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Nick D

Another Battery Question

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Sorry to set eyes rolling again but here goes....

 

Having taken your advice on my previous postings I had a Victron Smart Gauge fitted a few months ago and have been on a couple of trips since and am trying to get used to the various readings and what they mean.  I know from reading others comments that I shouldn’t pay too much attention to the SoC, percentage and time remaining readings, so I have largely discounted these and concentrated instead on the voltage,  current and consumed ah readings.  We are normally moored on a marina with shore line (not liveaboard).  When we left on our trip this time, the voltage was around the 13.6v mark which I believe means that the charger was in float mode. After the engine running for approx 5 hrs each day we are around 14.4v when the engine is turned off and are consuming around 100ah until the following morning.  I think this means we are in the absorption stage.  For the first few days our voltage in the morning was around the 12.4 mark but more recently, it’s hovering nearer 12.1v on similar, if not lower consumption.  

 

My question is why might this be? I have an idea that it might be that I am not running the engine long enough to go into Float but on reading some of the other posts, some people seem to think this might not make much of a difference.  We have now been off shoreline for about ten days of a four week cruise.  We are planning to visit a marina overnight in a couple of days time and I hope to go on a shore line overnight to top up the batteries fully. Is this a good idea?  For information I have 4x110ah batteries which are one year old.

 

any thoughts would be appreciated.

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The reading we need is the charging current just before you turn off. A glib answer is you are not charging the batteries enough so they start the evening partially discharged.

 

100 Ah overnight seems very high to me at this time of year. I doubt I use    even half of that with an electric fridge.

 

keep charging until the charging current at 14.4 volts is around 8 to 10 amps. then the batteries will be all but fully charged.

 

14.4volts on its own is no indication that the batteries are fully charged. Fully charging could tame many hours more.

 

Yes, good idea, but when cruising try to fully charge the batteries as often as you can. I expect the charger on the shoreline will go into float too early so when it does turn it off and one again a few times.

Edited by Tony Brooks

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So that suggest you are getting your batteries fully charged  as long as its measuring domestic charge current.

 

Alternators do not normally have a float voltage. it stays at 14.4 for ever until you turn the engine off. It may even go higher.

 

Any dry cells, hot batteries or bulging battery ends but at a 4 amp tail current I doubt it. Any would suggest a shorting cell or three.

 

Probably not a flat battery plus large alternator problem. I await other ideas with great interest.

 

 

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8 minutes ago, Nick D said:

The current is normally about 4amps when I turn the engine off

How are you measuring the 4 amps ?

 

(Most reliable method would be with a clamp meter directly over the alternator cable)

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Sorry Tony, I don’t understand what you are saying

Just now, Alan de Enfield said:

How are you measuring the 4 amps ?

 

(Most reliable method would be with a clamp meter directly over the alternator cable)

From the Smartguage read out

5 minutes ago, Tony Brooks said:

So that suggest you are getting your batteries fully charged  as long as its measuring domestic charge current.

 

Alternators do not normally have a float voltage. it stays at 14.4 for ever until you turn the engine off. It may even go higher.

 

Any dry cells, hot batteries or bulging battery ends but at a 4 amp tail current I doubt it. Any would suggest a shorting cell or three.

 

Probably not a flat battery plus large alternator problem. I await other ideas with great interest.

 

 

Sorry Tony, I don’t understand what you are saying/implying

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Smartguages don't read amps, only volts and percentage charged and 4 volts is not a credible reading.

 

You need an ammeter to read amps and if you have one it needs to be measuring the domestic battery charging current, not the engine battery. The engaging battery will normally be fully charged within half an hour of starting.

 

I can'. make "alternators do not normally have a float voltage" much clearer.

 

100 amp hours consumption overnight seems very high to me and if you only have a Smartguage I have no idea where that figure comes form. At present it seems to me it is not to be trusted.

 

If the squeal and lack of power is related to alternator load (and I am not saying it is) then either you are woefully undercharging your batteries or something else is discharging them. That might be a shorting cell but the talk of 4 amps on a Smartguage means all bets are off. Something is not correct. Possibly your understanding. Any chance of a photo of this "Smartguage"?

 

 

 

 

 

 

Edited by Tony Brooks

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To avoid confusion I think you have a Victron BMV, the Smartgauge is supplied by Merlin and does not measure amps, or amphours it only shows Volts and gives a SoC as a percentage. In some magical way it is remarkably good at getting the percentage nearly right. The BMV gives a lot more information the important ones being Volts and Amps, the amphour value is useful, but because it has a peukert 'correction' value is not usually 100% correct, unless you have used the exact mix of large and small loads. As you correctly said the time left and Soc are not always reliable. We generally consider batteries fully charges when the volts are above 14.1 and the current is below 4 amps.

 

Tony posted whilst I was typing

 

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Ok, sorry my fault. From what you have said it’s a BMV.  So I am getting 14.4v and 4amps when I turn off the engine - that seems ok?  It’s just that they don’t seem to be lasting as long each day

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2 minutes ago, Detling said:

To avoid confusion I think you have a Victron BMV, the Smartgauge is supplied by Merlin and does not measure amps, or amphours it only shows Volts and gives a SoC as a percentage. In some magical way it is remarkably good at getting the percentage nearly right. The BMV gives a lot more information the important ones being Volts and Amps, the amphour value is useful, but because it has a peukert 'correction' value is not usually 100% correct, unless you have used the exact mix of large and small loads. As you correctly said the time left and Soc are not always reliable. We generally consider batteries fully charges when the volts are above 14.1 and the current is below 4 amps.

 

Tony posted whilst I was typing

 

Absolutely. I am now veering to "operator error" probably caused by a lack of understanding. I bet its very flat batteries in the morning.

 

That is one problem the suppliers of large alternators do not warn you about.

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They are not very flat in the morning. 12.18v this morning. Thought that was ‘safe’?

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When left unnatended is your boat kept on shore line with charger/combi switched on? If the batteries have been left near flat on a few occasions in the past they will probably be goosed before you fitted the bmv??

2 minutes ago, Nick D said:

They are not very flat in the morning. 12.18v this morning. Thought that was ‘safe’?

What is running overnight? My mains fridge is on 24/7 365 but we dont use the quantity of leccy thingies you seem to be using. I have had 12 volt fridges that used more as they used to run far more frequently and for longer periods.

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32 minutes ago, Tony Brooks said:

 

 

Any dry cells, hot batteries or bulging battery ends but at a 4 amp tail current I doubt it. Any would suggest a shorting cell or three.

 

 

That’s what I didn’t understand!

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53 minutes ago, Nick D said:

Sorry to set eyes rolling again but here goes....

 

Having taken your advice on my previous postings I had a Victron Smart Gauge fitted a few months ago and have been on a couple of trips since and am trying to get used to the various readings and what they mean.  I know from reading others comments that I shouldn’t pay too much attention to the SoC, percentage and time remaining readings, so I have largely discounted these and concentrated instead on the voltage,  current and consumed ah readings.  We are normally moored on a marina with shore line (not liveaboard).  When we left on our trip this time, the voltage was around the 13.6v mark which I believe means that the charger was in float mode. After the engine running for approx 5 hrs each day we are around 14.4v when the engine is turned off and are consuming around 100ah until the following morning.  I think this means we are in the absorption stage.  For the first few days our voltage in the morning was around the 12.4 mark but more recently, it’s hovering nearer 12.1v on similar, if not lower consumption.  

 

My question is why might this be? I have an idea that it might be that I am not running the engine long enough to go into Float but on reading some of the other posts, some people seem to think this might not make much of a difference.  We have now been off shoreline for about ten days of a four week cruise.  We are planning to visit a marina overnight in a couple of days time and I hope to go on a shore line overnight to top up the batteries fully. Is this a good idea?  For information I have 4x110ah batteries which are one year old.

 

any thoughts would be appreciated.

Ok so just to clarify then, you have a Victron BMV battery monitor, not a Smartgauge. How long do you normally run the engine per day?

 

The 14.4v and 4A does indicate well-charged batteries anyway, although ours get down to below 1A when they are properly charged over a long period.

 

Looking at the voltage to determine SoC is only any good if the load on the batteries is near zero. So it is possible that when you had 12.4v in the morning, it was with very little load, and when you had 12.1v it was with something taking a fair bit of current. So it would be helpful to quote the voltage AND the current, to give us an idea whether something is pulling the voltage down when you take the reading.

 

All that said, it does seem likely that you are losing capacity. My experience of el cheapo 110AH “leisure” batteries is that they are pants! We had 2 sets, both were down to 50% capacity after 6 months, much of that time being on shore power. Fizzing them up with a couple of hours at 15.5v did restore the capacity for a while  but after 2 years they were dead.

 

This is why I wouldn’t contemplate having el cheapo leisure batteries again, and why we have Trojan T105s. Now in their 5th year with no apparent loss of capacity.

Edited by nicknorman
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6 minutes ago, mrsmelly said:

When left unnatended is your boat kept on shore line with charger/combi switched on? If the batteries have been left near flat on a few occasions in the past they will probably be goosed before you fitted the bmv??

What is running overnight? My mains fridge is on 24/7 365 but we dont use the quantity of leccy thingies you seem to be using. I have had 12 volt fridges that used more as they used to run far more frequently and for longer periods.

Yes, we leave the charger on when away from the boat on shoreline. I don’t think they have gone flat in the last year though the marina electric did ‘short’ on our pontoon tho we sorted it in 2/3 days so probably not long enough to goose them. We have a 12v fridge and Waco ‘cooler’ also 12v. If I wake up in the night, the usage is normally reading around 2/3 amps. Maybe it’s the fridge/cooler?  I normally leave the inverter on overnight as I have experimented with it on or off and it seems to make little difference

8 minutes ago, nicknorman said:

Ok so just to clarify then, you have a Victron BMV battery monitor, not a Smartgauge. How long do you normally run the engine per day?

 

The 14.4v and 4A does indicate well-charged batteries anyway, although ours get down to below 1A when they are properly charged over a long period.

 

Looking at the voltage to determine SoC is only any good if the load on the batteries is near zero. So it is possible that when you had 12.4v in the morning, it was with very little load, and when you had 12.1v it was with something taking a fair bit of current. So it would be helpful to quote the voltage AND the current, to give us an idea whether something is pulling the voltage down when you take the reading.

 

All that said, it does seem likely that you are losing capacity. My experience of el cheapo 110AH “leisure” batteries is that they are pants! We had 2 sets, both were down to 50% capacity after 6 months, much of that time being on shore power. Fizzing them up with a couple of hours at 15.5v did restore the capacity for a while  but after 2 years they were dead.

 

This is why I wouldn’t contemplate having el cheapo leisure batteries again, and why we have Trojan T105s. Now in their 5th year with no apparent loss of capacity.

We normally run the engine for about 5hrs per day.  I suspect we might have el cheapo batteries although they weren’t actually cheap as they were fitted in an emergency and I didn’t have any choice!

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9 minutes ago, nicknorman said:

Ok so just to clarify then, you have a Victron BMV battery monitor, not a Smartgauge. How long do you normally run the engine per day?

 

The 14.4v and 4A does indicate well-charged batteries anyway, although ours get down to below 1A when they are properly charged over a long period.

 

Looking at the voltage to determine SoC is only any good if the load on the batteries is near zero. So it is possible that when you had 12.4v in the morning, it was with very little load, and when you had 12.1v it was with something taking a fair bit of current. So it would be helpful to quote the voltage AND the current, to give us an idea whether something is pulling the voltage down when you take the reading.

 

All that said, it does seem likely that you are losing capacity. My experience of el cheapo 110AH “leisure” batteries is that they are pants! We had 2 sets, both were down to 50% capacity after 6 months, much of that time being on shore power. Fizzing them up with a couple of hours at 15.5v did restore the capacity for a while  but after 2 years they were dead.

 

This is why I wouldn’t contemplate having el cheapo leisure batteries again, and why we have Trojan T105s. Now in their 5th year with no apparent loss of capacity.

Tend to agree. My batteries died this week at just over twelve months old despite being mollycoddled (living aboard full time.) I reckon they were down to about 50% capacity. Bought some leisures to tide us over, but Trojans next spring. Must be cheaper in the long run.

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1 minute ago, Nick D said:

Yes, we leave the charger on when away from the boat on shoreline. I don’t think they have gone flat in the last year though the marina electric did ‘short’ on our pontoon tho we sorted it in 2/3 days so probably not long enough to goose them. We have a 12v fridge and Waco ‘cooler’ also 12v. If I wake up in the night, the usage is normally reading around 2/3 amps. Maybe it’s the fridge/cooler?  I normally leave the inverter on overnight as I have experimented with it on or off and it seems to make little difference

My cheapos last two years if I am off mains but I charge religously every day if not cruising or otherwise cruise several hours. These cheapos are now over two years old and still perform well when off shoreline, however in the last two years we have been hooked up fifty percent of the time so its not realy relevant. Cheapos do a great job IF you follow my regime but if you dont they will not accept abuse. Others like Nick buy more expensive ones and feed them on a regular basis and give them names and read the bedtime stories and some appear to last longer. It depends really how you view batteries, to me they are prcisely as diesel and consumable, to others they are a thing of joy to be looked at and cuddled. The reason I know mine still work is the gauge says so as I dont see them from one month to the next.

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I am  suspicious of the unspecified "Waco cooler". May cool boxes work on the pelter principle and have no thermostat. A quick google sheds little light on the subject. If it is one of these then it will be very power hungry.

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My last two sets have been from Britmarine and are around a 100 squids ish I think at present. 

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3 minutes ago, Nick D said:

Waco ‘cooler’ also 12v

What is the current draw (wattage) for this 'cooler'.

Many 12v coolers are designed to be used in cars (and only when the engine is running) and they have no thermostat fitted.

If it is (say) 60 watt it could be drawing 5 amps continuously (mine did until I got rid of it).

 

What make (presumably actually Waeco) & model is it ?

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Just now, Tony Brooks said:

I am  suspicious of the unspecified "Waco cooler". May cool boxes work on the pelter principle and have no thermostat. A quick google sheds little light on the subject. If it is one of these then it will be very power hungry.

They certainly do!!

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3 minutes ago, Alan de Enfield said:

What is the current draw (wattage) for this 'cooler'.

Many 12v coolers are designed to be used in cars (and only when the engine is running) and they have no thermostat fitted.

If it is (say) 60 watt it could be drawing 5 amps continuously (mine did until I got rid of it).

 

What make (presumably actually Waeco) & model is it ?

Yes, it is ‘Waeco’ and yes, it does have a thermostat. I don’t know the draw so will have to dig out the book but if my night time usage is between 2/3 amps then presumably it would suggest that this might not be the culprit?

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so 3 amp draw all the time your batteries are not charging, say 19 hours is some 57Ah over one batters useful capacity

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11 minutes ago, mrsmelly said:

My last two sets have been from Britmarine and are around a 100 squids ish I think at present. 

That is about what I paid yesterday. Hope they do better than the last lot! What surprised me was they appeared to lose capacity quickly, unlike other sets I have had over the years. Life is too short to be peeing about with battery postmortems, so I told my wife to buy some new ones; it was our wedding anniversary so I said she could treat me.

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