Sulpherous smell - a cautionary note

wooslehunter

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I used the boat a couple of weeks ago and after motoring to the mooring, I noticed a sulpherous smell.

When I next tried to use the boat last Friday, the engine was sluggish to turn over & the alternator light stayed on. When I measured the battery voltage with the engine running, I measured 38V!!! OK - it's a 24V battery bank but still way above the 28V it should be under charge situations. I shut down & started to check things over.

The system has a simple alternator regulator that's separate from the alternator. I didn't want to run the engine again & in fact it turned out the batteries were fried & in no condition to start again. I measured the voltages on the regulator pins & they seemed to be OK. So initially it looked like the reg had developed a fault. I removed it & bench tested it. The bench test looked OK, so back to the boat. The symptoms of over charging pointed me at the sense wire. I measured the resistance of the connection from the regulator sense pin to Bat + & found it open circuit. After removing the alternator to get better access to the wiring, I found the other end of the sense wire had broken away.

Fault found. Since the regulator thought the battery voltage was low, it pushed the alternator up to maximum.

Although this cost me a new set of engine batteries, I think I got away lightly. The alternator diodes could have blown costing me a new unit. Even worse, the fried batteries had started top swell & it's not unknown for batteries to explode under these conditions.

I'll be adding an audible alarm over the winter which will indicate the over-charge situation.
 

prv

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Ouch, that is scary, especially the possibility of blowing acid everywhere. Glad it didn't get that far.

Some regulators have a battery temperature sensor which would hopefully prevent this.

Pete
 

Richard10002

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When I read the thread title I knew what was coming - if you smell sulphur, the chances are that your batteries are getting ready to explode, so stop everything, perhaps have a cautious look, and take appropriate steps.

I'm not actually sure what I would do if I was on a motor boat at sea - grab a tow? Pan Pan? Advise the Coastguard who might launch a lifeboat?
 

Tiller Girl

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In no way wishing to undermine the importance of the message here, back in July we motored out of West Mersea heading off for Ramsgate and I was just about to put up the sails when I smelt a sulpherous smell. I checked the charge rate and it was fine, lifted the bridgedeck (old fashioned MAB) and sniffed the engine space where the batteries are located - all fine and nothing amiss and clearly no sulpherous aroma 'down below'. I am pretty certain have just come out of the Quarters in a bit of a lollup, the motion had stirred up the bit of stagnant seawater that gets retained in my cockpit drains releasing the smell into the cockpit. The smell cleared and has not been back.
 

Richard10002

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Hence my suggestion of a cautious look and appropriate steps... which might be to have a less cautious look, a bit of a feel, and a bit of a closer sniff. If all seems well, run the engine, check the charging voltage, another feel and a sniff and, if all still seems well, carry on with caution.
 

lw395

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I thought:
Sulphurous smell?
Near Port Solent at low tide?

Seriously though, a worry for everyone with aftermarket alternator regulators.
A case for having a nice simple voltmeter and checking it now and then.
 

Resolution

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Another endorsement from me to all those boat owners who, like me, find electrics an uninteresting puzzle. Our brand new Trojan house batteries died due to neglect over the winter (the service engineer ran off with our money and did none of the winter jobs he had contracted to do). When we tried charging them up in the spring it all seemed OK at first and they held some charge, just enough for a few days use. Voltmeter reading between 12.5 and 14 just as usual. Needed a lot of water to top up, so I knew plates had been exposed and damage done, but we were out in the sticks away from sources of new batteries. A couple of weeks later in a marina on shorepower I smelt the sulphurous smell, checked and boy were they boiling away vigorously. Put a hand down to test the temperature of the box and nearly burnt myself, it was far too hot to touch. Disconnected everything, took out a small mortgage and bought four new Vartas, the only make available. When they came out the dead Trojans were very warped. Looking back, I hate to think what could have happened either from the gas igniting or from the battery cases melting / exploding or whatever.
Moral of the story: if you smell any sulphurous wiffs, take action quickly.
 

wooslehunter

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Some interesting points.

If I'd been at sea when I found the problem, I'd have shut down immediately. But, what to do next? If I'm motoring rather than sailing, there's a reason. So, more than likely I'd need to get a tow or carry on motoring. One quick fix is to loosen the alternator bolts and disconnect the belt. Now the engine can run & the alternator will not charge the batteries. Since a diesel needs no power to run, unlike a petrol engine, I could run for as long as the fuel lasts. One problem (not for me though) would be the limit on the battery power for other things. But, it's not too much of a problem having all electrics shut down. Luckily (for once) my split system would come into its own. I have a 24v engine system & a 12v domestic system with twin alternators. Since the engine batteries had been fried, I'd have been reluctant to shut down the engine once restarted, since I may not have been able to start.

But at least I would not have had to get a tow. Certainly in the Solent these days, coastie is reluctant to task any emergency resources for a tow & generally ask if you're a member of Seastart or if there's anyone else that could give a tow.

On the point of after market regs, mine isn't. It's a C.A.V. type for my old engine. But the point is still valid. It's worth asking what would happen if the sense wire were to be disconnected if you're buying an after market reg. Mine's very simple, but a more complex one could easily decide not to charge if the battery sense volts is way too low or in fact way too high. I did call Sterling & their tech guy told me that their regs are designed to cut out under over voltage faults on battery or alternator output. Seems logical to me that anything that claims to be advanced would do so. I have no relations with Sterling but just know of their products.
 

Tiller Girl

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If I disconnect the belt on my engine, I also stop the coolant pump So that would not work. I suppose a belt that was short enough to cut out just the alternator would do though.
 

wooslehunter

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Seems like a reasonable spare to carry. It may in fact guarentee you never have an alternator fault....... (isn't that something like an inverse sod's law?)
 

William_H

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Some interesting points.


I did call Sterling & their tech guy told me that their regs are designed to cut out under over voltage faults on battery or alternator output. Seems logical to me that anything that claims to be advanced would do so. I have no relations with Sterling but just know of their products.

I don't know if what you said is what you meant but of course all regulators are designed to reduce output if voltage out is too high. That is what a regulator does. Maybe Mr Stirling was snowing you.
It could be a worthwhile investment to fit a high voltage alarm on the electrics perhaps combined witha low voltage alarm. I don't know if they are available comercially but not so hard to make.
If you had a boiling battery situation removal of the field wire from the alternator or regualtor with an external regulator should stop charge or if necessary remove/cut the main power wire output from the alternator. it might kill the diodes but might not in any case safer than a hot battery. (explosion) Or just turn off the battery isolator switch but do make sure every electrical device is also turned off. Alternator could conceivably continue to push high volktage into the electrical system.
Over voltage lack of regulation is not so uncommon as a fault. My son's Toyota Camry did it and I have seen light aircraft have the problem. (very dangerous very expensive to fix all the damaged electronics)
good luck olewill
 

charles_reed

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Tows?
Take off the belt and stop the indirect coolant?
Run round in circles clucking?

Just disconnect the battery that is overheating.
It's a pretty commonplace occurrence - it's happened to me 3 times in my first 10 years of 38 years experience of an inboard engine.
It's more likely with a "smart" external battery controller, than the on-board one.
Invariably caused by battery failure and best avoided by a bit of preventative maintenance on your batteries. Even if it's a subject that you find uninteresting.
I've seen two boat fires caused by runaway overcharge of batteries - in both the boats were write-offs and in one the (Greek) SaR had to intervene.
 
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.....One quick fix is to loosen the alternator bolts and disconnect the belt. Now the engine can run & the alternator will not charge the batteries.....
A simple quick fix on a Diesel engine is to simple turn off the ignition. This disconnects the power to the alternator regulator so the batteries can't charge but the engine will still run. You will also not have instrument power so when you want to turn off the engine you may have to turn the ignition back on momentarily to power a fuel disconnect solenoid.
 

Tiller Girl

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A simple quick fix on a Diesel engine is to simple turn off the ignition. This disconnects the power to the alternator regulator so the batteries can't charge but the engine will still run. You will also not have instrument power so when you want to turn off the engine you may have to turn the ignition back on momentarily to power a fuel disconnect solenoid.

Is that right? If it did wouldn't that blow the diodes on the Alternator? On my Volvo (as far as I am aware and I might be wrong - hence me asking the question) turning off the power at the panel (which isn't really an ignition switch) merely disconnects the instrument panel and the power generated by the alternator doesn't go through that.
 
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Is that right? If it did wouldn't that blow the diodes on the Alternator? ...
The key driven switch sends power to the instruments and the starter solenoid and the alternator regulator. No power to the regulator means no volts on the field wire which means no volts generated by the alternator so nothing to blow the diodes.

How many people turn off the ignition switch by mistake without causing any problem?
 

RichardS

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Then please enlighten us all and tell us what does happen.

Well with my engines and Tillergirl's turning off the ignition switch whilst the engine is running does not disconnect the alternator from the batteries and the charging current keeps flowing into the batteries for the reason that Tillergirl explains.

Perhaps your system does interrupt battery charging but, if it does, I believe that you are likely to blow the regulator.

Richard
 

Mrnotming

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Not drifting just to say the sterling aftermarket controller Which on our MD 2030 has a temp wire battery post attachment.
Problem is that most of us have more than one domestic battery, so information is more incomplete the more domestic batteries one has fitted.
I.e. Only one battery can be monitored according to the curt but obliging Mr. Sterling.
No easy solution,love to hear of one.
 

Tiller Girl

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Can I make it clear that I don't know what happens - and I want to because this is a potential situation that might happen. I have always thought that turning off the 'ignition' left the alternator charging. If that is wrong, it would be handy to know. I appreciate that turning off the main battery switch while the engine is running (with 'ignition' on is a no-no.
 
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