BMV, Smartgauge, ammeter....

[WotEver]

50 minutes ago, nicknorman said:

Yes there is a secret way to adjust the voltage reading. Since SG only measures voltage, once that is measured correctly the SG will be accurate

The disadvantage of performing a field calibration being that it will revert if you ever perform a factory reset. As long as you’re aware of that then you can of course calibrate it again. 

56 minutes ago, Dr Bob said:

If you have a naturally curious mind, then why not get a BMV which gives you voltage plus Amps and Amp hours used. Far more info to get your brain around? 

Perhaps because you’d like to know the true SoC of the bank as opposed to a wildly inaccurate guess?

 

A BMV (or similar) coupled with a Smartgauge gives the ideal monitoring for a LA bank imho. 

[cuthound]

But the accuracy of a BMV, or indeed any measuring instrument, will also depend upon it being in calibration.

 

There are many companies offering certificated meter calibration services, unfortunately none of them are cheap.

[Alan de Enfield]

10 hours ago, grahame r said:

How does one go about re-calibrating a Smart Gauge?

Take the cover off and 'bend the needle' until it points to the correct voltage.

[WotEver]

1 minute ago, cuthound said:

But the accuracy of a BMV, or indeed any measuring instrument, will also depend upon it being in calibration.

 

There are many companies offering certificated meter calibration services, unfortunately none of them are cheap.

But due to the way a BMV works you would have to have it recalibrated fortnightly, which you would be unable to do without first knowing the capacity of your batteries. (Which is time consuming and wasteful of energy unless you also have a Smartgauge...)

[Dr Bob]

6 minutes ago, WotEver said:

But due to the way a BMV works you would have to have it recalibrated fortnightly, which you would be unable to do without first knowing the capacity of your batteries. (Which is time consuming and wasteful of energy unless you also have a Smartgauge...)

......but that is only if you want to try and get an accurate SoC reading from the BMV. I never look at the SoC on my BMV. I used tail current to tell me when I am full, far better than the SG and then a combination of voltage and amps out to give me an indication of how much i had left in the batteries.

My comment about a naturally inquisitve mind was that ...that brain could deal with the info from a BMV. The SG is for people who dont think as much.

I repeat.....why do you need to know your SoC accurately other than when charging and the tail current tells you that and the SG doesnt.

Having both will give you all the info you need but it is a bit overkill for someone who can think it through.

[cuthound]

23 minutes ago, WotEver said:

But due to the way a BMV works you would have to have it recalibrated fortnightly, which you would be unable to do without first knowing the capacity of your batteries. (Which is time consuming and wasteful of energy unless you also have a Smartgauge...)

 

Only for the percentage SoC reading...

 

The amps and volts readings may or may not be  in calibration which will affect those readings, olus the amp hours used reading.

[MtB]

1 hour ago, WotEver said:

Perhaps because you’d like to know the true SoC of the bank as opposed to a wildly inaccurate guess?

 

Oh the irony!!

 

 

[Nightwatch]

You guys do this on poipoise don't you? Just to confuse.

 

i have a Victron 702 or something similar. Is that a BMV?

[Dr Bob]

5 minutes ago, Mike the Boilerman said:

 

Oh the irony!!

 

 

....but if you use an iron, the BMV will be a benefit as you can see how much current you will be running.

[MtB]

21 minutes ago, Dr Bob said:

I repeat.....why do you need to know your SoC accurately

 

Basically, the SG is only of any use to tell you when you need to start re-charging your batteries. As is often pointed out here, it is of no help at all in determining when they are fully charged, regardless of whether it is correctly calibrated or not.

 

And to know when to start charging does not require any degree of accuracy. 

 

So overall, a correctly calibrated SG is about the same amount of use as a wrongly calibrated one.

 

 

[Dr Bob]

1 minute ago, Nightwatch said:

You guys do this on poipoise don't you? Just to confuse.

 

i have a Victron 702 or something similar. Is that a BMV?

Yep.

[MtB]

3 minutes ago, Nightwatch said:

You guys do this on poipoise don't you? Just to confuse.

 

i have a Victron 702 or something similar. Is that a BMV?

 

I think it might be. Or there again maybe not.... I can't remember.

 

Hope that helps

[Nightwatch]

4 minutes ago, Dr Bob said:

Yep.

Oh! Thank you. 

Is this a good thing to have. I always wanted a smartguage, but was overruled by the electrician who 'did' our engine ole rewire. Concerned about 'expert' set up and regular resetting.

 

I use it mainly to ascertain charging amps going in. Amp hrs used as a guide. And voltage in each bank as knowledge.

2 minutes ago, Mike the Boilerman said:

 

I think it might be. Or there again maybe not.... I can't remember.

 

Hope that helps

As always!!

Edited June 15, 2019 by Nightwatch

[MtB]

44 minutes ago, WotEver said:

But due to the way a BMV works you would have to have it recalibrated fortnightly, which you would be unable to do without first knowing the capacity of your batteries.

 

This is massively over-exaggeratifying the problem with a BMV.

 

Yes batteries gradually reduce in capacity over time, but for a user using it to watch tail current and resting voltage to determine when to start and stop charging, this is not relevant, so it would not need recalibrating fortnightly, or ever. 

 

 

[Nightwatch]

Phew!

[WotEver]

26 minutes ago, Mike the Boilerman said:

 

This is massively over-exaggeratifying the problem with a BMV.

 

Yes batteries gradually reduce in capacity over time, but for a user using it to watch tail current and resting voltage to determine when to start and stop charging, this is not relevant, so it would not need recalibrating fortnightly, or ever. 

 

 

Only if you wish to ignore the gurt big SoC reading.

 

What’s the point of having a readout that you don’t ever look at because it’s so wildly inaccurate? How many times have we read “I regularly get my batteries up close to 90%” when they do no such thing because they’ve believed the BMV?

1 hour ago, Dr Bob said:

I repeat.....why do you need to know your SoC accurately

I repeat... so that you have an accurate idea of where the batteries are prior to recharging. 

 

 

Edited June 15, 2019 by WotEver
Insert a ?

[gbclive]

11 hours ago, Mike the Boilerman said:

Aha, two more peeps come out of the woodwork with dodgy smartgauges!!

Very droll Mike?

In my case, I guess it’s just that with the knowledge that there was a period of poor quality control in the calibration of SG’s, I’d like to increase my confidence that mine is OK.

I suppose the obvious step for me is to beg, borrow or steal a certified voltmeter - if the results confirm mine is accurate, then no need to go any further.

 

Incidentally, thanks to knowledge gleaned here, I think I have an effective monitoring setup and a basic understanding on each gauge’s strengths and limitations.

So BM1 for charging tail current and also overall charge or drain on the domestic batteries.

MT5 for setting up the Tracer MPPT solar controller and general amusement.

SG for approx SOC when no charging is occurring.

 

 

 

 

[Dr Bob]

Smartgauge will become redundant once Li's become common.?

[Alan de Enfield]

7 minutes ago, gbclive said:

 

 

 

Your BM1 would suggest that you have 0.5 amps charge at 13.7 volts.

 

The MT50 would suggest that you have 5.4 amps charge at 13.8v

 

Questions ????????

[WotEver]

1 minute ago, Dr Bob said:

Smartgauge will become redundant once Li's become common.?

Of course it will. It was designed for LA banks. 

[Tony Brooks]

11 minutes ago, gbclive said:

Very droll Mike?

In my case, I guess it’s just that with the knowledge that there was a period of poor quality control in the calibration of SG’s, I’d like to increase my confidence that mine is OK.

I suppose the obvious step for me is to beg, borrow or steal a certified voltmeter - if the results confirm mine is accurate, then no need to go any further.

 

Incidentally, thanks to knowledge gleaned here, I think I have an effective monitoring setup and a basic understanding on each gauge’s strengths and limitations.

So BM1 for charging tail current and also overall charge or drain on the domestic batteries.

MT5 for setting up the Tracer MPPT solar controller and general amusement.

SG for approx SOC when no charging is occurring.

 

 

 

 

 

 

Only if you mean amps in and amps out. No if you mean Ah in.

[gbclive]

11 minutes ago, Alan de Enfield said:

Your BM1 would suggest that you have 0.5 amps charge at 13.7 volts.

 

The MT50 would suggest that you have 5.4 amps charge at 13.8v

 

Questions ????????

Good question Alan - the fridge draws 3 or 4 amps when the compressor is running and I’m guessing that there were some other small loads to make up the difference in current. My BM-1 is set up to measure the net figure.

However the 0.1 volt difference is another reason I would like to confirm voltage accuracy.

20 minutes ago, Tony Brooks said:

Only if you mean amps in and amps out. No if you mean Ah in.

Yep - sorry if sloppy terminology.

 

[Tony Brooks]

3 minutes ago, gbclive said:

Yep - sorry if sloppy terminology.

 

I guessed you meant that but a newby might not and I don't think one can risk undermining the "ignore Ah in and percentage of charge" message. As the other  Tony said, how often do we read about battery problems when the boater is relying on the percentage charged readout.

[Bod]

Just to be awkward. 

A Smartguage creates the State of Charge, by comparing the rate of change of voltage, over time. 

Does the volt meter need to be totally correct, or would the same result be obtained by a meter that was consistently different over its range?

I guess that the only person to know would be Gibbo. 

 

Bod

[WotEver]

2 hours ago, Bod said:

Does the volt meter need to be totally correct...

Yes.