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Jamiebrookes

Leisure battery connecting

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Hi

As anyone got a wiring diagram showing the best and efficient way to connect 3 leisure batteries together please. I've seen a few ways but I don't know which is the best method. Thanks

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What do you mean by "best"? What do you mean by "most efficient", are you talking about the amount of materials, absolutely maximising battery life, getting the minimum voltdrop across the components or keeping things simple but still effective?

 

With just 3 x 12V domestic batteries wired to provide a 12V supply the simplest yet effective way is to connect all the positives together, all the negatives together, and then ensure the positive leads are all on one end of the bank and the negatives on the other. Ensure the interlinks between batteries are the same length.

 

If you want a Rolls Royce job that is better electrically in theory but may not be any better in practice then each battery is connected to the positive and negative busbars, again with all leads being of equal length. The main pos & neg supply cables then run to the busbars.

 

Do not skimp on cable size. basically the thicker the better.

 

 

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In practice it doesn't matter a toss how you configure the interconnects, as long as the wires are nice and fat (technical term). 

 

But if you like obsessing about irrelevancies, the diagrams above should help!

 

 

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The first and second diagrams show the same methid, albeit one for 3 and one for 4 batteries. The third diagram may be theoretically a (very) little better, but is needlessly complicated.

.

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In my view as I stated in the second post. As jamiebrooks's first image as long as the cables are thick enough. No need for busbars unless you are obsessing over differential voltdrop during charging & discharging.

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I used to work with 3 phase uninterruptible power supplies to provide critical standby power to banks and data centres. They always used one or more 400 volt battery, comprising 200 x 2 volt lead acid cells or several 400 volt strings of batteries in parallel. 

 

They always used the connections used in diagrams 1 and 2.

 

As others have said anything more complex is unnecessary providing you use adequately sized cables.

Edited by cuthound
Missing letter

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I'm considering replacing my leisure batteries (4 x 115ah) so I've been looking around to check the validity of the wiring system in my boat. I found this interesting article smartgauge.co.uk/batt_con.html about the pros and cons of various connection methods, including calculations. It looks like you can get quite big differences in individual battery load using the first method even with fat cables. I was told today that one way to get max life from a bank connected like that is to shuffle the batteries occasionally - like I'll ever get round to that 😑 

It looks like I need to get some rewiring done on my boat even if I keep the batteries, the solar is connected bottom negative to top positive as per the plan but the main distribution point and the inverter feed come off two different points along the battery chain, which according to the article will result in uneven loading. I will do some more research before getting the spanners out though.

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14 minutes ago, Peter Sloe roamin said:

I'm considering replacing my leisure batteries (4 x 115ah) so I've been looking around to check the validity of the wiring system in my boat. I found this interesting article smartgauge.co.uk/batt_con.html about the pros and cons of various connection methods, including calculations. It looks like you can get quite big differences in individual battery load using the first method even with fat cables. I was told today that one way to get max life from a bank connected like that is to shuffle the batteries occasionally - like I'll ever get round to that 😑 

It looks like I need to get some rewiring done on my boat even if I keep the batteries, the solar is connected bottom negative to top positive as per the plan but the main distribution point and the inverter feed come off two different points along the battery chain, which according to the article will result in uneven loading. I will do some more research before getting the spanners out though.

IMO the chap that wrote that knows what he is talking about

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11 hours ago, ditchcrawler said:

IMO the chap that wrote that knows what he is talking about

+1 from me.

Gibbo, who wrote that series of articles, really does know his stuff, both through theory, and practical experience.

 

Bod 

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12 hours ago, Peter Sloe roamin said:

I'm considering replacing my leisure batteries (4 x 115ah) so I've been looking around to check the validity of the wiring system in my boat. I found this interesting article smartgauge.co.uk/batt_con.html about the pros and cons of various connection methods, including calculations. It looks like you can get quite big differences in individual battery load using the first method even with fat cables. I was told today that one way to get max life from a bank connected like that is to shuffle the batteries occasionally - like I'll ever get round to that 😑 

It looks like I need to get some rewiring done on my boat even if I keep the batteries, the solar is connected bottom negative to top positive as per the plan but the main distribution point and the inverter feed come off two different points along the battery chain, which according to the article will result in uneven loading. I will do some more research before getting the spanners out though.

First method on the Smartguage website or first method illustrated in this thread? If you mean the later then as far as I am concerned you do not understand things. The first method shown in this thread is, in fact method 2 on the Smartguage website.

 

As so often stated on here and apparently still ignored ALL positive connections be they load or charging should go to one end terminal of the bank and all the negatives to the other. It seems your don't so it is  probably time to get the load connections to the ends of the bank. Just be sure what you think is a whole bank is not split into domestic & inverter banks, a bit like the engine and domestic banks are split. It is easy to tell because you will find a "missing" positive interlink. If by chance there is a separate inverter battery bank then usually you get better battery life by combining them into one big bank as per the Smartguage advice.

 

 

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On 10/08/2019 at 14:28, Jamiebrookes said:

So where is the best place for cables and busbar

strange questions....................... if you know what you are doing, it's maybe OK to DIY, else get a qualified, experienced and insured BOAT electrician. 

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2 hours ago, Tony Brooks said:

First method on the Smartguage website or first method illustrated in this thread? If you mean the later then as far as I am concerned you do not understand things. The first method shown in this thread is, in fact method 2 on the Smartguage website.

 

As so often stated on here and apparently still ignored ALL positive connections be they load or charging should go to one end terminal of the bank and all the negatives to the other. It seems your don't so it is  probably time to get the load connections to the ends of the bank. Just be sure what you think is a whole bank is not split into domestic & inverter banks, a bit like the engine and domestic banks are split. It is easy to tell because you will find a "missing" positive interlink. If by chance there is a separate inverter battery bank then usually you get better battery life by combining them into one big bank as per the Smartguage advice.

 

 

I didn't mention a specific method, however my batteries are connected in parallel group of four - with no division into groups. The previous owner got Onboard Solar to fit a pair of panels and they are connected right across the bank as shown in smartgauge article method 2. The inverter (which I assume was an original fit) is connected to +ve on battery one and the -ve on battery three and the +ve feed to the distribution point comes off the positive terminal of battery two. As you say, some work needed there. My boat is a 2003 John White build and fit out and I assume they set up the wiring like that.

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2 minutes ago, Peter Sloe roamin said:

I didn't mention a specific method, however my batteries are connected in parallel group of four - with no division into groups. The previous owner got Onboard Solar to fit a pair of panels and they are connected right across the bank as shown in smartgauge article method 2. The inverter (which I assume was an original fit) is connected to +ve on battery one and the -ve on battery three and the +ve feed to the distribution point comes off the positive terminal of battery two. As you say, some work needed there. My boat is a 2003 John White build and fit out and I assume they set up the wiring like that.

Picture please. It doesn't matter how well you explain it, a picture will be clearer.

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20 hours ago, Paul C said:

Picture please. It doesn't matter how well you explain it, a picture will be clearer.

Here is the layout. The starter battery is in the middle of the row of leisure batteries. I show some with positive at the top and some with negative uppermost because that's how they are installed. Thanks for asking for the picture by the way - it forced me to learn how to do it! 1838359548_batteryconnections.gif.065c119a53d7786d77411a34a863f07a.gif

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On 23/08/2019 at 21:37, ditchcrawler said:

IMO the chap that wrote that knows what he is talking about

 

On 24/08/2019 at 08:52, Bod said:

+1 from me.

Gibbo, who wrote that series of articles, really does know his stuff, both through theory, and practical experience.

 

Bod 

 

 

He appears to know his stuff but those of us who know less are in no position to judge and confirm his expertise. In any given subject, even those who only a little more than oneself, appear expert.

 

I'm not saying Gibbo is wrong, but I  AM saying I suspect the differences in battery performance between different interconnect configurations is negligible in practice, provided the interconnects are fat, and I have yet to read anything by Gibbo that convinces me otherwise. He 'talks a good book', but people here seem to swallow everything he says unquestioningly.

  • Greenie 1

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...... All hail the smartgauge (correctly calibrated, of course). It is my go to God! 

Edited by rusty69

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46 minutes ago, Peter Sloe roamin said:

Here is the layout. The starter battery is in the middle of the row of leisure batteries. I show some with positive at the top and some with negative uppermost because that's how they are installed. Thanks for asking for the picture by the way - it forced me to learn how to do it! 1838359548_batteryconnections.gif.065c119a53d7786d77411a34a863f07a.gif

:o    ...................................       so much simpler if you use busbars.

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54 minutes ago, Peter Sloe roamin said:

Here is the layout. The starter battery is in the middle of the row of leisure batteries. I show some with positive at the top and some with negative uppermost because that's how they are installed. Thanks for asking for the picture by the way - it forced me to learn how to do it! 1838359548_batteryconnections.gif.065c119a53d7786d77411a34a863f07a.gif

Keep most things as they are, but move the +12v "Loads" connection one battery to the left, ie to the same point as the inverter + wire (shown in black on this diagram ??? ). Then move the inverter negative connection - and presumably you have a negative connection for all your 12v loads too - one battery to the right, ie to the same point as the solar panel negative is connected. That should be better.

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29 minutes ago, Keeping Up said:

Keep most things as they are, but move the +12v "Loads" connection one battery to the left, ie to the same point as the inverter + wire (shown in black on this diagram ??? ). Then move the inverter negative connection - and presumably you have a negative connection for all your 12v loads too - one battery to the right, ie to the same point as the solar panel negative is connected. That should be better.

Exactly what I trie

 

Edited to add. That battery layout seems a

d to say in my last post in this topic. As long as the interlinks are fat enough his will be as good as anything unless you want to get anal about battery balancing and are happy to  spend money on cables and or busbars.

 

My own three domestic battery bank has the input/output lads connected to the centre battery so there is no way it can be balanced but they are still in their seventh year and doing what is needed.

 

Edited to add. That battery layout seems a recipe for confusion. Personally I would take the rewiring opportunity to move the start battery to one end of the bank so the  domestic batteries are in one block but the long interlinks would require shortening so they are the same length as the others for the optimum degree of unbalance. The RH two will need spinning through 180 degrees as well

Edited by Tony Brooks

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1 hour ago, Mike the Boilerman said:

He appears to know his stuff but those of us who know less are in no position to judge and confirm his expertise. In any given subject, even those who only a little more than oneself, appear expert.

Gibbo certainly knows his stuff and is one of the world’s leading experts on LA battery use and abuse. As with any other expert though, you are completely free to ignore his advice. 

 

1 hour ago, Mike the Boilerman said:

I'm not saying Gibbo is wrong, but I  AM saying I suspect the differences in battery performance between different interconnect configurations is negligible in practice, provided the interconnects are fat, and I have yet to read anything by Gibbo that convinces me otherwise.

He supplies some figures prior to ‘example 2’ on the battery interconnects page but once again, you’re completely at liberty to ignore them, or indeed disprove them if you have alternative calculations. 

 

Note that repeating others’ assertions that ‘fat’ interconnects solve the problem is to ignore the fact that Gibbo refers to the resistance of the connections, not the fat cables on their own. 

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