Smart Gauge vs Nasa BM-1

[Gibbo]

I was just going to reply to a post with a reliable way of preventing amp hour counters going out of synch, but am disappointed to find all his posts have gone.

 

Well that would be useful information so why not start a new thread just on that subject?

[smileypete]

Well that would be useful information so why not start a new thread just on that subject?

All it needs is 2 things, a relay that comes on when the battery is under charge, and an extra shunt about 10x the resistance of the amp-hour counter's shunt.

 

Just connect the one side of the relay contacts and extra shunt together so they're in series. Then connect the other side of the relay contacts and extra shunt across the amp-hour counter's shunt.

 

Now when the battery is under charge, the relay will close and about 10% of the charge current will be diverted through the extra shunt, bypassing the amp-hour counter's own shunt. This will cause the amp hour counter to under read, by about 10%.

 

So when the amp-hour counter says 100% of the amp-hours have been returned, in fact 110% of the amp hours have been returned.

 

OK the amp hour counter's charge current reading won't be so accurate, but it's a small price to pay for an amp-hour count that doesn't drift the wrong way.

 

cheers,

Pete.

Edited March 1, 2011 by smileypete

[Chalky]

All it needs is 2 things, a relay that comes on when the battery is under charge, and an extra shunt about 10x the resistance of the amp-hour counter's shunt.

 

Just connect the one side of the relay contacts and extra shunt together so they're in series. Then connect the other side of the relay contacts and extra shunt across the amp-hour counter's shunt.

 

Now when the battery is under charge, the relay will close and about 10% of the charge current will be diverted through the extra shunt, bypassing the amp-hour counter's own shunt. This will cause the amp hour counter to under read, by about 10%.

 

So when the amp-hour counter says 100% of the amp-hours have been returned, in fact 110% of the amp hours have been returned.

 

OK the amp hour counter's charge current reading won't be so accurate, but it's a small price to pay for an amp-hour count that doesn't drift the wrong way.

 

cheers,

Pete.

 

You've just added in a correction for batteries ability to accept charge - this should already be in the software.

[MoominPapa]

You've just added in a correction for batteries ability to accept charge - this should already be in the software.

My Ah counter calculates this correction on-the-fly. It will tell you what it thinks it is (and allow you to set a fixed value.) When my last set of batteries were dying, this charge efficiency factor went sky-high (ie lots of energy going into the batteries was not coming out again (at least as electricity).

 

MP.

[churchward]

All it needs is 2 things, a relay that comes on when the battery is under charge, and an extra shunt about 10x the resistance of the amp-hour counter's shunt.

 

Just connect the one side of the relay contacts and extra shunt together so they're in series. Then connect the other side of the relay contacts and extra shunt across the amp-hour counter's shunt.

 

Now when the battery is under charge, the relay will close and about 10% of the charge current will be diverted through the extra shunt, bypassing the amp-hour counter's own shunt. This will cause the amp hour counter to under read, by about 10%.

 

So when the amp-hour counter says 100% of the amp-hours have been returned, in fact 110% of the amp hours have been returned.

 

OK the amp hour counter's charge current reading won't be so accurate, but it's a small price to pay for an amp-hour count that doesn't drift the wrong way.

 

cheers,

Pete.

Interesting but after reading all that I don't know why some folk find it hard to realise why many will opt for a Smartgauge with its simple wiring/fitting and accurate SOC.

[smileypete]

Interesting but after reading all that I don't know why some folk find it hard to realise why many will opt for a Smartgauge with its simple wiring/fitting and accurate SOC.

Or why not get one of these (cute!) and a basic ammeter.

 

Accurate SoC is only really important for telling when the batt is fully charged.

 

If you discharge a leisure batt to anywhere between say 40-60% SoC, yer still get yer moneys worth.

 

Now go and read p22 of the Smartgauge manual

 

cheers,

Pete.

Edited March 1, 2011 by smileypete

[Chalky]

Or build your own with an LM3914 and 10 LEDS. I bought a cheep LCD panel meter off ebay for £5 that runs off the voltage being sensed. More accurate and cheaper, but it only tells me volts...

[WotEver]

Now go and read p22 of the Smartgauge manual

Yup, read it. It finishes with...

Whatever happens, whenever SmartGauge “gets it wrong”, SmartGauge realises, corrects itself, and uses

the information to modify its battery models and algorithm. An amp hours counter simply “gets it wrong”,

does nothing about it, and runs further and further adrift from the true state of charge.

 

Tony

[Robin2]

Yup, read it. It finishes with...

 

Whatever happens, whenever SmartGauge “gets it wrong”, SmartGauge realises, corrects itself, and uses

the information to modify its battery models and algorithm. An amp hours counter simply “gets it wrong”,

does nothing about it, and runs further and further adrift from the true state of charge.

 

Tony

 

And when, exactly, while its making up its mind, do you switch your charger off?

[WotEver]

And when, exactly, while its making up its mind, do you switch your charger off?

Your charger's ammeter (or outboard ammeter) should be sufficient to indicate that. Alternatively, if you switch off your charger too early, SG will almost instantly show you the error of your ways by getting back into sync and showing a <100% SOC. So you'd just switch the charger back on for a while. After a very short time you'd soon get the hang of it.

 

Re-read JustMe's post about how it works for him with his very large off-grid setup.

 

Tony

 

I tried to paste the link, but this thread's broken (possibly because of all the deleted posts) - it's #120

Edited March 2, 2011 by WotEver

[Robin2]

Your charger's ammeter (or outboard ammeter) should be sufficient to indicate that. Alternatively, if you switch off your charger too early, SG will almost instantly show you the error of your ways by getting back into sync and showing a <100% SOC. So you'd just switch the charger back on for a while. After a very short time you'd soon get the hang of it.

 

 

 

Well "getting the hang of it" does not provide a means to automatically switch off the generator at the instant the battery becomes full whereas amp-hour counting would if returning 120% (or whatever percentage you prefer) of what you take out is sufficient.

Edited March 2, 2011 by Robin2

[smileypete]

Yup, read it. It finishes with...

 

Whatever happens, whenever SmartGauge “gets it wrong”, SmartGauge realises, corrects itself, and uses

the information to modify its battery models and algorithm. An amp hours counter simply “gets it wrong”,

does nothing about it, and runs further and further adrift from the true state of charge.

LMAO!

 

Remember The Gospel according to Gibbo, chapter 1, verse 3...?

 

'Amp Hour counters do not work!'

 

What it doesn't say is that for reasonably healthy batts at acceptance voltage, an ammeter gives an instant and definitive indication that the batts are fully charged, and only costs from around £15.

 

Why is Gibbo developing a Smartguage that also read amps? Because the current model gets it's SoC wrong at the time when accuracy is most important.

 

cheers,

Pete.

[WotEver]

LMAO!

 

Remember The Gospel according to Gibbo, chapter 1, verse 3...?

 

'Amp Hour counters do not work!'

Correct. I'm glad we're agreed on that.

 

AH Counters do not work.

 

Ammeters, however, are very useful devices, which is probably why they're incorporated into Gibbo's new device.

 

Tony

 

... amp-hour counting would if returning 120%...

or 110%, or 130%, or 140%, or 150%, or 160%, or 200% depending on the state of the batteries... how would you know?

 

Tony

Edited March 2, 2011 by WotEver

[Robin2]

Correct. I'm glad we're agreed on that.

 

AH Counters do not work.

 

 

You are being disingenuous. Even the Smartgauge website acknowledges that they will work if they are properly managed.

 

You will also see that the amp hours counter tells you they are full when they are empty, empty when they are full and all sorts of other rubbish unless you continually pay attention to the amp hours counter, reprogram it, reset it, test your batteries and reset Peukert's exponent etc.

 

or 110%, or 130%, or 140%, or 150%, or 160%, or 200% depending on the state of the batteries... how would you know?

 

Tony

 

I guess I was not as clear as I should have been. I meant returning 120% (for example) after drawing energy from a fully charged battery. In that case I would know the state of charge exactly.

[WotEver]

I guess I was not as clear as I should have been. I meant returning 120% (for example) after drawing energy from a fully charged battery. In that case I would know the state of charge exactly.

On the contrary, I think it was me that wasn't being clear.

 

You have some batteries. They're about 30 months old. You've taken out 100 amps. How much do you have to put back? How do you know the percentage? Where does this 120% example come from?

 

As the batteries age, so the percentage increases to an infinite number. Your 120% example eventually becomes 100% innaccurate. At least the current (sorry) SG is only ever a maximum of 10% out.

 

"getting the hang of it" does not provide a means to automatically switch off the generator at the instant the battery becomes full

Where is it documented that it does?

 

It also won't make your tea, get you out of bed in the morning, warm the cabin, or solve the meaning of life.

 

Tony

[RLWP]

<snip> or solve the meaning of life.

 

Tony

 

Damn! I shall have to buy an iPad instead then

 

Richard

[WotEver]

Damn! I shall have to buy an iPad instead then

 

Richard

Bill Gates reckons iPads get the maths wrong...

 

Tony

[boots]

Kettle & Pan???

 

http://support.microsoft.com/kb/934198 => "a calculation error may occur when you resume the computer from standby" (Windows Xp, 64 bit)

 

Martin

[Guest]

I can definitely see a lot of envy creeping in here against the SG.

[smileypete]

Correct. I'm glad we're agreed on that.

 

AH Counters do not work.

I was being tongue in cheek.

 

 

I can definitely see a lot of envy creeping in here against the SG.

I can definitely see a lot of misunderstanding of voltmeters, ammeters, amp-hour counters, and batteries. Particularly from 'the faithful'

 

And I've never seen a user manual that includes marketing information.

 

Whether you discharge a leisure batt to 40% or 60% SoC it just doesn't really matter. What matters is getting it fully charged regularly.

 

cheers,

Pete.

[WotEver]

Whether you discharge a leisure batt to 40% or 60% SoC it just doesn't really matter.

It does if you want to know if you can watch the telly or if you have to save/charge the batteries instead.

 

SWMBO wouldn't know one end of a voltmeter from another, but she could easily understand "Never take the batteries below 55% on the Smart Gauge".

 

And that's its purpose.

 

Tony

[bobtom]

On the contrary, I think it was me that wasn't being clear.

 

You have some batteries. They're about 30 months old. You've taken out 100 amps. How much do you have to put back? How do you know the percentage? Where does this 120% example come from?

 

As the batteries age, so the percentage increases to an infinite number. Your 120% example eventually becomes 100% innaccurate. At least the current (sorry) SG is only ever a maximum of 10% out.

 

 

Where is it documented that it does?

 

It also won't make your tea, get you out of bed in the morning, warm the cabin, or solve the meaning of life.

 

Tony

 

But would it tell me when to turn my fridge off?

 

My ammeter tells me that, when its running, my fridge draws 6amps. When I'm charging I turn the fridge up to full. When my ammeter shows that my charger is putting out 6amps then its time to turn the fridge off. If I dont then I'm just wasting energy.

 

Hope that all this makes sense.

 

Tom

[nb Innisfree]

I don't understand this obsession with charging to 100% SoC, truly fully charging a battery takes 24hrs or more, so if charging with an alternator or genny you are only going to get a nominal or symbolic full charge. If as we do you use partial state of charging i.e. stopping when acceptance voltage is reached and doing a 'full' charge once a week, deciding then when batts are full before turning charger/alternator off really is a waste of time, the best you can hope for is a long absorption and float which is only ever going to be 12 hours at the most (8am to 8pm) and in reality more like 8 hrs.

 

ETA: We used to charge until acceptance was reached but as batts are nearly knackered we have to spend most of our daily charging in absorption. In case of any confusion, 'acceptance' is the end of bulk charging phase

.

Edited March 2, 2011 by nb Innisfree

[WotEver]

Where is it documented that it does?

 

It also won't make your tea, get you out of bed in the morning, warm the cabin, or solve the meaning of life.

 

But would it tell me when to turn my fridge off?

[Guest]

I was being tongue in cheek.

 

 

 

I can definitely see a lot of misunderstanding of voltmeters, ammeters, amp-hour counters, and batteries. Particularly from 'the faithful'

 

And I've never seen a user manual that includes marketing information.

 

Whether you discharge a leisure batt to 40% or 60% SoC it just doesn't really matter. What matters is getting it fully charged regularly.

 

cheers,

Pete.

You are saying nothing new or original Pete.

 

As has been said by the faithful/satisfied customers more times than I care to recall(remember I don't have an SG, although I know people who have, and who fit them)they REMOVE THE NEED to understand voltmeters, ammeters blah blah. That was the design criteria. So simple a kid could understand it.

I could calculate the correct pressure for my car tyres, taking into account the shape,load, size, blah blah, but there is a chart and a machine at Asda that does it all for me for the sum of 20p. Because that is what people want, and that is what they are prepared to pay. That is what drives the market.

 

I don't know what your statement means "And I've never seen a user manual that includes marketing information." I assume this relates to the SG manual.

 

Having worked on fork lift batteries for a large part of my life, it may come as a surprise that I am aware of the need to recharge them fully and regularly!