Mastervolt BTM-iii not accurate

[Maine Sail]

Originally Posted by sailinglegend

The best advice on how and why SmartGauge works comes from the inventor Chris Gibson who I quoted in part above. Here is the link to his FULL post from 2005 on Battery Monitors and SmartGauge. MainSail's post is a very good independent test of the product.

Smartbank battery management - Page 2
post number #42

Be very careful interpreting what Chris said. I have had o-scopes on the Smart Gauge and not seen or now recorded anything out of the ordinary. It is essentially database driven with a learning algorithm. They work remarkably well... Just too bad there is no database inside it for LiFePO4, because then I could round file my Link-Pro....

[exMaggieDrum]

Originally Posted by Maine Sail

Be very careful interpreting what Chris said. I have had o-scopes on the Smart Gauge and not seen or now recorded anything out of the ordinary. It is essentially database driven with a learning algorithm. They work remarkably well... Just too bad there is no database inside it for LiFePO4, because then I could round file my Link-Pro....

I hope I am not violating some major internet etiquette rule in copying from the ybr.com forums as referenced by Maine Sail here. But I got the most from this post by Chris Gibson there Smartbank battery management - Page 5:

"You may recognise my name.

James Hortop alerted me to this thread and forum. I felt it fair to present some further information from my side which may help clear a few things up.

This won't come in any particular order of importance.

I do not discount the use of amp hours counters. I use one on my own boat. Whilst I (being of a technical bent) can understand it and get the best from it, my girlfriend and children cannot. To them, the device is useless, they simply cannot understand what it is telling them, let alone how to correctly set the device up. They would be left completely in the dark (perhaps literally) if the device ran out of sync.

I am not new to this business. I ran (in fact owned) the UK technical service centre, and the central technical point for all of Europe, for Heart Interface and Cruising Equipment (manufacturers of the Link 10) for over 10 years and spent a great proportion of such time giving technical support to owners of the entire range of Cruising Equipment amp hours counters, from the original amp hour plus right through to the Link 2000R.

It became very apparent, very early on, that for many people these devices were of no use whatsoever. The problem of them running out of sync with the batteries is not a *theoretical* problem that may *sometimes* happen, it is a very *real* problem that causes *huge* problems for a *huge* number of users.

During my time giving this technical support I looked very carefully into the reasons for the amp hours counters running adrift.

The reasons are many, far more numerous than "not setting the unit up correctly initially" or "not fully recharging". Here I list just a few of them.....

Peukert's effect makes a huge difference to the results these devices give. Peukert's exponent changes throughout the life of a battery. Initially, during the first few tens of cycles it decreases. It then stabilises for a few tens of cycles, it then starts to increase. So unless tests are done regularly to calculate the new Peukert's exponent, the amp hours counter will begin to run adrift.

As batteries age, their capacity falls. Amp hours counters cannot track this. So after 3 years of use, your amp hours counter may tell you that you are regularly discharging your 600 amp hour battery to 300 amp hours (50% capacity - the sensible limit). Whereas in actual fact you are discharging your (now tired) 400 amp hour battery bank to 25% thus greatly accelerating it's eventual death. The non technical person will be clueless about this problem.

Charge efficiency is apparently a simple concept: amps out/amp in *100. In practice this doesn't work. The results are different for the same battery depending upon the discharge current and/or the charge current. Different charge efficiencies can be got from the same battery simply by varying the charge or discharge current.

As the charge efficiency is used by the amp hours counter to calculate recharge profiles, you will see that the *ideal* recharge count-up will be at varying rates depending upon the discharge rate. In pratice it will be the same for each cycle and therefore incorrect.

There is an effect similar to Peukert's effect during charging (charging at 40 amps does *not* return twice as much energy as charging at 20 amps - it returns less). Unfortunately, unlike Peukert's effect, there is no way to calculate it's effects. The effects can be measured, but they cannot be predicted.

These are just a few of the many problems that cause amp hours counters to run adrift.

It really is a *major* problem for *many* people.

Technically minded people are probably happier with, and more suited to using, a fully fledged, Peukert corrected amp hours counter such as the later Link 2000 (early units were not Peukert corrected) or a Link 10, DCM600 E-501 etc etc etc.

Non technically minded people have a *very* low success rate with these devices.

Fleet vehicle users have tried amp hours counters but the learning curve is simply too long and complicated for them. The problem of running out of sync unless *everyone* involved in the installation *and* use of the equipment is educated in it's use makes them no use whatsoever to these people. Likewise hire boats.

SmartGauge is aimed at these people. It is not aimed at technically minded people who, as I say above, would be much better off with an amp hours counter.

However not everyone is technically minded, not everyone has the time to learn the intricacies of an amp hours counter and not everyone can be bothered. And those that are not, may still want to know "how much power is left". For these people, SmartGauge is ideal. These are the people SmartGauge is aimed at.

And, as testified by James Hortop, the device does indeed work. And it cannot run out of sync, which is the main problem the device was designed to avoid.

As the device is aimed at people who either do not have the technical knowledge required for efficient use of an amp hours counter, or perhaps people who simply can't be bothered with all that, it was decided that simplicity and speed of installation was also an important factor. Hence the shuntless design.

The people SmartGauge is aimed at are not interested in "what is my charge rate?" or "how much power does my fridge use?". Just like I am not interested in how fast a petrol pump fills my car up. They and I are interested in "how much is left?"

SmartGauge is not a "fancy voltmeter". It is a battery state of charge meter.

SmartGauge does and will display the charge status during charging. It cannot do this to better than a guaranteed accuracy of 10%. We state this on the website because we are honest. In practice 2 or 3% is usually the achieved figure but we cannot guarantee this. Amp hours counters can be out by *much* more than this during recharge. Several hundred amp hours adrift after just 5 or 6 cycles is *not* exaggerated speculation. It is fact. I have been involved in the supply, manufacture and design of amp hours counters for over 15 years, it is a *very* well known problem within the industry.

My own Link 2000R is setup perfectly yet during recharge it is not uncommon to see a recharge from, say, - 200 amp hours up to -30 amp hours, then the counter reset to zero because the Link has detected the charge parameters being met. This equates to an error at the end of the charge cycle of over 15%

Conversely I also regularly see the meter reach 0 amp hours yet still there is a quite heavy charge current flowing. This is the same error but in the opposite direction.

During cruising, or vehicle use, it is a very common situation for the batteries to not reach a fully charged state for, sometimes, weeks on end. When this happens, the amp hours counter can *easily* run adrift by twice the capacity of the battery bank in 3 weeks. Again, this is not speculation, this is the result of many years of involvement, design and tests with these types of units.

As to the matter of "value for money". Well again, that depends upon the user. If an amp hours counter simply does not work for a non technical user yet a SmartGauge does, then which represents the best value?

You have to remember that not everyone understands volts, amps, amp hours, Peukert, charge efficiency etc. And for those that don't, an amp hours counter will not do what they require of a battery monitor. i.e. it will not tell them the state of charge of their batteries.

Obviously I am not prepared to disclose how SmartGauge works. Anyone who asks me to do so is simply being totally unreasonable.

But to say that only voltage can be measured via 2 wires is *completely* incorrect.....

Pull a brief current pulse from the battery and measure the voltage drop, this will give an indication of internal resistance.

Present an AC voltage across the battery and measure the phase angle and amplitude of the resultant current. This will show the AC impedance of the battery.

Do the same thing with a wide variety of frequencies and analyse the results. This is know as AC impedance spectrography.

These are very well known methods of battery measurements. They all involve "2 wires". There are *many* more that can be made with 2 wires.

SmartGauge is brand new technology. And there is always severe resistance to anything that breaks new ground. Everyone we approach with the device has the same reservations..... "it can't work". The fact is it does work.

Merlin Equipment made the same comment initially "yea yea yea, two wires, won't work". After testing the unit for some considerable time John Hortop's (James' father) response to me was ".... and the SmartGauge, well, that's bloody brilliant"

The trade customers who have bought units have all been back and bought more. The few end users who have bought it have all reported that they are happy with the results.

SmartGauge was launched at the beginning of september so it is relatively new on the market. A very small number have been sold, roughly 160 units. This is in addition to the 48 units that remain in the field from the beta testers. None have reported that the device doesn't work or that there are any problems.

For clarification, SmartGauge is not aimed at technically minded people. They can get along quite happily with an amp hours counter. Even when the unit runs out of sync, an experienced user can usually know this from the voltage and current readings. A non technical user cannot.

Non technically minded people have a very low success rate with amp hours counters. This is a fact. It isn't speculation. SmartGauge addresses that issue.

Just because someone is not technically minded, does not mean that they are not entitled to know how much power they have left in their batteries. Just because someone owns a boat or RV, or drives an ambulance does not mean they will be technically minded.

If I didn't know there was a market for SmartGauge I would not have wasted my time and money developing it. I would have made yet another amp hours counter (I have designed 2 in the past) followed by hundeds of hours on the 'phone explaining why it has run out of sync.

Of course, the ideal solution, to suit everyone, would be an amp hours counter, using the SmartGauge algorithm to put right the deficiencies of the amp hours counter.

Now I wonder..........

As to comments regarding the website, if someone wishes to make *constructive* comments or correct any technical issues I will be more than happy to listen. To make comments such as "long winded diatribe" to me just sounds like a euphemism for "I couldn't understand it" or "I couldn't be bothered reading it" or perhaps "I have a hidden agenda for slandering this device". Of course, I may be wrong, it may simply be genuine suspicion due to the sheer number of useless equipment that is often peddled.

If that is the case, then I can understand some of the coments. However to state "is simply a fancy voltmeter" without any experience of the device is, I believe, rather unfair. Not to mention, technically, totally incorrect.

As far as I am aware, there is no information on the website that is technically incorrect. Of course I am human and may have made mistakes. But I certainly would not tell lies about matters technical. My wages depend upon my technical knowledge. If I was seen to be incorrect in such matters, I would soon have problems with some of my large commercial customers.

As to alternator controllers not being required on modern installations, if you read the entire article, and think carefully about it, you will see that what is said is, indeed, correct. As James Hortop testifies.

And I agree that I should change the sentence "split charge diodes do not work" to "split charge diodes do not work properly". Because they don't.

As I said, constructive criticism is more than welcome. I would greatly appreciate it.

Thankyou for taking the time to read this.

Chris Gibson"

I just checked the price at my chandlery, and with a significant discount the Smartguage is well over $300. And it is a pretty ugly panel IMO. I have not been a fan of other SOC meters for all the (ad nauseum) reasons that Chris states in the above post. I am NOT going to go out and buy the Smartguage. I MIGHT recommend that someone else consider it for their boat. I will continue to use my own volt/amp meter to monitor my own batteries just as Chris says is entirely OK and accurate - provided you understand what is happening. Based on Chris' experience alone, he should know more about what he is talking about than any other person I have run into in a long while. BUT - he invented the Smartguage, owns the company/patents (I presume) so I would still take all his comments about how well it works with a huge grain of salt. I do take his word that he is a 100% honest person but.... I have had very good luck with Balmar products otherwise. I do wish there was some scientific/engineering explanation that could be given for how the meter works, as well as some unbiased reviews as to how well they work.

[Mark Thurlow]

For a start we should thank Chris and people like him for their input. So thank you.

However returning to the Mastervolt BTM-iii:

I have ( or rather had) a similar problem with another similar Mastervolt meter

Some one said " see what the batteries say and see if this is the reading coming to the back of the meter" - this is volts I am talking about here. My results were different and I traced the problem to loose and incorrect wiring. Once this was solved and everything was running from one circuit of batteries (I had 5) I tested the output from the +ve and -ve ends of the battery circuit at the batteries (the shunt) and then direct with a new wire to the back of the meter and the readings were the same.

Next I rebooted the meter by removing the power from the terminal at the meter (term 1 I think but check the manual). Once powered up again and connected to the shunt at the batteries I was reading volts correctly.

Amp hours you have had covered by many but again bottom line is charge the batteries fully and then reset the meter taking account of the age and state of the batteries to give you a realistic starting figure of total amps ie if new give them the manufacturer's amph if 3 years old maybe a lot less!

Hope that helped.

BTW Mastervolt's help desk was brilliant in the UK.. have you tried the US one?

Mark

[Stu Jackson]

In addition to Maine Sail's fine website, try this:

For everyone installing a battery monitor: The "Gotcha Algorithm" thread, a "MUST READ"

Link-series Charging Algorithms -- The "Gotcha" Factor!

DEFAULTS are factory settings that are made to be modified to suit your setup.