SmartGuage

[blackrose]

Thanks, what I meant is that I can read a voltmeter & ammeter, but unlike some who have posted on this thread, I'm not sure what the readings mean.

 

I am not an Electricl engineer, but I have got sufficient wherewithall, to be able to read a Voltmeter and Ammeter, and know what is going on.

 

As far as I can make out the "fuel guage" (amp hours remaining) readings on even the most expensive monitors are estimates and should be taken as a general guide only, so I'm not sure if it's really worth paying for this function. Can this be estimated with a voltmeter & ammeter only?

[GUMPY]

Thanks, what I meant is that I can read a voltmeter & ammeter, but unlike some who have posted on this thread, I'm not sure what the readings mean.

As far as I can make out the "fuel guage" (amp hours remaining) readings on even the most expensive monitors are estimates and should be taken as a general guide only, so I'm not sure if it's really worth paying for this function. Can this be estimated with a voltmeter & ammeter only?

 

OK some free information

 

Despite what other may say on this forum:

 

A volt meter will give you an indication of the state of charge of your batteries provided that they are at rest ( not charging or discharging) and have been for a while, this is temperature dependant and the figures are as follows the temps are at 70deg farenheit you will need to add 0.09v for every 10deg F that the temperature is lower and subtract if its higher.

 

100% 12.74

75% 12.54

50% 12.33

25% 12.15

0% 11.84

 

You should NEVER discharge your batteries below the 50% figure shown in the table above:

 

An ammeter will tell you what cuttent is going in or out of your batteries, useful to know if you have left something switched on or that your charger is working.

 

You can also tell if the charger is working as the voltage will rise while its charging.

 

The way the % meter works is you tell it the size of your batteries and it subtracts any usage from the total and adds any charging to the total so if you have a 200Ah bank and you use 100Ah and then charge until you have put back 50Ah it will read 75%.

 

There is no way with an ammeter that you can tell what the state of your batteries are as it only makes a measurement at any instant in time unless you have one with a % use meter built in.

 

 

Teaching never has been one of my strong points

 

 

 

 

J

 

Edited cos I couldnt get the table to display

Edited October 2, 2006 by idleness

[blackrose]

OK some free information

 

Despite what other may say on this forum:

 

A volt meter will give you an indication of the state of charge of your batteries provided that they are at rest ( not charging or discharging) and have been for a while, this is temperature dependant and the figures are as follows the temps are at 70deg farenheit you will need to add 0.09v for every 10deg F that the temperature is lower and subtract if its higher.

 

100% 12.74

75% 12.54

50% 12.33

25% 12.15

0% 11.84

 

You should NEVER discharge your batteries below the 50% figure shown in the table above:

 

An ammeter will tell you what cuttent is going in or out of your batteries, useful to know if you have left something switched on or that your charger is working.

 

You can also tell if the charger is working as the voltage will rise while its charging.

 

The way the % meter works is you tell it the size of your batteries and it subtracts any usage from the total and adds any charging to the total so if you have a 200Ah bank and you use 100Ah and then charge until you have put back 50Ah it will read 75%.

 

There is no way with an ammeter that you can tell what the state of your batteries are as it only makes a measurement at any instant in time unless you have one with a % use meter built in.

Teaching never has been one of my strong points

J

 

Edited cos I couldnt get the table to display

 

Thanks that's very clear - free info is what this forum is for!

 

I think I let my batteries fall below 12.33v before I installed a battery charger. This was only during the first 3 months from new. Now they're contstantly charged with 3 step charger, but I wonder if I've damaged them?

[GUMPY]

Thanks that's very clear - free info is what this forum is for!

 

I think I let my batteries fall below 12.33v before I installed a battery charger. This was only during the first 3 months from new. Now they're contstantly charged with 3 step charger, but I wonder if I've damaged them?

 

I always give out unbiassed and free info, its just that certain people dont belive it and do their best to shoot it down by spouting CENSORED and then get their gnomes to spout CENSORED as well

 

So long as you didnt leave them for a period below 12.33 then you should be OK.

That figure is at 70degF so if it was winter it would be higher.

 

Batteries are a disposable item, they dont last for ever. I get about 4-5 years out of a set but that was without float charging I will be interested to see how long this set last as when on the moorings as I now float them 24/7.

 

 

J

[DHutch]

Yeah, we moniter the state of charge of our batterys using only a voltmeter. With an ampter to moniter instantainous useage/charge.

 

We have a list of values very simular to that that idleness posted, although (purely from memory) ours are a very little higher at the top end, and doubled, as we have a 24v system.

- I think 100% is 26.2volts on ours, off the top of my head.

 

We veiw the meter in the morning (after 10hours of zero-load condiotions) and we feel it gives an accurate enough reading for our uses.

- We only really both to read it when we spending a time without moving anywhere. If where just about to move off, we dont usally both, as there going to get charged anyway.

 

The ampmeter (+/- 75amp shunt type) allow us to quickly see how much power we're using, Vs how much power we putting in.

- Which is usefull espcially initally when your trying to get a feel for how much everything uses etc.

- It was also almost invaluable when we where sorting out our alternator, as it clearly showed if/when that was charging, and how much it was puting in.

 

If where stoped for a while, and the batterys are getting low (such as 2 weeks a bealepark) our standard proceadue is to run the mains battery charger from the gennertor untill the charge rate drops down to a sensable rate.

- At first you get the full 25amps for a while, then shortly after it dropeds to around 16amps, which is sits on for roughly an hour. Then it drops down to 6/8amps, and we knock the genny off.

(bearing in mind for a 12v system, equvenlent current[amps] is double)

 

 

Daniel

[blackrose]

I always give out unbiassed and free info, its just that certain people dont belive it and do their best to shoot it down by spouting CENSORED and then get their gnomes to spout CENSORED as well

 

Come on, give it up... you'll make yourself ill.

 

I just spoke to someone from Merlin Powerstore http://www.power-store.com/?id=160 who stock the SmartGauge. They say the reason it's not on their website is because it's not quite "consumer ready". When I asked what that meant I was told it's not as visually attractive as some other products and you have to mount it by using self adhesive velcro strips on the back (ok, no big deal).

 

The other thing I didn't realise is that beacuse it's shuntless it has no +/- amps in/out function, meaning in certain situations you might actually be drawing more than you're charging without realising it.

 

However, what the smartguage does have is amps as a % state of charge, and Merlin (who conducted the tests described on the smartguage website), found this function to be more accurate than any other amp hour monitor they tested.

 

Also, unlike other monitors using shunts, installation with light guage cables is easier.

 

A fairly balanced view of a supplier.

Edited October 2, 2006 by blackrose

[GUMPY]

I just spoke to someone from Merlin Powerstore http://www.power-store.com/?id=160 who stock the SmartGauge. They say the reason it's not on their website is because it's not quite "consumer ready". When I asked what that meant I was told it's not as visually attractive as some other products and you have to mount it by using self adhesive velcro strips on the back (ok, no big deal).

 

As I said in post number two on this thread

 

The other thing I didn't realise is that beacuse it's shuntless it has no +/- amps in/out function, meaning in certain situations you might actually be drawing more than you're charging without realising it.

 

As I said in post number two in this thread, it does register if you are discharging more then charging the % figure drops.

 

However, what the smartguage does have is amps as a % state of charge, and Merlin (who conducted the tests described on the smartguage website), found this function to be more accurate than any other amp hour monitor they tested.

 

True

 

Also, unlike other monitors using shunts, installation with light guage cables is easier.

 

A fairly balanced view of a supplier.

 

Go back and look at the first reply I made to your origional post and re read it, I say exactly the same as they do.

 

 

I think that you have just confirmed all the points that I have made

 

J

Edited October 2, 2006 by idleness

[blackrose]

Go back and look at the first reply I made to your origional post and re read it, I say exactly the same as they do.

I think that you have just confirmed all the points that I have made

 

J

 

I read your post quite thoroughly the first time thank you. However, if there's one thing I have learned from living on a boat it's that I will never under any circumstances take the first opinion or advice that's offered to me. I ask around and then make up my own mind.

 

I wasn't one of the product's detractors and if you look back over the thread you'll find I never contradicted any of those points - I don't have enough knowledge on the subject to do so & have simply been asking questions.

 

Anyway back to the topic, is a % amp hour figure rising or falling quite as good as a real-time ammeter where you can see your exact inputs & outputs?

Edited October 2, 2006 by blackrose

[GUMPY]

Anyway back to the topic, is a % amp hour figure rising or falling quite as good as a real-time ammeter where you can see your exact inputs & outputs?

 

 

They do different jobs so cannot really be compared

Although I have no experience of the BM1 it looks like a reasonable unit and will tell you both.

You know what I would reccomend

J

[oasis]

They do different jobs so cannot really be compared

Although I have no experience of the BM1 it looks like a reasonable unit and will tell you both.

You know what I would reccomend

J

Hi I am new to NB and the forum and I have been trawling the forums picking up on invaluable advice and concepts. Thank you for those.

 

My previous life had me involved with predictive process control. It basically controls the output of manufacturing by eliminating the need for fancy time based integrals. In real life this means if you had to bake a cake over a certain time then predictive control would look at your cake mixture and ramp up the temp to whats required, keep it there for the time its required and then ramp it down and switch off the stove. The only variables would be the amounts of moisture and raisins (say) you have in the mixture.

 

So the clues to how Smartguage works are the graphs given in the second pages link - AH to Voltage at certain temps and cycles. Using these graphs Smartguage probably predicts the rate of voltage rise (charging) or voltage depletion (on load). It then probably correlates this to the AH left on the battery bank, similar to comparing the graphs, only real unknown being the temperature. But I doubt temp would be a real problem - maybe make a 5% difference which would even out over time. The number of cycles would not make a huge difference either looking at the graphs.

 

People can check their charge/discharge by looking at their voltages over time but Smartguage picks up this almost instantly.

 

I hope I have helped with the understanding of the 2 wire voltage monitoring and how (I AM GUESSING)it works.

 

I will definitely be buying a Smartguage before I set off on a long cruise.

[RLWP]

Hi I am new to NB and the forum and I have been trawling the forums picking up on invaluable advice and concepts. Thank you for those.

 

My previous life had me involved with predictive process control. It basically controls the output of manufacturing by eliminating the need for fancy time based integrals. In real life this means if you had to bake a cake over a certain time then predictive control would look at your cake mixture and ramp up the temp to whats required, keep it there for the time its required and then ramp it down and switch off the stove. The only variables would be the amounts of moisture and raisins (say) you have in the mixture.

 

So the clues to how Smartguage works are the graphs given in the second pages link - AH to Voltage at certain temps and cycles. Using these graphs Smartguage probably predicts the rate of voltage rise (charging) or voltage depletion (on load). It then probably correlates this to the AH left on the battery bank, similar to comparing the graphs, only real unknown being the temperature. But I doubt temp would be a real problem - maybe make a 5% difference which would even out over time. The number of cycles would not make a huge difference either looking at the graphs.

 

People can check their charge/discharge by looking at their voltages over time but Smartguage picks up this almost instantly.

 

I hope I have helped with the understanding of the 2 wire voltage monitoring and how (I AM GUESSING)it works.

 

I will definitely be buying a Smartguage before I set off on a long cruise.

 

Hi Oasis, welcome to the forum.

 

If you've been digging back to 2006 you must have been very busy.

 

I imagine Gibbo will be along in a bit to let you have some more information on how he designed the Smartgauge

 

Richard

[oasis]

Hi Oasis, welcome to the forum.

 

If you've been digging back to 2006 you must have been very busy.

 

I imagine Gibbo will be along in a bit to let you have some more information on how he designed the Smartgauge

 

Richard

Thanks for the welcome Richard. These posts have really given me an understanding of the basics and I also enjoy the comments passed by the people with an axe to grind. Its all good stuff and fun really. (Most of the time)

[Robin2]

I am a little concerned that the Smartgauge supporters are over-simplifying the story.

 

There is no magic about discharging a battery to 50% or any other level. Deeper discharges shorten battery life - 50% is worse than 80% and 40% is worse than 50%.. The better battery manufacturers have charts showing how many discharges are possible at different levels of discharge. How low you decide to discharge your battery is an economic question - is the deeper discharge giving you something (like shorter charge times) that offsets the reduced battery life. It seems a bit pointless to pay extra for a deep-discharge battery and then not deep-discharging it! Or it may make sense to buy cheap batteries and replace them more often.

 

One thing is for sure, if you don't charge the batteries fully from time to time they will age much more quickly. I suspect not charging them fully may be more damaging than deep discharges of an otherwise well maintained battery.

 

From what I have read the only reliable way to measure the state of charge is to measure the density of the battery acid with an accurate hydrometer.

 

I agree with the general view that an ammeter or an amp-hour counter cannot tell the state of your battery but they can be very useful. An ammeter will show the current consumption of your different appliances which is valuable information for minimizing your electricity usage. It can also show instantaneously whether you are charging or discharging your battery and by how much. For example I use this to help me set the engine speed to generate enough power for my washing machine and to reduce RPM when the WM heating cycle is over. An amp-hour counter will show how much you have taken out of your battery - which may be the signal that it is time to run your generator. The amp-hour counter will also tell you that you have not yet put enough current back into your battery - you certainly need to put back a lot more than you took out.

 

The Smartgauge is designed to "learn" about your battery over time so it is not useful if you disconnect it from the batteries regularly, or switch it between batteries. However I am not convinced that using one set of batteries all the time is the most economical way to meet your electricity needs.

[nb Innisfree]

To indicate whether power is going in or out of a batt needs an ammeter not an ah counter.The only use I can see for an ah counter is to do a power audit, using it to decide when to charge and when to stop is based on shifting sands, i.e. ah used from what if there is no practical way of calculating what batt capacity there is left anyhow? Smartgauge is still the only way of indicating what energy expressed as percentage is left in the battery, it doesn't tell you how much actual energy is left and I'm not aware of anything that can.

[Albion]

snipped

 

The Smartgauge is designed to "learn" about your battery over time so it is not useful if you disconnect it from the batteries regularly, or switch it between batteries. However I am not convinced that using one set of batteries all the time is the most economical way to meet your electricity needs.

 

I'm not sure why you would want to swap a Smartgauge about between battery banks any more than you would want to swap around any other instrument panel mounted meters or gauges in the real world of the majority of people. You sound as if you have some specific purpose in mind that doesn't match the requirements of the majority of SG purchasers but, if you do, you can't blame the SG for not suiting your purposes surely?

Roger

[oasis]

To indicate whether power is going in or out of a batt needs an ammeter not an ah counter.The only use I can see for an ah counter is to do a power audit, using it to decide when to charge and when to stop is based on shifting sands, i.e. ah used from what if there is no practical way of calculating what batt capacity there is left anyhow? Smartgauge is still the only way of indicating what energy expressed as percentage is left in the battery, it doesn't tell you how much actual energy is left and I'm not aware of anything that can.

What I was trying to say is that SG uses (probably) a statistical predictive approach, it is nothing new really. Based on the Ah to voltage curves (graph)of the battery, once you capture the rate of voltage charge - or discharge - it should be easy enough to get the corresponding Ah increase or depletion. At a high rate of depletion the temperature will probably change but the predictive software should cater for this. So 2 wire voltage capture is a very feasible method I THINK. A % of what left can be translated to actual based on the total amount of battery power one has. What I read is if you are below 50% then the batteries aren't happy.

 

I don't think it is as simple as I make out. The initial conception, trials and software developement must have taxed a few brain cells allright. And I would like to repeat that this is how I think SG works. I will be buying one.

[nb Innisfree]

What I was trying to say is that SG uses (probably) a statistical predictive approach, it is nothing new really. Based on the Ah to voltage curves (graph)of the battery, once you capture the rate of voltage charge - or discharge - it should be easy enough to get the corresponding Ah increase or depletion. At a high rate of depletion the temperature will probably change but the predictive software should cater for this. So 2 wire voltage capture is a very feasible method I THINK. A % of what left can be translated to actual based on the total amount of battery power one has. What I read is if you are below 50% then the batteries aren't happy.

 

I don't think it is as simple as I make out. The initial conception, trials and software developement must have taxed a few brain cells allright. And I would like to repeat that this is how I think SG works. I will be buying one.

 

My last post was in response to Robin2.

 

Problem with your theory is the Smartgauge isn't an ah counter + it can't calculate what's left based on capacity of battery because that is an unknown quantity.

[Gibbo]

I am a little concerned that the Smartgauge supporters are over-simplifying the story.

 

The 50% rule (as it's known) is covered on the website. It is made very clear that 50% is not some magic number.

 

It seems a bit pointless to pay extra for a deep-discharge battery and then not deep-discharging it! Or it may make sense to buy cheap batteries and replace them more often.

 

If you buy deep cycle batteries, they will still last longer by not deep cycling them. The 50% rule still applies.

 

From what I have read the only reliable way to measure the state of charge is to measure the density of the battery acid with an accurate hydrometer.

 

Unfortuately not. SG only tells one the SoC if the state of health is already known.

 

Example. A battery is down to 80% state of health due to sulfation. In a typical battery this will mean that around 15% to 20% of the acid is now tied up in sulfate crystals. Fully charge that battery (ie as fully as it is ever going to be) and an SG reading will tell you it is only 80% to 85% charged. Which is clearly wrong. It's as fully charged as it can be.

[Robin2]

I'm not sure why you would want to swap a Smartgauge about between battery banks any more than you would want to swap around any other instrument panel mounted meters or gauges in the real world of the majority of people. You sound as if you have some specific purpose in mind that doesn't match the requirements of the majority of SG purchasers but, if you do, you can't blame the SG for not suiting your purposes surely?

Roger

 

You are largely correct. My concern is that having a Smartgauge one may be tempted to treat all of the batteries as a single bank which I don't think is the most ecomonic solution. One could, of course, buy a separate Smartgauge for each bank - but that would be expensive.

 

 

Unfortuately not. SG only tells one the SoC if the state of health is already known.

 

Example. A battery is down to 80% state of health due to sulfation. In a typical battery this will mean that around 15% to 20% of the acid is now tied up in sulfate crystals. Fully charge that battery (ie as fully as it is ever going to be) and an SG reading will tell you it is only 80% to 85% charged. Which is clearly wrong. It's as fully charged as it can be.

 

This is interesting. I guess another way of interpreting the same info is that when the SG won't go back to "full" SoC the batteries are sulphated.

 

As a matter of curiosity is there any advantage (or disadvantage) in replacing the acid with fresh stuff at "full" SoC?

[Gibbo]

My concern is that having a Smartgauge one may be tempted to treat all of the batteries as a single bank which I don't think is the most ecomonic solution.

 

Yes, we know you don't think so. The fact that you're wrong and have been told so by a whole list of people doesn't seem to be keeping you from believing this pipe dream

 

 

This is interesting. I guess another way of interpreting the same info is that when the SG won't go back to "full" SoC the batteries are sulphated.

 

 

If, by SG you mean SmartGauge then no, it will go back to full. According to SmartGauge the new 100% is what they will reach after having accounted for sulfation.

 

If you mean specific gravity then yes. But what use is it? The specific gravity shows 80% which could be 80% state of charge or 80% state of health with no way of knowing the difference.

 

 

As a matter of curiosity is there any advantage (or disadvantage) in replacing the acid with fresh stuff at "full" SoC?

 

It won't achieve anything other than increasing internal corrosion. There won't be any lead and lead dioxide to react with it.

Edited December 17, 2010 by Gibbo

[Robin2]

 

If you mean specific gravity then yes. But what use is it? The specific gravity shows 80% which could be 80% state of charge or 80% state of health with no way of knowing the difference.

 

 

I presume if you spent a long time charging a battery and the SpGr did not respond you could reasonably assume that the state of health was down, rather than the state of charge. (This was the sense in which I posed the question).

[Pretty Funked Up]

I know its a bit of an advert but THISpage has usefull info.

[Gibbo]

I presume if you spent a long time charging a battery and the SpGr did not respond you could reasonably assume that the state of health was down, rather than the state of charge. (This was the sense in which I posed the question).

 

Yes, absolutely. Now back to the SpGr reading, what use is it to show you state of charge? It won't.

[Robin2]

Yes, absolutely. Now back to the SpGr reading, what use is it to show you state of charge? It won't.

 

Should I infer from your answer that a Smartgauge would be able to tell the state of charge of a battery in poor health. That seems to me to imply that the Smartgauge works on the assumption that the user carries out sufficiently long charges sufficiently often for it to be reasonably certain that the highest voltage it registered represents a full charge. However if the original problem is that the user is not charging for long enough (because it is expensive and irritating) how will the Smartgauge ever get the correct data?

 

Not that I am suggesting that SpGr is an alternative. I just had not realized that upper limit of the SpGr declined as the battery got sulphated. (I do get useful information from you - in spite of appearances )

[Pretty Funked Up]

how will the Smartgauge ever get the correct data?

 

Surely that is a trade secret.