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Charging of domestic batteries


rowland al

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Just now, rowland al said:

You are probably right about that. But to confuse things, I did get something I didn't order. Maybe it's better?! :)

They might even confirm how it’s to be wired up if you ask them nicely ;)

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2 hours ago, smileypete said:

 

Maybe this is why it's good idea to just pony up £100 or so and buy a Nasa BM1 or BM2, it greatly restricts choice, which can be a bad thing if there's too much of it... :unsure:

I will wait a few more days before I say 'told you so' to rowland....get a NASA. Not quite the time yet. 

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On 19/11/2017 at 22:26, Dr Bob said:

I will wait a few more days before I say 'told you so' to rowland....get a NASA. Not quite the time yet. 

Me too.

I'm beginning to conclude those arguing in the other thread that a Smartgauge is easier to install than a shunt based ammeter are right, however!!

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On 19/11/2017 at 23:51, Richard10002 said:

All of this is tending to confirm that I made the right decision to pony up the £100+ for a NASA BM2 :)

 

This would have been my preferred ammeter too (for the big display) but it doesn't work on 24v. So a BMV702 does the job but a torch and glasses are needed to see the display!

Richard, as an aside, was your Smartgauge one of those turning out to be wrongly calibrated when checked? I was compiling a list the other day and couldn't remember if yours was one known to be factory calibrated wrongly.

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25 minutes ago, Mike the Boilerman said:

 

This would have been my preferred ammeter too (for the big display) but it doesn't work on 24v. So a BMV702 does the job but a torch and glasses are needed to see the display!

Richard, as an aside, was your Smartgauge one of those turning out to be wrongly calibrated when checked? I was compiling a list the other day and couldn't remember if yours was one known to be factory calibrated wrongly.

I have no idea whether it's correctly calibrated or not, and not really sure how to test. So I'm not on the list. 

When I got my Smartgauge the buttons didn't work properly. They replaced it.

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Blast them with charge whenever possible, make it your over-arching long-term goal.

Be worryingly obsessive and fastidious, question your Methodology whenever possible.

Are you entirely convinced it's really all worth the bother though?

Batteries are deeply inefficient, stubborn bastards and that's all there is to know.

Providing you are mindful of the' financial cost and energy losses of storing energy, are parsimonious in your use and expectations, have a simple, correctly cabled and suitably sized battery bank/charging circuit, to include at least one (1), preferably two (2) independent/switchable man sized alternators and a built-in suitably rated diesel genny in case of Acts of God it's all acedemic

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On 20/11/2017 at 00:39, Richard10002 said:

I have no idea whether it's correctly calibrated or not, and not really sure how to test. So I'm not on the list. 

When I got my Smartgauge the buttons didn't work properly. They replaced it.

I bet its bloody miles out like mine, which would totally explain the total loss of your Trojans.

Do you have a digital multimeter?

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8 hours ago, Dr Bob said:

I will wait a few more days before I say 'told you so' to rowland....get a NASA. Not quite the time yet. 

I would advise getting one of those clamp meters before getting an Ebay special, would still be quids in over a NASA.

 

7 hours ago, Mike the Boilerman said:

Me too.

I'm beginning to conclude those arguing in the other thread that a Smartgauge is easier to install than a shunt based ammeter are right, however!!

Yes but it's not the shunt that's the problem here.

You could always charge to "100%" + N hours, where N is determined by a clamp meter. And an accurate voltmeter is always handy, and almost as easy to install as the SG. ;) But would N vary over time and temperature I wonder?

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1 hour ago, smileypete said:

I would advise getting one of those clamp meters before getting an Ebay special, would still be quids in over a NASA.

 

Yes but it's not the shunt that's the problem here.

You could always charge to "100%" + N hours, where N is determined by a clamp meter. And an accurate voltmeter is always handy, and almost as easy to install as the SG. ;) But would N vary over time and temperature I wonder?

How accurate are clamp meters for measuring DC current at 12v compared with using a shunt? Wouldn't they be affected by magnetic fields close by like from the alternator? 

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9 hours ago, Mike the Boilerman said:

Me too.

I'm beginning to conclude those arguing in the other thread that a Smartgauge is easier to install than a shunt based ammeter are right, however!!

That’s the point we were attempting to make. 

9 hours ago, Mike the Boilerman said:

Just a shame they can't be relied upon to work properly, out of the box.

But they can. Do you need me to link to Merlin’s post again so you can read it properly?

2 hours ago, smileypete said:

but it's not the shunt that's the problem here.

He hasn’t installed it and had a Big Bang yet ;)

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28 minutes ago, rowland al said:

How accurate are clamp meters for measuring DC current at 12v compared with using a shunt? Wouldn't they be affected by magnetic fields close by like from the alternator? 

They’re reasonable. Usually within a couple of percent, and it’s trends that you’re looking for as much as absolute figures. The huge drawback of a hand held clamp meter though is that you have to dive down into the engine ‘ole (or wherever your batteries live) every time you want to read them. An ammeter/Ah counter/SmartGauge gives a constant readout at arm’s reach. 

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  • 2 weeks later...
On 20/11/2017 at 06:30, smileypete said:

I would advise getting one of those clamp meters before getting an Ebay special, would still be quids in over a NASA.

 

Yes but it's not the shunt that's the problem here.

You could always charge to "100%" + N hours, where N is determined by a clamp meter. And an accurate voltmeter is always handy, and almost as easy to install as the SG. ;) But would N vary over time and temperature I wonder?

A bit of an update. I decided to order a clamp meter as suggested by someone here earlier. What a great idea and tool and less hassle than wiring up the cheapo digital meter with shunt. 

 

Anyway, I have confirmed with it that the analogue ammeter fitted to the boat is reasonably accurate and seems to be wired into the the alternator output. So it measures the current going to the starter battery, domestic batteries and will show the current draw of any loads connected to the domestic circuit so long as engine is running (charging). 

 

The clamp meter has also confirmed my estimate of an evenings typical power requirements. Mainly a few LED lights, 12v TV, occasional water pump action at around 15amps over the entire evening.

 

The 2 x 6v Trojans appear to be on their way out as they only take a couple of amps even when the voltage at the battery is around 12.4v. Maybe the problem here is that I don't have the luxury of being able to trickle charge them overnight! I now see the virtues of a solar panel now even though we cruise a lot. 

 

So before investing in a solar panel, I'm trying an experiment out with a reasonably good quality single calcium 75ah 12v 'starter' battery,. I haven't gone below 70% capacity in an evening yet. More to the point, it charges up to almost 100% after only a couple hours engine running. That is already saving me lots in diesel.

 

So the only question now is, how many cycles will I get out of it before that's knackered?! Place your bets folks. 

 

BTW, Tony, I tried to measure AC voltage ripple  from the alternator. Positive probe to 12v alt O/P and negative probe to case of alternator. The meter seemed to read very randomly even values like 100v!! So, not quite sure what's going on there. I did wonder whether the high magnetic fields in the alternator were messing up the readings. Definitely no high voltages on the boat!. 

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33 minutes ago, rowland al said:

A bit of an update. I decided to order a clamp meter as suggested by someone here earlier. What a great idea and tool and less hassle than wiring up the cheapo digital meter with shunt. 

 

Anyway, I have confirmed with it that the analogue ammeter fitted to the boat is reasonably accurate and seems to be wired into the the alternator output. So it measures the current going to the starter battery, domestic batteries and will show the current draw of any loads connected to the domestic circuit so long as engine is running (charging). 

 

The clamp meter has also confirmed my estimate of an evenings typical power requirements. Mainly a few LED lights, 12v TV, occasional water pump action at around 15amps over the entire evening.

 

The 2 x 6v Trojans appear to be on their way out as they only take a couple of amps even when the voltage at the battery is around 12.4v. Maybe the problem here is that I don't have the luxury of being able to trickle charge them overnight! I now see the virtues of a solar panel now even though we cruise a lot. 

 

So before investing in a solar panel, I'm trying an experiment out with a reasonably good quality single calcium 75ah 12v 'starter' battery,. I haven't gone below 70% capacity in an evening yet. More to the point, it charges up to almost 100% after only a couple hours engine running. That is already saving me lots in diesel.

 

So the only question now is, how many cycles will I get out of it before that's knackered?! Place your bets folks. 

 

BTW, Tony, I tried to measure AC voltage ripple  from the alternator. Positive probe to 12v alt O/P and negative probe to case of alternator. The meter seemed to read very randomly even values like 100v!! So, not quite sure what's going on there. I did wonder whether the high magnetic fields in the alternator were messing up the readings. Definitely no high voltages on the boat!. 

So when you are running the engine shortly after the domestics being at 12.4v, what is the voltage across the domestic battery terminals? I find it very hard to believe that you are getting a decent charging voltage if the batteries are only taking 2A. You need to sort out this conundrum before spending money on new batteries.

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32 minutes ago, cereal tiller said:

Yes indeed it was, I Trust that you were not Disconcerted by my observations ,your Preoccupation with the Sun Crossword and the befuddled Expression on your Face seemed to Indicate Otherwise?

Toodle Pip.

I used to like you,  sun crossword! I wouldn't wipe someone elses backside with that rag

The rest is a remarkably accurate rendering of me :)

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25 minutes ago, tree monkey said:

I used to like you,  sun crossword! I wouldn't wipe someone elses backside with that rag

No! No! No!  You really shouldn't have said that. :stop:

It's an image I'm now struggling to clear from my mind and I don't know which I'm unavoidably wondering most - why you would do that at all or exactly which newspaper you would be happy to do it with. :sick:

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18 minutes ago, Sea Dog said:

No! No! No!  You really shouldn't have said that. :stop:

It's an image I'm now struggling to clear from my mind and I don't know which I'm unavoidably wondering most - why you would do that at all or exactly which newspaper you would be happy to do it with. :sick:

We used to use the Yorkshire Post - on ourselves not other people. The ink came off it easily.

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3 minutes ago, croftie said:

Ofcause its important but how many times over the last couple of months has this been covered

Not enough if OP thinks he can fully charge his battery in 2 hours, quite obviously. 

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