strong heavily built battery case was blown into several pieces, mainly the top part. Being hit with one would have been very serious. I never put anything on my terminals but others will be along with advice as to what and why they do as I think some things are a good idea. That particular boat had about a dozen batteries and was on shoreline charge when it went off.

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3 hours ago, Capnbob said:

Well, I left the engine bay open for 3 hours to disperse the hydrogen, and nothing's been connected since. And, to be fair, it was the charger that claimed to be fit and forget, not the batteries.

 

The grenade reference is a bit terrifying, insn't it? Battery was warm mercifully, not untouchable, so I hope that means some tolerance left. Not that it matters, I'll be binning them soon. I have a part delivery from Tayna now, just waiting for battery 3 which, apparently, DHL lost in transit. Just hope all the cables swap smoothly over from old to new.

 

BTW, vaseline or not on the terminals?

 

Despite working with batteries for over 40 years, I have only seen the aftermath of one battery explosion, so it is not very common.

 

It was a healthy 50 volt telecoms battery comprising 25 x 2 volt cells on trickle charge.

 

Decorators had covered it with a plastic sheet whilst they painted above its,  the plastic sheet trapped the evolved hydrogen and when one of them pulled the sheet off the battery, a static electricity sparked ignited the hydrogen.

 

Luckily only 3 cells exploded,  but the fragments of glass embedded themselves in the concrete walls and ceilings and the spilt acid stained the vinyl floor covering.

 

Luckily the cells that exploded were at the other end of the battery to the guy pulling the plastic sheet which retained some of the glass, lead and acid, so he was uninjured.

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