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OK, I have two domestic leisure banks, bow and stern, once upon a time maybe 500ah, now probably 400.

They are all agm batteries and not very accessible, all new four years ago. 

I have two solar panels but this summer it's been a struggle even to get to the voltages I've been getting previously. Possibly lack of bright sunlight.

Does this mean I should have the bow  batteries replaced if it gets to the stage that the 12v fridge struggles. Or do I wait till I can't charge my tablet, phone, reading lamp?

The only new gadget is the LED Halo reading lamp, I use it as my main source of lighting nowadays. The bow battery bank is taking the hit for charging the water pump, USB  gadgets plus the fridge.

The stern batteries seem to have given up sending energy to their usb sockets following a fitter having a look in the area.  I suspect a loose wire as my car radio only works sometimes, generally can be kicked in to life by running the engine. 

I have an LED voltage reader which shows that the bow battery bank is going  down to 12.2 v, overnight. I think it used to be 12.4. I've even seen it below 12v.

Do I just wait till I can't charge the gadgets unless the engine is running? It seems to be taking more engine running than ever before.

PS it's been raining for several weeks. The daylight hours are getting less every day, its relentless!

 

Edited by LadyG
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36 minutes ago, LadyG said:

OK, I have two domestic leisure banks, bow and stern, once upon a time maybe 500ah, now probably 400.

They are all agm batteries and not very accessible, all new four years ago. 

I have two solar panels but this summer it's been a struggle even to get to the voltages I've been getting previously. Possibly lack of bright sunlight.

Does this mean I should have the bow  batteries replaced if it gets to the stage that the 12v fridge struggles. Or do I wait till I can't charge my tablet, phone, reading lamp?

The only new gadget is the LED Halo reading lamp, I use it as my main source of lighting nowadays. The bow battery bank is taking the hit for charging the water pump, USB  gadgets plus the fridge.

The stern batteries seem to have given up sending energy to their usb sockets following a fitter having a look in the area.  I suspect a loose wire as my car radio only works sometimes, generally can be kicked in to life by running the engine. Could it  be on the starter battery ?, not a great idea!

I have an LED voltage reader which shows that the bow battery bank is going  down to 12.2 v, overnight. I think it used to be 12.4. I've even seen it below 12v.

Do I just wait till I can't charge the gadgets unless the engine is running? It seems to be taking more engine running than ever before.

PS it's been raining for several weeks. The daylight hours are getting less every day, its relentless!

 

 

Unless you can get a rough idea of Ah in during charging and Ah out overnight, I don't see how you can decide, as they are difficult to access. It could be a lack of charging (what is the rested voltage when night falls, so no solar), loss of capacity as you suspect, or a cell starting to short. The only way to test them for a live-aboard is to take one out of use, fully charge it so after several hours of being off charge the voltage reads 12.8 ish, and leave it a few days and remeasure the voltage. It should be all but the same as the first reading. If it has dropped, the there is probably a shorting cell, but that dos not rule out a loss of capacity. If you have a battery monitor, you can check for that by fully charging the bank (12.7 to 12.8 rested voltage), zero the monitor's Ah out reading, and the next morning take the rested voltage and the Ah out. So, for example, rested voltage show the state of charge of 12.2 to 12.3 which is close to a true 50% charged, Ah out = (say) 30Ah, so when 100% charged the capacity is 60Ah.

 

Gibbo used to say that when batteries had lost 50% of their capacity, they needed replacing.

 

 

 

 

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2 hours ago, LadyG said:

OK, I have two domestic leisure banks, bow and stern, once upon a time maybe 500ah, now probably 400.

They are all agm batteries and not very accessible, all new four years ago. 

I have two solar panels but this summer it's been a struggle even to get to the voltages I've been getting previously. Possibly lack of bright sunlight.

Does this mean I should have the bow  batteries replaced if it gets to the stage that the 12v fridge struggles. Or do I wait till I can't charge my tablet, phone, reading lamp?

The only new gadget is the LED Halo reading lamp, I use it as my main source of lighting nowadays. The bow battery bank is taking the hit for charging the water pump, USB  gadgets plus the fridge.

The stern batteries seem to have given up sending energy to their usb sockets following a fitter having a look in the area.  I suspect a loose wire as my car radio only works sometimes, generally can be kicked in to life by running the engine. Could it  be on the starter battery ?, not a great idea!

I have an LED voltage reader which shows that the bow battery bank is going  down to 12.2 v, overnight. I think it used to be 12.4. I've even seen it below 12v.

Do I just wait till I can't charge the gadgets unless the engine is running? It seems to be taking more engine running than ever before.

PS it's been raining for several weeks. The daylight hours are getting less every day, its relentless!

 

no where near 400Ah from what you say, you are probably using less than 100Ah and they are effectively flat. What we don't know is how often you fully recharge them, that would be about 8 hours engine running to take a 500Ah bank from 12 volts to fully charged

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48 minutes ago, ditchcrawler said:

no where near 400Ah from what you say, you are probably using less than 100Ah and they are effectively flat. What we don't know is how often you fully recharge them, that would be about 8 hours engine running to take a 500Ah bank from 12 volts to fully charged

Yes, I am currently running the engine an hour per day, i upped this to four hours when it dipped, but not four hours every day.

 

There is an ammeter at the stern which  starts at minus 30 amps, (the arm swings to the right) which could well be what I use every day, ive rarely seen this at minus 50, obviously kept the engine running till i got back to normal. I am being a minimalist at the moment.

It takes about an hour to move to minus 5 amps, I could let it run for another three hours and I think it will come down to about minus 2.5.

This is ananalogue ammeter.

There are probably five batteries on board, one will be the starter, so probably not monitored. 

I will be visiting a boatyard for diesel, and will ask if I can charge overnight, at least that would get me back on track. 

The LED meter at the bow usually shows 12.2 or even 12.4 first thing in the morning, it is currently 12.5, (18.00hours), next to no solar today.

Edited by LadyG
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1 hour ago, cuthound said:

Personally I think that its time to change the batteries when they no longer do what you want then to do. 

 

If they are still meeting your needs, then there is no need to change them. That point will be different for different users.

That's my theory, whilst the batteries still run the fridge overnight and have enough charge in the morning to last until we start the engine then I don't need to replace them.

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Maybe post a photo of this ammeter because minus 30 amps seems a weird reading to me unless you were using a fair amount of electricity from the batteries. It sounds weird, if it is a simple ammeter, then it should jump from negative to positive as soon as you start and run the engine. I would expect it to jump to 50 amps plus for a short while.  wonder of it is an Amp Hour counter, that could act as you describe.

 

FWIW, I agree with those saying that while they do what theuyshould they are fine, but you do risk having to buy more with little notice or time.

Edited by Tony Brooks
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We would recommend fitting a 'Smartgauge' or something similar - to monitor the condition of your batteries.

We replace our batteries when it is no longer possible to get them back to 100% state of charge after running the engine or generator for six hours or so.

Edited by NB Alnwick
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When you lose the sun an hour a day on the engine wont put back what you are using. It will probably take between 3 to 4 hours per day just to put back what you are using if you dont have a good amount of solar energy.

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3 hours ago, LadyG said:

OK, I have two domestic leisure banks, bow and stern, once upon a time maybe 500ah, now probably 400.

They are all agm batteries and not very accessible, all new four years ago. 

I have two solar panels but this summer it's been a struggle even to get to the voltages I've been getting previously. Possibly lack of bright sunlight.

Does this mean I should have the bow  batteries replaced if it gets to the stage that the 12v fridge struggles. Or do I wait till I can't charge my tablet, phone, reading lamp?

The only new gadget is the LED Halo reading lamp, I use it as my main source of lighting nowadays. The bow battery bank is taking the hit for charging the water pump, USB  gadgets plus the fridge.

The stern batteries seem to have given up sending energy to their usb sockets following a fitter having a look in the area.  I suspect a loose wire as my car radio only works sometimes, generally can be kicked in to life by running the engine. Could it  be on the starter battery ?, not a great idea!

I have an LED voltage reader which shows that the bow battery bank is going  down to 12.2 v, overnight. I think it used to be 12.4. I've even seen it below 12v.

Do I just wait till I can't charge the gadgets unless the engine is running? It seems to be taking more engine running than ever before.

PS it's been raining for several weeks. The daylight hours are getting less every day, its relentless!

 

I'm no battery specialist but two points spring to my mind. 1) why have you got two domestic battery banks? (or am I misreading something?) Why aren't they both together near to the alternator that will be charging them? I don't know how long your boat is (if it is a dinky little cruiser, then my point isn't relevant) but if it is a narrow boat you are going to have a lead charging the bow batteries coming from the engine at the stern, why is that a good idea?

 

The second point is just an observation, I also have about 500aH of AGM batteries (also now 4 years old) the last AGM's I had lasted me 7 years and I'm hoping for the current batteries to do much the same, I did make a point of keeping them pretty well charged though.

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38 minutes ago, Tony Brooks said:

Maybe post a photo of this ammeter because minus 30 amps seems a weird reading to me unless you were using a fair amount of electricity from the batteries. It sounds weird, if it is a simple ammeter, then it should jump from negative to positive as soon as you start and run the engine. I would expect it to jump to 50 amps plus for a short while.  wonder of it is an Amp Hour counter, that could act as you describe.

Oops, its a Sunpro amps and when I thought it was negative, it's actually the positive side, there is also a voltmeter,  which is showing 13.65 apprxx, engine is now running.

20241028_184319.jpg

33 minutes ago, Wanderer Vagabond said:

I'm no battery specialist but two points spring to my mind. 1) why have you got two domestic battery banks? (or am I misreading something?) Why aren't they both together near to the alternator that will be charging them? I don't know how long your boat is (if it is a dinky little cruiser, then my point isn't relevant) but if it is a narrow boat you are going to have a lead charging the bow batteries coming from the engine at the stern, why is that a good idea?

R

The second point is just an observation, I also have about 500aH of AGM batteries (also now 4 years old) the last AGM's I had lasted me 7 years and I'm hoping for the current batteries to do much the same, I did make a point of keeping them pretty well charged though.

Bow batteries

Yes, well, once upon a time there was a bow thruster, so that bank is still available to charge everything near the bow. The USB,  the inverter, and the water pump nav light, some internal lighting, are in the bow area so it's not such a mad idea, the run is 57ft approx, and the cables seem to be up to the job.

The rear batteries,

one starter battery, ie another bank.

And one or two extra batteries , the third bank, which powers some internal lights and maybe the shower waste.

I am a bit fanatical about monitoring my batteries, but this summer has been really dull, so I am not sure they have been fully charged every week.

The solar panels feed in to the stern, but their energy also moves to the bow batteries.

I've left the engine on tonight, I think ive just let them go down too far this week.

Edited by LadyG
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26 minutes ago, LadyG said:

Oops, its a Sunpro amps and when I thought it was negative, it's actually the positive side, there is also a voltmeter,  which is showing 13.65 apprxx, engine is now running.

 

As long as the engine was revving at around 1200 rpm then 13.65 volts suggests a very high charging current, but 30 amps is not that high, so I am wondering about the alternator or the wiring.

 

"The cable seem up to the job", so what is the volt drop along those cables? That might explain the 13.65V. Get a length of any old cable, connect a multimeter set to 20V DC from the bow battery positive and wherever the other end of that cable ends up (another bank positive, a charge splitter etc. Then take a reading with the engine revving and that 30 amps or more flowing. In theory, it should read zero and you don't really want it to read any more than 0.3 volts. Repeat for the negative, same results expected.

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41 minutes ago, Tony Brooks said:

Maybe post a photo of this ammeter because minus 30 amps seems a weird reading to me unless you were using a fair amount of electricity from the batteries. It sounds weird, if it is a simple ammeter, then it should jump from negative to positive as soon as you start and run the engine. I would expect it to jump to 50 amps plus for a short while.  wonder of it is an Amp Hour counter, that could act as you describe.

 

FWIW, I agree with those saying that while they do what theuyshould they are fine, but you do risk having to buy more with little notice or time.

I think we are OK, as the bow batteries are the biggest consumer, and are furthest from the alternator, I think I would probably manage with replacing them. 

Im trying to get my head round the amp meter, but at least the voltage on that voltmeter seems OK.

Everything seems to be working.

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42 minutes ago, LadyG said:

I am a bit fanatical about monitoring my batteries, but this summer has been really dull, so I am not sure they have been fully charged every week.

 

 

I am sure they have not, if you think an hour of engine charging is anywhere near enough for lead acid batteries during dull spells, especially if you do it a not much more than idle.

5 minutes ago, LadyG said:

I think we are OK, as the bow batteries are the biggest consumer, and are furthest from the alternator, I think I would probably manage with replacing them. 

Im trying to get my head round the amp meter, but at least the voltage on that voltmeter seems OK.

Everything seems to be working.

 

I expect that ammeter is a very simple moving iron meter where the whole current is flowing through it. They are often supplied with undersized cable for marine domestic alternators, that does nothing to help charging. Exactly what it is telling you depends upon where and how it is connected, so can't help with what it should say and what it is telling you.

 

FWIW, as far as I am concerned your whole battery setup is mad, but I have told you that before, when you had the previous battery problems.

 

After many hours of engine charging at about 1000 to 1200 rpm the voltmeter should read between about 14.2 and 14.4V, and the ammeter should inly show a very few amps and that reading should have stopepd dropping over half an hour or so. Then the batteries will be as fully charged as they can be.

Edited by Tony Brooks
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5 minutes ago, LadyG said:

I think we are OK, as the bow batteries are the biggest consumer, and are furthest from the alternator, I think I would probably manage with replacing them. 

Im trying to get my head round the amp meter, but at least the voltage on that voltmeter seems OK.

Everything seems to be working.

 

I think your ammeter is connected to show alternator --> Bow thruster battery current (except its wired backwards, so negative values are current going in). Since this is only one "half" of what is going into and coming out of the batteries (and might be less than that - where is the solar connected) its somewhat meaningless in itself. 

 

Which battery bank is the fridge connected to? The fridge is the biggest consumer.

 

A battery in itself, isn't a "consumer" in the sense that things either charge up batteries ie convert other energy into electricity; store electricity; or "consume" electricity by changing it to something else eg lights, fans. Talking of a battery as a consumer is just confusing terminology.

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25 minutes ago, Tony Brooks said:

 

As long as the engine was revving at around 1200 rpm then 13.65 volts suggests a very high charging current, but 30 amps is not that high, so I am wondering about the alternator or the wiring.

 

"The cable seem up to the job", so what is the volt drop along those cables? That might explain the 13.65V. Get a length of any old cable, connect a multimeter set to 20V DC from the bow battery positive and wherever the other end of that cable ends up (another bank positive, a charge splitter etc. Then take a reading with the engine revving and that 30 amps or more flowing. In theory, it should read zero and you don't really want it to read any more than 0.3 volts. Repeat for the negative, same results expected.

Err, well, the 13.65, is at the rear, where the alternator is charging, its a 70 amp? Charger, so sized for the 33hp engine, I suppose. But it's been like that for 25 years, so I think it's OK

The voltage on the analogue meter is creeping up towards 14, so charging is taking place, that's probably an extra 40mins today, and I think it needs the same tomorrow.

I'm not sure what you mean 13.65 is the charging voltage, I am reading the rear analogue voltmeter, and I assume this is telling me the batteries are  at 13.65, Now after 40 mins , probably 13.85. I kinda thought that batteries should be charged to that sort of level, or more, say 14.2?

I am only reading the voltage at the rear voltmeter, there is an LED meter at the bow.

I know they are running a 12v system, but that's on the output side.?

I will need to charge longer tomorrow, till I get better data.

I had an idea that my agm batteries would be happy at a lower voltage than lead acid, , but now I'm beginning to doubt that idea.

The LED meter in the bow is now showing 12.62, ten minutes after stopping the engine.

Edited by LadyG
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Just now, LadyG said:

I'm not sure what you mean 13.65 is the charging voltage, I am reading the voltmeter, and I assume this is telling me the batteries are now at 13.65, Nnow after 40 mins , probably 13.85. I kinda thought that batteries should be charged to that sort of level.

I know they are running a 12v system, but that's on the output side.?

 

Yes, 13.65 volts, is, we hope, the charging voltage. but it is not the battery voltage when charging has been stopped. Thinking it means the batteries are charged is a very common misconception. You need both voltage and current readings to know when the batteries are fully charged, and even 14.4V ish charging voltage does not tell you they are fully charged without an ammeter reading.

 

You need rested voltages to get any idea about a batter's state of charge, say ah hour after charging is stopped or sooner if you have had a moderate load on the batteries, like a fridge motor or water pump run, but nothing running way you measure it.

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@LadyG Has me on ignore so can someone suggest she formulates a plan for her battery upgrade soon because she does not want to be having a telephone conversation similar to this thread if her batteries finally die in January.

 

The dual banks are a source of confusion, maybe the answer is to decommission the forward bank to create new locker space and install 300Ah of lithium in the stern.

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2 hours ago, ditchcrawler said:

how often you fully recharge them, that would be about 8 hours engine running to take a 500Ah bank from 12 volts to fully charged

 

Point Of Order...

 

It doesn't matter how big or how small the bank is, with a "suitable charge source" it still takes the same amount of time to "fully charge" a battery bank from a given state of discharge. In my own experience its more like 12 hours to get from 50% SoC to fully charged*.

 

* Depending on what one considers 'fully charged'. One can always squeeze just a leetle bit more in, can one not? 

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26 minutes ago, MtB said:

 

Point Of Order...

 

It doesn't matter how big or how small the bank is, with a "suitable charge source" it still takes the same amount of time to "fully charge" a battery bank from a given state of discharge. In my own experience its more like 12 hours to get from 50% SoC to fully charged*.

 

* Depending on what one considers 'fully charged'. One can always squeeze just a leetle bit more in, can one not? 

Do you let your batteries go down to 50% SoC? Generally I don't let mine go below about 83% and that only happens when travelling and (obviously) running the engine whilst the washing machine is heating up. My SoC meter isn't that reliable however, I assume that the batteries are fully charged when the ammeter gives a charging rate of 9 amps or below. Like I said I'm no battery expert but this strategy did mean that my last bank of AGM batteries lasted for 7 years.

 

I think I'm kind of with Tony on this one, having two domestic battery banks does sound a bit weird. The original front battery bank were obviously to power the now removed bow thruster and would have only had very intermittent use so would have stayed fully charged most of the time (despite the 57' charging cable). To now be running half of the boat electrics on them seems, to me, a bit unwise.:unsure:

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50 minutes ago, Wanderer Vagabond said:

Do you let your batteries go down to 50% SoC? Generally I don't let mine go below about 83% and that only happens when travelling and (obviously) running the engine whilst the washing machine is heating up. My SoC meter isn't that reliable however, I assume that the batteries are fully charged when the ammeter gives a charging rate of 9 amps or below. Like I said I'm no battery expert but this strategy did mean that my last bank of AGM batteries lasted for 7 years.

 

I think I'm kind of with Tony on this one, having two domestic battery banks does sound a bit weird. The original front battery bank were obviously to power the now removed bow thruster and would have only had very intermittent use so would have stayed fully charged most of the time (despite the 57' charging cable). To now be running half of the boat electrics on them seems, to me, a bit 

There's not much I can do about the basic wiring,  if I have to replace the bow batteries, so be it, easier than re wiring the whole boat !

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8 minutes ago, LadyG said:

There's not much I can do about the basic wiring,  if I have to replace the bow batteries, so be it, easier than re wiring the whole boat !

 

You would not have to rewire the whole boat, providing the present charging cables are large enough to feed the main current user at the front, the fridge plus a little extra. Bypass any charge splitter for the bow batteries. Change the bow batteries for a couple of bus bars and add the new batteries to the bank at the stern. All cables should already be suitably fused, but can't be sure.

 

I agree that changing the batteries to LPF is not so simple.

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43 minutes ago, Tony Brooks said:

 

You would not have to rewire the whole boat, providing the present charging cables are large enough to feed the main current user at the front, the fridge plus a little extra. Bypass any charge splitter for the bow batteries. Change the bow batteries for a couple of bus bars and add the new batteries to the bank at the stern. All cables should already be suitably fused, but can't be sure.

 

I agree that changing the batteries to LPF is not so simple.

Very unlikely I'll go down that route, the last guy I had on board  said it would take him an hour to identify what was happening at the moment, me, I just turn off each isolator  (plenty to choose from) in turn to find out what's happening. There is a diagram somewhere but I've never been asked about that.

The first so called electrician was charged with replacing all the batteries but got it wrong  I later identified yet another one still connected, by the smell , it was obviously still connected! 

Wiring from the stern direct to the fridge means running a cable down one side and halfway back the other, and return!

None of the cables are easy to access, ive painted the panels, the walls and the deckhead, several coats .

I just can't take on any project likely to fail!

Edited by LadyG
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