CO alarm in the night - Unsure of cause

[Tracy D'arth]

3 minutes ago, Chewbacka said:

Just for interest I copied this from the Honeywell web site regarding CO alarms - “The electrochemical CO sensors used in the majority of our products do have a cross-sensitivity to elemental hydrogen (H2) gas, with the precise degree of cross-sensitivity depending on the model in question.” 
 

Well there you go, I think. What was that in plain English?   If the OP has a hydrogen build up in his boat he had better do something about ventilating it and quickly.  Else....................................................

 

 

 

 

BANG!

 

 

 

 

[DShK]

I don't think it's hydrogen sulphide as I've never had a whiff of smell from them. I'm inclined to believe they are sulphated - interpolating between the smartguage and the amp counter, they have about half the capacity they should. I can see on the victron app for the solar panels, they are usually only in the absorption phase for maybe 2 hours - the bulk phase is long (partly due to my use of my desktop PC during the day), a 2 hour absorption phase and then float for the rest of the day. The previous owner said they "are 4 years old so should have plenty of life left" - but that's four years of overcharging. I don't know if overcharging would cause sulphation or shorting though?

 

Anyway, either way it seems my batteries need replacing. I've heard trojans mentioned a lot - looking at getting these (they are the same size so should drop in nicely too) https://www.tayna.co.uk/industrial-batteries/trojan/t-105-x6/ Would these be a good buy, or any other recommendation?

Edited August 21, 2022 by DShK

[cuthound]

25 minutes ago, DShK said:

 I don't know if overcharging would cause sulphation or shorting though?

 

Overcharging is one of the things to try to revive a sulphated battery. The technical term for it is "equalising charge", where when the battery is fully charged, the battery voltage is raised to about 16 volts for an hour or so to try to convert the lead sulphate back to spongy lead. The success rate depends on how long the battery has been left less than fully charged. The longer it is left the harder it is to reconvert the lead sulphate back to spongy lead.

 

Persistent overcharging can cause battery shorts because it can "shake" the active material from the positive plates out, where it can build up at the bottom of the battery until it shorts the plates.  It can also cause the plates to buckle and short in cheaper batteries because the plates are often thinner and the separators poorly designed.

[DShK]

1 minute ago, cuthound said:

 

Overcharging is one of the things to try to revive a sulphated battery. The technical term for it is "equalising charge", where when the battery is fully charged, the battery voltage is raised to about 16 volts for an hour or so to try to convert the lead sulphate back to spongy lead. The success rate depends on how long the battery has been left less than fully charged. The longer it is left the harder it is to reconvert the lead sulphate back to spongy lead.

 

Persistent overcharging can cause battery shorts because it can "shake" the active material from the positive plates out, where it can build up at the bottom of the battery until it shorts the plates.  It can also cause the plates to buckle and short in cheaper batteries because the plates are often thinner and the separators poorly designed.

Ah that's good to know, thanks.

 

I wonder if I've managed to inherit batteries that are both sulphated and shorting 😄

 

I'm going to take the opportunity to install a battery isolation switch - there isn't one which to me seems weird. There are 3 isolation style switches - one isolates the alternator (and starter) (never quite understood why the alternator needs isolating). The other two I never figured out why they do, the wiring is spaghetti. But they certainly don't isolate the batteries!

[Tracy D'arth]

3 minutes ago, DShK said:

Ah that's good to know, thanks.

 

I wonder if I've managed to inherit batteries that are both sulphated and shorting 😄

 

I'm going to take the opportunity to install a battery isolation switch - there isn't one which to me seems weird. There are 3 isolation style switches - one isolates the alternator (and starter) (never quite understood why the alternator needs isolating). The other two I never figured out why they do, the wiring is spaghetti. But they certainly don't isolate the batteries!

The isolation switch should isolate the alternator, BSS requirement. If buying a switch, ignore the rubbish red key one, buy a decent one that won't let you down.

[Tony Brooks]

16 minutes ago, DShK said:

Ah that's good to know, thanks.

 

I wonder if I've managed to inherit batteries that are both sulphated and shorting 😄

 

I'm going to take the opportunity to install a battery isolation switch - there isn't one which to me seems weird. There are 3 isolation style switches - one isolates the alternator (and starter) (never quite understood why the alternator needs isolating). The other two I never figured out why they do, the wiring is spaghetti. But they certainly don't isolate the batteries!

 

Sulphated almost certainly but that is true for almost any boat LA battery more than a few months old. It just depends upon the degree.

 

Shorting, I don't know until we get an idea of the relative times taken to fully charge them and then discharge to 50%, but with no smells and the time this has been going on I suspect probably not. Is there any localized overheating of cells when on charge, if not a short is either in the very early stages or unlikely.

 

I think that you are getting very hung up on the overcharging thing. Within reason charging at too high a voltage will only dry the batteries out, long term it may cause plate shedding and cell shorts, but it won't cause sulphation. Boats cruise for 6 hours or more with the charging voltage around 14.4 volts, and it causes no problems. Think of all those hire boats doing rings that may well run for far longer. I am also beginning to think the CO alarm may have nothing to do with the boat batteries. Remember hydrogen will go up to the roof and out the vents. How far up the cabin side is your CO alarm and where is it in relation to the batteries.

 

Remember LadyG found a battery she had no idea was there, might you have a hidden battery that is shorting?

 

 

 

 

[DShK]

40 minutes ago, Tracy D'arth said:

The isolation switch should isolate the alternator, BSS requirement. If buying a switch, ignore the rubbish red key one, buy a decent one that won't let you down.

Ah interesting, wonder what the logic is there - the previous owner mumbled something about the alternator pulling current when not in use... Yeah, I will find one that is rated for the full load of the inverter + the rating of the 12v consumer unit (100amps)

 

17 minutes ago, Tony Brooks said:

 

Sulphated almost certainly but that is true for almost any boat LA battery more than a few months old. It just depends upon the degree.

 

Shorting, I don't know until we get an idea of the relative times taken to fully charge them and then discharge to 50%, but with no smells and the time this has been going on I suspect probably not. Is there any localized overheating of cells when on charge, if not a short is either in the very early stages or unlikely.

 

I think that you are getting very hung up on the overcharging thing. Within reason charging at too high a voltage will only dry the batteries out, long term it may cause plate shedding and cell shorts, but it won't cause sulphation. Boats cruise for 6 hours or more with the charging voltage around 14.4 volts, and it causes no problems. Think of all those hire boats doing rings that may well run for far longer. I am also beginning to think the CO alarm may have nothing to do with the boat batteries. Remember hydrogen will go up to the roof and out the vents. How far up the cabin side is your CO alarm and where is it in relation to the batteries.

 

Remember LadyG found a battery she had no idea was there, might you have a hidden battery that is shorting?

 

 

 

 

 

Can't speak on how often the previous owners fully charged the batteries. Until recently I was doing it virtually every day as I was just in the marina with solar not adequate to keep me going, so I routinely plugged in and left it.

 

I didn't notice any heating of the cells when it was last mentioned in this thread, I can check again, I can only feel the top of the batteries from where they are located though!

 

I only mention the overcharging as the charger was set too high, I figured this perhaps could overtime, do damage.

 

I don't know how sensitive these are to hydrogen, but there is only one vent in the back cabin+engine room when the pigeon box is closed. See below for alarm location - the batteries are beside the engine in the engine room forward of this.

 

Hmm, I don't think it's likely there is another battery - there isn't somewhere to hide one in the engine room/back cabin that I haven't already poked about it. Plus no thick battery cables leading off randomly.

 

 

 

 

 

[Tony Brooks]

17 minutes ago, DShK said:

Ah interesting, wonder what the logic is there - the previous owner mumbled something about the alternator pulling current when not in use... Yeah, I will find one that is rated for the full load of the inverter + the rating of the 12v consumer unit (100amps)

 

 

Can't speak on how often the previous owners fully charged the batteries. Until recently I was doing it virtually every day as I was just in the marina with solar not adequate to keep me going, so I routinely plugged in and left it.

 

I didn't notice any heating of the cells when it was last mentioned in this thread, I can check again, I can only feel the top of the batteries from where they are located though!

 

I only mention the overcharging as the charger was set too high, I figured this perhaps could overtime, do damage.

 

I don't know how sensitive these are to hydrogen, but there is only one vent in the back cabin+engine room when the pigeon box is closed. See below for alarm location - the batteries are beside the engine in the engine room forward of this.

 

Hmm, I don't think it's likely there is another battery - there isn't somewhere to hide one in the engine room/back cabin that I haven't already poked about it. Plus no thick battery cables leading off randomly.

 

 

I simply do not understand the "charger was set too high". Lead calcium batteries gas in excess of 14.6 volts while lead antinomy gas around 14.4 (ballpark figures) and Trojans (lead antinomy) advise something like 14.8V and top up regularly, so nothing amiss there. The float voltage (used when the charger decides the batteries are full but often not) is set to 13.7 whereas I would expect it to be 13.6 or a bit less.

 

Unless the alternator has a shorting diode or is incorrectly wired it can not "draw current" unless the ignition is left turned on, or if it does, it will only be a very few mA, so that seems to be bull. As Tracy explained the BSS requires a master switch to isolate the whole engine electrical circuit, so that sounds normal There should also be one for the domestic system. Sometimes another is fitted to the inverter feed.

 

Checking the top of the batteries will be fine, but, as I said, I am doubting you have a shorting cell unless the hydrogen sulphide has made you go nose blind as it can.

 

As hydrogen rises it should with a normal boat trim it should more towards the front of the boat, not the back and in any case it should escape from any high level vents unless you are stirring the air as you move about.

[Ronaldo47]

Older (1940's) books on battery charging used to recommend charging until all cells were gassing freely. In the pre-electronic era, charging was often done at approximately constant current using a high voltage source (such as DC mains) and determining the charging current using a bank of resistors or carbon filament lamps connected between  the battery and the voltage source. 

 

The traditional way to try to cure a badly  sulphated battery was to charge at a low current for a long time,  periodically adjusting the electrolyte strength in bad cases.  Crystalline sulphate does not conduct electricity, so trying to charge a sulphated batyery at a normal rate, means that the  currrent is forced to flow via the non-sulphated parts. The consequential high current density leads to localised heating, and because crystalline sulphate has a different coefficient of thermsl expansion from lead, the resulting differential thermal expansion results in loss of active material from the plates. Keeping the  charging current low reduces the localised heating and, if sulphation is not too far advanced, can allow much of the sulphate to be converted back to lead/lead peroxide without coming loose. In these days when time is money, it is uneconomic for a garage to spend the time needed to restore run-down batteries in this way, but I have done it with car batteries at home, using old 12V bulbs of varous wattages in series with my chargers to determine the charging current.   

 

Various posters on this forum who have solar panels and whose boats had not been used over winter, have reported that their batteries were in much better state when resuming cruising in the spring, than they had been when last used the previous autumn. Presumably the long slow trickle charging provided by solar during the winter months, had been effective in reversing  sulphation.

[DShK]

25 minutes ago, Tony Brooks said:

 

I simply do not understand the "charger was set too high". Lead calcium batteries gas in excess of 14.6 volts while lead antinomy gas around 14.4 (ballpark figures) and Trojans (lead antinomy) advise something like 14.8V and top up regularly, so nothing amiss there. The float voltage (used when the charger decides the batteries are full but often not) is set to 13.7 whereas I would expect it to be 13.6 or a bit less.

 

Unless the alternator has a shorting diode or is incorrectly wired it can not "draw current" unless the ignition is left turned on, or if it does, it will only be a very few mA, so that seems to be bull. As Tracy explained the BSS requires a master switch to isolate the whole engine electrical circuit, so that sounds normal There should also be one for the domestic system. Sometimes another is fitted to the inverter feed.

 

Checking the top of the batteries will be fine, but, as I said, I am doubting you have a shorting cell unless the hydrogen sulphide has made you go nose blind as it can.

 

As hydrogen rises it should with a normal boat trim it should more towards the front of the boat, not the back and in any case it should escape from any high level vents unless you are stirring the air as you move about.

Right, as was discussed earlier in the thread, the charger was set to 0.4V above what these batteries wanted. I don't have a strong enough understanding of battery chemistry to know if, long term, that would have an impact on the batteries beyond gassing. It sounds like it wouldn't.

 

Ah, the previous owner did give me a spare alternator they sent off for repairs, perhaps that had a shorting diode.

 

Definitely not nose blind! I am cooking as I type this and can smell it no problem.

 

Hmm, I typically keep the doors between the front and back of the boat shut, no idea if that'd make a difference.

 

 

19 minutes ago, Ronaldo47 said:

Older (1940's) books on battery charging used to recommend charging until all cells were gassing freely. In the pre-electronic era, charging was often done at approximately constant current using a high voltage source (such as DC mains) and determining the charging current using a bank of resistors or carbon filament lamps connected between  the battery and the voltage source. 

 

The traditional way to try to cure a badly  sulphated battery was to charge at a low current for a long time,  periodically adjusting the electrolyte strength in bad cases.  Crystalline sulphate does not conduct electricity, so trying to charge a sulphated batyery at a normal rate, means that the  currrent is forced to flow via the non-sulphated parts. The consequential high current density leads to localised heating, and because crystalline sulphate has a different coefficient of thermsl expansion from lead, the resulting differential thermal expansion results in loss of active material from the plates. Keeping the  charging current low reduces the localised heating and, if sulphation is not too far advanced, can allow much of the sulphate to be converted back to lead/lead peroxide without coming loose. In these days when time is money, it is uneconomic for a garage to spend the time needed to restore run-down batteries in this way, but I have done it with car batteries at home, using old 12V bulbs of varous wattages in series with my chargers to determine the charging current.   

 

Various posters on this forum who have solar panels and whose boats had not been used over winter, have reported that their batteries were in much better state when resuming cruising in the spring, than they had been when last used the previous autumn. Presumably the long slow trickle charging provided by solar during the winter months, had been effective in reversing  sulphation.

Interesting. I guess I could try putting my charger on a really low current output and try that (there is a limit to how low I can go though, given I'm a liveaboard) I feel like properly recovering sulphated batteries is probably a fool-errand though? I had a battery charger for my camper which promised to "reverse sulphation" by blasting it with high frequency high voltage, or something. If it had been actually figured out how to reverse sulphation, we'd all be doing it and not worrying so much about looking after our batteries!

 

 

Frankly I'm at a loss of what to do beyond just replacing them all...

[manxmike]

My boat had been wired by someone who had a very vague idea of 12 volt wiring. I rather think he/she had acquired a lot of brown wire and had knitted it into the strangest loom I have ever seen.

I can't help wondering if some of your problem might be caused by the wiring on your boat creating oddities for the batteries. I am no expert, just years of playing with the wiring harnesses on older british motorbikes and discovering the problems that can be caused by using the wrong thickness wire, incorrect connections and strange fuses.

I was going to re-wire, but I sold the boat before I got round to it.

Edited August 22, 2022 by manxmike

[cuthound]

15 hours ago, DShK said:

Right, as was discussed earlier in the thread, the charger was set to 0.4V above what these batteries wanted. I don't have a strong enough understanding of battery chemistry to know if, long term, that would have an impact on the batteries beyond gassing. It sounds like it wouldn't.

 

Ah, the previous owner did give me a spare alternator they sent off for repairs, perhaps that had a shorting diode.

 

Definitely not nose blind! I am cooking as I type this and can smell it no problem.

 

Hmm, I typically keep the doors between the front and back of the boat shut, no idea if that'd make a difference.

 

 

Interesting. I guess I could try putting my charger on a really low current output and try that (there is a limit to how low I can go though, given I'm a liveaboard) I feel like properly recovering sulphated batteries is probably a fool-errand though? I had a battery charger for my camper which promised to "reverse sulphation" by blasting it with high frequency high voltage, or something. If it had been actually figured out how to reverse sulphation, we'd all be doing it and not worrying so much about looking after our batteries!

 

 

Frankly I'm at a loss of what to do beyond just replacing them all...

 

When the batteries are fully charged they will automatically restrict the current to a low value (typically less than 1% of their Ah capacity). So to maintain a low current you need to increase the charge voltage to about 16 volts. Then it becomes an equalising charge.

 

However if the battery has been left in a sulphated condition for a long time (more than a coupe of weeks) equalising is unlikely to remove the sulphation.

[DShK]

1 hour ago, manxmike said:

My boat had been wired by someone who had a very vague idea of 12 volt wiring. I rather think he/she had acquired a lot of brown wire and had knitted it into the strangest loom I have ever seen.

I can't help wondering if some of your problem might be caused by the wiring on your boat creating oddities for the batteries. I am no expert, just years of playing with the wiring harnesses on older british motorbikes and discovering the problems that can be caused by using the wrong thickness wire, incorrect connections and strange fuses.

I was going to re-wire, but I sold the boat before I got round to it.

My impression of what I've seen so far is that it's not a *neat* job, there are some things that I don't pariticularly like (using chocolate boxes instead of properly crimped connections, no protective caps over the battery terminals etc). Oh and the surveyor did find that the 240v (earth? Neutral? don't remember) was reversed. But it seems like a competent enough install generally. Wires are proper 12v automotive grade, of appropriate thickness. 12V goes through a consumer unit, relays are used for split charging and to only allow the tunnel light to be on when the engine is running etc. Isolation switches are properly rated for the current. I am going to improve it over time but it's certainly not as bad as you describe. Of course there could be something going on that I haven't seen!

8 minutes ago, cuthound said:

 

When the batteries are fully charged they will automatically restrict the current to a low value (typically less than 1% of their Ah capacity). So to maintain a low current you need to increase the charge voltage to about 16 volts. Then it becomes an equalising charge.

 

However if the battery has been left in a sulphated condition for a long time (more than a coupe of weeks) equalising is unlikely to remove the sulphation.

I am wary about doing an equalising charge given they gas enough to set the alarm off at much lower voltage. I guess I would just need to make sure the water is topped off and keep an eye on them/keep it well vented. The gassing and the limited capacity has been a problem since I bought the boat so I suspect that equalising won't help much though.

[cuthound]

Early gassing and limited capacity are indicative of sulphated batteries.

 

Do they charge and discharge quicker than you would normally expect?

 

[DShK]

6 minutes ago, cuthound said:

Early gassing and limited capacity are indicative of sulphated batteries.

 

Do they charge and discharge quicker than you would normally expect?

 

Looking at the smartguage at around 50% charge, amp counter shows about 150-170 ah used. It's a 675ah bank, so I am missing about half the capacity. It's hard for me to compare to "brand new" batteries in this setting, having not had them. I have noticed the absorption phase, as per my victron solar app, seems to only last a couple of hours. My understanding is that this should last a lot longer before sitting on float all day? (from the solar).

[rusty69]

Be careful relying on the smartgauge unless you know it to be correct. A number of them, including mine, were checked with a callibrated DVM and found to be  out.  Now, recalibrate, it is much better. 

 

They are also more accurate, I seem to recall, when discharging rather than charging. 

Edited August 22, 2022 by rusty69

[DShK]

28 minutes ago, rusty69 said:

Be careful relying on the smartgauge unless you know it to be correct. A number of them, including mine, were checked with a callibrated DVM and found to be  out.  Now, recalibrate, it is much better. 

 

They are also more accurate, I seem to recall, when discharging rather than charging. 

Yeah I've heard a certain number of them had issues. When doing a full charge I would look at the tail current rather than the SG, and at the end of the day I usually take a look at my battery voltage on the victron app. It's not a perfect figure either as I always have something running - even if it's just my router/AP. But I know those will drag the voltage on the batteries down, so if they look a decent voltage with those then I'm okay. I don' rely on any one thing in particular as I know they all have their downsides.

[Tony Brooks]

 FWIW Mr Smartguage (Chris Gibson - Gibbo)used to say that when batteries had lost 50% of capacity they should be considered as time for new ones

Edited August 22, 2022 by Tony Brooks

[DShK]

1 hour ago, Tony Brooks said:

 FWIW Mr Smartguage (Chris Gibson - Gibbo)used to say that when batteries had lost 50% of capacity they should be considered as time for new ones

Roger. Think I'll bite the bullet and get new batteries. At least I'll enjoy the increased capacity! 

 

Thanks again everyone for the input, I really appreciate it as ever. I'll update when the damn alarm goes off after I replace them, because of course it will 😆

[cuthound]

1 hour ago, Tony Brooks said:

 FWIW Mr Smartguage (Chris Gibson - Gibbo)used to say that when batteries had lost 50% of capacity they should be considered as time for new ones

 

Yes, commercial companies specify batteries of 125% capacity and replace at 80%, thus ensuring 100% of what capacity is actually needed is available throughout their life.

 

With boats, batteries should be replaced when the lack of capacity becomes an irritation for you rather than a fixed figure, for example when the TV and lights won't last until you go to bed. 🤣

[DShK]

14 minutes ago, cuthound said:

 

Yes, commercial companies specify batteries of 125% capacity and replace at 80%, thus ensuring 100% of what capacity is actually needed is available throughout their life.

 

With boats, batteries should be replaced when the lack of capacity becomes an irritation for you rather than a fixed figure, for example when the TV and lights won't last until you go to bed. 🤣

For me, because I have a 4x 375W solar panels, the increased capacity would make better use of my panels - giving me better staying power when the sun isn't out as much. I'd much rather have to get the generator out every few days rather than every day when it's fully overcast etc.

 

I have a miscellanous battery question I will ask here, if I may, rather than clutter the forum up with more question threads -

 

How does a high current load offset by a high current charge effect the batteries? I know that high power draw (heaters and the like) are bad for the long term health of the batteries. How does that effect the batteries if the current being drawn is matched by the batteries being charged?

 

I believe advanced interverters will pass through a shoreline to the 240v system when plugged in, hence why it's okay for me to plug my electric immersion water heater as it bypasses the batteries. I've been looking at solar hot water dump load systems, and the one I saw wasn't as advanced as I had thought - it just looked like a relay to swap between a 240v and 12v input. This got me thinking - would that be bad for the batteries? Seems like it would be, at the very least, if the sun went behind a cloud and you didn't notice. My assumption was there would be a "smart" system available which would detect when batteries were on float/absorption and only then begin to heat the water.

 

Maybe this does need it's own thread!

[Tony Brooks]

Providing the charge source is providing the same or greater currant than the load's demand it will have no effect on the batteries. Even if the load is more than the charge source output you only need to concern yourself with the difference between the two, and often it is not that much

[Alan de Enfield]

2 hours ago, DShK said:

Maybe this does need it's own thread!

 

Example :

1) If your battery charger is charging at 50 amps, and you are using your 1kw Immersion heater via the inverter, drawing 100 amps, then you are taking 50 amps out of the battery, so you can (sorta) get an hours usage out of the 100ah battery without doing too much damage.

 

2) If your battery charger is charging at 100 amps, and you are using your 1kw Immersion heater via the inverter, drawing 100 amps, then you are taking zero (nil / nowt/nothing) amps out of the battery.

[DShK]

Ah, so it's discharging the battery quickly that can cause the damage then, gotcha! Thanks.

[Tony Brooks]

Just now, DShK said:

Ah, so it's discharging the battery quickly that can cause the damage then, gotcha! Thanks.

 

And charging it quickly, but I doubt many boats have charging equipment that is capable of reaching those levels. The higher the current in either direction the greater the heating effect, the gassing potential, and plate distortion leading to material shedding.