battery monitoring

[nicknorman]

Just prove the statements with manufacturers direct data. The military do not use the smartgauge.

You are wrong - Ish

 

The military use the Smartgauge algorithm in the Datacell. Take a look at this webpage, click on battery monitoring

 

http://www.merlinequipment.com/markets/defence/

 

This is the device sometimes known as "son of Smartgauge" and that which we mentioned uses the Smartgauge algorithm 90% of the time. It also contains a shunt but the primary use of that is to enable a battery health calculation, ie comparing the actual SoC from the Smartgauge algorithm, with the AH taken out using an AH-counting algorithm.

[WotEver]

And here's the data sheet: http://www.merlinequipment.com/page/document.asp?id=641

[KJT]

Thanks guys.

I think for me, the smartgauge will suit my requirements. It seems to be a popular choice on the whole.

Found them for £120 + £5.95 postage at cactus navigation and marine. It appears they have a uk distributer, so no import taxes!

Writing as a numpty boater with little knowledge of electrics, I think you have made the right choice. When I bought my boat it came with a Victron BMV 602S. Due to my ignorance of needing to reset it periodically I flattened my AGM's a couple of times. I fitted a Smartgauge a couple of years ago and think it's brilliant in it's simplicity. I often compare the two but the SG seems to be more believable to my 'real world' use. Having learnt how to use the BMV correctly (I think), I find it is useful for it's charge/discharge ammeter readings, but I prefer to use the SG to tell me when to start charging. I have not had any battery issues since.

If I had to choose between them? Smartgauge, every time.

 

Ken

Edited January 21, 2016 by NB Ellisiana

[Graham.m]

And here's the data sheet: http://www.merlinequipment.com/page/document.asp?id=641

 

Sorry gents that looks like and I have no reason to believe it is anything other than a very high grade amp reading style battery monitor, albeit well hardened. One thing I do know if you were told anything it would have been a major breach of company confidentiality and certainly being linked to any military project of any sort could have been even more of a breach of security Acts. Thus whatever you believe you were told I have very solid reasons to believe that it did not apply to the product you have linked to; including links to defence provision manufacturers, it is a different world in terms of the secrecy, security vetting etc with jobs being lost over very small indiscretions.

 

So don't try and make the gauge anything other than it is a battery fuel gauge that like most, I cannot say all because I do not know, battery monitors is not perfect and has problems. Some that some people would consider major and others who do not have the knowledge and experience cannot see or understand.

 

I do know that a portion of people seem to have both, which does not surprise me as marrying the two together deals with most if not all the problems of both types.

Edited January 21, 2016 by Graham.m

[WotEver]

 

Sorry gents that looks like and I have no reason to believe it is anything other than a very high grade amp reading style battery monitor, albeit well hardened.

Whatever your belief you are mistaken.

 

It is as Nick and I have described. Two Smartgauges, one of which has a shunt. Over 90% of its time it displays and reports on the one which doesn't have a shunt.

 

Tony

Writing as a numpty boater with little knowledge of electrics, I think you have made the right choice. When I bought my boat it came with a Victron BMV 602S. Due to my ignorance of needing to reset it periodically I flattened my AGM's a couple of times. I fitted a Smartgauge a couple of years ago and think it's brilliant in it's simplicity. I often compare the two but the SG seems to be more believable to my 'real world' use. Having learnt how to use the BMV correctly (I think), I find it is useful for it's charge/discharge ammeter readings, but I prefer to use the SG to tell me when to start charging. I have not had any battery issues since.

If I had to choose between them? Smartgauge, every time.

 

Ken

Absolutely, Ken. SmartGauge doesn't tell you "everything" about your batteries - it isn't designed to. What it does tell you, as a simple 'fuel gauge', is when to charge your batteries and for how long.

 

It is ideal for the non-technical user.

 

Tony

[Graham.m]

Whatever your belief you are mistaken.

 

It is as Nick and I have described. Two Smartgauges, one of which has a shunt. Over 90% of its time it displays and reports on the one which doesn't have a shunt.

 

Tony

 

 

Well in that case using your favourite words to me proof and evidence

 

 

Absolutely, Ken. SmartGauge doesn't tell you "everything" about your batteries - it isn't designed to. What it does tell you, as a simple 'fuel gauge', is when to charge your batteries and for how long.

 

It is ideal for the non-technical user.

 

Tony

 

Ah I see you have now incorrectly give it another attribute it tells you how long to charge the batteries for rot

Edited January 21, 2016 by Graham.m

[nicknorman]

Sorry gents that looks like and I have no reason to believe it is anything other than a very high grade amp reading style battery monitor, albeit well hardened. One thing I do know if you were told anything it would have been a major breach of company confidentiality and certainly being linked to any military project of any sort could have been even more of a breach of security Acts. Thus whatever you believe you were told I have very solid reasons to believe that it did not apply to the product you have linked to; including links to defence provision manufacturers, it is a different world in terms of the secrecy, security vetting etc with jobs being lost over very small indiscretions.

 

So don't try and make the gauge anything other than it is a battery fuel gauge that like most, I cannot say all because I do not know, battery monitors is not perfect and has problems. Some that some people would consider major and others who do not have the knowledge and experience cannot see or understand.

You are comical Graham. You [appear to] know zilch about this but are happy to tell us that we are lying or at least "mistaken". I guess you don't know much about the military market apart from what you've seen on the telly but, whilst certainly a military project funded by the military will be shrouded in secrecy and probably covered by the OSA, there is a lot of stuff out there developed by commercial companies for the military market. Such stuff can be bought by anybody (sanctions aside). Such stuff is often a militarisation of a COTS product, compliant with the relevant mil standards, and the Datacell 2 is such a product. Gibbo (the designer) discussed concepts for improvement of the Smartgauge on this forum in order to tap into a relatively large user base, and the Datacell was the outcome of that development (along with a lot of other input of course). Surprisingly he wasn't sent to the Tower for a beheading for revealing that the Datacell contained the Smartgauge algorithm ... NOT! Of course what he always resolutely refused to do is to give any hint on the nature of the Smartgauge algorithm, that is the only relevant commercial confidentiality. You have no idea about any of this because you weren't a participant in the forum at the time, but to extrapolate from this that it isn't true is illogical.

 

So once again, the Datacell comprise a Smartgauge algorithm and a shunt, with some additional software to merge the two to give, for example, battery health as well as battery SoC. This is a fact and you can bay at the moon all you like, it's still the case.

 

No doubt it is not fitted to the latest eurofighter etc but it is fitted to run of the mill military vehicles, along with lots of other COTS hardware that has a mil spec approval.

Edited February 17, 2016 by DHutch

[nicknorman]

This from one of the Datacell 2 brochures. Sound familiar?

 

Using a blend of traditional battery monitoring technology and unique mathematical models written for different battery types, DataCell II overcomes the difficulties experienced by users with conventional ampere hour counters (mainly long

term inaccuracy for SoC (state of charge)). DataCell is not effected by the nature of live vehicle electrical systems (batteries under varying load, in different temperatures, peaks and spikes). As it does not require complex, power hungry electronic sensors on the batteries. It also does not suffer from power consumption issues associated with Ohmic (impedance) based units.

As well as monitoring batteries, DataCell II can be used to comprehensively manage power on-board.

 

http://www.unitronix.com.au/VehiclesAndSystems/ProductPages/PowerSystems/PDFDatasheets/UNITRONIX-Merlin-DataCell%20II%20Brochure.pdf

[Tony Brooks]

My answer to Graham's post yesterday where he said he advocated using the BVM to show amp hours

 

 

I agree, probably with 100% accuracy but what will the OP do with the answer. He does not know his actual battery capacity and probably does not know how discharged it was. All he can do is make a guess, might a swell fit an ammeter and monitor tail current.

 

I forgot to add that if the amp hour measurement is of how may Ahs have supplied to the battery the boater it is still meaningless because the boater has no idea how many of those amp hours has been converted to lead oxide. This is the basic problem with Ah counters, the conversion efficiency alters over battery age, temperature, and more I understand,so it is all but impossible to get the recharge state correct by measuring Ah supplied.

[Graham.m]

My answer to Graham's post yesterday where he said he advocated using the BVM to show amp hours

 

 

I forgot to add that if the amp hour measurement is of how may Ahs have supplied to the battery the boater it is still meaningless because the boater has no idea how many of those amp hours has been converted to lead oxide. This is the basic problem with Ah counters, the conversion efficiency alters over battery age, temperature, and more I understand,so it is all but impossible to get the recharge state correct by measuring Ah supplied.

 

Don't think I disagreed with you. On the charging front the use of the BMV or other amp reading monitor assists by allowing the monitoring of tail currents

Edited January 21, 2016 by Graham.m

[blackrose]

The Sterling has a light display so just switch the master of and count 10 and read the current.

 

I thought voltage readings were only accurate for estimating SoC if there had been no load or charge for several hours?

 

Edit: Sorry, just realised you said current so perhaps I don't know what I'm talking about...

Edited January 21, 2016 by blackrose

[Graham.m]

 

I thought voltage readings were only accurate for estimating SoC if there had been no load or charge for several hours?

 

Edit: Sorry, just realised you said current so perhaps I don't know what I'm talking about...

 

I have days like that

 

Current does not need to wait for the surface charge on the plates to dissipate just a few seconds for the meter on the charger to stabilise

Edited January 21, 2016 by Graham.m

[GUMPY]

Will we ever get another useful thread on battery charging?

never again unless a certain poster stops obfuscating

[Graham.m]

Hmm well slightly wishing I hadn't done this because I haven't done it in the best way and made a bit of a booboo which the circling vultures will pounce on! Basically I think I should have waited until the batteries had done another cycle or two having been on float for a month (which always upsets them!) and secondly I took the batteries down to around 50% SoC which is a region not really seen by the Smartgauge as I never normally let it go below about 65%. Since the Smartgauge is a learning device, it cannot be too surprising if when it is taken into an area it hasn't learnt, it is not very good.

 

Anyway, the graph is shown here. Hopefully self-explanatory and just to mention that I was deliberately using quite a bit of juice - I can certainly eek out our 450AH bank better than this. Yup the smartgauge seems to fall off a cliff a bit towards the end, however once I had finished the discharge I turned everything off and after 15 mins the voltage was around 12.27 which tends to support the MS estimate of SoC.

 

Discharge.JPG

 

What was the Gauge SoC after 15 minutes?

 

It looks from your graphs that the gauge could not cope with the drain for the 2 kW kettle

 

 

So of course one is then stuck with the figures at the end of the discharge, to start the charge process. The Smartgauge was clearly significantly under-reading the SoC at this point. On this graph, note that the current axis is on the right ie it started at around 165A before rapidly falling off.

 

I couldn't quite decide whether to continue the charge until fully charged or not. If I had have done so, I think you can see by the shape of the graphs that the two figures were converging but since the starting point for the SG was bad this didn't seem particularly useful. I therefore decided to terminate the charge prematurely in order to demonstrate one of the SGs major advantages which is that when it does go wrong, it self corrects without any user intervention. More of that in the next post.

 

Recharge.JPG

 

I think one of the things this exercise has demonstrated to me is just how complex battery chemistry is. It is easy to think of a simple model but the reality is complicated. For example, when I started to recharge the current was 165A, rapidly fell off to 125A, but then for some strange reason increased back to 130A. What is going on!

 

Yep battery chemistry is not as simple as some think. looking at your charging graph it looks to me as if the would both have been low. and the SG the lower of the two. But difficult to be sure

 

Pity you did not have the conviction to continue

[Graham.m]

Oh on the learning side surely the SG has been on your batteries for, well since April last years and seen frequent application of kettles etc.

 

As the batteries are less than a year old and if the discharge/charge regime has been as good as you have suggested, I suspect they are not very far from full capacity if down at all.

[WotEver]

Oh on the learning side surely the SG has been on your batteries for, well since April last years and seen frequent application of kettles etc.

I took the batteries down to around 50% SoC which is a region not really seen by the Smartgauge as I never normally let it go below about 65%. Since the Smartgauge is a learning device, it cannot be too surprising if when it is taken into an area it hasn't learnt, it is not very good.

It seems to me that it was after the batts dropped below around 65% that the discrepancy increased.

 

Tony

[nicknorman]

Oh on the learning side surely the SG has been on your batteries for, well since April last years and seen frequent application of kettles etc.

 

As the batteries are less than a year old and if the discharge/charge regime has been as good as you have suggested, I suspect they are not very far from full capacity if down at all.

Batteries are 2 years old but never mind, I'm fairly confident that they are at original capacity.

 

Yes the SG has seen frequent application of the kettle, what it hasn't seen is that happening below 65%. I'm sure SG's model must vary according to the SoC and I think it is lack of exposure in this region, rather than to that effect, that is the issue.

 

Anyway it should be fairly easy to do it again but with higher SoC. I can time the kettle, note the current and get a pretty good idea of the AH taken out.

 

I've also found in the past that the batteries seem lazy when taken into a region they have not been in recently - an extension of the "lazy having spent a month on float" which is a definite and repeatable effect. The chap from Trojan was talking about the types of crystals formed etc (the reason why the batteries have reduced capacity when new) and I think this has something to do with it.

 

 

Pity you did not have the conviction to continue

 

It wasn't a lack of conviction, it was a decision based on the inappropriate starting point. And as I said, it will show a more interesting facet which is how SG recovers from its mistakes automatically, unlike an AH gauge that would require user intervention.

[Graham.m]

It seems to me that it was after the batts dropped below around 65% that the discrepancy increased.

 

Tony

 

I don't think so the drop away started at about 80%, and from 70% down with the exception of the kettle kink at about 60% slope is falling away

[dmr]

Hmm well slightly wishing I hadn't done this because I haven't done it in the best way and made a bit of a booboo which the circling vultures will pounce on! Basically I think I should have waited until the batteries had done another cycle or two having been on float for a month (which always upsets them!) and secondly I took the batteries down to around 50% SoC which is a region not really seen by the Smartgauge as I never normally let it go below about 65%. Since the Smartgauge is a learning device, it cannot be too surprising if when it is taken into an area it hasn't learnt, it is not very good.

 

Anyway, the graph is shown here. Hopefully self-explanatory and just to mention that I was deliberately using quite a bit of juice - I can certainly eek out our 450AH bank better than this. Yup the smartgauge seems to fall off a cliff a bit towards the end, however once I had finished the discharge I turned everything off and after 15 mins the voltage was around 12.27 which tends to support the MS estimate of SoC.

 

Discharge.JPG

 

Interesting stuff, thanks for posting this.

I have always suspected the Smartgage (sg) is not totally linear, but am still amazed at how well it does from a voltage only input.

Gibbos instructions do say that the sg is most accurate in the 50% region????. I half suspect that he brings in different algorithms at different states of charge. I think you might be wrong about the sg needing to learn about the 50% region, I think mine shows similar behaviour and its been down there a few times. I suspect that if you went a bit lower the two readings might even start to converge again.

 

As I (we) believe the sg is working from a series of clues rather than a definitive measurement its not really surprising that your sudden very high discharges sends it off in a wrongish direction for a while???

 

..............Dave

[Graham.m]

 

It wasn't a lack of conviction, it was a decision based on the inappropriate starting point. And as I said, it will show a more interesting facet which is how SG recovers from its mistakes automatically, unlike an AH gauge that would require user intervention.

 

But in this case where the battery capacity is static after two years there is nothing for an Ah gauge to recover from and it should be the same for the Sgauge. What you are telling me is that any change to routine battery use throws the Sgauge, yet the Ah gauge seems to have coped.

[nicknorman]

Anyway, just to mention that I am disappointed in these results, normally I see a much closer correlation between the SG and the MS. However, being a scientist one has to publish results even if one doesn't like them!

[nicknorman]

 

But in this case where the battery capacity is static after two years there is nothing for an Ah gauge to recover from and it should be the same for the Sgauge. What you are telling me is that any change to routine battery use throws the Sgauge, yet the Ah gauge seems to have coped.

Yes clearly the AH gauge has done a better job (well that's my interpretation anyway) but please don't do a circling vulture thing, rather, take it in context which is that my AH gauge is set up properly (not out of the box) and I know my bank's capacity. It is also much more expensive than the SG and more importantly, much harder to install.

 

With everything going for it, an AH gauge is better (that being correctly set capacity and routine resetting to 100% by fully charging). However please remember that in the real world these gauges are owned by numpties and most AH gauges are not set up properly with the correct capacity, and thus tell lies (viz my friends whose lights went out with 80% SoC showing on the AH gauge). An incorrectly set up or out of sync AH gauge can have massive errors.

 

Meanwhile the SG requires no intervention and does a reasonably good job regardless of the actual bank capacity etc. When it makes a mistake, it learns and corrects itself unlike an AH gauge. This is why the SG is recommended for folk who just want to fit and forget, ie most people.

[peterboat]

dont worry i took my batteries right down today with kettle then washing machine, there was about 8 amps of solar. at the end of discharging my bm2 was showing 11.9 volts and a soc of 40 percent within an hour they had recovered to 12.2 volts and when i returned at 6 ish they were showing 12.5 volts and about 70 percent soc. i had a fridge freezer running plus a fan for the composting toilet. i think all gauges read strange when you are romoving large amounts of amps from batteries

[Graham.m]

Yes clearly the AH gauge has done a better job (well that's my interpretation anyway) but please don't do a circling vulture thing, rather, take it in context which is that my AH gauge is set up properly (not out of the box) and I know my bank's capacity. It is also much more expensive than the SG and more importantly, much harder to install.

 

With everything going for it, an AH gauge is better (that being correctly set capacity and routine resetting to 100% by fully charging). However please remember that in the real world these gauges are owned by numpties and most AH gauges are not set up properly with the correct capacity, and thus tell lies (viz my friends whose lights went out with 80% SoC showing on the AH gauge). An incorrectly set up or out of sync AH gauge can have massive errors.

 

Meanwhile the SG requires no intervention and does a reasonably good job regardless of the actual bank capacity etc. When it makes a mistake, it learns and corrects itself unlike an AH gauge. This is why the SG is recommended for folk who just want to fit and forget, ie most people.

 

I am just commenting on what you have posted. I am not surprised that the Ah gauge has performed OK on good deep cycle batteries, I have seen it before. I would be interested to see the experiment repeated on cheap flood leisure batteries, that is where I believe the Ahgauge SoC will go wrong. Re the Sgauge maybe the same will apply, I don't know.

 

One of my requirements is that a Bmonitor should follow the battery regardless of the lack of a routine. The data you have posted suggests that the Sgauge may not be able to cope with a variable routine whereas on good quality batteries the Ahgauge seems able to.

 

Well done

[Loafer]

 

I am just commenting on what you have posted. I am not surprised that the Ah gauge has performed OK on good deep cycle batteries, I have seen it before. I would be interested to see the experiment repeated on cheap flood leisure batteries, that is where I believe the Ahgauge SoC will go wrong. Re the Sgauge maybe the same will apply, I don't know.

 

One of my requirements is that a Bmonitor should follow the battery regardless of the lack of a routine. The data you have posted suggests that the Sgauge may not be able to cope with a variable routine whereas on good quality batteries the Ahgauge seems able to.

 

Well done

 

Especially if the Ahgauge has just been re-set with a known capacity. That will drift away if not managed. Nick's is managed.