Battery Condition Monitor

[chris w]

As stated in my original post, 'Alnwick' runs on a 24v setup and, as far as I can see, this equipment is designed for 12v systems. The 24v monitoring systems that I have found so far appear to be extremely expensive which is why I have now made the decision to buy a 'Smartgauge' which is competitively priced and appears to be relatively easy to fit.

The Smartgauge is great at doing what it's designed to do, but note that it doesn't measure current and so you will still need to install some shunts in addition.

 

Chris

[Roger Gunkel]

What would be the symptom if it's not? Having installed the NASA BM-1 my Victron's Low battery light has been coming on. Coincidence or problem with my installation, or likely problem with my batteries? The current being shown on discharge is just a few amps.

 

Can you just replace the 100 amp shunt with a bigger one?

 

The shunt that comes with the BM-1 should handle up to 650ah of battery bank. If you have more than that, then you are operating outside its design range, but what symptoms you would get I have no idea. What is your bank size?

 

Roger

[charles123]

Currently we have absolutely nothing, but I'd be interested in adding something if it were not silly money.

 

Whilst I acknowledge that Smart Gauge almost certainly attempts to do what no other monitor currently can, I'm an old fashioned soul who does like the comfort feel of actually seeing "net" amps going into or out of the battery, and to get an idea of how fast.

 

It seems a great shame that one has to buy multiple products in the £100 to £150 price range to achieve everything, but the fact that so many of you are saying you have SmartGauge plus A N Other seems to confirm that's the only way of doing it.

 

As I can't justify a £250 to £300 investment in battery and charging monitoring, my guess is we'll soldier on with none. As I've never had a flat battery in normal use, (famous last words !), and our charging seems to keep up with use, I guess we'll probably manage, but I appreciate things are very different for live-aboards who are not able to move much in the winter months.

 

Alan

 

Surely the Nasa has more functionality than the smartgage and is 30% cheaper and has shunt which smartgauge does not because it does not measure the amps going in or coming out which the NASA does

 

NASA does the following

The unit continuously monitors voltage, current (charge or discharge), number of amp/hours (charge or discharge), the batteries state of charge and the time to charge or discharge.

 

Smartgauge does

 

Battery state of charge (percentage) for main auxiliary battery bank.

 

* Battery voltage for 2 battery banks.

 

* Ultra low power consumption.

 

* User programmable alarms for low voltage, high voltage, low status etc

 

 

Charles

[chris w]

Surely the Nasa has more functionality than the smartgage and is 30% cheaper and has shunt which smartgauge does not because it does not measure the amps going in or coming out which the NASA does

 

NASA does the following

The unit continuously monitors voltage, current (charge or discharge), number of amp/hours (charge or discharge), the batteries state of charge and the time to charge or discharge.

 

Smartgauge does

 

Battery state of charge (percentage) for main auxiliary battery bank.

 

* Battery voltage for 2 battery banks.

 

* Ultra low power consumption.

 

* User programmable alarms for low voltage, high voltage, low status etc

 

 

Charles

The NASA does not measure state-of-charge (SOC), it measures ampere-hours (AH's). The Smartgauge measures SOC. These two measurements are not the same.

 

What you need ideally is the batteries SOC not the AH's. Any attempt to measure AH accurately will fail due to the complexity of the mathematics involved and the many variables. The Smartgauge takes no account of AH but measures the batteries' SOC through a different method directly. The method is proprietary but I believe I know what the method involves and it would indeed be far more accurate than measuring AH's.

 

The analogy is that on a car you have a fuel gauge which is effectively the SOC of the car. If instead you had a flow meter which told you the rate you were using fuel (equivalent to AH's) rather than the absolute amount left, then one can see that the latter is not as useful.

 

Chris

[Gibbo]

The analogy is that on a car you have a fuel gauge which is effectively the SOC of the car. If instead you had a flow meter which told you the rate you were using fuel (equivalent to AH's) rather than the absolute amount left, then one can see that the latter is not as useful.

 

That's a good analogy. We can extend that to show why amp hours counting is always going to fail..............

 

We have a 100 litre tank, it is empty, we put petrol into it and measure how much we put in, we measure in 95 litres.

 

We then measure how much goes out of the tank and into the engine.

 

Subtract one from the other and hey presto, we know how much petrol is in the tank. Dead simple.

 

The measurements will have an error of around 1%. So we actually put in somewhere between 94 and 96 litres. If it's 94, then after 60 or so fills the tank is actually only half full yet we think it is at 95 litres. That's close to a 50% error after 2 months liveaboard!

 

Then add in the following problems:-

 

The petrol tank shrinks as it gets older (battery capacity loss due to aging).

If we take the petrol out of the tank quickly we find that some petrol simply dissappears into thin air (Peukert's effect) so the amount removed from the tank is more than the amount we measure going into the engine.

A similar problem happens when filling up. If we fill up quickly and measure in 95 litres we find that some of it dissappears and the tank only has (say) 70 litres added to it.

If we regularly remove more than half the capacity of the tank we find that the tank shrinks even faster (accelerated aging due to exceeding the 50% rule).

If we put in 95 litres, then drain the tank into a bowl and measure it we find there is actually only 75 litres in there (charge efficiency).

The amount of petrol we can get out of the tank varies depending upon the outside temperature.

The amount of petrol we can get out varies depending upon how fast the tank was filled on each individual occasion over the last 6 months.

If we fill the tank up but then leave it sitting for a month, when we come back 15 litres of petrol have simply evaporated.

With all those problems (and they're really only the beginnings) it's a wonder that amp hours counters stand even a slight chance of working!

 

These are not hopeful "excuses" about why amp hours counters don't work. They are the result of researching them because they don't work in order to find out why and come up with something that does work.

 

Gibbo

[Roger Gunkel]

Surely the Nasa has more functionality than the smartgage and is 30% cheaper and has shunt which smartgauge does not because it does not measure the amps going in or coming out which the NASA does

 

NASA does the following

The unit continuously monitors voltage, current (charge or discharge), number of amp/hours (charge or discharge), the batteries state of charge and the time to charge or discharge.

 

Smartgauge does

 

Battery state of charge (percentage) for main auxiliary battery bank.

 

* Battery voltage for 2 battery banks.

 

* Ultra low power consumption.

 

* User programmable alarms for low voltage, high voltage, low status etc

 

 

Charles

 

I have no technical knowledge to agree or disagree with Gibbo or Chris, but have a great respect for the electrical knowledge of both of them.

 

What I will say is that NASA claim in their promotion and manual for the BM1 battery nonitor, that it shows current state of charge and time to charge/discharge at the current rate, in addition to ah and volts. My own experience with my BM1 is that the SOC indicated and time to discharge is reasonably accurate enough to give a practical guide for daily use, with my own experience roughly corresponding with the readings.

 

I have added this link to the BM1 on Nasa's site. NASA BM1 for those who want to look further. There is also a PDF manual .

 

Roger

[churchward]

As stated in my original post, 'Alnwick' runs on a 24v setup and, as far as I can see, this equipment is designed for 12v systems. The 24v monitoring systems that I have found so far appear to be extremely expensive which is why I have now made the decision to buy a 'Smartgauge' which is competitively priced and appears to be relatively easy to fit.

 

After Father Christmas was good enough to supply me with a Smartgauge this year I fitted it this week. It is as simple to install as Gibbo says on his website. For me I don't see myself wanting an amp/hr meter for current measurement, I don't want to fit shunts (being an electrickery novice I want to keep things simple) and a percentage charge tells me what I want to know i.e. "should I charge the batteries?" and "have I charged them enough yet?"

 

As I say wiring was straight forward and after fitting a blade fuse box it was a matter of running the 3 wires to the unit. I shall make use of the alarm function later so there will be other wiring to do at that point. I did go a bit over board with the thickness of the wire run as I only had 2mm squared to hand (being a tight wad I didn't want to buy more) to use but since Gibbos instructions say a "minimum of 1mm squared" I assume an excess makes no difference.

 

So far I am very pleased with it and I hope you will be too. It is simple in design but a very clever application.

 

If I had known about Smartguage etc when I bought my boat rather than recently I would have gone for the complete solution and fitted the Smartbank split charging system as well. However, I have a Sterling Alternator to Battery charger which the Smartgauge at least is demonstrating works in terms of getting the bank up to 100%

Edited January 2, 2009 by churchward

[Dutch]

I have no technical knowledge to agree or disagree with Gibbo or Chris, but have a great respect for the electrical knowledge of both of them.

 

What I will say is that NASA claim in their promotion and manual for the BM1 battery nonitor, that it shows current state of charge and time to charge/discharge at the current rate, in addition to ah and volts. My own experience with my BM1 is that the SOC indicated and time to discharge is reasonably accurate enough to give a practical guide for daily use, with my own experience roughly corresponding with the readings.

 

I have added this link to the BM1 on Nasa's site. NASA BM1 for those who want to look further. There is also a PDF manual .

 

Roger

 

Just how easy is this to fit?

[estwdjhn]

One question about a smart gauge - can you clear its memory to "start again".

 

Given that a boat's batteries only last so long, and when they die, the new set will be totally different, does it take a smartgauge a while to get used to new batteries, or does it reset in some way, automatic or manual.

 

I ask as one whose current battery monitoring consists of a voltmeter wired to a plug, and whose cabin batteries are currently cheepo starter batteries. Should I have any spare cash sloshing about at some point, I'm tempted to fit a Smart gauge, as it will probably either save me diesel or batteries (or maybe both). I'm keeping the starter batteries till they die, on the grounds that I've no other use for them, but when they go, I'll replace them with somthing actually intended for leisure use (I know thats another whole can of worms, but I'll leave that till the current set pack up).

[Gibbo]

One question about a smart gauge - can you clear its memory to "start again".

 

Yes. You just do a "reset to factory defaults" (details in the manual or ask me) which will turn it back to "as new - know nothing" status.

 

Given that a boat's batteries only last so long, and when they die, the new set will be totally different, does it take a smartgauge a while to get used to new batteries, or does it reset in some way, automatic or manual.

 

You can either reset it which puts it back to "as new" or you can just leave it and will learn the new batteries over the next few days (no matter how different in size). Might take up to 4 or 5 days but it will learn them. If you do a "reset" it will catch up within in about 24 to 48 hours depending upon how often you actually charge and discharge.

 

Gibbo

[Roger Gunkel]

Just how easy is this to fit?

 

I found it extremely easy to install, and my electrical knowledge is tentative at best, mainly learned from Gibbo's site. It basically involves taking the shunt to your battery earth terminal and connecting the earth lead to the other side of the shunt, then four simple connections to the meter. All the cables are supplied and the insructions are easy to follow. The instruction manual is available as a download at the link I posted previously.

 

Once the unit is installed, you need to enter details of your battery bank size, making allowances for deterioration due to age etc. You also need to zero the settings will all 12v units off, then switch something on for a few minutes to let it calculate whats going on. I needed to adjust mine for a few days as my batteries were poorer than I thought, but now I find it pretty accurate.

 

Roger

[Justme]

I'm tempted to fit a Smart gauge, as it will probably either save me diesel or batteries (or maybe both).

 

 

I dont want to put you off fitting a SmartGauge (I love mine) but I would bet that currently you are under charging your batts by a large margin & that fitting the gauge will INCREASE your charging costs, but your batts will work better & last longer.

 

Justme

[Dutch]

I found it extremely easy to install, and my electrical knowledge is tentative at best, mainly learned from Gibbo's site. It basically involves taking the shunt to your battery earth terminal and connecting the earth lead to the other side of the shunt, then four simple connections to the meter. All the cables are supplied and the insructions are easy to follow. The instruction manual is available as a download at the link I posted previously.

 

Once the unit is installed, you need to enter details of your battery bank size, making allowances for deterioration due to age etc. You also need to zero the settings will all 12v units off, then switch something on for a few minutes to let it calculate whats going on. I needed to adjust mine for a few days as my batteries were poorer than I thought, but now I find it pretty accurate.

 

Roger

[/quote

 

Thanks for that,i have seen both the smartguage and this one. To be honest i feel that the Smartguage is overpriced,i know it is a quality product but not 30% better than the NASA BM1

 

 

Mike

[Roger Gunkel]

Thanks for that,i have seen both the smartguage and this one. To be honest i feel that the Smartguage is overpriced,i know it is a quality product but not 30% better than the NASA BM1

 

 

Mike

 

I would make no claim that either is better or worse than the other, only that different people have different requirements.

 

I have never seen or used the Smartguage, but as it is built by Gibbo's company, I would expect it to be reliable and well made with good product support. However I felt that The NASA BM1 was more suited to my particular requirements with more of the functionality that I was looking for and also produced by a respected company. After many months of use I am still pleased, as I am sure are users of the Smartguage. Horses for courses

 

Roger

[Billypownall]

I would make no claim that either is better or worse than the other, only that different people have different requirements.

 

I have never seen or used the Smartguage, but as it is built by Gibbo's company, I would expect it to be reliable and well made with good product support. However I felt that The NASA BM1 was more suited to my particular requirements with more of the functionality that I was looking for and also produced by a respected company. After many months of use I am still pleased, as I am sure are users of the Smartguage. Horses for courses

 

Roger

With a 100 amp output limit am I right in thinking that the NASA BM1 cannot be fitted by me as we have a 3000 watt inverter which we use to it's limit at times ?

[chris w]

With a 100 amp output limit am I right in thinking that the NASA BM1 cannot be fitted by me as we have a 3000 watt inverter which we use to it's limit at times ?

Correct. You would need a 300A shunt minimum.

 

Chris

[Justme]

And a meter that will show / read 300amps.

 

You could just use the meter & a diff shunt but have to do a calculation to get the real reading from the meter.

 

Justme

[Big John]

And a meter that will show / read 300amps.

You could just use the meter & a diff shunt but have to do a calculation to get the real reading from the meter.

1) How do you decide what shunt is required?

2) Where could you get such a shunt?

[bottle]

I believe the shunt is matched to the meter ie. 300amp meter, 300amp shunt.

 

The shunt should be available from the same place as the meter.

[charles123]

Correct. You would need a 300A shunt minimum.

 

Chris

 

We are talking here about the capability of measuring current (that the smartgauge does not do). So if you want to see whats going into the bank at say different revs (eg so you can optimize the output of the alternator at certain revs for charging for example) or see what current you are drawing with your appliances in use (which the smartgauge does not do) so you can manage what current you are using eg turn things off. Then don't buy a smartgauge

 

The use of the BM1 to measure bank voltage (which gives you the state of charge of the bank) does not need a shunt (that's why the smartgauge does not have one) is not affected by having or not having a shunt (of any size)

 

Going back to your point. Would I be correct in saying when the inverter is in use the BM1 wont be able to measure the amps drawn however at other times when the inverter is not in use which is most of the time, it will be able to measure what is going into the battery bank (and out) assuming the alternators output does not exceed 100 amps?

 

I don't think we are comparing like with like here BM1 v smartgauge. It is claimed that the smartgauge does more accurately measure the state of charge, I don't know enough about boat electrics to say that is correct or not, if NASA rolled out its expert he may well argue that its method of measurement is no less accurate than the vendor of the smartgauge says

 

The BM1 is more functional, a lot cheaper, better presented (in my opinion) as easy to fit and has stronger company credentials

 

As always you pays your money and takes your choice

 

Charles

 

Charles

[chris w]

The use of the BM1 to measure bank voltage (which gives you the state of charge of the bank) does not need a shunt (that's why the smartgauge does not have one) is not affected by having or not having a shunt (of any size)

 

Charles

To repeat what I said above, the BM1 does NOT measure state of charge (SOC). It measures the ampere-hours (AH) used (or put back) and computes a state of charge from that info. This will be an approximation because measuring AH is fraught with inaccuracies due to battery chemistry and load.

 

The Smartgauge does NOT measure SOC by monitoring the battery voltage - that would require the batteries to be off-load for a few hours. It measures SOC accurately by another (proprietary) method. It can do this whether the batteries are on-load or off-load. In simple terms, it does this by measuring the batteries' internal resistance (although this is not the full story). This has a direct relationship with SOC regardless of load.

 

The Smartgauge does not measure current, so a shunt and ammeter will still be needed to monitor currents. If you read Gibbo's web pages you will understand why measuring AH's gets progressively more inaccurate against time whereas the Smartgauge gets progressively more accurate against time.

 

Chris

[Gibbo]

I will answer each point in turn...........

 

The BM1 is more functional,

 

Sort of agreed. The NASA measures current which SmartGauge does not. That is the only difference with regard to the NASA having more functions.

 

Against that you have to weigh in the fact that the state of charge shown by the NASA will NEVER be more accurate than SmartGauge and will often be so far off reality that it might as well not be there. This isn't speculation.

 

a lot cheaper,

 

30% cheaper. Depends on your definition of " a lot"

 

better presented (in my opinion)

 

You could well be right. It does look prettier.

 

as easy to fit

 

Not even close. The NASA is roughly 20 times more complex to install. Requires more (quantity) and more expesnive tools and equipment to install and is roughly 10 times more complex to set up and still doesn't work as well with regard to state of charge display.

 

and has stronger company credentials

 

I have no idea upon what you base that. Could you please provide details? It sounds like a personal opinion with nothing to back it up.

 

Gibbo

[carlt]

The BM1 has stronger company credentials

 

I have no idea upon what you base that. Could you please provide details? It sounds like a personal opinion with nothing to back it up.

 

Have you put a man on the moon?

Edited January 5, 2009 by carlt

[Gibbo]

Have you put a man on the moon?

 

 

Has America? I have lots of references that state quite categorically that they haven't. Admittedly the same people also swear blind they can get free energy from magnets, gravity wheels and water electrolysis.

 

(for those not paying attention it's a different NASA)

 

Gibbo

[PaddingtonBear]

Ok, the time has come for me to ' fess up'. Despite trying to fight the fight for the KISS wing of Canalworld, and having lost our spiritual leader to the clutches of Gibbo and his Smartguage clan and with pride coming before a fall I thought that I would test my batteries, you know the ones that I claimed could be charged in an hour. WELL I WAS WRONG, i USUALLY AM ,and my battery banks were both down to 11.69v which Moomin of the parish said is not good. I appears that manual changeover switch has not been working so both the banks were operating as one, no wonder that I could get them to last about 6 or so days!. Much to my embarasment I have plugged into the 240v and set my multistage charger to do its worst,for the first time in nearly 3 years. I shall not however be going over to the other side. My sympathies are very much in line with the thoughts of Alan Fincher and I would rather put the £300 towards my next set of batteries. What is a shunt anyway and what is its function?

Edited January 5, 2009 by PaddingtonBear