Battery in dangerous state

[AlanM6]

Having recently fitted my new 25amp charger this one http://www.caravantechnology.com/Premium-Caravan-and-Leisure-25A-Charger-P112C15.aspx I was surprised that after 24hrs of charging that the LED light was still showing red and not green as it should have when batteries were fully charged.I tested the batteries using a multimeter. 1 starter read 12.75 amps and the 2 leisure batteries read 14.7 amps Knowing that I would be away from my boat for 4 or 5 days I thought it would be safer to leave the charger on in sleep mode, this I believe trickles 8 amps into the batteries. Returning to my boat today there was a very strong smell of acidy rotten eggs so I imeadiatley turned off the power to the charger.

Ive googled (Batteries and bad egg smell) all of the info ive found tells me that this means that one or all of the batteries are in a dangerous state,

beyond repair and libel to explode.

So what do I do now, how do I identify the bad battery or does it mean that I have to buy 3 new batteries.

Help

Thanks AM6

[WotEver]

Are they wet cell batteries? If so, is the electrolyte level good in all cells? What SG reading does a hydrometer show?

 

Tony

[AlanM6]

Wet cell batteries, Tony I topped them up last month it took about a litre to do all 3 batteries i haven.t got a hydrometer I guess thats my next buy.

[cereal tiller]

Could be overcharging,or one or more cells have shorted,this happens when the products of sulphation drop off the plates and build up at the bottom of the battery case.

 

check the batteries individually to see if just one has failed.

 

when connecting or disconnecting,take EXTREME care not too cause sparks,do not move connections around until the batteries have been off charge for an hour or so.make sure the area is WELL ventilated.

[alan_fincher]

I tested the batteries using a multimeter. 1 starter read 12.75 amps and the 2 leisure batteries read 14.7 amps

.

You mean volts,presumably ?

 

Was the 14.7 across the leisure ones with the charger connected to them, and running, or with the charger disconnected ?

 

I'm kind of guessing you were looking at a charging voltage, not at batteries that have been taken off charge.

 

But, even so, if you disconnect a charger, then stick a voltmeter across the batteries, it will not give a true state of charge, as an effect known as "surface charge" will cause the initial readings to be artificially high, until the battery has stood for a significant while, and lost that "surface charge".

 

I may have some of my terminologies slight wrong - I'm sure someone will be all too keen to point out if I do!

[WotEver]

Wet cell batteries, Tony I topped them up last month it took about a litre to do all 3 batteries i haven.t got a hydrometer I guess thats my next buy.

Alan, if they took a litre then they were well down, which could well mean they're also on their way out (probably not the engine start, just the doms). Hydrogen Sulphide (sulfide), which is the rotten egg smell, is more often than not the sign of a dry cell. In turn that generally means a dead battery.

 

Yes, a hydrometer is your first step (they're less than a fiver). Report back with the results

 

Tony

[Titan]

I recomend they (cool down ) you say you read amps? do you mean voltage ? As you have changed charger does this indicate you had a faulty charger before? It seems quite likely that your new charger is over charging to me, proceed with caution check with hydrometer, a typical egg smell is when batteries are being cooked!!! if you have an amp clamp try using this to check the amp rate going into batteries as when on charge the rate will decrease as batterie resistance increases. I fear you may need to replace the batteries and double check charger suitability, good luck Martin

[Bob18]

Usual set of questions when approaching a battery that might be dead/dying:

Do you have a volt meter?

Have you checked the electrolyte levels

Do the batteries feel hot if you touch the cases?

Is there a strange smell around the batteries?

Can you hear a fizzing coming from the batteries?

 

You've done one of the quickest tests going!

 

Oh Poo Sticks, that smell of rotten eggs - you did the right thing and stopped charging.

Simple test - If possible check the electrolyte level in each battery. You may be assailed by a repeat attack of the eggs from one of more cells in which case you know which battery has handed its notice in and wishes to depart NOW.

Compare the electrolyte level between cells in each battery - they should be more or less the same, and all be above the plates.

 

Now for a harder set of tests You need to have a volt meter for this, even the cheapest digital one will work.

Disconnect all three batteries then measure the voltage on each battery - are they all about the same, and all over 12V? A dead cell will reduce the battery voltage by about 2V, so its quite easy to find out which battery has retired...

What is the voltage of each battery? After a few hours of rest it should be somewhere around 12.5V, but given you've probably got a dead battery it may not be there just now because the dead one will probably have pulled the others down in sympathy.

 

Give the apparently good batteries a short charge - say 20-30 minutes, and keep a close eye and nose on them - I'd do this one battery at a time so you aren't mislead quickly measure its voltage and have a feel of the case, let it stand for a bit (say 20-30 minutes while you test charge another battery) and remeasure its voltage.

 

I fear it probable if you find that one of the domestic batteries is dead the other one will follow it fairly rapidly.

 

Just seen your comment about the three batteries needing "about a litre of water" between them - that's getting towards the top limit of what I would expect to put into a healthy battery - did you note if most of it went into one battery or cell (probably not as you weren't looking so don't worry)

[by'eck]

Most likely a cell gone short circuit in one of your bank. If on charge check to find which battery is warmer than the others & isolate.

 

If not on charge disconnect each battery in turn & after a short while to let them settle, measure the off-load voltage. The one causing the problem will probably be showing less than 11 volts.

[AlanM6]

You mean volts,presumably ?

 

Was the 14.7 across the leisure ones with the charger connected to them, and running, or with the charger disconnected ?

 

I'm kind of guessing you were looking at a charging voltage, not at batteries that have been taken off charge.

 

But, even so, if you disconnect a charger, then stick a voltmeter across the batteries, it will not give a true state of charge, as an effect known as "surface charge" will cause the initial readings to be artificially high, until the battery has stood for a significant while, and lost that "surface charge".

 

I may have some of my terminologies slight wrong - I'm sure someone will be all too keen to point out if I do!

 

Yes I mean volts AlanSorry about that

[JDR]

I've used trickle chargers on bike batteries whenever I've had access to a gargage (or front room) and I doubt they supplied more than 500ma, albeit on a 25Ah battery. 8A over 24hrs into a 220ah bank=192A.I know the batteries will only be taking somewhere close to that figure in the bulk phase but that doesn't sound like a trickle charge to me.

 

I was looking at the 40A version of this charger and it mentioned over temp and over charge protection what does the manual say? I get nervous leaving the boat with the charger running even if I know it has hours to go, I'm always thinking what if I don't get back to the boat for any reason.

 

I've never owned an expensive charger, is there any point in trickle charging banks on a boat? I would have thought a pair of 110ah batteries with no load would take a long time to discharge.

[Bob18]

All batteries self discharge with time, so keeping them float charged will overcome this, particularly if you are only going to use them every couple of weeks or more during the winter.

 

The self discharge rate depends on lots of things, but is higher than many people realise (one quoted range is 2-20% per month), - and it can get faster the more the battery is discharged. Also not everything turns off "properly", things like pumps, fridges, TVs, radios and so on may all just "go to sleep", but are actually drawing some power from the battery.

 

Temperature compensation is very useful on batteries that are being float charged, this allows the battery to be kept at exactly the correct voltage for its temperature (generally slightly lower in winter and high summer than spring and autumn). Normally this is done with one sensor attached somewhere on the outside of the battery - fancier set-ups will have multiple sensors, but that tends to be at much higher currents and prices than we see on narrowboats)

[smileypete]

Wet cell batteries, Tony I topped them up last month it took about a litre to do all 3 batteries i haven.t got a hydrometer I guess thats my next buy.

How old are these batts?

 

cheers,

Pete.

[alan_fincher]

Yes I mean volts AlanSorry about that

And was that 14.7 measured with the batteries being charged, or not, please ?

[AlanM6]

How old are these batts?

 

cheers,

Pete.

Not really sure how old the batteries are but at least 2 years. If appearance is anything to go by they look in good condition, I,m guessing that each cell took about an egg cup full of water to top up. I could hear them fizzing or bubbling during the charge they got warm but not hot. I rang the marine electrician that installed my charger he has told me to disconnect and seperate the batteries and he will pop out early next week and do a drop test on them. I do have a spare battery (new) but i,m arfaid to connect this just incase there is a fault with the charger I dont want to overcook the new one. Thank you all for your help I will let you know how I get on.

Alan M6

[Keeping Up]

I reckon the charger is faulty.

 

Almost all 3-stage chargers work in a similar fashion: they deliver their maximum current until the voltage reaches a pre-set figure (bulk phase); then they provide a fixed voltage for a set period of time (absorption phase); finally they reduce the voltage and keep it there.

 

from its LED reading your charger seems to be stuck in either the first or second phase (can't be more specific without knowing the detailed spec of the charger) despite the fact that he voltage has reached 14.7 volts. Since that is well above the gassing voltage I am not surprised that after several days there was a lot of gas around. The batteries may be perfectly OK, in fact once topped up they may actually have benefitted from the experience.

[Guest]

I reckon the charger is faulty.

 

Almost all 3-stage chargers work in a similar fashion: they deliver their maximum current until the voltage reaches a pre-set figure (bulk phase); then they provide a fixed voltage for a set period of time (absorption phase); finally they reduce the voltage and keep it there.

 

 

This is exactly what our Mastervolt Combi does, our batteries do seem to fizz and bubble a bit on 'bulk' but settle on 'absorption' and more so on 'float'.

 

I was worried when I read above that 'fizzing' could be an issue as I seemed to recall charging caravan batteries that fizzed a bit when being charged but didn't seem to suffer any harm.

[by'eck]

I reckon the charger is faulty.

 

Almost all 3-stage chargers work in a similar fashion: they deliver their maximum current until the voltage reaches a pre-set figure (bulk phase); then they provide a fixed voltage for a set period of time (absorption phase); finally they reduce the voltage and keep it there.

 

from its LED reading your charger seems to be stuck in either the first or second phase (can't be more specific without knowing the detailed spec of the charger) despite the fact that he voltage has reached 14.7 volts. Since that is well above the gassing voltage I am not surprised that after several days there was a lot of gas around. The batteries may be perfectly OK, in fact once topped up they may actually have benefitted from the experience.

 

What you have not taken into account is that a single faulty battery in a bank can load the others, never allowing the bank voltage as seen by the charger, to reach the point of the absorption phase. The charger just keeps dumping high current to the batteries until you spot the problem or something dramatic happens.

 

I have had this happen twice with different smart chargers over a period of years. There was never a fault with either charger.

[Timleech]

I reckon the charger is faulty.

 

Almost all 3-stage chargers work in a similar fashion: they deliver their maximum current until the voltage reaches a pre-set figure (bulk phase); then they provide a fixed voltage for a set period of time (absorption phase); finally they reduce the voltage and keep it there.

 

from its LED reading your charger seems to be stuck in either the first or second phase (can't be more specific without knowing the detailed spec of the charger) despite the fact that he voltage has reached 14.7 volts. Since that is well above the gassing voltage I am not surprised that after several days there was a lot of gas around. The batteries may be perfectly OK, in fact once topped up they may actually have benefitted from the experience.

 

Shouldn't the length of absorbtion charge vary with the battery capacity? If so, how is it done, & if not..??

 

Tim

[Bob18]

Most certainly the length of the absorption phase will vary with battery type, size, condition and applied voltage.

 

The only sure fire way of finding out if you've reached the end of the phase is to stop charging, let the battery rest and measure the voltage, compare that voltage with the data for the battery and make the decision to either continue charging at the absorption charge voltage, reduce to float voltage, or stop charging.

A secondary guide, which is more commonly used, is battery temperature, towards the end of the absorption phase the battery temperature will increase more rapidly, obviously this is OK if the ambient temperature is fairly constant, but if you've been charging on a cool night then the sun comes up and the ambient temperature will increase quite rapidly and the battery temperature will increase. This however is safe side situation, as if the charger now goes into "float" the battery will still accept charge, it just won't be charging as quickly as it might.

[by'eck]

Shouldn't the length of absorbtion charge vary with the battery capacity? If so, how is it done, & if not..??

 

Tim

 

Yes, with some chargers its for a fixed period, with others its manually adjustable, usually in increments of 30 mins to match the bank size. Intelligent ones though automatically calculate the necessary absorption time based on drawn current drop & memorise it.

[GUMPY]

Yes, with some chargers its for a fixed period, with others its manually adjustable, usually in increments of 30 mins to match the bank size. Intelligent ones though automatically calculate the necessary absorption time based on drawn current drop & memorise it.

And I think that you will find if you look back through the forum that adaptive charging doesn't work.

I know many chargers offer it but unless you can program the battery type and size into the charger then it just wont work. You will need to search the forums for the reasons I CBA to find the postings from Gibbo

[by'eck]

And I think that you will find if you look back through the forum that adaptive charging doesn't work.

I know many chargers offer it but unless you can program the battery type and size into the charger then it just wont work. You will need to search the forums for the reasons I CBA to find the postings from Gibbo

 

I'm sure your right, but in ignorance of battery capacity its probably better than nothing.

 

Even if the charger allows programming of battery type & capacity, this is only going to be correct with a new set as capacity will reduce with age.

[WotEver]

And I think that you will find if you look back through the forum that adaptive charging doesn't work.

I know many chargers offer it but unless you can program the battery type and size into the charger then it just wont work. You will need to search the forums for the reasons I CBA to find the postings from Gibbo

Yes indeed. It actually does the opposite of what you want.

 

Tony

[Keeping Up]

What you have not taken into account is that a single faulty battery in a bank can load the others, never allowing the bank voltage as seen by the charger, to reach the point of the absorption phase. The charger just keeps dumping high current to the batteries until you spot the problem or something dramatic happens.

 

I have had this happen twice with different smart chargers over a period of years. There was never a fault with either charger.

 

On the contrary. The OP says it is reaching 14.7v. The charger should definitely interpret this as having reached the absorption phase.

 

The length of the absorption phase will almost certainly be a fixed (presettable) time. I cannot imagine that this can be preset to be a matter of days on this charger.

 

Actually (heresy moment here) I believe IIRC that some of Gibbo's arguments against adaptive charging were flawed - but this is not the time or place to re-open that argument