Battery Monitors and Capacity

[GeoffS]

Yes. Thank you all for the comments and help. Wish me luck!!

[nicknorman]

1 hour ago, Richard10002 said:

I've not been dissing the Smartgauge, merely pointing out its limitations. which myself and MtB ignored in ignorance to the detriment of our batteries.

 

I’ve just checked my two SoC meters. The AH-counting gauge is showing 93%. The SG is clearly very inaccurate above 80% as it is showing ... 93%. All monitoring devices have limitations, but SG’s are nothing to get too excited about. MtB killed his batteries by routinely leaving them discharged for a week, and also because his SG is out of calibration. Yes, selling out of cal gauges is BAD but that is a manufacturing quality control issue, not a design issue.

When you have a gauge designed to indicate SoC, when 100% SoC is not defined nor is 0% defined, it’s always going to be a bit non-binary, but it is pretty good at it from a real-world perspective, and better than other SoC gauges.

[Dr Bob]

3 hours ago, GeoffS said:

Update.

As far as I can see all negatives are going through the shunt and nothing else is connected apart from the Smartgauge.

At 11.30 am Saturday arrived at boat having left charger on. Gone to Float all saying 100%. Disconnected Solar. Inverter and Webasto on. 12V fridge running

15.30 12.7V SG 97% Victron - 15AH

17.30 126V 93% -21AH

Laptop TV/DVD and phone on.

21.30 12.4V 70% -47AH

Sunday

8.00 12.3V 63% -69AH

10.30 12.2V 60% -77AH

15.30 12.2V 57% -92AH

17.30 12.2V 56% -97AH

Decision needed now, do I leave them to discharge further and see what happens or do I turn on the charger (I have hook up available).

 

 

I am not sure I totally buy into them only being 200A capacity. Not enough data to be sure.

It seems from the data on 'sunday' that the batteries have been discharging at a rate of 2.5 to 3 Amp per hour so that means there is a load on the batteries. It is not clear from the data what is drawing the power. Let us assume there is something drawing that power. Let us also assume the system was at 100% SoC at the start.

The Voltage is showing 12.2V at the load of 2.5-3A. The voltage at rest will be higher. I would guess at least 0.1v but this will be dependent on the system and in particular the capacity of the bank (which we dont know). I do know that my system with over 500Ahr (660Ahr installed) at 1.5A draw  will read 0.1V under the rest voltage. I guess the voltage is therefore 12.3V (mayabe plus a little) on the limited information - a pure guess. On my system with the experience of looking everyday for 4 months I would be guessing reasonably accurately. The tables I use

http://modernsurvivalblog.com/alternative-energy/battery-state-of-charge-chart/

would suggest that equates to 65% ish SoC - so the -97AH is 35% of the capacity so the total capacity is just short of 300Ahr. Of course there are other tables with differnent results but the one I linked to seemed to work well with my batteries when they were new. This is considerably more than the 200Ahrs someone above posted but still bad for newish batteries. Loosing a third of capacity is more likely than loosing half, given the OPs success with batteries unless the batteries are faulty. I dont think you have enough info to decide. Everyone seems to be thinking the SG is correct - ie if the voltage is correct so the SoC will be correct. It may not be if the model used doesnt cope with outliers - ie a system outside the limits of the model regression analysis (I assume it uses linear regression to calculate outputs).

 

[WotEver]

28 minutes ago, Dr Bob said:

Everyone seems to be thinking the SG is correct - ie if the voltage is correct so the SoC will be correct.

Yes, because it will be.

Don’t forget that using only his SmartGauge OP got 8 years out of his previous bank.

One of the problems with your post above is that it has insufficient data points (and that the voltage is only indicated to one decimal point). Using OP’s figures the voltage was 12.2V for 7 hours, and that’s obviously incorrect. During those 7 hours he used 20Ah and the indicated SoC dropped by 4%, again this can’t be correct because it equates to a capacity of 500Ah. That’s the danger of using only a small data range. Your calculations state that he remained at 65% SoC for 7 hours whilst using 20Ah.

If he consumed 20Ah over 7 hours that’s a load of less than 3A which would hardly depress the voltage at the batteries at all. 

I too think his capacity is down to around  220Ah based on 97Ah removed to bring him down to 56% SoC. 

To get a better idea I think OP needs to repeat the exercise a few times, with varying discharge rates, and see how consistently the capacity equates to 220Ah. 

Lastly, the inner workings of SmartGauge are a self-correcting algorithm based on real-world testing of thousands of batteries over a period of many years. More than that is unknown. 

[nicknorman]

"Discharging at a rate of 2.5 to 3 amps per hour" loses you credibility!

[Dr Bob]

45 minutes ago, nicknorman said:

"Discharging at a rate of 2.5 to 3 amps per hour" loses you credibility!

I meant discharging at  2.5 amps over an hour. 

..........and to Tony, yes, the voltage numbers are not consistent hour to hour and much more data is needed. Fully agree he needs to do this more. 

9 hours ago, WotEver said:

Yes, because it will be.

Don’t forget that using only his SmartGauge OP got 8 years out of his previous bank.

One of the problems with your post above is that it has insufficient data points (and that the voltage is only indicated to one decimal point). Using OP’s figures the voltage was 12.2V for 7 hours, and that’s obviously incorrect. During those 7 hours he used 20Ah and the indicated SoC dropped by 4%, again this can’t be correct because it equates to a capacity of 500Ah. That’s the danger of using only a small data range. Your calculations state that he remained at 65% SoC for 7 hours whilst using 20Ah.

If he consumed 20Ah over 7 hours that’s a load of less than 3A which would hardly depress the voltage at the batteries at all. 

I too think his capacity is down to around  220Ah based on 97Ah removed to bring him down to 56% SoC. 

To get a better idea I think OP needs to repeat the exercise a few times, with varying discharge rates, and see how consistently the capacity equates to 220Ah. 

Lastly, the inner workings of SmartGauge are a self-correcting algorithm based on real-world testing of thousands of batteries over a period of many years. More than that is unknown. 

Algorithms are models and are 'trained' on a data set. If your data set is outside the training range the the model then they may not be correct. I am sure they can be calibrated wrong. Also lets get voltage to 2 Dec places. 12.29V to 12.20V is almost 10% of SoC. 

Edited October 23, 2017 by Dr Bob
Added a bit

[GeoffS]

Apologies for the data not being accurate enough. I was rounding the Voltages but realise now that 2 DP is needed and makes a big difference. However thanks to all your suggestions I think the conclusion must be that the batteries are depleted and therefore, in my opinion, were not fit for the intended purpose when bought 5 months ago. Whether the capacity now is 200 or even 300AH (and I appreciate I need better data to deduce this) is for me a little bit academic and I need to start a discussion with the supplier. How likely any success is I am doubtful and I may have to put this down as a very expensive learning lesson. Thanks again.

[Alan de Enfield]

10 minutes ago, GeoffS said:

How likely any success is I am doubtful and I may have to put this down as a very expensive learning lesson.

I think that you are unlikely to get much satisfaction from the battery supplier.

The guarantees tend to be to cover 'manufacturing faults' (cases split, terminals become disconnected etc.), claiming that they have lost 50% of their capacity after 5 months is unlikely to be down to manufacturing faults, and in their eyes, you could have done 'anything to them in that time' - maybe repeatedly taken them down to (say) 6 volts.

Had you taken the batteries back after (say) one week you may of had a case - but - it is possible to destroy batteries in a matter of days so it is always going to be 'a difficult one' to argue.

You have nothing to lose so you may as well try.

[MtB]

On 23/10/2017 at 09:25, GeoffS said:

I may have to put this down as a very expensive learning lesson. Thanks again.

 

A lesson we might all draw from this and that isn't often picked apart is the way different brands of lead acid batteries are more or less tolerant/susceptible to less than perfect charging. NN periodically comments on how pleased he is with the performance of his Trojans having previously used el cheapo batteries. Superficially both Trojans and el cheapos are the same type of battery (i.e. open cell lead acid) so why do they behave so differently?

I've also read people comment on here periodically about how pleased they are with their AGM batteries and how much better than LA they are, and I've yet to read any discussion of the reasons for these empirical reports. I find myself wondering if the OP's charging regime is actually less than optimum but his old AGMs, (and perhaps all AGMs) are tolerant and survived 8 years. But the new sealed LA batteries need looking after fr more carefully and the identical same charging regime has led to their rapid demise.

[Alan de Enfield]

3 minutes ago, Mike the Boilerman said:

 

A lesson we might all draw from this and that isn't often picked apart is the way different brands of lead acid batteries are more or less tolerant/susceptible to less than perfect charging. NN periodically comments on how pleased he is with the performance of his Trojans having previously used el cheapo batteries. Superficially both Trojans and el cheapos are the same type of battery (i.e. open cell lead acid) so why do they behave so differently?

I've also read people comment on here periodically about how pleased they are with their AGM batteries and how much better than LA they are, and I've yet to read any discussion of the reasons for these empirical reports. I find myself wondering if the OP's charging regime is actually less than optimum but his old AGMs, (and perhaps all AGMs) are tolerant and survived 8 years. But the new sealed LA batteries need looking after fr more carefully and the identical same charging regime has led to their rapid demise.

Good thoughts and valid questions.

[nicknorman]

27 minutes ago, Mike the Boilerman said:

 

A lesson we might all draw from this and that isn't often picked apart is the way different brands of lead acid batteries are more or less tolerant/susceptible to less than perfect charging. NN periodically comments on how pleased he is with the performance of his Trojans having previously used el cheapo batteries. Superficially both Trojans and el cheapos are the same type of battery (i.e. open cell lead acid) so why do they behave so differently?

I've also read people comment on here periodically about how pleased they are with their AGM batteries and how much better than LA they are, and I've yet to read any discussion of the reasons for these empirical reports. I find myself wondering if the OP's charging regime is actually less than optimum but his old AGMs, (and perhaps all AGMs) are tolerant and survived 8 years. But the new sealed LA batteries need looking after fr more carefully and the identical same charging regime has led to their rapid demise.

But in my case, I found my cheapo leisure batteries were down to 50% capacity after 6 months of leisure use.

So I got a new set of cheapo leisure batteries. After 6 months they were down to 50% capacity, although I discovered than kicking them with an equalisation charge did recover them temporarily until intervals between needed equalisation got closer and closer. I eked them out to 2 years but it was a struggle.

Then I got the Trojans and 4 years later, with no dramas, they are still at full rated capacity.

We have exactly the same usage and charging regime as we always did.

This is why I conclude that cheapo leisure (dual purpose) batteries aren’t fit for use as domestic batteries. It is all down to the plate materials and construction - dual purpose cheapo leisure are basically just starter batteries with thin plates designed to give 100s of amps for a few seconds, and lots of calcium to reduce water consumption.

Trojans have thicker plates with lots of antimony. Some relevant info here: http://batteryuniversity.com/learn/article/lead_based_batteries

Edited October 23, 2017 by nicknorman

[MtB]

On 23/10/2017 at 10:09, nicknorman said:

But in my case, I found my cheapo leisure batteries were down to 50% capacity after 6 months of leisure use.

So I got a new set of cheapo leisure batteries. After 6 months they were down to 50% capacity, although I discovered than kicking them with an equalisation charge did recover them temporarily until intervals between needed equalisation got closer and closer. I eked them out to 2 years but it was a struggle.

Then I got the Trojans and 4 years later, with no dramas, they are still at full rated capacity.

We have exactly the same usage and charging regime as we always did.

This is why I conclude that cheapo leisure (dual purpose) batteries aren’t fit for use as domestic batteries. It is all down to the plate materials and construction - dual purpose cheapo leisure are basically just starter batteries with thin plates designed to give 100s of amps for a few seconds, and lots of calcium to reduce water consumption.

Trojans have thicker plates with lots of antimony.

 

So the difference you report is down to the fact they are completely different batteries?

Could this not apply too in the case of the OP? 

[nicknorman]

OMG the Smartgauge truly is hopeless. This morning the AH gauge is showing 77% and the SG is showing 80%. Completely useless. I’m going to sue Gibbo for my missing 3%.

2 minutes ago, Mike the Boilerman said:

 

So the difference you report is down to the fact they are completely different batteries?

Could this not apply too in the case of the OP? 

Yes. I’d say that his previous AGMs were fit for purpose. “Dual” purpose leisure batteries, being basically starter batteries, are not fit for purpose as domestic batteries IMO. And with a stated life of 250 cycles to 50% SoC, they are not going to last long in a live aboard scenario even if they were perfectly looked after and did perform to that spec.

[nicknorman]

6 minutes ago, Mike the Boilerman said:

 

So the difference you report is down to the fact they are completely different batteries?

Could this not apply too in the case of the OP? 

Oh and in case you missed it, have a look at this link I added as an edit:

http://batteryuniversity.com/learn/article/lead_based_batteries

[MtB]

On 23/10/2017 at 10:16, nicknorman said:

OMG the Smartgauge truly is hopeless. This morning the AH gauge is showing 77% and the SG is showing 80%. Completely useless. I’m going to sue Gibbo for my missing 3%.

Yes. I’d say that his previous AGMs were fit for purpose. “Dual” purpose leisure batteries, being basically starter batteries, are not fit for purpose as domestic batteries IMO. And with a stated life of 250 cycles to 50% SoC, they are not going to last long in a live aboard scenario even if they were perfectly looked after and did perform to that spec.

 

So given the team seems to think the OP's new batteries are probably el cheapos in pretty boxes, this seems to be the root of the problem then dunnit.

Are all AGMs the same or are there big variations in internal design and construction, as there are in LA batteries? I'm wondering about buying some for my own boat next. Or is the answer contained in the link you just added? (I'll read it anyway, thanks.) 

[dmr]

40 minutes ago, Mike the Boilerman said:

 

A lesson we might all draw from this and that isn't often picked apart is the way different brands of lead acid batteries are more or less tolerant/susceptible to less than perfect charging. NN periodically comments on how pleased he is with the performance of his Trojans having previously used el cheapo batteries. Superficially both Trojans and el cheapos are the same type of battery (i.e. open cell lead acid) so why do they behave so differently?

I've also read people comment on here periodically about how pleased they are with their AGM batteries and how much better than LA they are, and I've yet to read any discussion of the reasons for these empirical reports. I find myself wondering if the OP's charging regime is actually less than optimum but his old AGMs, (and perhaps all AGMs) are tolerant and survived 8 years. But the new sealed LA batteries need looking after fr more carefully and the identical same charging regime has led to their rapid demise.

Need to choose words carefully here. Wot you mean is different types of batteries rather than different brands.

And as you know from first hand experience, the brand is often nothing more than the the label that the middleman sticks on a batch of generic batteries moments before he sells them.

My own experience is that Trojans are in a very different league to cheapo leisures of any brand. The only exception to this was the Elecsols which were not particularly cheap and in a league of their own for crapness.

I expect other brands of "Trojan" like Crown and US would be just as good, but not quite sure about Powerline as in general you get what you pay for.

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

[nicknorman]

9 minutes ago, Mike the Boilerman said:

 

So given the team seems to think the OP's new batteries are probably el cheapos in pretty boxes, this seems to be the root of the problem then dunnit.

Are all AGMs the same or are there big variations in internal design and construction, as there are in LA batteries? I'm wondering about buying some for my own boat next. Or is the answer contained in the link you just added? (I'll read it anyway, thanks.) 

I have no personal experience of AGMs but I get the feeling there is not a huge variation in design/construction/quality. But with my friends the Trojans sitting in the back, why would I have any interest in other types of batteries? Love is blind!

[MtB]

On 23/10/2017 at 10:34, dmr said:

Need to choose words carefully here. Wot you mean is different types of batteries rather than different brands.

 

No I chose carefully and meant 'brands'. Trojan, and the OP's Exide sealed are both brands of LA batteries are they not? And the less well informed reader of this board might see LA batteries mentioned constantly without differentiating between Trojans, Crown, Rolls etc and <all the rest>.

But then AGMs are also LA batteries, are they not? And the 'Trojan type' of battery is often sub-categorised as 'semi-traction' but to me that term is vague and muddled. My own Trojanoids are (supposedly) semi-traction yet people here sometimes think Trojans are a better brand of semi-traction than mine. So brand really does seem to be important.  

 

(Edit to re-choose my words more carefully!)

Edited October 23, 2017 by Mike the Boilerman

[dmr]

1 minute ago, nicknorman said:

I have no personal experience of AGMs but I get the feeling there is not a huge variation in design/construction/quality. But with my friends the Trojans sitting in the back, why would I have any interest in other types of batteries? Love is blind!

"On a boat everything is a compromise"

AGMs do appear to have some real advantages, but also some disadvantages, including the price. There are many ways to go boating and so for some boaters the balance must swing in favour of AGMs. 

I also can see few reasons to use anything except Trojans, though would be really tempted by 2v tractions if only they would fit in the space available.

At some point these new fangled Di-Lithium things full of electronics will be the way to go, but not just yet.

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

[nicknorman]

Mid-morning coffee (Nespresso machine) and a slice of toast (electric toaster) later, plus lazy daytime TV, we now have AH gauge on 73% and SG on 75%. Curses, I’ve had to phone my solicitor to change the law suit from 3% to 2%. But I’m definitely going to rip out the useless SG and replace it with something more accurate. Apparently seaweed is quite good. Or was that for the weather?

Edited October 23, 2017 by nicknorman

[dmr]

5 minutes ago, nicknorman said:

Mid-morning coffee (Nespresso machine) and a slice of toast (electric toaster) later, plus lazy daytime TV, we now have AH gauge on 73% and SG on 75%. Curses, I’ve had to phone my solicitor to change the law suit from 3% to 2%. But I’m definitely going to rip out the useless SG and replace it with something more accurate. Apparently seaweed is quite good. Or was that for the weather?

The Smartguage does appear to loose its way a little bit sometimes, then sorts itself out later. From what we know about how it works and what it says in the instruction book this is pretty much to be expected.

I let my batteries go a bit low again last week (38% !!!!!!!) and did feel it possibly went a little bit wrong down there, maybe because it does not get enough practice.

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

[Richard10002]

4 minutes ago, nicknorman said:

Mid-morning coffee (Nespresso machine) and a slice of toast (electric toaster) later, plus lazy daytime TV, we now have AH gauge on 73% and SG on 75%. Curses, I’ve had to phone my solicitor to change the law suit from 3% to 2%. But I’m definitely going to rip out the SG and replace it with something more accurate. Apparently seaweed is quite good. Or was that for the weather?

When you say Ah gauge, what do you mean? Is it something like a NASA BM2 SOC reading? Or are you taking Ah used reading and calculating SOC from your estimate of capacity?

The fact that you may have an incredibly accurate Smartgauge at all states of charge is fine but, if you read the manual, Gibbo makes it clear that it is not to be expected at all times.

Thus it is entirely possible that MtB and myself are right in what we now say, and it is entirely possible that you are correct in what you say about your particular Smartgauge on your particular system.

 

[nicknorman]

2 minutes ago, dmr said:

"On a boat everything is a compromise"

AGMs do appear to have some real advantages, but also some disadvantages, including the price. There are many ways to go boating and so for some boaters the balance must swing in favour of AGMs. 

I also can see few reasons to use anything except Trojans, though would be really tempted by 2v tractions if only they would fit in the space available.

At some point these new fangled Di-Lithium things full of electronics will be the way to go, but not just yet.

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

Yes it’s a pity Lithiums are still so pricy. But we did meet a chap on the KandA with lithiums (along with a very high tec boat) he was very pleased with them and whilst they are very expensive still, one of his points was that you get to use all the badged capacity and thus only need perhaps 1/2 the AH capacity that you would if they were LA, and also that with a big modern alternator like our 175A one, they take all that current (and a lot more) for charging for most of the charge period thus cutting right down on engine running time for continuous-moorer types. A 180AH lithium can be charged at up to 500A. Thinking about it, with our 175A alternator and Travelpower running the Mastervolt Combi 100A, I could pump 275A into one. That really would cut down charge time to say 1/2 hr a day for a light user.

2-boats MtB is rich, he should get one and try it out. It would certainly solve his problems!

[MtB]

On 23/10/2017 at 10:58, nicknorman said:

2-boats MtB

 

Err... do you know something I don't?

[dmr]

12 minutes ago, Mike the Boilerman said:

 

No I choise carefully and meant 'brands'. Trojan, and el cheapos are both brands of LA batteries are they not? And the less well informed reader of this board might see LA batteries mentioned constantly without differentiating between Trojans, Crown, Rolls etc and <all the rest>.

But then AGMs are also LA batteries, are they not? And the 'Trojan type' of battery is often sub-categorised as 'semi-traction' but to me that term is vague and muddled. My own Trojanoids are (supposedly) semi-traction yet people here sometimes think Trojans are a better type of semi-traction than mine. So brand really does seem to be important.  

 

I reckon there are broadly 4 "types" of lead acid battery.

Starter/car/leisure batteries    Thin plates, calcium, smallest shortest cells.

Semi Traction "Trojans"  Thicker plates, Antimony, bigger and taller cells (more reserve space for shedded crap). Usually 6 volt.

Traction. Even thicker plates? Antimony, very big and very tall cells. Always 2 volts

AGM, a few variants but the acid is not a free liquid but trapped in an absorbent material.

There are then various sub-types to these types, some with significant differences, and some "hybrids" like the 12 volt Trojans.

Each type has various brands.

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