Battery Connections

[Badger]

I saw on a previous discussion a link to this webpagehttp://www.smartgauge.co.uk/batt_con.html.Could I ask,on my boat I have many smaller connections to the neg and the pos battery posts.Do I have to move all of these to the opposite end of the bank?.Or is it just the main battery leads and the feeds from the alternator and battery charger etc.The results look convincing,but it would mean a lot of extended or replaced cables if I have to change all the connections to one or other of the posts.Could someone clarify this please.

 

Regards Badger

[Scotty]

I saw on a previous discussion a link to this webpage http://www.smartgauge.co.uk/batt_con.html

Yes, the batteries on my boat are connected as shown in this pic from the smartguage site:

ie: All positives to one end of the battery bank, all negatives to the other.

[Ex- Member]

Well that's sloved the reason I had a battery fail, the one the leads were connected to . I connected the leads equally to one of the central batteries in a bank of 6 which now clearly was the cause of the batteries failure. Bit of re-wiring next weekend i think.

 

Great post cheers

[Ex- Member]

I saw on a previous discussion a link to this webpagehttp://www.smartgauge.co.uk/batt_con.html.Could I ask,on my boat I have many smaller connections to the neg and the pos battery posts.Do I have to move all of these to the opposite end of the bank?.Or is it just the main battery leads and the feeds from the alternator and battery charger etc.The results look convincing,but it would mean a lot of extended or replaced cables if I have to change all the connections to one or other of the posts.Could someone clarify this please.

 

Regards Badger

 

I've just read through all that link. The same applies to the charging leads also from what I can gather. I'll definitely do as the site suggests having one failed battery already. I always had it in my mind that wiring batteries in the way i did would put more stress on that particular battery, but asking around the general consensus was that it made no difference. Clearly this guy has done his homework, and wiring them in the way he suggests convinces me that it's more efficient and will extend battery life. I have visited this site before with regard to other electrical componants but never came across that particular link. Glad I have now

Edited June 1, 2008 by Julynian

[bottle]

Badger

 

It would be ideal, if all your various negatives and positves went to one connection block (each) and only one cable (large) was connected to the battery terminal.

[Gibbo]

I saw on a previous discussion a link to this webpagehttp://www.smartgauge.co.uk/batt_con.html.Could I ask,on my boat I have many smaller connections to the neg and the pos battery posts.Do I have to move all of these to the opposite end of the bank?.Or is it just the main battery leads and the feeds from the alternator and battery charger etc.The results look convincing,but it would mean a lot of extended or replaced cables if I have to change all the connections to one or other of the posts.Could someone clarify this please.

 

Ideally all of them should be at opposite corners. Which can be a real ball-ache if there are lots of smaller cables to extend.

 

However there is a simple "workaround". Keep all your small connections where they are now (presumeably at the wrong end of the battery bank) but disconnect them from the batteries. Instead, connect them to one thick cable and treat the end of that cable as the battery post for the smaller cables. Then run that new thick single cable to the correct post. I've done this many times myself rather than extending 30 or so cables.

 

Gibbo

Edited June 1, 2008 by Gibbo

[Nickhlx]

Ideally all of them should be at opposite corners. Which can be a real ball-ache if there are lots of smaller cables to extend.

 

However there is a simple "workaround". Keep all your small connections where they are now (presumeably at the wrong end of the battery bank) but disconnect them from the batteries. Instead, connect them to one thick cable and treat the end of that cable as the battery post for the smaller cables. Then run that new thick single cable to the correct post. I've done this many times myself rather than extending 30 or so cables.

 

Gibbo

 

 

Would it not be technically better from a voltage drop / current distribution point of view to connect the main incoming / outgoing cable to the centre of each run of Pos's and Neg's ? ( if a little less convenient / tidy / pretty ) ?

 

It would share the current into each battery down each tail a bit more equally ?

 

Nick

[Gibbo]

Would it not be technically better from a voltage drop / current distribution point of view to connect the main incoming / outgoing cable to the centre of each run of Pos's and Neg's ? ( if a little less convenient / tidy / pretty ) ?

 

It would share the current into each battery down each tail a bit more equally ?

 

Nick

 

No, that would be almost as bad as connecting them both at the same end. The bulk of the current would be with the middle battery that you've connected directly to with the ones further away producing and receving less current.

 

Gibbo

[Nickhlx]

No, that would be almost as bad as connecting them both at the same end. The bulk of the current would be with the middle battery that you've connected directly to with the ones further away producing and receving less current.

 

Gibbo

 

 

I guess you are thinking of the voltage drop in the link cables - the link cables between the post with "the external cable" on and the next battery would be dropping most volts ( millivolts )and so on... so if you make it opposite ends of the bank, then each battery would be "balanced" with a progressive drop down each "run" ?.... Agreed !

 

Yep... can see that now !! How much drop is there in a typical link cable / connection, at say 100 Amps ?

 

Surely must be a very few millivolts with good connections and clean posts etc ? I will try and measure it sometime...

 

Nick

[smileypete]

Could I ask,on my boat I have many smaller connections to the neg and the pos battery posts.Do I have to move all of these to the opposite end of the bank?

 

What are the smaller connections for? Do they have fuses near or at the battery?

 

 

cheers,

Pete.

[Ex- Member]

What are the smaller connections for? Do they have fuses near or at the battery?

 

 

cheers,

Pete.

 

Generally all your 12 volt requirements should be supplied from a 12 volt fused panel. So just a single lead from the battery bank to the said panel via an isolator switch. I made the mistake of wiring a water pump directly to the battery bank, not good when you need to switch it off when you run ou t of water. so it's now wired through the 12 volt panel. In the link it does state that other connections direct to the battery bank should be avoided, which makes sense, as when they take power they'll upset the equalibruim you're trying to achieve.

 

Basically all that should be connected to your battery bank is a charge in pos and neg, and pos and neg out with appropriate sized cable, to your supply requirements 12 volt panel and or inverter if you have one. I do have a bilge pump connected direct to the battery bank also, so I think I might move this to the 12 volt panel also, although it's hardly ever used

[Gibbo]

How much drop is there in a typical link cable / connection, at say 100 Amps ?

 

Surely must be a very few millivolts with good connections and clean posts etc ? I will try and measure it sometime...

 

It's on that webpage that you didn't read

 

Gibbo

[Nickhlx]

It's on that webpage that you didn't read

 

Gibbo

 

 

You are right ( which web page ?? )

 

Nick

[Ex- Member]

You are right ( which web page ?? )

 

Nick

 

THIS ONE

 

http://www.smartgauge.co.uk/batt_con.html

[Badger]

Ideally all of them should be at opposite corners. Which can be a real ball-ache if there are lots of smaller cables to extend.

 

However there is a simple "workaround". Keep all your small connections where they are now (presumeably at the wrong end of the battery bank) but disconnect them from the batteries. Instead, connect them to one thick cable and treat the end of that cable as the battery post for the smaller cables. Then run that new thick single cable to the correct post. I've done this many times myself rather than extending 30 or so cables.

 

Gibbo

 

Hey,what a simple solution...I hadn't thought of that.I dont know yet what all the smaller connections are yet,I will check them out when I'm on the boat.I know one is the bilge pump,another are the neg and pos for a small inverter.So if I was to move say the pos bat lead to the other end of the bank,and put the smaller connections on a flying lead as you suggested......What about the other smaller connections on the neg post-can I leave them where they are?.

 

Badger

[Gibbo]

Hey,what a simple solution...I hadn't thought of that.I dont know yet what all the smaller connections are yet,I will check them out when I'm on the boat.I know one is the bilge pump,another are the neg and pos for a small inverter.So if I was to move say the pos bat lead to the other end of the bank,and put the smaller connections on a flying lead as you suggested......What about the other smaller connections on the neg post-can I leave them where they are?.

 

 

Yes

 

Gibbo

[Nickhlx]

Great read, that link... However isn't taking feed from the "middle" of a bank of 4 pretty much what this snip below is saying is a good compromise ? i.e in a bank of 4 batteries, take the "main" positive lead off no.2 and the "main" negative off no. 3 ...... which is probably what I will be ending up specifying ( four batteries )

 

 

Even with 8 batteries it is possible to get reasonable balancing by placing the main "take off" feeds from somewhere down the chain instead of from the end batteries. Remember, count the number of links each battery needs to run through to reach the final loads and get these as equal as possible.

 

Nick

[Gibbo]

Great read, that link... However isn't taking feed from the "middle" of a bank of 4 pretty much what this snip below is saying is a good compromise ? i.e in a bank of 4 batteries, take the "main" positive lead off no.2 and the "main" negative off no. 3 ...... which is probably what I will be ending up specifying ( four batteries )

 

 

Even with 8 batteries it is possible to get reasonable balancing by placing the main "take off" feeds from somewhere down the chain instead of from the end batteries. Remember, count the number of links each battery needs to run through to reach the final loads and get these as equal as possible.

 

Nick

 

It doesn't mean take them from the middle. It means, for example, take the positive feed from (say) 1/4 the way DOWN and the negative feed from (say) 1/4 the way UP the opposite side.

 

Not from the middle.

 

On a bank of 4, taking one from batt 2 and one from batt 3 isn't taking them from the middle either.

 

I shall run some calcs on taking the feeds from batt 2 and 3 on a bank of four and see what it does. Gut feeling tells me it will be worse balancing than taking them from the end because the end two batteries will be running through 3 links and the middle two only through one link each but I shall do the sums and report back Sir.

 

Gibbo

[Badger]

Yes

 

Gibbo

I think I will be giving it a go first chance I get.I only have 3 x 110amps in my leisure bank,so anything to reduce power consuumption is a must.

 

Badger

[smileypete]

Great read, that link... However isn't taking feed from the "middle" of a bank of 4 pretty much what this snip below is saying is a good compromise ? i.e in a bank of 4 batteries, take the "main" positive lead off no.2 and the "main" negative off no. 3 ...... which is probably what I will be ending up specifying ( four batteries )

 

 

Even with 8 batteries it is possible to get reasonable balancing by placing the main "take off" feeds from somewhere down the chain instead of from the end batteries. Remember, count the number of links each battery needs to run through to reach the final loads and get these as equal as possible.

 

With a string of four, if you make the 'last' link on each side 3x the resistance of the other ones it should balance fine.

 

So either use thinner wire and/or make it longer. By rearranging the links the same size wire can be used without it looking untidy, I can post a sketch if you like.

 

I've got a feeling I could be wrong in which case Gibbo is likely to say so.

 

cheers,

Pete.

Edited June 1, 2008 by smileypete

[Gibbo]

With a string of four, if you make the 'last' link on each side 3x the resistance of the other ones it should balance fine.

 

So either use thinner wire and/or make it longer. By rearranging the links the same size wire can be used without it looking untidy, I can post a sketch if you like.

 

I've got a feeling I could be wrong in which case Gibbo is likely to say so.

 

cheers,

Pete.

 

Eh? That will make it worse. You want them 3 X LESS resistance (and that's ignoring the fact that the internal resistance of the batteries changes as they discharge which complicates things). Or just wire it properly to start with from opposite corners.

 

Gibbo

[Kristian]

Yes this is quite right, as per the drawing in the last post the batteries should be split, ie + lead to the first termial on the first battery and the - lead to the last terminal on the last battery. or other way round it dont matter which way!!

This is how ive got my leads wired in along with the solar panels!

Look at it this way if you have it wired up the other (wrong) way.

Battery 2 wont be full until battery 1 is full, and battery 3 wont be full until 2 is fully charged, and so on and so on!

The reverse is true when you do any mircowaveing or run the hover via an inverter, it tries to drag 1000watts or so out the first battery on wonder they get fu**ed so soon!

BUT this dont happen if you split the charge leads!!!!!!!!!!!!!

Kristian.

[smileypete]

Eh? That will make it worse. You want them 3 X LESS resistance (and that's ignoring the fact that the internal resistance of the batteries changes as they discharge which complicates things). Or just wire it properly to start with from opposite corners.

 

This is what I mean:

 

 

cheers,

Pete.

[Gibbo]

This is what I mean:

 

 

cheers,

Pete.

 

Well..... let's number them 1 to 4 from left to right.......

 

Discharge. Current from battery 1 travels from the +ve post through "special" 3 X link to battery 4, then through the top 2 links, through the load, back through the bottom 2 links. A total of 7 links.

 

Now take battery 2. Discharge, current travels directly to the load then returns and travels through 1 bottom link. Total of 1 link.

 

Battery 3 current goes through 1 link.

 

Battery 4 through 7.

 

I think I'd be hard pressed to find a worse wiring arrangement! (though give me time and I might be able to).

 

Gibbo

Edited June 1, 2008 by Gibbo

[Nickhlx]

Well..... let's number them 1 to 4 from left to right.......

 

Discharge. Current from battery 1 travels from the +ve post through "special" 3 X link to battery 4, then through the top 2 links, through the load, back through the bottom 2 links. A total of 7 links.

 

Now take battery 2. Discharge, current travels directly to the load then returns and travels through 1 bottom link. Total of 1 link.

 

Battery 3 current goes through 1 link.

 

Battery 4 through 7.

 

I think I'd be hard pressed to find a worse wiring arrangement! (though give me time and I might be able to).

 

Gibbo

 

 

 

Articulated well - I was struggling to see how it could be better, but was finding it difficult to put into words....

 

Nick