Smart gauge - - charging update

[bottle]

Stupid statement but I imagine If I turned of 12v from the control board,when we go to bed, the smart gauge will be at the same in the morning when 12v restored,

It would be, if you turned everything off including the courtesy lights and the inverter.

 

Have a look, just before going to bed, at the gauge, note reading and see what it is in the morning, over a few days with different combinations of offs and ons you will get a feel of what is using the power overnight.

[nicknorman]

It's a bit worrying when two of the three electronic gurus on the forum don't agree.

 

I think we need SmileyPete to come along and adjudicate.

 

In fairness, I am not sure NN had noted how far from 100% Spuds' batteries had been.

Not worrying at all - quite normal! I would just ask those with an opinion of the SG whether they have one? Whether they have looked at the circuitry in detail? Whether they have another means of determining SoC with which to compare the SG's readings?

 

Going back to the point about 100% as I have said repeatedly, it judges when it has got to 100% merely when a certain amount of time has passed at a certain charging voltage. On subsequent cycles it may tweak this slightly but considering it is primarily "seeing" the nature of the charging device's voltage, and yet it can cope quite happily with several different types of charging in the same installation - alternator, charger, solar - this tweaking must be minor.

 

The issue of knowing when 100% is reached is not quite the same as knowing the discharge characteristics after that. If the SG has never seen a discharge from 100% to say 70% then there is obviously room for it to improve its accuracy with experience in this range the first time it does experience it.

 

I'm sure it does get a bit more accurate in its discharge readings once it has been cycled up to 100%, my main point is that this does not correlate to its ability to know when to display 100%. The "tweaking" will of course depend on how far away the programmed model is from reality, but with a standard bank in good condition, why would this be far?

[Timleech]

Re the 'charging to 100%', is it really worthwhile doing this every time? I'm talking from the battery life/economics point of view, rather than SG 'learning'.

There's lots of engine time/fuel/noise etc. etc., to be weighed against reduction in battery life. Is it not a common model to charge to, say, 80/85% daily and 100% weekly, for those living aboard? Just asking, not something that I have to worry about, but all contributors to this thread seem to be pushing the 100% or near every time as the One True Path.

 

Tim

[bottle]

Tim

 

That is what I and others have been advocating all the time it is a balance between life style, battery life and charging costs.

 

My advice is charge to 95% SOC every time, as that is quite easy and then every one, two, three or four weeks charge to true 100% SOC

 

At this time of year with solar, my batteries are hitting 100% SOC, nearly every day.

 

 

Note for Nick.

 

Yes I know, insert that long word, the 100% SOC is not truly obtainable.

[Ex- Member]

Tim

 

That is what I and others have been advocating all the time it is a balance between life style, battery life and charging costs.

 

My advice is charge to 95% SOC every time, as that is quite easy and then every one, two, three or four weeks charge to true 100% SOC

 

At this time of year with solar, my batteries are hitting 100% SOC, nearly every day.

 

 

Note for Nick.

 

Yes I know, insert that long word, the 100% SOC is not truly obtainable.

 

My advice is charge to 95% SOC every time, as that is quite easy and then every one, two, three or four weeks charge to true 100% SOC

At this time of year with solar, my batteries are hitting 100% SOC, nearly every day.

 

 

We're finding this too, our Outback controller even states "CHARGED" following Floating for periods of time. This can occur in the morning too so on a sunny day the battery is staying fully charged or there about's for quite a few hours.

 

As Tim suggests though, if this wasn't happening as a matter of course I wouldn't be forcing a 100% charge per day, to achieve this through generation would be very costly in diesel, unless you cruise a lot daily anyway.

 

Through the winter though we tried to get at least a 100% charge in per week.

[bottle]

 

 

We're finding this too, our Outback controller even states "CHARGED" following Floating for periods of time. This can occur in the morning too so on a sunny day the battery is staying fully charged or there about's for quite a few hours.

 

As Tim suggests though, if this wasn't happening as a matter of course I wouldn't be forcing a 100% charge per day, to achieve this through generation would be very costly in diesel, unless you cruise a lot daily anyway.

 

Through the winter though we tried to get at least a 100% charge in per week.

 

Agreed

[BargeeSpud]

I believe it was Gibbo himself that stated that SG would not give accurate results on a bank that had lost more than 50% of its capacity. How 'not accurate' that might be, I have no idea.

Nothing whatsoever.

 

I posted asking if you had synchronised SG as per the instructions. The instructions offer two methods - manually, or wait for two discharge/recharge cycles.

 

You replied: "The instructions do not say anything like that, you can simply leave the unit to get on with it & it will synchronise itself.". I pointed out in post 64 that it won't, unless you discharge and recharge the bank a couple of times. You have repeatedly told us that you have not recharged to anywhere close to 100%.

 

Tony

Absolutely so.

 

OK, so what am I supposed to believe? My reliable battery charger that goes into float mode when the batteries are fully charged, or a gauge that I've never had any experience with?

 

Which one would you rely on if you were in the same situation I was?

 

I'm not going to get into any stupid arguments over this, I believe that I followed the set up to the letter & you're telling me that I haven't. Not a lot I can do about that is there? Apart from resetting & starting all over again with the first 3 - 4 charges via the charger & using the Eberspacher for hot water whilst I do it.

[bottle]

So batteries are fully charged, because the charger says so.

 

So, set the Smartgauge to 100% SOC as it says in the instructions, because you know they are fully charged.

 

Then come back in a few days and let us know your findings.

[nicknorman]

OK, so what am I supposed to believe? My reliable battery charger that goes into float mode when the batteries are fully charged, or a gauge that I've never had any experience with?

 

Which one would you rely on if you were in the same situation I was?

 

I'm not going to get into any stupid arguments over this, I believe that I followed the set up to the letter & you're telling me that I haven't. Not a lot I can do about that is there? Apart from resetting & starting all over again with the first 3 - 4 charges via the charger & using the Eberspacher for hot water whilst I do it.

There is a major presumption that when the charger goes into float mode, the batteries are fully charged. Some chargers are well known for going into float prematurely. I don't think you mentioned the charger make/model?

 

Next time this happens, stick a clamp meter on the charger lead, cycle the power on the charger ( which will hopefully go back into absorption briefly) and tell us what the charge current is, also the battery terminal voltage whilst still in absorption.

 

My guess is that the SG is right and the charger is going to Float prematurely.

[Timleech]

Veering slightly off topic, I don't suppose it's an original thought but don't remember seeing it mentioned before -

 

Suppose you have an Ah counting battery monitor and a Smartgauge.

If you set the monitor to your theoretical battery capacity (or indeed any known capacity), and compare indicated percentage on discharge with that on the Smartgauge, you ought to get a useful indication of real battery capacity?

 

Edit - maybe Son of Smartgauge does this automatically? I have no idea. Is it on the market yet? Could ordinary mortals afford it if it were?

 

Tim

Edited April 27, 2014 by Timleech

[nicknorman]

Veering slightly off topic, I don't suppose it's an original thought but don't remember seeing it mentioned before -

 

Suppose you have an Ah counting battery monitor and a Smartgauge.

If you set the monitor to your theoretical battery capacity (or indeed any known capacity), and compare indicated percentage on discharge with that on the Smartgauge, you ought to get a useful indication of real battery capacity?

 

Edit - maybe Son of Smartgauge does this automatically? I have no idea. Is it on the market yet? Could ordinary mortals afford it if it were?

 

Tim

Yes definitely to your first supposition, this is what I do. To your second supposition I can only presume so.

[WotEver]

 

OK, so what am I supposed to believe? My reliable battery charger that goes into float mode when the batteries are fully charged, or a gauge that I've never had any experience with?

The gauge. Because that's telling you the truth.

 

Tony

My guess is that the SG is right and the charger is going to Float prematurely.

Agreed 100%.

 

I wouldn't say it would struggle if the SoC never reaches 100%. Yes it will be less accurate, but to a degree dependant on how far removed the profile of the bank is from the "standard profile" programmed into the SG.

Nick - you are absolutely correct. I was completely wrong to suggest that the bank had to hit 100% for SG to get a handle on the bank's SoC.

 

I've just spoken to Gibbo about it and to quote the most relevant sentence from his email: "For synchronising, there are several ways it can happen. The most common occurrence is: the actual state of charge has to cross the indicated state of charge. i.e. if the indicated SoC is at (say) 65%, the actual SoC has to pass through 65% (either discharging or charging). It will then sync up instantly."

 

The fact that Spud has never charged beyond 81% has no relevance to SG's accuracy but is of course killing his batteries. The quote that SG gave 'loads of meaningless readouts' I suspect simply means that he's killed his batteries and doesn't like SG telling him so.

 

Tony

[smileypete]

Going back a bit to the OPs situation, for living on a boat off grid a reasonable plan could be:

 

1. Pick up a few bits about batts and charging

2. Buy a Smartguage (optional - really! ) or a decent panel voltmeter.

3. Buy a DC clamp ammeter or a shunt panel ammeter

4. Install a decent amount of solar

5. Buy a genny if winter power needs demand

6. Maybe replace leisure batts when kaput with decent semi tractions

 

A few bits about batts and charging:

 

They DO like a lengthy FULL charge from time to time

They DO like a correct absorption charge voltage

They DON'T like discharge below 50%, but tractions are OK to 20%

The 'resting voltage' when idle can be a reasonable approximation to state of charge (SoC)

The 'tail current' when charging is a good approximation to full SoC

 

cheers, Pete.

~smpt~

Edited April 27, 2014 by smileypete

[nicknorman]

 

I've just spoken to Gibbo about it and to quote the most relevant sentence from his email: "For synchronising, there are several ways it can happen. The most common occurrence is: the actual state of charge has to cross the indicated state of charge. i.e. if the indicated SoC is at (say) 65%, the actual SoC has to pass through 65% (either discharging or charging). It will then sync up instantly."

 

 

Phew, got away with that one then! I am always a bit nervous that Gibbo is going to make a reappearance to beast me for trying to reverse engineer his baby and getting it wrong! Did you get the impression that he still followed these sorts of threads anonymously, or that he had completely lost interest in CWDF?

[George94]

 

Phew, got away with that one then! I am always a bit nervous that Gibbo is going to make a reappearance to beast me for trying to reverse engineer his baby and getting it wrong! Did you get the impression that he still followed these sorts of threads anonymously, or that he had completely lost interest in CWDF?

 

 

Well, it's good to have that sorted, even if I have no idea how the SG knows what the real state of charge is when it crosses it.

 

From now on, NN, you are the undisputed SG guru (in the absence of the inventor).

Edited April 27, 2014 by George94

[nicknorman]

 

... even if I have no idea how the SG knows what the real state of charge is when it crosses it.

 

 

We can only guess of course, but I think it is along the lines of finding a solution to a set of simultaneous differential equations. Bear in mind the SG measures voltage to a very high resolution (but only a mediocre accuracy). An easy one would be where the voltage remains completely constant for a while. That means the battery is not being discharged significantly, and so the voltage could be put into a table of rested voltages against SoC to come up with the current SoC. If the voltage is decreasing (I am only considering the discharge case, not the charging case here), that means there is a load on the battery. The rate of decrease can be used to determine the magnitude of the load as a proportion of the battery size (the SG deals totally in relatives, not absolutes). Knowing the relative load will allow the algorithm to compensate the current voltage reading for the discharge rate based on a battery model, so again come up with the SoC. If the rate of decrease changes, this is because additional loads have been switched on (or off), but when the rate of change of change (second derivative) is zero again that means the load is constant and so the SoC can be determined. If the rate of change of voltage becomes zero for a while (meaning all, or nearly all, loads are off) then once again the SG can determine the SoC from the voltage. It can then look back at its estimates based on the calculated load (rate of change of voltage) and see how accurate they were. If they were not accurate, it can tweak its co-efficients so as to improve the accuracy next time. This process seems described by Gibbo (in the manual?) where he says that the SG is looking for opportunities to verify itself (my paraphrasing since I can't be bothered to look it up.

 

Anyway, when you put all the above waffle into a computer algorithm as I said I think you would end up with some simultaneous differential equations, the co-efficients of which start out as a standard battery model but are then refined as the SG learns the particular battery's behaviour in more detail.

 

If I am making it sound easy I don't mean to. There must have been a huge amount of work to get it all working throughout the range of possible battery life experiences (charging at any rate, surface charge effect, discharging at any rate from virtually nothing to massive). Although the principle of measuring voltage is easy, the implementation of the algorithms must surely be very complicated and super respect to its inventor for doing it so well.

 

Or maybe that is all BS!

Edited April 27, 2014 by nicknorman

[George94]

 

We can only guess of course, but I think it is along the lines of finding a solution to a set of simultaneous differential equations. Bear in mind the SG measures voltage to a very high resolution (but only a mediocre accuracy). An easy one would be where the voltage remains completely constant for a while. That means the battery is not being discharged significantly, and so the voltage could be put into a table of rested voltages against SoC to come up with the current SoC. If the voltage is decreasing (I am only considering the discharge case, not the charging case here), that means there is a load on the battery. The rate of decrease can be used to determine the magnitude of the load as a proportion of the battery size (the SG deals totally in relatives, not absolutes). Knowing the relative load will allow the algorithm to compensate the current voltage reading for the discharge rate based on a battery model, so again come up with the SoC. If the rate of decrease changes, this is because additional loads have been switched on (or off), but when the rate of change of change (second derivative) is zero again that means the load is constant and so the SoC can be determined. If the rate of change of voltage becomes zero for a while (meaning all, or nearly all, loads are off) then once again the SG can determine the SoC from the voltage. It can then look back at its estimates based on the calculated load (rate of change of voltage) and see how accurate they were. If they were not accurate, it can tweak its co-efficients so as to improve the accuracy next time. This process seems described by Gibbo (in the manual?) where he says that the SG is looking for opportunities to verify itself (my paraphrasing since I can't be bothered to look it up.

 

Anyway, when you put all the above waffle into a computer algorithm as I said I think you would end up with some simultaneous differential equations, the co-efficients of which start out as a standard battery model but are then refined as the SG learns the particular battery's behaviour in more detail.

 

If I am making it sound easy I don't mean to. There must have been a huge amount of work to get it all working throughout the range of possible battery life experiences (charging at any rate, surface charge effect, discharging at any rate from virtually nothing to massive). Although the principle of measuring voltage is easy, the implementation of the algorithms must surely be very complicated and super respect to its inventor for doing it so well.

 

Or maybe that is all BS!

 

Rest assured, you're not making it sound easy to this boater who did A level maths almost half a century ago!

 

Respect indeed!

 

Thanks for the explanation.

[BargeeSpud]

So batteries are fully charged, because the charger says so.

 

So, set the Smartgauge to 100% SOC as it says in the instructions, because you know they are fully charged.

 

Then come back in a few days and let us know your findings.

 

OK, I'll do that. What I'll do is run the charger for at least 6 hours & if it gets to 100% on the SG, then I'll see how quickly I discharge & then repeat the process with the charger & take it from there.

 

Can't say when I'll get back with the results, I am quite busy for the next few days.

 

There is a major presumption that when the charger goes into float mode, the batteries are fully charged. Some chargers are well known for going into float prematurely. I don't think you mentioned the charger make/model?

 

Next time this happens, stick a clamp meter on the charger lead, cycle the power on the charger ( which will hopefully go back into absorption briefly) and tell us what the charge current is, also the battery terminal voltage whilst still in absorption.

 

My guess is that the SG is right and the charger is going to Float prematurely.

 

It's a Sterling Pro Digital which I've had for about 10 years I think, so maybe it's past it's best even though I've rarely used it since fitting solar some 5 years ago. I've only started using it regularly since I started living aboard last November. Can't say I fully grasp what you suggest in para 2, but I'm sure I'll work it out!

 

 

Look fellas, I'm not trying to be difficult or rubbish SG, far from it, I've invested too much time & money to simply write it off as a bad buy. I need to be able to work it out & get my charging regime sorted so that I can trust what it tells me, my real regret is that I disposed of my Adverc DCM. If I'd kept that & ran them both in tandem, maybe I wouldn't be having so much trouble getting to grips with the SG.

[WotEver]

 

Did you get the impression that he still followed these sorts of threads anonymously, or that he had completely lost interest in CWDF?

Gibbo no longer has any interest whatsoever in CWDF. If he'd been here when this thread started it would probably ended in a slanging match and he simply can't be bothered any longer. I don't post here myself much these days for similar reasons. Chris W also left a few years back, again for the same reasons.

 

Tony

[nicknorman]

Gibbo no longer has any interest whatsoever in CWDF. If he'd been here when this thread started it would probably ended in a slanging match and he simply can't be bothered any longer. I don't post here myself much these days for similar reasons. Chris W also left a few years back, again for the same reasons.

 

Tony

Its a shame, he had a lot to give. Actually I think debate on technical subjects is far more polite these days. Just don't mention CCers and you are fine!

[WotEver]

 

I need to be able to work it out & get my charging regime sorted so that I can trust what it tells me

You can trust what it's telling you. If you sort out your charging regime to at least get into the low 90% SoC region daily then the readings will make more sense to you (and your batteries will last a lot longer)

 

Tony

[johnmck]

 

All my working life I dealt with people under stress. Now retired, my chill out is my boat and the people who share this interest. I am not after an arguament, life is too short. Sometimes, I think many who view this site are put off from posting in fear of being shot down in flames, which I think a shame.

 

But, when I read a post, "Hang on, where are you? I will pop down and help" my faith is restored and that really is the spirit of CWDF.

[Phil Ambrose]

All my working life I dealt with people under stress. Now retired, my chill out is my boat and the people who share this interest. I am not after an arguament, life is too short. Sometimes, I think many who view this site are put off from posting in fear of being shot down in flames, which I think a shame.

 

But, when I read a post, "Hang on, where are you? I will pop down and help" my faith is restored and that really is the spirit of CWDF.

Somebody please give John a greenie from me as I'm on my BB and can't do them on it.

Phil

[bigcol]

After my status charging reaching 100% yesterday

Going to bed and then reading 92% before

Turning off inverter

Turning of fridge

Only thing on is courtesy led lights though 24v

 

Woke up status reading 62%

Webasto came on from 5am till 9am

We had 2 showere before we went to early doctors appointment 7.30 till 8.30 , came back it's 56%,

Radio on 19.5 v through own little inverter.

Where does the charge go?

 

Engine on again for charging

 

Will defo look at solar panels next, mate had a panel and controller fitted Saturday, and his raving about it

 

Col

[nicknorman]

After my status charging reaching 100% yesterday

Going to bed and then reading 92% before

Turning off inverter

Turning of fridge

Only thing on is courtesy led lights though 24v

Woke up status reading 62%

Webasto came on from 5am till 9am

We had 2 showere before we went to early doctors appointment 7.30 till 8.30 , came back it's 56%,

Radio on 19.5 v through own little inverter.

Where does the charge go?

Engine on again for charging

Will defo look at solar panels next, mate had a panel and controller fitted Saturday, and his raving about it

Col

Is that a typo or what you meant to put - 92% when you went to bed and 62% when you woke up?