Leisure Battery bank connection, SmartGauge and cables.

[pedroinlondon]

I am finally nearly ready to fit two Trojan leisure batteries I bought months ago. I understand that leisure bats are connected in series, but what cable and terminals are the most appropriate for my bats?

img 1 My link

img 2 My link

I should ask the company who sold them but cannot find the invoice or records of them... If anyone could send me a link to a discussion elsewhere on these forums that gets to the point or some other link I would appreciate it. About SmartGauge monitors, which one would you say it's the best for a very simple and basic 12V - two battery set up? Their website has all kinds of fancy sophisticated monitors but I would like to know if anyone here has used a extremely basic monitor and is happy with it. Not necessary by SGauge but they seem to be the common choice. Thanks a lot y'all!!

[Arthur Brown]

First, get those batteries charged! "Months ago" is not good for batteries

[Ex- Member]

I am finally nearly ready to fit two Trojan leisure batteries I bought months ago. I understand that leisure bats are connected in series, but what cable and terminals are the most appropriate for my bats?

img 1 My link

img 2 My link

I should ask the company who sold them but cannot find the invoice or records of them... If anyone could send me a link to a discussion elsewhere on these forums that gets to the point or some other link I would appreciate it. About SmartGauge monitors, which one would you say it's the best for a very simple and basic 12V - two battery set up? Their website has all kinds of fancy sophisticated monitors but I would like to know if anyone here has used a extremely basic monitor and is happy with it. Not necessary by SGauge but they seem to be the common choice. Thanks a lot y'all!!

 

Links not working for me!

[ditchcrawler]

Can't open your links but a couple of questions.

What voltage are the batteries, I have 6 volt Trojans and what voltage is your boats electric system?

[bottle]

I understand that leisure bats are connected in series

 

Only if you want to double the voltage output. ie, two 6v will give 12v, two 12v will give 24v.

 

If your boat is 12v and you have two batteries that are 12v they must be wired in parallel.... positive to positive, negative to negative.

 

cable size will mainly depend on length of cables, I would suggest a minimum of 35mm², mine are 50mm² and that is on a 24v system.

 

As for gauges you pays your money and takes your choice, the simplest to tread and understand is the Smartgauge (£170), a much cheaper method is a voltmeter and an ammeter but you will need to be able to interpret the readings.

[pedroinlondon]

Links not working for me!

 

Sorry! I had the picasa album as private. Try again please.

 

Can't open your links but a couple of questions.

What voltage are the batteries, I have 6 volt Trojans and what voltage is your boats electric system?

 

 

Sorry! I had the picasa album as private. Try again please.

Thanks for that. I seem to remember now, that in series the total amount would be added, so to speak. My lights and pumps are 12 v and the batts 12 volt, therefore I will need to connect them in parallel, right?

 

Only if you want to double the voltage output. ie, two 6v will give 12v, two 12v will give 24v.

 

If your boat is 12v and you have two batteries that are 12v they must be wired in parallel.... positive to positive, negative to negative.

 

cable size will mainly depend on length of cables, I would suggest a minimum of 35mm², mine are 50mm² and that is on a 24v system.

 

As for gauges you pays your money and takes your choice, the simplest to tread and understand is the Smartgauge (£170), a much cheaper method is a voltmeter and an ammeter but you will need to be able to interpret the readings.

 

Thanks for clearing that up. I had a feeling that connecting batts in a series would increase the total output. The battery bank will be only about 2 meters from the switch panel. I understand the manual meter and an equation would suffice for my needs but I don't really fancy doing that on a regular basis, but I was under the impression that SGauce came in various models, from talking to a boat fitter last summer. So that model is the most commonly used?

[trackman]

At present there is only one Smartgauge. I would recommend it highly.

It can connect to 2 battery banks to give voltage readings for each and the %age charge of one. Normally you would make that your domestic bank.

It needs one negative connection and a fused connection to the positive of each of the 2 battery banks. That's it! No shunts or anything.

Rumour has it that a new version is no its way, but I'm perfectly happy with this one.

[Skye]

Only if you want to double the voltage output. ie, two 6v will give 12v, two 12v will give 24v.

 

If your boat is 12v and you have two batteries that are 12v they must be wired in parallel.... positive to positive, negative to negative.

 

cable size will mainly depend on length of cables, I would suggest a minimum of 35mm², mine are 50mm² and that is on a 24v system.

 

As for gauges you pays your money and takes your choice, the simplest to tread and understand is the Smartgauge (£170), a much cheaper method is a voltmeter and an ammeter but you will need to be able to interpret the readings.

 

Good post

 

Also check the voltage of the batteries because I believe Trojan do 6v 8v and 12v

[pedroinlondon]

At present there is only one Smartgauge. I would recommend it highly.

It can connect to 2 battery banks to give voltage readings for each and the %age charge of one. Normally you would make that your domestic bank.

It needs one negative connection and a fused connection to the positive of each of the 2 battery banks. That's it! No shunts or anything.

Rumour has it that a new version is no its way, but I'm perfectly happy with this one.

 

Thanks. Less choice is better for decision making It's not as expensive as I thought it would be. My link

 

Good post

 

Also check the voltage of the batteries because I believe Trojan do 6v 8v and 12v

 

Will do. I'm pretty sure they are 12V but just in case.

[Grace and Favour]

Thanks. Less choice is better for decision making It's not as expensive as I thought it would be. My link

 

 

 

 

Great bit of kit,

[nicknorman]

Thanks. Less choice is better for decision making It's not as expensive as I thought it would be. My link

 

 

 

Will do. I'm pretty sure they are 12V but just in case.

The ones in your photos are 12v - it says so on the label!

 

As for the interconnect cables, it depends on the rest of your system. If you have a large inverter, 70mm² would be better, otherwise I would go for 50mm² since although 35mm² might be adequate, for a little extra cost you allow for future upgrading.

 

The Smartgauge is the easiest to install (no shunt) and gives a reasonable indication of State of Charge. It does not however show current in or out of the batteries, so if that's important to you, get a gauge with a shunt.

[smileypete]

Thanks for that. I seem to remember now, that in series the total amount would be added, so to speak. My lights and pumps are 12 v and the batts 12 volt, therefore I will need to connect them in parallel, right?

Right, but take the positive off one corner and the negative off the diagonally opposite corner IYSWIM, so the positive and negative bank connections are NOT going to the same batt.

 

cheers, Pete.

~smpt~

[nicknorman]

Right, but take the positive off one corner and the negative off the diagonally opposite corner IYSWIM, so the positive and negative bank connections are NOT going to the same batt.

 

cheers, Pete.

~smpt~

For the connections to the alternator and boat systems, Yes. For the connections to the SG, No - they should go to just one battery (either).

[pedroinlondon]

The ones in your photos are 12v - it says so on the label!

 

As for the interconnect cables, it depends on the rest of your system. If you have a large inverter, 70mm² would be better, otherwise I would go for 50mm² since although 35mm² might be adequate, for a little extra cost you allow for future upgrading.

 

The Smartgauge is the easiest to install (no shunt) and gives a reasonable indication of State of Charge. It does not however show current in or out of the batteries, so if that's important to you, get a gauge with a shunt.

Not inverter planned, but will probably succumb to one eventually. I'll go for the 50mm.

[Barry]

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?

Edited March 18, 2013 by Bazza2

[smileypete]

For the connections to the alternator and boat systems, Yes. For the connections to the SG, No - they should go to just one battery (either).

Not sure I agree there. If you had a bank of 8 batts commmoned together at 2 points for +ve and -ve, would you attach the SG to the common points or just to one of the batts?

 

cheers, Pete.

~smpt~

Edited March 18, 2013 by smileypete

[matty40s]

For the connections to the alternator and boat systems, Yes. For the connections to the SG, No - they should go to just one battery (either).

no they shouldn't, the smartgauge should be fed across the bank.

[nicknorman]

Not sure I agree there. If you had a bank of 8 batts commmoned together at 2 points for +ve and -ve, would you attach the SG to the common points or just to one of the batts?

 

cheers, Pete.

~smpt~

Direct to one of the batts. As Gibbo is at great pains to repeatedly point out in his instructions, if you connect it "via" somewhere else, it wont work properly. So if you connect it via interconnect leads that might have high currents flowing in them, and hence a bit of voltage drop, it won't work properly. As we now know, it is critical that it senses the battery voltage at the terminals. If you think about it, if you have multiple batteries in parallel (and discounting issues of poor interconnect leads) and assuming the bats are of the same chemistry (not necessarily the same original or actual capacity) they should all be at the same relative state of charge for a given voltage.

[GUMPY]

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?

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

[nicknorman]

no they shouldn't, the smartgauge should be fed across the bank.

I think you are wrong! Can you justify your comment?

 

...

 

No, in fact you are right! Just checked the manual and it does show connecting SG across the bank diagonally. Doesn't seem the right way to do it to me for the reasons already mentioned, but if Lord Gibbo has spoken it must be right!

Edited March 18, 2013 by nicknorman

[GUMPY]

Direct to one of the batts. As Gibbo is at great pains to repeatedly point out in his instructions, if you connect it "via" somewhere else, it wont work properly. So if you connect it via interconnect leads that might have high currents flowing in them, and hence a bit of voltage drop, it won't work properly. As we now know, it is critical that it senses the battery voltage at the terminals. If you think about it, if you have multiple batteries in parallel (and discounting issues of poor interconnect leads) and assuming the bats are of the same chemistry (not necessarily the same original or actual capacity) they should all be at the same relative state of charge for a given voltage.

Not going to argue but you are wrong

It needs to be connected across the whole bank direct to the batteries, otherwise it will only be looking at one battery and will give false readings.

 

ETA

 

Just look at the diagram in the SG quick start manual..............

Edited March 18, 2013 by Loddon

[Skye]

Not sure I agree there. If you had a bank of 8 batts commmoned together at 2 points for +ve and -ve, would you attach the SG to the common points or just to one of the batts?

 

cheers, Pete.

~smpt~

 

I believe you could be right here Pete, I'd want to monitor the whole bank. If I suspected a problem with one bat then I would test each one with a volt meter first.

 

Having said that the manufacturers of the SG may have different ideas and would give their reasoning behind it.

[nicknorman]

Not going to argue but you are wrong

It needs to be connected across the whole bank direct to the batteries, otherwise it will only be looking at one battery and will give false readings.

 

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!

Edited March 18, 2013 by nicknorman

[GUMPY]

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 was just stating a Fact!

Was it you that was a bit disbeliveing of what SG was telling them?

[nicknorman]

I was just stating a Fact!

Was it you that was a bit disbeliveing of what SG was telling them?

Yes but when you state a fact that differs from a fact stated by someone else, isn't that arguing? Or does it not count if you turn out to be right?

 

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!