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Battery help please


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2 hours ago, Dr Bob said:

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.

And I applaud you for that. I think the rules using volts and amps are  simple but you get curved balls thrown in. If I had solar I wouldn't be up before it was charging so if I didn't know better my batteries could easily be below (the magic) 50% but the voltage would be elevated by the solar, like wise if I read the volts while the boss is making the coffee the voltage is depressed. Now you and me can both allow for this because we realise whats happening. If we could just say charge at 12.2 volts and when the voltage is 14.4 and the current down to 3 amps they are charged life would be reliability simple, well it would be if boat fitters fitted suitable instrumentation, 

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2 minutes ago, ditchcrawler said:

And I applaud you for that. I think the rules using volts and amps are  simple but you get curved balls thrown in. If I had solar I wouldn't be up before it was charging so if I didn't know better my batteries could easily be below (the magic) 50% but the voltage would be elevated by the solar, like wise if I read the volts while the boss is making the coffee the voltage is depressed. Now you and me can both allow for this because we realise whats happening. If we could just say charge at 12.2 volts and when the voltage is 14.4 and the current down to 3 amps they are charged life would be reliability simple, well it would be if boat fitters fitted suitable instrumentation, 

You are right about solar in the summer ......there is no way I am up before it kicks in even on a cloudy day. In the winter I look at the volts first thing for my at rest  or 'nearly at rest' - as long as its only a couple of amps going out, but in the summer, I look at it before going to bed as that is a few hours after last charge and given the evening demand - chargers/tv/sky/rasp pie/electric blanket for duck etc will be free of surface charge. A glance each day tells you +/- 5 % SoC where you are when cross checked with Ahr out. I also check tail current at the end of a day boating and Ahrs in/out, or if no boating what the solar has put back in. First thing in the morning I check the Ahrs out. For me, the thing I dont hear other people saying is to try to identify differences day to day. Now its summer, I rarely see less than 12.55V even if stuff is running last thing at night (as it is fully charged by 7pm). If one night I saw 12.2V, I would immediately know a curved ball has appeared and I would be on to it. In the winter the 'nearly at rest voltage' rarely falls more than 12.50V. Get into a routine and then you can react to big swings but keep an eye on long term drift. Winter and summer are different.

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57 minutes ago, Dr Bob said:

the thing I dont hear other people saying is to try to identify differences day to day.

I mentioned noticing ‘trends’ by which I meant the above. 

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1 hour ago, Dr Bob said:

You are right about solar in the summer ......there is no way I am up before it kicks in even on a cloudy day. In the winter I look at the volts first thing for my at rest  or 'nearly at rest' - as long as its only a couple of amps going out, but in the summer, I look at it before going to bed as that is a few hours after last charge and given the evening demand - chargers/tv/sky/rasp pie/electric blanket for duck etc will be free of surface charge. A glance each day tells you +/- 5 % SoC where you are when cross checked with Ahr out. I also check tail current at the end of a day boating and Ahrs in/out, or if no boating what the solar has put back in. First thing in the morning I check the Ahrs out. For me, the thing I dont hear other people saying is to try to identify differences day to day. Now its summer, I rarely see less than 12.55V even if stuff is running last thing at night (as it is fully charged by 7pm). If one night I saw 12.2V, I would immediately know a curved ball has appeared and I would be on to it. In the winter the 'nearly at rest voltage' rarely falls more than 12.50V. Get into a routine and then you can react to big swings but keep an eye on long term drift. Winter and summer are different.

And it is what I was also trying to get at when I said "it takes a degree of understanding of what is going, inferences to be drawn and what is to be expected. "

 

That is where the problems creep in, for whatever reasons there are any number of peopel out there who do nots eem capable of grasping the basic concepts and neither can they draw inferences from what they are looking at.

 

I think the vast majority of us with any knowledge of the subject agree with the "use volts for recharge time and amps for stop charging time and recharge as soon as possible" but its the problems with getting an accurate rested voltage figure where the problems starts so the Smartguage with all it foibles is probably as good as it gets for identifying when its time to stop discharging and start charging.

 

I must observe that I have few problems getting a proper rested voltage reading these days because of the need to have a pee in the wee small hours (I was going to write relieve myself but knowing some on the the forum thought better of it!)

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1 hour ago, Tony Brooks said:

 

 

I must observe that I have few problems getting a proper rested voltage reading these days because of the need to have a pee in the wee small hours (I was going to write relieve myself but knowing some on the the forum thought better of it!)

I don't put my glasses on

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1 hour ago, Tony Brooks said:

... its the problems with getting an accurate rested voltage figure where the problems starts so the Smartguage with all it foibles is probably as good as it gets for identifying when its time to stop discharging and start charging.

Just so :)

 

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8 hours ago, WotEver said:

No it doesn’t!  Where on earth did you invent that from?

 

Absolute rubbish. 

You are correct... it doesn't!! But I havent invented it, and it isnt rubbish!!

 

What it says in the manual is something along the lines of it being inaccurate by up to about 10% when charging, and cannot be relied upon to tell you when the batteries are fully charged - it's probably the bit on page 28 that I think MtB has referred to in one of his posts above.

 

What I said about 80% was something that somebody here said that Gibbo had said to them:

 

Gibbo is reported to have said that the Smartgauge is not accurate when discharging if it reads 80% or above.... he is also reported to have said, "but so what?? Why does anyone need to know what their SOC is, if it's above 80%" so it's a bit of hearsay - but I know I read it, I didn't doubt that it was the truth when I read it and nobody disabused the poster of his assertion at the time. I could probably find the post but, given that the search facility isn't great, it would take hours and hours, and life is a bit too short. ... I dont know the guy but, from what I have read of him, I can almost imagine him saying it, and I actually tend to agree with him.

 

Whatever the details, I think it is a fact that relying on a Smartgauge to tell you when your batteries are full is a recipe for quick sulphation of batteries.

 

I dont want to argue with you... I actually see you as someone here whose expertise on this kind of thing is well respected, and well worth listening to....  but nor do I want ANYBODY, with little/no knowledge of battery management, to think for one moment that a Smartgauge is useful as a battery gauge for anything other than a guide as to SOC when discharging, and a guide as to when it would be good to think about starting to charge their batteries.

 

It should not be relied upon, on its own, to give any kind of accurate indication that the batteries are full.

 

Your sentences: "If you do understand all of the interactions of voltage vs load then you don’t need a SmartGauge. It’s designed specifically for someone who doesn’t understand the nitty gritty and just wants a simple to understand gauge which will show with a fair degree of accuracy how full their batteries are (or aren’t!) ", could be taken, in isolation, and out of context, by "someone who doesn’t understand the nitty gritty", to mean exactly what it says and, as one of the posters here whose expertise on this kind of thing is well respected, you can imagine them doing so.

 

6 hours ago, Mike the Boilerman said:

 

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...

The manual states that an SG is not accurate when charging thus, by default, it will not be accurate when a solar panel is charging the batteries.

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6 hours 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.

This I agree with.... You need something, in addition to a Smartgauge, to tell when your batteries are full.

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7 minutes ago, Richard10002 said:

nor do I want ANYBODY, with little/no knowledge of battery management, to think for one moment that a Smartgauge is useful as a battery gauge for anything other than a guide as to SOC when discharging, and a guide as to when it would be good to think about starting to charge their batteries.

Absolutely. That’s what it’s for. 

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9 minutes ago, Richard10002 said:

Your sentences: <snip> could be taken, in isolation, and out of context...

So don’t do that. They were written in the context in which they were written; on the subject of SoC when the batteries are not on charge. Take almost any sentence out of context and its intention can be misconstrued. 

 

Nobody except you and Mike has referred to using a SmartGauge to determine when the batteries are charged, so I really don’t know why you’re banging on about the fact that it shouldn’t be done. Even the manual says it shouldn’t be done. 

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It’s very simple really. 

 

If you have some some knowledge of batteries and their foibles or have the desire to learn such then all you need is a voltmeter and an ammeter. 

 

If you don’t have such knowledge and don’t wish to acquire it then all you need is an ammeter and a SmartGauge. 

 

If you you want to know lots more about where and when your electrons are going walkies then replace the ammeter with a battery monitor such as a BMV. 

 

Or don’t. It matters not to me personally, it’s simply my advice and I couldn’t really care less if anyone wishes to ignore it. 

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17 minutes ago, WotEver said:

Nobody except you and Mike has referred to using a SmartGauge to determine when the batteries are charged, so I really don’t know why you’re banging on about the fact that it shouldn’t be done. Even the manual says it shouldn’t be done. 

We bang on about it because it is what we did... we screwed up four hundred quids worth of batteries, and we wont be the only ones.... but we are two who are prepared to be vocal about it in order to help others to avoid the same problems.

 

The manual is a lot of pages of quite small print. The bit of the manual that says "it shouldnt be done" is around page 28, and is one paragraph, or so, on that page, so easily missed by many... particularly those who dont understand the nitty gritty.

 

Some people continue to say things which lead others, who are perhaps new to this type of thing, to perceive Smartgauge as a simple fuel gauge for batteries - That's what I did, and I think it's what MtB did.

 

People need to know that it isn't, and that it is limited in its usefulness.

 

 

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10 hours ago, Mike the Boilerman said:

If and when the Smartgauge production stops, and I can't see that being too long now, the second hand value of them will rocket as they will acquire cult status.

It will be the only bit of my boat that does :offtopic:

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