Another battery problem?

[Deleted User YDKXO]

I didn't want to drift MedMilo's excellent thread on a similar subject with this question so I've started a separate thread. Just before I left our boat in SoF about 10 days ago to come home I noticed that the voltmeter reading for the service batteries was 28.4V. I was surprised to see this as normally the voltmeter shows a reading of around 26.5V when fully charged. We had been in port for 2 days so the batteries should have been fully charged. I didnt have time to investigate this further but as a precaution I left the battery charger turned off

Is a reading of 28.4V abnormal and if so what is likely to be the cause? As I said the battery charger has been off for 10 days now. There is no load on the batteries other than potentially a bilge pump activation. How long can batteries remain off charge in temps 10-15degC?

The batteries are standard lead acid units about 3 yrs old and have shown no sign of deterioration recently

 

[mcanderson]

Mike, I unplug my boat and turn everything off between visits. Our guy who looks after Orpheus turns everything back on when he washes it the day travel down. No issues in 3 years on the med. Batteries now at 5 years old.

 

[BruceK]

Mike you don't perchance have solar panels or similar you haven't accounted for?

 

[Portofino]

I didn't want to drift MedMilo's excellent thread on a similar subject with this question so I've started a separate thread. Just before I left our boat in SoF about 10 days ago to come home I noticed that the voltmeter reading for the service batteries was 28.4V. I was surprised to see this as normally the voltmeter shows a reading of around 26.5V when fully charged. We had been in port for 2 days so the batteries should have been fully charged. I didnt have time to investigate this further but as a precaution I left the battery charger turned off

Is a reading of 28.4V abnormal and if so what is likely to be the cause? As I said the battery charger has been off for 10 days now. There is no load on the batteries other than potentially a bilge pump activation. How long can batteries remain off charge in temps 10-15degC?

The batteries are standard lead acid units about 3 yrs old and have shown no sign of deterioration recently

In my anecdotal advice is 28 V -plus more is perfectly normal -relax .

Been using a professional guardiene for the past 11 y -9 Sunseeker -2 Itama ( his main job is looking after Rivas) -they Allways leave the charger on .
Modern ones have a float ,trickle charge function .
lead acid in the SS lasted 7 y .
AGM,s in the Itama were new in June 14 when it was commissioned from 3-1/2 years in a hanger .
V guage for both Doms and Engine is Allways way over 24 ,---- 28, even higher 29 ?

Can some one explain the rational for turning the shore power and /or charger off ps , in a boat that's not being used ?
My classic cars are allways on a trickle charger - with lead acid bats , while not used for months on end .

Sulphating of the plates is accelerated by long (ish) periods of incomplete charge .
So leaving them at even 90 % charge cap will reduce life .
Therefore because they naturally discharge on there own ,and in a boat via occasional bilge pump -say rain natural water ingress and folks leaving lights on -even the guardiene /boat cleaner ' it's madness if have a " all singing n dancing " charger cum bat conditioner to turn it OFF
Flipping the coin over charging via a dare say it primitive charger will accelerate Sulphating and reduce bat life .
Think what's happened in 16 y since the millennium with phones and computers .
Marine Chargers are on a similiar curve albeit not as steep
Do you still have a 16 y old phone ?

 

[MapisM]

Can some one explain the rational for turning the shore power and /or charger off ps , in a boat that's not being used ?

Well, limiting the risk of an onboard fire ain't such a silly reason, I reckon.
In several boats, it's expressively specified to not leave shore power on while the boat is unattended.
Mind, I for one don't turn it off when I'm out for dinner.
But I never leave it on when I'm not onboard for days.

 

[MapisM]

Is a reading of 28.4V abnormal and if so what is likely to be the cause?

M, imho the answer to your first question is yes, but I'm afraid I don't know is the answer to the second.
If you're positive about the battery bank being at 100%, a defective charger would be my GUESS, but I'm not writing it in capital for nothing.

Fwiw, I surely don't agree with PF that 28+ V is an acceptable FLOAT charge, with a modern multi-stage charger and a battery bank in good working order.
The 26.5 you mentioned is right on the money, in my experience.

 

[Portofino]

Well, limiting the risk of an onboard fire ain't such a silly reason, I reckon.
In several boats, it's expressively specified to not leave shore power on while the boat is unattended.
Mind, I for one don't turn it off when I'm out for dinner.
But I never leave it on when I'm not onboard for days.

Still baffled --- is that the same fire risk ,which means at home /work /shopping / centres close at night unattended
Folks turn the power off?
How does your car alarm , house alarm ,heating all work with bat off or power off ?

You are shortening the life bats leaving them on there own .
A Fiat punto car bat is €50 , from a supermarket -prob open on Sunday too ! set of big boat bats €1000,s + locating and install hassle !

Give you 1-2 marks out of 100 for "fire risk " -for turning the charger off and shore power

 

[Portofino]

M, imho the answer to your first question is yes, but I'm afraid I don't know is the answer to the second.
If you're positive about the battery bank being at 100%, a defective charger would be my GUESS, but I'm not writing it in capital for nothing
Fwiw, I surely don't agree with PF that 28+ V is an acceptable FLOAT charge, with a modern multi-stage charger and a battery bank in good working order.
The 26.5 you mentioned is right on the money, in my experience.

Here's the spec sheet see page 12 for the 24v 100ah shows the "float "
Mike need to find his own and check
http://www.dolphin-charger.com/en/p...es/produits/pdf/user-manual-dol-pro-fr-en.pdf

 

[sarabande]

Mike

I can't think of a reason for high voltage, unless the charger was going through a 'float test' phase when you looked at the meter. Your concern is a justification for looking at a remote battery monitoring system, plus remote control of the mains.

 

[rafiki_]

Still baffled --- is that the same fire risk ,which means at home /work /shopping / centres close at night unattended
Folks turn the power off?
How does your car alarm , house alarm ,heating all work with bat off or power off ?

You are shortening the life bats leaving them on there own .
A Fiat punto car bat is €50 , from a supermarket -prob open on Sunday too ! set of big boat bats €1000,s + locating and install hassle !

Give you 1-2 marks out of 100 for "fire risk " -for turning the charger off and shore power

Apologies but I disagree. Your charger is a transformer, changing 240ish v to 12ish or 24ish. It is therefore creating heat energy as part of the process, which of course, can cause things to fail, hence increasing the fire risk. Batteries can also fail, and if being charged, can then get too hot and pop. Of course, the probability is low, but still an unnecessary risk.

 

[A_8]

I say its a real risk keeping the charger on, twice and on different chargers I have had a malfunction where the charged did not go into float state and stayed in a high charge state. This causes the batteries to get very hot and If you have traditional led acid batteries this state will also produce very flammable gases.

 

[MapisM]

is that the same fire risk, which means at home...

LMAO, you obviously never worked as a firefighter, did you?
With her 4 tons of fuel and half a ton of batteries, it takes my whole neighbourhood (and then some) to reach a comparable fire load.
That's not the point, anyway. When I leave my boat unattended, I have absolutely nothing running, and I disconnect the batteries. Their life would be equally shortened if stored on a shelf...

 

[MapisM]

Here's the spec sheet see page 12 for the 24v 100ah shows the "float"

Well, interestingly it mentions 26.4 V for FLA batteries.
I'm not sure to understand why it also mentions 27.2 for airtight FLA batteries (and I struggle to imagine how the charger can "see" the difference), but that's still well below 28, anyway...

 

[petem]

It would be interesting to see the Venn diagram of boat fires showing the numbers where all power is off, power is on and no appliances in use and third ly where power is on and being consumed by a dehumidifier or similar thing.

 

[Portofino]

Well, interestingly it mentions 26.4 V for FLA batteries.
I'm not sure to understand why it also mentions 27.2 for airtight FLA batteries (and I struggle to imagine how the charger can "see" the difference), but that's still well below 28, anyway...

Page 23 of the link suggest a "scanning function "
Relating to another parallel thread -MedMilo + sq 65 woes -if you read the link carefully -sorry guys -the whole thing needs to be set up -wire size ,Lenght , etc being crucial ---and the little dial at install setting up correctly to match the bat types

I,am no expert so called a boat sparkie in to check a fridge in 2015 that intermittently kept cutting out on the dock .
A faulty charger ,original 2001 -40ah was diagnosed ,apparently they decay ,the transformer effect just decreases ,it was giving out max -4 ah only
The main charging was actually being done when we were motoring via the alternators with a spli diode -engines 1st then topping up Doms .
So with reasonably medium to heavey Domestic use on the dock ,like 2-3 days the V to one fridge went below its threshold .
Tech as moved on in 15 years
A new bigger 100ah was fitted .thing is with latest tech --- for now --- think phones !

Safety wise for A8 and Rafiki -I,ll list them
There's a trip on the dock ,
A trip on the breaker board .
An internal fuse in the unit .
Another fuse on the + ve terminals
Temp monitors on the bats .

We not talking about a "primitive " Halfords charger you dad used in the 70 ,s and clipped on for 13 hours overnight ,that was too hot to touch in the Am -- agreed boiling /cooking the lead acid .Then after this went and bought a new bat

Also re shore power on ,in the bigger pic apart from the charger left on ,we or correctly the professional Guardiane fits oil filled tube heater s to all the spaces from Oct -April .---In SoF -he removes em in the season
So far that regime is in my " if it ain't broke don,t fix it " book .I,am not challenging that --assume he and his team know what they are doing
So far -no damp , no mould , no nowt -everything all dry and warm .

I think you have to accept tech moves on --and trust it

 

[Portofino]

It would be interesting to see the Venn diagram of boat fires showing the numbers where all power is off, power is on and no appliances in use and third ly where power is on and being consumed by a dehumidifier or similar thing.

Even more interesting
Age of said appliances -?
Who fitted them ?

But the really inspector Clouseau stat is the recent financial health of the owner --- wonder what that may tell us ?

 

[skipmac]

Exploding batteries aside, back to your original question.

Answer depends on a few factors so my response will include some assumptions or qualifiers.

I didn't want to drift MedMilo's excellent thread on a similar subject with this question so I've started a separate thread. Just before I left our boat in SoF about 10 days ago to come home I noticed that the voltmeter reading for the service batteries was 28.4V. I was surprised to see this as normally the voltmeter shows a reading of around 26.5V when fully charged.
We had been in port for 2 days so the batteries should have been fully charged. I didnt have time to investigate this further but as a precaution I left the battery charger turned off

Is a reading of 28.4V abnormal and if so what is likely to be the cause?

If you had been in port with the charger on for two days then I would expect the batteries to have reached full state of charge and a correctly functioning, three stage smart charger should then drop to the float stage leaving the batteries around the 26.5 V you expected. However, if some time close to when you checked the voltage you had used some significant battery power that could have kicked the charger back into bulk or absorption mode which would normally be over 28 V.

This begs the question, was the charger still on or had it just been turned off when you checked the voltage? If so, then of course you were seeing the voltage of the charger or residual charging voltage on the batteries and not the actual battery voltage which will not stabilize fully for some hours after all charging sources and loads are off.

As I said the battery charger has been off for 10 days now. There is no load on the batteries other than potentially a bilge pump activation. How long can batteries remain off charge in temps 10-15degC?

Depends on the battery type. Standard FLA (flooded lead acid) batteries will self discharge but slowly. If the bilge pump doesn't draw them down they should be just fine for many weeks but wouldn't want to leave them for many months.


The batteries are standard lead acid units about 3 yrs old and have shown no sign of deterioration recently

 

[PowerYachtBlog]

Well, limiting the risk of an onboard fire ain't such a silly reason, I reckon.
In several boats, it's expressively specified to not leave shore power on while the boat is unattended.
Mind, I for one don't turn it off when I'm out for dinner.
But I never leave it on when I'm not onboard for days.

Modern fully electronic battery chargers (Victron or Mastervolt are good bench marks) are near to impossible to create a fire. Yes there is a 0.0001%
On the contrary older generation battery chargers are very prone to over heating and cause one. With those I would be very careful.
IMO it is more about the battery charger you have. Still in Winter when nothing I switch by BC for like a day in every two weeks just to give battery voltage stability.
On the dry I turn everything off.

 

[Deleted User YDKXO]

Mike, I unplug my boat and turn everything off between visits. Our guy who looks after Orpheus turns everything back on when he washes it the day travel down. No issues in 3 years on the med. Batteries now at 5 years old.

mcanderson I'm really in 2 minds about leaving the battery charger permanently connected for long periods whilst we're not on the boat. We have had one scary experience 3 yrs ago when we arrived at our boat after several weeks away with the battery charger connected to find the batteries completely flat (even the pasarelle wouldnt operate) and a hideous smell of gas in the engine bay. One or more of the batteries had fried themselves in our absence. Some marinas we have spent time in are very particular about leaving boats permanently connected to shorepower and specifically instruct berth holders not to. Indeed some marinas go around disconnecting boats from shorepower. Apart from that there's a big sign on the back of my boat next to the shorepower socket stating that the boat must not be left unattended with the shorepower connected. Having said that like a lot of people I usually leave my shorepower and battery charger permanently connected when leaving the boat, if allowed, and apart from the incident above I haven't had any other bad experiences in 25yrs of boating

I still would appreciate an answer to the question as to how long batteries can be left uncharged before they start to deteriorate permanently if anybody can throw some light on this

 

[Deleted User YDKXO]

In my anecdotal advice is 28 V -plus more is perfectly normal -relax .

Fwiw, I surely don't agree with PF that 28+ V is an acceptable FLOAT charge

Well, interestingly it mentions 26.4 V for FLA batteries.

However, if some time close to when you checked the voltage you had used some significant battery power that could have kicked the charger back into bulk or absorption mode which would normally be over 28 V.

Mmm getting some mixed messages here chaps The last comment by skipmac may be correct in that prior to leaving the boat I had been flushing each of the toilets several times with disinfectant so its possible that could have kicked the charger into bulk charge mode

FWIW the charger is a Mastervolt Mass 24/75 charger which I assume is the original on the boat which makes it 10yrs old. Is this what you guys describe as a 'smart' charger?