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Battery help please


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24 minutes ago, Dr Bob said:

Of course the voltage is not meaningless if you do not have absolutely everything turned off.

But ONLY IF YOU UNDERSTAND WHAT YOU’RE LOOKING AT!

25 minutes ago, Dr Bob said:

The smartgauge works it out!

Exactly!  It knows what it’s looking at. 

1 hour ago, Mike the Boilerman said:

 

I have two wrongly calibrated, Rusty has one, and there are a couple of others on here too. 

 

How many more do you want?!

Another one, obviously ;)

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8 minutes ago, Dr Bob said:

Absolutely. Excactly what I mean about serious boaters understanding how to look after their batteries. Follow your simplest rules.

You can do this with a basic knowledge of a BMV. They cannot follow your simple rules with only a smartgauge.

 

How about my hobby boats? Or anyone's hobby boats for that matter.

 

Mine get used, then moored up on the home mooring and a dozen or two AH drawn before I shut the doors and push off home. So they sit there for a week or two at a time with the batteries OFF and the solar panel (hopefully!) bringing them fully back up to 100%. I think this counts as 'looking after them'.

 

But will an SG accurately report the SoC with a solar panel attached do you think? Or will it confuse the heck out of the SG?

 

Just musing really...

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14 minutes ago, Dr Bob said:

They cannot follow your simple rules with only a smartgauge.

But the OP already has a BMV!

 

Nowhere did I suggest that she could do it with ‘only a SmartGauge’. I suggested that it would be a good companion for what she already had. 

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1 minute ago, Mike the Boilerman said:

 

But will an SG accurately report the SoC with a solar panel attached do you think? Or will it confuse the heck out of the SG?

 

Just musing really...

Nah, just stirring! .....but that is important if making a good curry.?

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1 minute ago, Dr Bob said:

Agreed. ? Hooray!

My argument is that anyone capable of cooking a good rump steak should be capable of that understanding.

 

 

What about vegetarians who never cook steaks? Do you think one of them could manage to understand a BMV??

:giggles:

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1 minute ago, Dr Bob said:

My argument is that anyone capable of cooking a good rump steak should be capable of that understanding.

I cook Rib Eye steaks regularly. Probably at least once a week on average. I get it spot on about 75% of the time. So what does that prove?

Just now, ditchcrawler said:

But that comes back to Tony's point, they aren't. 

Exactly :)

 

Just now, Mike the Boilerman said:

 

What about vegetarians who never cook steaks? Do you think one of them could manage to understand a BMV??

:giggles:

No. Vegetarians are odd. 

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5 minutes ago, Dr Bob said:

Agreed. ? Hooray!

My argument is that anyone capable of cooking a good rump steak should be capable of that understanding.

 

I ran a busy restaurant in an earlier life ?

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2 minutes ago, WotEver said:

I cook Rib Eye steaks regularly. Probably at least once a week on average. I get it spot on about 75% of the time. So what does that prove?

 

I'd get a BBQ and blame it on that!

Maybe you need to get an infrequent red thermometer?

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1 minute ago, Mike the Boilerman said:

 

On reflection there were actually six counted wrong on here, five users, six gauges. So there's your extra one you wanted!!

That’s not an extra one since Merlin posted on here though :P

 

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1 minute ago, Jeanie920 said:

I ran a busy restaurant in an earlier life ?

There you go Jeanie, you are all set.

7 minutes ago, Mike the Boilerman said:

 

What about vegetarians who never cook steaks? Do you think one of them could manage to understand a BMV??

:giggles:

Anyone who is good at stirring ......curries (that end up tasting nice) should be good to go as well.

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3 minutes ago, Dr Bob said:

But that is where we will have to disagree. It is quite simple if it is explained.

It is to you because your mind works that way, not everybody else's does. I had a brother in law, a genius in many ways. mathematician, could listen to a piece of music and then sit and write the score down. He found it impossible to comprehend anything that I would look upon as simple like change a 13 amp fuse in a plug top. his mind just didn't work that way, Undo a screw, no chance.

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9 minutes ago, Dr Bob said:

Nah, just stirring! .....but that is important if making a good curry.?

 

No, its a question I've asked on here periodically for about the last four years. Usually I'm assured the SG copes perfectly well with solar attached.

 

In the light of Page 28 however, I can't see how this can be. Page 28 states the SoC displayed is wrong when charging (or words to that effect), innit.  

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1 minute ago, Mike the Boilerman said:

Page 28 states the SoC displayed is wrong when charging (or words to that effect), innit

IIRC it can be up to 10% out when charging, but seeing as the batts are being charged and not discharged, so what? You're going to be using tail current to determine 100% SoC so the only time the Smartgauge reading matters is when you're discharging.

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Just now, ditchcrawler said:

It is to you because your mind works that way, not everybody else's does. I had a brother in law, a genius in many ways. mathematician, could listen to a piece of music and then sit and write the score down. He found it impossible to comprehend anything that I would look upon as simple like change a 13 amp fuse in a plug top. his mind just didn't work that way, Undo a screw, no chance.

I think you are underestimating the capabilities of a large number of peeps. A lot of peeps dont understand it because it has not been simple to know what to understand. There has been so much 'black magic' around battery management and lots of really confusing info. In the last few years, Tony, Nick, TonyB and others have debated battery maintenance to death BUT come out with simple rules. Once written down and agreed as the way to do it, it is available to learn and be picked up by the masses.

Maybe my brain does cope well with numbers......and I am crap at cooking steaks..... or stirring curries......... but we should continue to educate people for them to learn about voltage, Amps and Ahrs.

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1 minute ago, WotEver said:

IIRC it can be up to 10% out when charging, but seeing as the batts are being charged and not discharged, so what? You're going to be using tail current to determine 100% SoC so the only time the Smartgauge reading matters is when you're discharging.

 

No I'm not. I walk away from the boat whatever the state of the batteries and go home, and leave the solar to fill them up. I determine 100% SoC by knowing they have been on charge for two weeks ;) 

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A further scenario is my liveaboard. 560W of solar, Smartgauge, BMV 702 and a 12v fridge running 24/7.

 

The batteries (according to the SG) are always at 100% throughout the day. No tail current ever involved. Usually still 85% early in the morning, although it is light so solar is already doing its stuff. 

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8 minutes ago, Mike the Boilerman said:

 

No, its a question I've asked on here periodically for about the last four years. Usually I'm assured the SG copes perfectly well with solar attached.

 

In the light of Page 28 however, I can't see how this can be. Page 28 states the SoC displayed is wrong when charging (or words to that effect), innit.  

Tony's answer that it could be up to 10% out when charging is the sensible answer.

If you want a technical assessment - read on. If others dont want a technical input then skip this post.

The SoC number is obtained by the smartgauge using a model. As I have said a number of times, this is highly likely to be a multi linear regression model. All these models work by using a 'training set' to determine the relationship of voltage, voltage change with time and change of that change with time. With linear regression, to get accurate results, the 'real world' usage has to be within the range of the training set. The relationship is unlikely to be linear so multi linear is used but again the real world needs to be within the training set. To create a model (and especially a Universal model - ie it works for all LA batteries), you need a lot of data to create that training set which by the sound of it - Gibbo did - ie thousands of batteries, some driven down to death. Now the crunch. To predict performance with solar, the model would need to have results in the training set with solar charging the batteries. Given the differences in solar, viz panel size, cloud cover, type of controller, .....there would have to be lots of results used by Gibbo to add to that training set. Without lots of data, then the model would not be as accurate when solar is coming in. It is all however superfluous as Tony says there is up to 10% inaccuracy on charging over 90% which is when the solar is at its best, so not really worth discussing. Did Gibbo do lots of tests with solar. If he did then it probably works well. If he didnt then it wont but as Tony says it doesnt matter.

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38 minutes ago, ditchcrawler said:

It is to you because your mind works that way, not everybody else's does. I had a brother in law, a genius in many ways. mathematician, could listen to a piece of music and then sit and write the score down. He found it impossible to comprehend anything that I would look upon as simple like change a 13 amp fuse in a plug top. his mind just didn't work that way, Undo a screw, no chance.

That is pretty much what I was trying put across.

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To get back to the op given your cruising pattern id spend as little as possible on 800 amp hrs of lead acid batteries and try and look after them when i wasnt on mains.like you have tried to .  800 amp hour would be about 600 quid .

thats a lot less than 3000 which you have been quoted for esoteric batteries that you will have sitting getting older 330 days or so a year..

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