Designing 12v charging system from scratch

[nb Innisfree]

6 hours ago, Mike the Boilerman said:

The fact that my battery bank got destroyed by me stopping charging when the Smartgauge said 100%. Remember? 

Why did you stop charging when knowing SG can be inaccurate in that scenario? 

[rusty69]

6 minutes ago, nb Innisfree said:

Why did you stop charging when knowing SG can be inaccurate in that scenario? 

Cos he didn't rtfm

[nicknorman]

However we also need to remember that he bought fake batteries and repeatedly left them discharged for days on end. No doubt that was the fault of the SG too!

Edited December 9, 2017 by nicknorman

[MtB]

3 hours ago, nb Innisfree said:

Why did you stop charging when knowing SG can be inaccurate in that scenario? 

 

I didn’t know. I believed my shiny new smartgauge when it said 100%.

Then when my new batteries started dying I came on here asking how and why, and was told I can’t use the sg to determine 100%, they might only have been 90% as stated in the manual on page 30, ffs.

But my batteries were dying so fast even this small 90% error did not account for it so I checked my sg voltage reading against my DVM and found it over reading by 0.40v. This meant when using my particular sg to determine 100% the true Soc was probably closer to only 70% when i stopped charging. So my batteries were never charged above 70% for the whole four months it took me to identify the problem with my smartgauge. 

This is why I hold the smargauge primarily to blame for the rapid death of my new battery bank.  Granted I should have been using tail current to determine 100% soc but I didnt know that at the time. I believed my smartgauge display. And now today WotEver is once again stating the sg is usually accurate when displaying 100%, based only on the fact that nick Norman’s is. My experience is otherwise. 

[nb Innisfree]

4 hours ago, Mike the Boilerman said:

 

I didn’t know. I believed my shiny new smartgauge when it said 100%.

Then when my new batteries started dying I came on here asking how and why, and was told I can’t use the sg to determine 100%, they might only have been 90% as stated in the manual on page 30, ffs.

But my batteries were dying so fast even this small 90% error did not account for it so I checked my sg voltage reading against my DVM and found it over reading by 0.40v. This meant when using my particular sg to determine 100% the true Soc was probably closer to only 70% when i stopped charging. So my batteries were never charged above 70% for the whole four months it took me to identify the problem with my smartgauge. 

This is why I hold the smargauge primarily to blame for the rapid death of my new battery bank.  Granted I should have been using tail current to determine 100% soc but I didnt know that at the time. I believed my smartgauge display. And now today WotEver is once again stating the sg is usually accurate when displaying 100%, based only on the fact that nick Norman’s is. My experience is otherwise. 

OK, thanks for answering my query.

My missus always reads the instructions first for anything new, I always go with instinct first and usually end up doing it her way!  

I'm stubborn but not as much as I used to be  

[MtB]

2 hours ago, nb Innisfree said:

OK, thanks for answering my query.

My missus always reads the instructions first for anything new, I always go with instinct first and usually end up doing it her way!  

I'm stubborn but not as much as I used to be  

 

Well the most annoying bit is I’m like your missus and like to read the manual first. But the SG manual is so verbose and dull I fell asleep reading it after 25 pages, 

[rusty69]

11 minutes ago, Mike the Boilerman said:

 

Well the most annoying bit is I’m like your missus and like to read the manual first. But the SG manual is so verbose and dull I fell asleep reading it after 25 pages, 

If you fell asleep after 25 pages you should have read the important info on p22, but agree perhaps this should be printed on p1

[MtB]

9 minutes ago, rusty69 said:

If you fell asleep after 25 pages you should have read the important info on p22, but agree perhaps this should be printed on p1

 

I probably did read it but by then I was already half asleep from verbosity overload, and the point didn’t stick. Watever it was. 

But honestly, 30 pages? It was marketed as a simple fuel gauge for Batteries!

Anything needing 30 pages of instructions is not simple, which I should have realised but I fell for the lie. 

Oh and another point. If everything in the manual is so important it all should be printed on page 1.  

Edited December 10, 2017 by Mike the Boilerman

[nicknorman]

34 minutes ago, Mike the Boilerman said:

 

I probably did read it but by then I was already half asleep from verbosity overload, and the point didn’t stick. Watever it was. 

But honestly, 30 pages? It was marketed as a simple fuel gauge for Batteries!

Anything needing 30 pages of instructions is not simple, which I should have realised but I fell for the lie. 

Oh and another point. If everything in the manual is so important it all should be printed on page 1.  

But you’ve managed to write at least 30 pages on how hard done by you are! Are we supposed to still be awake?

[MtB]

On 10/12/2017 at 09:55, nicknorman said:

But you’ve managed to write at least 30 pages on how hard done by you are! Are we supposed to still be awake?

 

You seem to have managed it ok! 

Anyway I'm not claiming to be hard done by. I just feel the need to counter the relentless "SG is perfect" message/mantra pumped out continuously by WatEver.

[Capnbob]

14 hours ago, Tony Brooks said:

If you can be bothered to learn a but about batteries and charging then a digital ammeter and voltmeter is more than adequate for battery monitoring but if you can't then a Smartguage and ammeter is the best you can do.

Very happy to learn, Tony.  I have a feeling this was summarised somewhere, but can't track the process down now.

[Capnbob]

22 hours ago, Mike the Boilerman said:

 

I'm not sure why you think information in old threads goes 'out of date'

Well, one example, my sense is that once upon a time Smartguage (SG) was all the rage, but then it changed hands and Merlin sold them poorly calibrated, and that got reported in one or two threads, but the originals are still there saying SG is the bee's knees.

It's a fundamental weakness of a forum-based knowledge bank, like this is. Frequently needed information is generally MUCH better dealt with by a Wiki, which provides a single, easily accessed, easily updated page per topic. Forum threads on the other hand start on topic, then tend to  drift into communal rows (sorry, "exchanges of views").... as this one nearly did. Also with a Wiki things like "tail current", and "SOC" (which are meaningless to the newbie, but understandably offered as helpful shorthand by those who know what they are talking about) can easily be explained in context.

Nobody chooses to ignore the invaluable advice of the manual, or the gigabytes of advice buried in forums, but to most newcomers identifying the real-world meaning from the mountain of words is an uphill struggle.

Anyway... in the light of the generous advice offered to my original post, I think I'm going to get a decent mains charger, and learn how to:

"use an ammeter and a voltmeter to establish state of charge, especially when charging" (?);
hunt down the meaning of "tail current" which I gather is vitally important;
calibrate a smartguage and interpret its misleading advice.

Although I know the answers to all these are almost certainly buried somewhere within the forums, I'd be grateful for any pointers or summaries...

 

[MtB]

On 10/12/2017 at 09:12, rusty69 said:

If you fell asleep after 25 pages you should have read the important info on p22, but agree perhaps this should be printed on p1

 

Do us a favour and point out the important info on p22 you mention, there's a good chap. The board and I will be forever ever grateful because I can't see anything of any special importance!

Oh and for anyone here considering buying a Smartgauge, this page is one of 34 all in a similar vein and writing style you will be expected to have read and understood, before you may ask any questions on here  

 

 

[MtB]

Yes there are 34 PAGES of this impenetrable stuff. I'm sure my own posts on the subject are FAR less dull and sleep-inducing!

[rusty69]

5 minutes ago, Mike the Boilerman said:

 

Do us a favour and point out the important info on p22 you mention, there's a good chap. The board and I will be forever ever grateful because I can't see anything of any special importance!

Oh and for anyone here considering buying a Smartgauge, this page is one of 34 all in a similar vein and writing style you will be expected to have read and understood, before you may ask any questions on here  

 

 

 

[MtB]

On 10/12/2017 at 10:28, rusty69 said:

 

 

Ok so now there are two different manuals in existence. How confusing!!!!!!!!!

But in the case of my particular smartgauge, this 10% figure is demonstrably wrong. Mine is about 30% out. 

[rusty69]

9 minutes ago, Mike the Boilerman said:

 

Ok so now there are two different manuals in existence. How confusing!!!!!!!!!

Maybe i've got the one that only goes to 90% of the full version?

9 minutes ago, Mike the Boilerman said:

But in the case of my particular smartgauge, this 10% figure is demonstrably wrong. Mine is about 30% out.

But yours are faulty! And wot do we do with faulty goods? altogether now, we return them.

There's a hole in my bucket dear mtb..................

Edited December 10, 2017 by rusty69

[MtB]

On 10/12/2017 at 10:35, rusty69 said:

Maybe i've got the one that only goes to 90% of the full version?

 

OR.... perhaps as my SG was supplied reading too many volts it came with a matching manual, with too many pages?

On 10/12/2017 at 10:19, Capnbob said:

Well, one example, my sense is that once upon a time Smartguage (SG) was all the rage, but then it changed hands and Merlin sold them poorly calibrated, and that got reported in one or two threads, but the originals are still there saying SG is the bee's knees.

 

Ah I see what you mean. And this certinly seems to be true. To be fair Merlin are very aware of their blooper in selling wrongly calibrated SGs for a while and have probably pulled their socks up by now. I'll be testing this by buying a third sooner or later and I'll post about it here, after the fact.

 

[MtB]

On 10/12/2017 at 10:19, Capnbob said:

Anyway... in the light of the generous advice offered to my original post, I think I'm going to get a decent mains charger, and learn how to:

"use an ammeter and a voltmeter to establish state of charge, especially when charging" (?);
hunt down the meaning of "tail current" which I gather is vitally important;
calibrate a smartguage and interpret its misleading advice.

Although I know the answers to all these are almost certainly buried somewhere within the forums, I'd be grateful for any pointers or summaries...

 

Answering your questions in order...

1) You can't establish SoC whilst charging with any degree of accuracy. The best you can do is measure the tail current to see when you are approaching fully charged. For this you use the ammeter. A voltmeter can be used to estimate the state of charge of a battery rested for half an hour, by accurately reading the voltage and looking it up on a chart. Or memorising the chart once you've done it a lot!

2) Tail current is the charge current as the battery approaches the mythical state 'fully charged', when being charged at a specific voltage specified by the battery manufacturer, usually (but not always) 14.4.

3) A Smartgauge might confidently display 100% when the battery is nothing like fully charged. This is the trap. So use 'tail current' instead. The main use for a SG is to know when to start charging. When it gets down to 50%, start charging. Also after two days of use, start charging regardless. These 'rules' are compromises really, as in a perfect world you must "fully recharge you battery after every discharge" to roughly quote the Trojan manual. 

[MtB]

On 10/12/2017 at 10:35, rusty69 said:

Maybe i've got the one that only goes to 90% of the full version?

But yours are faulty! And wot do we do with faulty goods? altogether now, we return them.

There's a hole in my bucket dear mtb..................

 

But mine are out of guarantee. There is another poster here who tried to get his wrongly calibrated SG replaced and Merlin told him to shove it, as his too was out of guarantee. Well Merlin may not have used those actual words, but that is the gist of what he said they said. 

Besides I can recalibrate them myself as you well know!

[rusty69]

1 minute ago, Mike the Boilerman said:

 

But mine are out of guarantee. There is another poster here who tried to get his wrongly calibrated SG replaced and Merlin told him to shove it, as his too was out of guarantee. Well Merlin may not have used those actual words, but that is the gist of what he said they said. 

"As suggested - here we are Gents! If anyone thinks they have an issue with a SmartGauge it's important to us. I am sorry it has taken us so long to catch up. The SmartGauge is an absolutely fantastic product so we clearly need to address your concerns. If anyone has a unit that they believe has this problem then please call us to arrange its return. If we conclude there is a problem then we will replace it immediately free of charge. I will say that we have conducted reviews on a couple of the small number of units returned to us and found there to be no issue however we also don't doubt the experience of many customers on this forum. You know your electrics far better than us. In addition to replacing any units found to be faulty, we will also offer an "at cost" upgrade to our DataCell I or DataCell II battery monitors if you are interested. The DataCell I will monitor multiple battery banks for voltage and SoC. The DataCell II will also monitor SoH (State of Health) as well as other parameters too... (Blame Gibbo - he's still at it!)... 01202 697979"

[cereal tiller]

Just now, Mike the Boilerman said:

 

But mine are out of guarantee. There is another poster here who tried to get his wrongly calibrated SG replaced and Merlin told him to shove it, as his too was out of guarantee. Well Merlin may not have used those actual words, but that is the gist of what he said they said. 

I could Swap your Smart gauge with mine?

The one I have reads 6 AMPS. still going into the 6 x 80 AH.  battery Bank as the Smart Gauge reaches an indicated 100%, so , 1 AMP P Battery.

Would think that that those Figures prove that the SG is working as it supposed to?

Just now, cereal tiller said:

I could Swap your Smart gauge with mine?

The one I have reads 6 AMPS. still going into the 6 x 80 AH.  battery Bank as the Smart Gauge reaches an indicated 100%, so , 1 AMP Per Battery.

Would think that that those Figures prove that the SG is working as it supposed to?

 

[rusty69]

1 minute ago, cereal tiller said:

I could Swap your Smart gauge with mine?

The one I have reads 6 AMPS. still going into the 6 x 80 AH.  battery Bank as the Smart Gauge reaches an indicated 100%, so , 1 AMP P Battery.

Would think that that those Figures prove that the SG is working as it supposed to?

Wow, yours measures Amps? that is smart

Edited December 10, 2017 by rusty69

[MtB]

On 10/12/2017 at 11:06, rusty69 said:

"As suggested - here we are Gents! If anyone thinks they have an issue with a SmartGauge it's important to us. I am sorry it has taken us so long to catch up. The SmartGauge is an absolutely fantastic product so we clearly need to address your concerns. If anyone has a unit that they believe has this problem then please call us to arrange its return. If we conclude there is a problem then we will replace it immediately free of charge. I will say that we have conducted reviews on a couple of the small number of units returned to us and found there to be no issue however we also don't doubt the experience of many customers on this forum. You know your electrics far better than us. In addition to replacing any units found to be faulty, we will also offer an "at cost" upgrade to our DataCell I or DataCell II battery monitors if you are interested. The DataCell I will monitor multiple battery banks for voltage and SoC. The DataCell II will also monitor SoH (State of Health) as well as other parameters too... (Blame Gibbo - he's still at it!)... 01202 697979"

 

Yep, a 100% turnaround in attitude once a bit of publicity begins to hit home.

No PM yet from this chap to me asking if he can come and collect mine though. FAR too much trouble, that would be. I have to do all the running for THEIR faulty product.

[cereal tiller]

1 minute ago, rusty69 said:

Wow, yours measures Amps? that is smart

Smarticass! the Boat's Ammeter Displays 6 Amperoonys ,you know what I meant.