Leisure Battery bank connection, SmartGauge and cables.

[Skye]

Isn't that arguing?

Yes you're right and I was wrong! I modified by post on the previous page. However mine is connected as I said, and seems to work fine. I suppose in reality with big interconnect leads (we have 70mm2) it probably doesn't make any difference.

 

I wonder why I connected it as I did, using the full installation/owners manual? Unfortunately that doesnt seem to be available on the internet and my copy is on the boat. I'll check when I get there at the weekend, though I'm probably clutching at straws!

 

The owners manual is the best bet the answer the none argument! ;o)

 

I think in reality yours will work quite fine unless you had a cell problem on the particular bat you have it coupled too.

Having said that, although it looks a good bit of kit, I doubt it would detect a problem with an individual cell in a bank.

[GUMPY]

The owners manual is the best bet the answer the none argument! ;o)

 

I think in reality yours will work quite fine unless you had a cell problem on the particular bat you have it coupled too.

Having said that, although it looks a good bit of kit, I doubt it would detect a problem with an individual cell in a bank.

 

It does in a round about way.

My daily consumption was always around 20% suddenly it went up to 35% nothing had changed in my routine.

Found I had a duff cell

 

Same when the batteries were ageing when new 20% after 5 years 25-30% again nothing had changed in my routine.

I did have one of the prototypes so been using them for a long time.

[Skye]

It does in a round about way.

My daily consumption was always around 20% suddenly it went up to 35% nothing had changed in my routine.

Found I had a duff cell

 

Same when the batteries were ageing when new 20% after 5 years 25-30% again nothing had changed in my routine.

I did have one of the prototypes so been using them for a long time.

 

Then you are using personal knowledge to interpret the reading. Perhaps future versions, and I have been led to believe one is due out, will have this built in. But we are now getting into diagnostics not just monitoring.

[Barry]

Not far out but that does not include the insulation so for H07 50 is about 15mm od and 70 is about 20, it varies of course depending on the cable type and insulation

 

Thanks Julian

 

My 10mm and 8mm diameter cable was the size of the copper cable ignoring the insulation

[Richard10002]

My SG works pretty well, although I did feel it was under-reading when the bats were very cold. This was with light loads on so with 70mm2 interconnect cables I can't see that it would make any difference. It would be easy to move the wires though and see if its makes any difference. But I'll check the full manual first!

 

How do you know that the SG "works pretty well"?

 

Unless you have something calibrated and accurate to compare it to, you are really only "feeling" that it works pretty well - aren't you?

 

I'm not being argumentative..... Merely wondering. Lots of people say that their SG works really well, but how do they know?

[Paul C]

What I'd like to know, is how Smartgauge works so well given that it measures one variable (voltage), where other meters measure 2 variables (voltage and current) to calculate their estimation of state of charge.

Edited March 18, 2013 by Paul C

[Skye]

How do you know that the SG "works pretty well"?

 

Unless you have something calibrated and accurate to compare it to, you are really only "feeling" that it works pretty well - aren't you?

 

I'm not being argumentative..... Merely wondering. Lots of people say that their SG works really well, but how do they know?

 

Well I feel my monitor is working ok, because I can read this, and I feel my key board is working ok, because I'm typing. I can not be sure the mouse will work until I click Add Reply not having anything calibrated to test it against

[Paul C]

Well I feel my monitor is working ok, because I can read this, and I feel my key board is working ok, because I'm typing. I can not be sure the mouse will work until I click Add Reply not having anything calibrated to test it against

 

So you're happy with the basic perception that the charge seems to be what you think it should be? In the same way, that your monitor is okay because its showing the stuff on the screen as you'd expect it; and the keyboard works because when you hit the keys, the letters/numbers etc appear on the screen? And the mouse works because when you move it, the pointer moves around the screen and stuff can be clicked?

 

Not challenging you - just saying that perception is everything!

[Skye]

So you're happy with the basic perception that the charge seems to be what you think it should be? In the same way, that your monitor is okay because its showing the stuff on the screen as you'd expect it; and the keyboard works because when you hit the keys, the letters/numbers etc appear on the screen? And the mouse works because when you move it, the pointer moves around the screen and stuff can be clicked?

 

Not challenging you - just saying that perception is everything!

I'm absolutely certain you talking to the wrong person!

[GUMPY]

What I'd like to know, is how Smartgauge works so well given that it measures one variable (voltage), where other meters measure 2 variables (voltage and current) to calculate their estimation of state of charge.

If you knew how it worked you would understand.

I do have a fair idea but you will have to work it out for yourself.

Its all down to battery behavior

[Pretty Funked Up]

Its all down to battery behavior

 

and doing feck loads of testing to find out for sure

[nicknorman]

How do you know that the SG "works pretty well"?

 

Unless you have something calibrated and accurate to compare it to, you are really only "feeling" that it works pretty well - aren't you?

 

I'm not being argumentative..... Merely wondering. Lots of people say that their SG works really well, but how do they know?

I also have a Mastershunt which, in case you didn't know, is an amp-hour counting sort of device. So the SG gives the SoC relative to the current battery capacity, the MS gives the SoC relative to the declared capacity not the actual capacity. So it's interesting to compare them and I have found that, with new batteries, they are fairly close. The only thing I have found is that when the batteries are very cold (the sit on the swim with just a fairly thin bit of wood between) the SG tends to under read, especially at first. It can go from 100 to 90% in a couple of hours with light loads, whilst the MS is still at say 98%.. However, by 50% they are both pretty close to each other (within say 5%).

 

Since they both have their own, different, sources of inaccuracy, it seems likely that the true answer lies somewhere between the two, and that gets me pretty close to the right answer.

[GUMPY]

I also have a Mastershunt which, in case you didn't know, is an amp-hour counting sort of device. So the SG gives the SoC relative to the current battery capacity, the MS gives the SoC relative to the declared capacity not the actual capacity. So it's interesting to compare them and I have found that, with new batteries, they are fairly close. The only thing I have found is that when the batteries are very cold (the sit on the swim with just a fairly thin bit of wood between) the SG tends to under read, especially at first. It can go from 100 to 90% in a couple of hours with light loads, whilst the MS is still at say 98%.. However, by 50% they are both pretty close to each other (within say 5%).

 

Since they both have their own, different, sources of inaccuracy, it seems likely that the true answer lies somewhere between the two, and that gets me pretty close to the right answer.

Try connecting SG as it should be and then reevaluate, even though you have 70mm cables there is a loss at every junction.

[Paul C]

If you knew how it worked you would understand.

I do have a fair idea but you will have to work it out for yourself.

Its all down to battery behavior

 

I don't have to work it out for myself, I can go to a shop and buy a Victron battery monitor instead. If Smartgauge uses some novel technology above & beyond being a voltmeter + some 'clever' algorithms (eg high frequency AC injection) then it ought to tell its prospective customers of this technology as good marketing. Making customers work out for themselves if/how something works, is not the right way to win them over!

 

As yet, my money is still in my hands rather than having bought a smartgauge. I'll stick with the basic voltmeter + ammeter combination until the Mk2 Smartgauge comes along (if Smartgauge is so great without a shunt, how come the Mk2 has a shunt?) and at that point I'll take a detailed look at its claims, see if they're plausible, and compare its specification and price with competitors.

[Grace and Favour]

I don't have to work it out for myself, I can go to a shop and buy a Victron battery monitor instead. If Smartgauge uses some novel technology above & beyond being a voltmeter + some 'clever' algorithms (eg high frequency AC injection) then it ought to tell its prospective customers of this technology as good marketing. Making customers work out for themselves if/how something works, is not the right way to win them over!

 

As yet, my money is still in my hands rather than having bought a smartgauge. I'll stick with the basic voltmeter + ammeter combination until the Mk2 Smartgauge comes along (if Smartgauge is so great without a shunt, how come the Mk2 has a shunt?) and at that point I'll take a detailed look at its claims, see if they're plausible, and compare its specification and price with competitors.

 

Maybe you would also have discouraged Herr Benz from developing his vehicles because they weren't perfect?

[Paul C]

Maybe you would also have discouraged Herr Benz from developing his vehicles because they weren't perfect?

 

Eh? What am I discouraging? Plenty of people want/need a device such as smartgauge, which is simple to connect (compared to fitting a shunt) and which gives the one thing they're after - the state of charge. As I see it, on this forum there is much support for Smartgauge so you'd need to conclude that its pretty successful.

 

I'm prepared to (well, already have) fitted a shunt so I can replace it with another if needs be; and I'm technically minded so I'm keen to know how stuff works behind the scenes. The fact that smartgauge's marketing masks this, is somewhat frustrating!

 

I think you picked a bad example too, because I have indeed owned 5 Mercedes Benz's over the years, and whilst they're not perfect (no car is....) they're pretty close to it. In fact I'd say its probably the best car I've ever owned.

[nicknorman]

Try connecting SG as it should be and then reevaluate, even though you have 70mm cables there is a loss at every junction.

I will (having checked the installation manual on the boat) but I thinkts unlikely to make any difference. There was some discussion about the real benefits of the diagonal bank connection scheme. I measured the voltage drop between adjacent bats and it was less than 10mV at 100A or more. At the 4A or so I had when comparing the rapidly dropping SG with the MS, that would be less than 1mV. That isn't going to make any difference. Anyway, they are much closer when the batts are warm.

 

?..if Smartgauge is so great without a shunt, how come the Mk2 has a shunt?...

 

Adding a shunt allows calculation of the actual bank capacity as opposed to the manufacturers stated value when new.

[Chris Pink]

I've seen cable described in terms of cross sectional area many times on here but I struggle to visualise it so I've had a go translating it to diameter just so I can get an idea of what it looks like in terms that I can understand.

 

Can someone in the attendant throng check my maths please

 

csa = pi x rsquared

 

70 = 3.142 x rsquared

 

rsquared = 70 divided by 3.142 = 22.28

 

r = square root of 22.8 = 4.77

 

diameter of 70mm squared csa cable = 4.77 x 2 = 9.54 mm

 

you'd use cable of 10mm diameter

 

 

 

 

And the diameter of 50mm squared csa cable is about 8mm?

 

 

 

Do I have that right?

 

No.

 

It varies according to how many and how fine the strands are - there's a fair amount of air in cheapo 25mm² cable ('tails' at screwfix) and the thickness of the insulation varies enormously.

 

So your sum is right for solid copper bar but that's not often used.

 

It's meaningless too as cable is always specified in mm² - or AWG = American Wire Gauge but is less common in the UK - and is almost always written on the cable too.

 

If you want to visualise it, best thing to do is to get 100mm (length) of each type and then you'll have a handy reference. When talking about large power cables there is so little of them anyway, visualising is not very important, more important in the smaller domestic sizes when the difference between 4mm² and 1.5² can be a Micawber one.

 

 

 

I think you picked a bad example too, because I have indeed owned 5 Mercedes Benz's over the years, and whilst they're not perfect (no car is....) they're pretty close to it. In fact I'd say its probably the best car I've ever owned.

 

Having travelled Europe as much on my back under as in a Mercedes 507 I'll have to disagree with you there.

[Paul C]

Having travelled Europe as much on my back under as in a Mercedes 507 I'll have to disagree with you there.

 

I Googled it but couldn't find which model you meant when you say Mercedes 507 - can you post a pic of one?

[nicknorman]

I think you picked a bad example too, because I have indeed owned 5 Mercedes Benz's over the years, and whilst they're not perfect (no car is....) they're pretty close to it. In fact I'd say its probably the best car I've ever owned.

 

Having hired a C class Merc last year in France, my first experience of the marque, I would say it was a fairly nasty, bloated car and quite plasticky for its price range. As for the hand (foot) brake, an ergonomic nightmare! I would never contemplate buying one.

[Chris Pink]

I Googled it but couldn't find which model you meant when you say Mercedes 507 - can you post a pic of one?

 

i probably blanked it from my mind. I was the worst build vehicle it has ever been my misfortune to work on. - actually I see it was a 508, a lot of the circus people had 608s which were a lot better though similar rubbish build quality (don't talk to me about king pins)

[Paul C]

Yeah I've heard the vans are rubbish, not the quality you'd expect and if you're after a smallish van, go for the VW Transporter; if a larger one, Transit or Iveco Daily.

 

I know what you mean regarding the build quality of later Mercedes'. The 'youngest' one I had was a series 2 W124 estate (1991 or so). It did everything asked of it, effortlessly, including towing some quite heavy loads; few/no mechanical issues despite a huge mileage (I'd bought secondhand) and was very comfortable. The others were W114 coupé and saloon. These were more basic (less equipment) but the quality shone through and again, were very quiet and comfortable to drive and use. Its generally accepted that the W124 replacement (W210) was a bit of a disaster, and they had to make a lot of effort with warranty issues on this car, and work to try rebuild the reputation, on later cars. Once computers and electronics came into motors, they were kind of at the forefront for new gizmos but this affected reliability a bit, so its little things which tend to go wrong on them, and get noticed.

[GUMPY]

i probably blanked it from my mind. I was the worst build vehicle it has ever been my misfortune to work on. - actually I see it was a 508, a lot of the circus people had 608s which were a lot better though similar rubbish build quality (don't talk to me about king pins)

There was a 507d

We used to have a 406 back in the mists of time

It was known as jinxy as if I remember correctly the reg was GI NX as it was registered in Giessen

Also not the most reliable vehicle

[Barry]

No.

 

It varies according to how many and how fine the strands are - there's a fair amount of air in cheapo 25mm² cable ('tails' at screwfix) and the thickness of the insulation varies enormously.

 

So your sum is right for solid copper bar but that's not often used.

 

It's meaningless too as cable is always specified in mm² - or AWG = American Wire Gauge but is less common in the UK - and is almost always written on the cable too.

 

If you want to visualise it, best thing to do is to get 100mm (length) of each type and then you'll have a handy reference. When talking about large power cables there is so little of them anyway, visualising is not very important, more important in the smaller domestic sizes when the difference between 4mm² and 1.5² can be a Micawber one.

 

 

Crikey Chris!

 

All I wanted was to know that I was roughly correct in converting a, to me, meaningless figure to one that means something to me in terms that I can understand.

 

I don't need a lecture on the intricacies - just to know that I'm in the right area

[Chris Pink]

Crikey Chris!

 

All I wanted was to know that I was roughly correct in converting a, to me, meaningless figure to one that means something to me in terms that I can understand.

 

I don't need a lecture on the intricacies - just to know that I'm in the right area

 

You weren't.

 

 

(better?)

 

 

Personally I find knowing a bit of background an aid to understanding but feel free to ignore what i've written, hopefully someone else will read it with their minds open.