Do I have a battery problem?

[Quandary]

Our engine battery was a Numax 24MF 80ah and gave good service for several years, in April I replaced it with a new battery of the same make and spec. from Tayna. The battery was on the boat charger until launch in May and since has only been charged by the alternator. I noticed that the new battery did not seem to have the oomph when starting that the old one used to have and when I measured the voltage after about a week at rest it was showing 11.7v. I took the new battery out, brought it home and put it on charge using the Optimate 'intelligent' 3 stage charger that my wife used for her sports car. After 2 days the charger was showing that the battery was fully charged, the voltage when disconnected from the charger was 12.87, after an hour it was 12.62, +4hrs it was 12.48, +24 12.40 and +48hrs down to 12.33.
This suggests to me that this is defective and simply not holding charge. Before I contact Tayna can anyone confirm that I am right to think this battery may be duff?

 

[Ammonite]

I had the same thing with the last 110ah SLA leisure battery I bought but after charging it a few more times and monitoring the discharge it "fixed" itself and has been fine ever since. Apparently this is not uncommon

 

[[2574]]

Sounds distinctly dodgy to me. Assuming no load then I think you're assessment is correct.

 

[TernVI]

When you disconnected it from the charger, it should have been at around 13.5V.
Dunno about optimates specifically, but some maintenance chargers work really slowly.
Unless you've seen the volts up at 14.3 or so for some hours and seen the current fall away to a suitable level, I'd suspect it was not fully charged.

There may be an acid stratification or similar issue.

It might be worth putting it on a dumb charger overnight. If you can measure the volts and current so much the better.

 

[Ammonite]

It was a dumb charger that resolved my issue. Not saying it will definitely work but as TernVI says it's worth a try

 

[Quandary]

I found an old 12v charger in the back of the garage which is probably about forty years old, that should be dumb enough? It has a hi/low switch which is stuck on high, I have connected it and it it is showing as charging with the needle all a tremble. With it connected the battery is now showing 12.55 across the terminals. Bit reluctant to leave it unattended overnight, will go out and check it again in an hour or two.
I enjoyed physics at school and got a distinction at 'O' level but as far as electrickery is concerned I am well out of my depth with the simplest stuff.

 

[Tranona]

If the engine start was fully charged when you fitted it new it should stay charged as the engine takes so little that the alternator puts it back within minutes. Dodgy battery - don't waste any time on it, return it.

 

[Gwylan]

Make sure all the leads and terminals are in good shape.

 

[Refueler]

Just a post after seeing Quandarys mention of the bog standard charger : >

I spent two days searching around locally to get a bog standard non smart charger last year !

Finally found one ...

Smart chargers are fine when all is good and batterys don't get dragged down low. Trouble is some will default to Error condition if battery is below a certain voltage (that voltage depends on the charger and can be as low as 9V or over 10V ... ) Second that some once they click off at full charge or revert to trickle .. BUT if the battery is then used - the Smart Charger may be one of those that will not reset and start charging again.

I have 3 smart chargers that do that. Charge and then fail to restart charge again when battery needs it. I found this out when I fitted separate charge monitors. The Smart Charger would charge up ... monitor shows good charge level - charger would then shut down .. battery fall and need charge .. charger did nothing.
They can also be fooled by charge splitters and 2 of my 3 refuse to work at all with charge splitter I have. Its why I wanted the bog standard unit ... that has no trouble at all with the splitter - a solid state electronic unit .... I'd give link to it - but they are no longer available ...

Pal of mine swears by a Ctrek Smart charger ... its now on my bench to find out why its not working !
But my Polish bog standard unit is still working fine ...

 

[William_H]

I am a bit of a fan of old style chargers. They consisted of a transformer producing about 14v AC RMS feeding a rectifier then to the battery often via series resistor. RMS measurement of AC is a bit like average and means the peak AC voltage can be 50% higher. Sometimes the resistor can be varied (switched) or the tapping on the transformer switched for more voltage or less.
So the voltage and hence current presented to the battery comes in waves from the AC either 50 or 100 times per second depending on full or half wave rectification.
The wave shape means that you have a period of high voltage so overcomes inherent voltage of the battery then a period where you get no current because the voltage is lower. It gives a different profile of current in versus battery charge state (inherent voltage) So it is easier to get that last bit of charge in when battery is near full.
The down side is that you can overcharge the battery. can cope with a very flat battery but may need more series resistance to avert overheating the charger. At least initially.
Interesting that they usually fit an analogue mechanical meter which very neatly averages the current in. So much to be said for the old. ol'will

 

[Skylark]

What type of battery is the Numax? This governs the charging parameters.

A rested voltage should be measured 12 hours after a full charge and 12.7v is 100% state of charge. The decay measured by OP suggests that the battery is knackered.

So-called intelligent / 3 stage chargers suit “modern” batteries but the bulk, absorption and float settings may vary between sealed lead acid, gel and AGM.

There is a 4th stage known as equalisation but caution in using it is required as it should not be needed with AGM and gel. Old style chargers can do this as they can supply a higher voltage, around 15v. This voltage effectively stirs-up the electrolyte and removes lose sulphation. This stage will also cause a loss of electrolyte by boiling. Hence the car batteries on our old cars fitted with dynamos, not alternators, required regular water top-up.

Given that the battery in question is only a few months old and has had little use, it’s unlikely that it can be raised from the dead. I’d spend time trying to understand why it’s died. Does it have a defect or has there been a drain? The root cause of its failure needs to be determined before a replacement is fitted.

 

[Refueler]

This stage will also cause a loss of electrolyte by boiling. Hence the car batteries on our old cars fitted with dynamos, not alternators, required regular water top-up.

mmmmmm actually dynamo's were generally not able to fully charge as do modern alternators and certainly did not provide the amp rates you see today with alternators. They also had very poor low rpm capability ...
The reason for topping up batterys - was because they did not have self return built in .. Later and most todays batterys reconstitute the vapours given off - reducing the fluid loss. You can still get batterys that require topping up and in fact can be more often with alternators better higher rates than the old days of dynamos.

 

[Refueler]

I am a bit of a fan of old style chargers. They consisted of a transformer producing about 14v AC RMS feeding a rectifier then to the battery often via series resistor. RMS measurement of AC is a bit like average and means the peak AC voltage can be 50% higher. Sometimes the resistor can be varied (switched) or the tapping on the transformer switched for more voltage or less.
So the voltage and hence current presented to the battery comes in waves from the AC either 50 or 100 times per second depending on full or half wave rectification.
The wave shape means that you have a period of high voltage so overcomes inherent voltage of the battery then a period where you get no current because the voltage is lower. It gives a different profile of current in versus battery charge state (inherent voltage) So it is easier to get that last bit of charge in when battery is near full.
The down side is that you can overcharge the battery. can cope with a very flat battery but may need more series resistance to avert overheating the charger. At least initially.
Interesting that they usually fit an analogue mechanical meter which very neatly averages the current in. So much to be said for the old. ol'will

The simple fact is an old style dumb 14.8V charger that 'dad' had is better suited to many jobs especially if you install a charge controller - the charger will not default off with it. As the charge controller cuts in / out - the charger will supply as asked. many smart chargers will not live with this.

I have this ready to be fitted as the main charge control when boat on mooring and in 'season' :

12V Battery Low Voltage Cut off Switch Controller Excessive Protection Module | eBay

It only needs the one charger / controller as using the 3 way switch to connect 1 + 2 battery will present both batterys as one ... the sense can be on the most used battery IMHO.

During long term non use / winter - I use these low rate maintainers - (I have for my Lawn Tractors - Boat batterys - any in fact that go to storage in winter) - they may be cheap chinese - but work excellently ...

Trickle RV For Truck Motorcycle ATV Car Battery Charger Maintainer A0Q7 B5S9 | eBay

I like simple .... no fuss ...

 

[TernVI]

The simple fact is an old style dumb 14.8V charger that 'dad' had is better suited to many jobs ...

But bear in mind the UK has reduced its nomnal mains voltage from 240 to 230 which can change a healthy 14.5V charge to a limp 13.9V float charge.
It's not as bad as that because most of the cheap transformers had poor regulation, but the charger I inherited from my Dad tends to be more like 3A than its nominal 8A.
I have a variable power supply which can do 14.5V at 20A if I want to measure things.

Batteries are odd and complex and subtle.
I would not write off the OP's battery just yet, I'd want to give it a proper test and check for rogue loads etc on the boat.

OTOH, the fallout of lockdown may mean there's some dodgy 'new' batteries about.
I've heard of some motorbike batteries filled last year and left on the shelf for too long without a charge.

 

[Refueler]

But bear in mind the UK has reduced its nomnal mains voltage from 240 to 230 which can change a healthy 14.5V charge to a limp 13.9V float charge.
It's not as bad as that because most of the cheap transformers had poor regulation, but the charger I inherited from my Dad tends to be more like 3A than its nominal 8A.
I have a variable power supply which can do 14.5V at 20A if I want to measure things.

Batteries are odd and complex and subtle.
I would not write off the OP's battery just yet, I'd want to give it a proper test and check for rogue loads etc on the boat.

OTOH, the fallout of lockdown may mean there's some dodgy 'new' batteries about.
I've heard of some motorbike batteries filled last year and left on the shelf for too long without a charge.

But AC voltage is RMS .... so that calculation of 14.5 reduced to 13.9 is only an averaged figure. The range of charge will actually more likely run from still slightly over 14.5 at peaks .... so the effect of the 10V RMS reduction is IMHO not an issue.
Even before any reduction in AC ... you still had charge range that dropped below 13.9 during the cycles.

 

[Skylark]

mmmmmm actually dynamo's were generally not able to fully charge as do modern alternators and certainly did not provide the amp rates you see today with alternators. They also had very poor low rpm capability ...

Maybe true but not relevant to the point I was trying to make. A dynamo and voltage regulator regularly charged at high voltage, the so-called equalisation stage of charge. It served a useful purpose but cost in terms of loss of electrolyte. Modern batteries and charges generally to not make use of this.

 

[Norv]

if your battery is losing charge when standing after being fully charged overnight 14.3v and drops to 12.6 you have a problem with the battery. i would replace it if it is new.

 

[Refueler]

Maybe true but not relevant to the point I was trying to make. A dynamo and voltage regulator regularly charged at high voltage, the so-called equalisation stage of charge. It served a useful purpose but cost in terms of loss of electrolyte. Modern batteries and charges generally to not make use of this.

We'll just agree to disagree .... I think you are mixing up two separate issues ....

 

[Graham376]

I've heard of some motorbike batteries filled last year and left on the shelf for too long without a charge.

Talking to Tayna about cost of carriage charges for flooded batteries to Portugal, I asked if they could send them dry and was surprised to hear most batteries leave factories filled these days.

 

[Refueler]

Talking to Tayna about cost of carriage charges for flooded batteries to Portugal, I asked if they could send them dry and was surprised to hear most batteries leave factories filled these days.

We still can get dry LA batterys over here ... not so many as before - but still available. Dealer just drops the bottle of goop in and away you go ...
What I find interesting is the stated Dry Charged ...