Battery charging

[Sandy]

Sigh!
There were two batteries fitted on the boat. Separately charged via a diode splitter.
Both batteries I deemed dead. I took them to BMS who commented that one of them had a cracked inspection window that might have been cased by overheating. I admitted I had witnessed charge rates of 40A.
I have replaced both batteries with the same make and type.
On running the engine and setting the alternator output to the recommended 14.4 volts, one battery was taking 36A.
The other was around 18.

Clear now?

Why sigh? Your postings, to this reader, were confusing.

This post paints a better picture.

My understand is. You have two battery banks fed by a splitting diode from one charging source. One battery wants to take 36 amps the other 18 amps. I don't see a problem as each bank will take what it needs.

Think of it in these terms: As you motor along, your engine battery will replace what it has used to start your engine quite quickly and say 'I'm full thank you' while your house battery will be sipping about the same number of amp as you are using for the domestic side.

 

[Tranona]

Why sigh? Your postings, to this reader, were confusing.

This post paints a better picture.

My understand is. You have two battery banks fed by a splitting diode from one charging source. One battery wants to take 36 amps the other 18 amps. I don't see a problem as each bank will take what it needs.

Think of it in these terms: As you motor along, your engine battery will replace what it has used to start your engine quite quickly and say 'I'm full thank you' while your house battery will be sipping about the same number of amp as you are using for the domestic side.

Suggest everybody read post#1 again. Seems clear to me particularly the first sentence. The confusion comes from posters not reading it then making their own (incorrect) assumptions.

 

[pmagowan]

Suggest everybody read post#1 again. Seems clear to me particularly the first sentence. The confusion comes from posters not reading it then making their own (incorrect) assumptions.

The original post is ambiguous.
"I have just replaced both" fine
"I suspect I might have cooked one" which one, the old or new?
When asked to clarify as to why suspect that, once again no reference to which battery, old or new.

Such is life, this is an internet forum and no nuance and clarity don't come easily.

This matters as either their is no problem, just an old battery doing what old batteries do, or there is a serious problem as new batteries should not do what old batteries do. then we can have the discussion re realistic vs perfect charging regimes

 

[Tranona]

The original post is ambiguous.
"I have just replaced both" fine
"I suspect I might have cooked one" which one, the old or new?
When asked to clarify as to why suspect that, once again no reference to which battery, old or new.

Such is life, this is an internet forum and no nuance and clarity don't come easily.

This matters as either their is no problem, just an old battery doing what old batteries do, or there is a serious problem as new batteries should not do what old batteries do. then we can have the discussion re realistic vs perfect charging regimes

NO. It is perfectly clear. No mention of the old batteries, only the new.

As I said it is others introducing irrelevant material like your "which one, old or new?" when he clearly describes following instructions from the supplier for charging the new ones. It is totally irrelevant what happened to the old ones,

 

[pmagowan]

NO. It is perfectly clear. No mention of the old batteries, only the new.

As I said it is others introducing irrelevant material like your "which one, old or new?" when he clearly describes following instructions from the supplier for charging the new ones. It is totally irrelevant what happened to the old ones,

So which battery is cooked?

"I have just replaced both domestic batteries with the same make - Hankook.
I suspect I may have cooked one of them by overcharging."

PS in the quote above I see mention of old and new batteries, do you not?

 

[Refueler]

Sigh!
There were two batteries fitted on the boat. Separately charged via a diode splitter.
Both batteries I deemed dead. I took them to BMS who commented that one of them had a cracked inspection window that might have been cased by overheating. I admitted I had witnessed charge rates of 40A.
I have replaced both batteries with the same make and type.
On running the engine and setting the alternator output to the recommended 14.4 volts, one battery was taking 36A.
The other was around 18.

Clear now?

Hi .... some of us caught on OK ...

Just out of interest about this alternator adjustment ... I've never seen adjustment on an alternator .. but usually on charge controller allied to Diode Splitter ... ie - the old days of Sterling and Adverc. The Controller could be adjusted by user or default to battery sense....

As to what alternators usually charge to - is not full - they are usually designed to cut off quite a way short of full ... add a Diode Splitter and you can be seriously short on charge ... reason for controller / boosters developing years ago

 

[Refueler]

NO. It is perfectly clear. No mention of the old batteries, only the new.

As I said it is others introducing irrelevant material like your "which one, old or new?" when he clearly describes following instructions from the supplier for charging the new ones. It is totally irrelevant what happened to the old ones,

I get the idea from GW's first post - he's looking for comment about BM's advice and also whether his regime can be at fault ... not wanting to 'cook' his new batterys. This then leads to ask questions to try and provide a reasonable answer. It certainly is not irrelevant.

 

[Sandy]

80% of communication is non-verbal.

We all have a full understanding of an issue in our head, if the understanding is correct or not is another matter, communicating that issue so that others understand is never easy.

Still it is all sorted and we can now watch the rain fall out of the sky. I have been informed that it is a Bank Holiday Weekend; more distractions from the refit, heavy traffic and rain.

Still waiting for summer 2022 here.

 

[B27]

Hi .... some of us caught on OK ...

Just out of interest about this alternator adjustment ... I've never seen adjustment on an alternator .. but usually on charge controller allied to Diode Splitter ... ie - the old days of Sterling and Adverc. The Controller could be adjusted by user or default to battery sense....

As to what alternators usually charge to - is not full - they are usually designed to cut off quite a way short of full ... add a Diode Splitter and you can be seriously short on charge ... reason for controller / boosters developing years ago

A typical 'dumb' alternator is not designed to cut off when or before the battery is full.
It chucks out 14 point something volts, less its output resistance for as long as the engine is running.
This is enough volts to overcharge a lead-acid battery, if given long enough.
Anything above about 13.6V will overcharge a lead acid battery eventually.
That's why we have multi-stage smart chargers and all that.

 

[Refueler]

A typical 'dumb' alternator is not designed to cut off when or before the battery is full.
It chucks out 14 point something volts, less its output resistance for as long as the engine is running.
This is enough volts to overcharge a lead-acid battery, if given long enough.
Anything above about 13.6V will overcharge a lead acid battery eventually.
That's why we have multi-stage smart chargers and all that.

I beg your pardon ?? Is that why alternators incorporate regulators in them (not just the 'bridge' rectifier) - as against the days of generators that had separate little boxes ?

Alternators have been since their placement on cars etc - been set to NOT charge 100% ... for the simple reason that it requires so long - in theory infinite time - to hit 100%. They typically charge to well short of that ... depending on brand can be anywhere from 90% and up.

Why do you think Sterling and Adverc made their gear ? It was not just for compensating splitters - it was primarily to achieve as much charge as possible towards that 100% ...

 

[Tranona]

So which battery is cooked?

"I have just replaced both domestic batteries with the same make - Hankook.
I suspect I may have cooked one of them by overcharging."

PS in the quote above I see mention of old and new batteries, do you not?

No. Just that new batteries have been fitted.

 

[PaulRainbow]

A typical 'dumb' alternator is not designed to cut off when or before the battery is full.
It chucks out 14 point something volts, less its output resistance for as long as the engine is running.
This is enough volts to overcharge a lead-acid battery, if given long enough.
Anything above about 13.6V will overcharge a lead acid battery eventually.
That's why we have multi-stage smart chargers and all that.

You really do need to stop posting incorrect stuff like this !

 

[B27]

You really do need to stop posting incorrect stuff like this !

You're even more ignorant than I thought.
It's quite funny really.

What's the Rainbow explanation of the basic operation of a smart charger?
Do you have any qualifications at all?

 

[B27]

I beg your pardon ?? Is that why alternators incorporate regulators in them (not just the 'bridge' rectifier) - as against the days of generators that had separate little boxes ?

Alternators have been since their placement on cars etc - been set to NOT charge 100% ... for the simple reason that it requires so long - in theory infinite time - to hit 100%. They typically charge to well short of that ... depending on brand can be anywhere from 90% and up.

Why do you think Sterling and Adverc made their gear ? It was not just for compensating splitters - it was primarily to achieve as much charge as possible towards that 100% ...

I think Sterling and Adverc and all that made 'alternator boosters' and so forth moderately popular last century for a few reasons.
Firstly it was the move away from 1-Both-2 switches to diode splitters introducing that diode loss.
Secondly, many boat engines were/are derived from plant (e.g. generator, digger..) engines which often had alternators regulating to lower voltages, 14.0 or so, because these engines were intended for higher duty cycle, so 14.4 would overcharge a battery and destroy it in a few months of 8 hour shifts. Cars typically only run a few hours a day, so a 70s/80s/90s car would have 14.4 or so as a compromise between quicker charging and battery life.
Thirdly, many yacht owners were wanting as much charging as possible in short periods of engine running, so were using boost voltages of 14.7 or similar. People using certain batteries like the famous T105 would allow gassing to happen and refill with water when needed.

If you look for a graph of voltage vs state of charge for various currents, you will find that 14.4V is ample to fully charge a lead-acid battery.
That's why a smart charger will use that sort of voltage and turned it down as it senses 100% approaching.

There are of course complications from variations to the basic lead/acid chemistry.

 

[pmagowan]

No. Just that new batteries have been fitted.

Oh, the old ones are still there in your understanding?
When I read the OP it suggests to me that old batteries were removed, new ones were put in in their place. A battery was suspected to be cooked, either one of the old ones or the new replacements (not clarified in OP). I originally suspected one of the new batteries was suspected cooked and asked why this was suspected but the reply, although also ambiguous, makes me think that it was actually the old one that was suspected cooked. Quite important distinction
You didn’t answer my questions so obviously I don’t know for sure what your understanding of the OP is, only that you think it is unambiguous

 

[B27]

A typical 'dumb' alternator is not designed to cut off when or before the battery is full.
It chucks out 14 point something volts, less its output resistance for as long as the engine is running.
This is enough volts to overcharge a lead-acid battery, if given long enough.
Anything above about 13.6V will overcharge a lead acid battery eventually.
That's why we have multi-stage smart chargers and all that.

You really do need to stop posting incorrect stuff like this !

We're waiting for you to explain exactly what you disagree with.
If you can.

 

[Refueler]

I think Sterling and Adverc and all that made 'alternator boosters' and so forth moderately popular last century for a few reasons.
Firstly it was the move away from 1-Both-2 switches to diode splitters introducing that diode loss.
Secondly, many boat engines were/are derived from plant (e.g. generator, digger..) engines which often had alternators regulating to lower voltages, 14.0 or so, because these engines were intended for higher duty cycle, so 14.4 would overcharge a battery and destroy it in a few months of 8 hour shifts. Cars typically only run a few hours a day, so a 70s/80s/90s car would have 14.4 or so as a compromise between quicker charging and battery life.
Thirdly, many yacht owners were wanting as much charging as possible in short periods of engine running, so were using boost voltages of 14.7 or similar. People using certain batteries like the famous T105 would allow gassing to happen and refill with water when needed.

If you look for a graph of voltage vs state of charge for various currents, you will find that 14.4V is ample to fully charge a lead-acid battery.
That's why a smart charger will use that sort of voltage and turned it down as it senses 100% approaching.

There are of course complications from variations to the basic lead/acid chemistry.

That long winded post - actually only goes to support what I posted in reply to your 'dumb alternator' post ...

 

[Tranona]

Oh, the old ones are still there in your understanding?
When I read the OP it suggests to me that old batteries were removed, new ones were put in in their place. A battery was suspected to be cooked, either one of the old ones or the new replacements (not clarified in OP). I originally suspected one of the new batteries was suspected cooked and asked why this was suspected but the reply, although also ambiguous, makes me think that it was actually the old one that was suspected cooked. Quite important distinction
You didn’t answer my questions so obviously I don’t know for sure what your understanding of the OP is, only that you think it is unambiguous

No they are not there - whatever would make anyone think that? Did you miss the word "replaced"? You are correct that post#5 was confusing but corrected in post#10. So it is back to the basic question of what has happened to 2 new batteries charged in accordance with the instructions. Anything that went on before is surely irrelevant? post#18 makes it very clear.

 

[PaulRainbow]

We're waiting for you to explain exactly what you disagree with.
If you can.

Who's "we" ?

I take you mean "you". You post so much nonsense on here about stuff you must have read about on the internet and misunderstood, i can't be bothered to correct it all.

 

[B27]

Who's "we" ?

I take you mean "you". You post so much nonsense on here about stuff you must have read about on the internet and misunderstood, i can't be bothered to correct it all.

So you're not capable of refuting any one sentence in the post in question?

I hope your customers deserve your service.....