BALANCED WIRING

Dougwe · Chief one feather

BALANCED WIRING

Joe50 · Guru

Doug, think this is an example of "balanced" wiring - it's how my "house" system is configured. Both batteries connected in parallel with load connected to positive of one battery while return ground is connected to the negative of the other battery.

Joe

Woody n Sue · Guru

Hmmm I would have thought that that was the only way to hook them up if they are 6 volt batteries to get 12 out of them
But if 12 v batteries that way would give you 24 v but I may be wrong

Dougwe · Chief one feather

Thanks Joe for the diagram as t explains it.

Woody, My understanding is the same as you but I just hadn't heard it as being Balanced Wiring. I have my two 12v batteries wired in parallel with nice short heavy cable, so it stays as 12v. If I did it the other way there could be a bit of a bang when I plugged in something.

Ondabeach · Senior Member

Woody n Sue, The pic that Joe put up doesn't change the voltage as the batteries are in parallel, not in series.

When you put batteries in parallel, the voltage stays the same but you add the Amp hour ratings. So, if you put 2 x 12v 75 amp hour batts in parallel you get 1 x 12v 150 amp hour batt.

This pic shows the difference.

******When wiring batts in paralle or in series, ALWAYS use batts with identical ratings******

When batteries are wired in parallel, the positive terminals are electrically identical to each other, as are the negative terminals. It makes no difference to have the load and ground connected to the terminals of different batts or the same batt.

Doug, the only 'balanced wiring' terminology I'm familiar with is to do with audio circuits, not power. Joe's pic simply shows 2 batts wired in parallel, if you put up a link to the other thread you mentioned, I'll check it out and see what they're talking about.

-- Edited by Ondabeach on Saturday 20th of June 2015 09:51:52 AM

-- Edited by Ondabeach on Saturday 20th of June 2015 09:54:21 AM

-- Edited by Ondabeach on Saturday 20th of June 2015 09:54:40 AM

-- Edited by Ondabeach on Saturday 20th of June 2015 10:06:59 AM

Sharke · Senior Member

My thinking of balanced wiring is that the total length of both positive and negative cable is the same and the resistance including battery is equal. Joes drawing shows this.

Cheers

Jeff

Dougwe · Chief one feather

Steve, it was in the thread just below this one by "UPO".

Ondabeach · Senior Member

Yes Jeff, nothing wrong with Joe's pic. I was just pointing out to Woody and Doug that putting batts in parallel doesn't give you double the volts, but that it doubles the capacity in amp hours.

Doug, I checked out the post by UPO and Joe is right in that the 'balanced wiring' that UPO was talking about is having the load connected to positive terminal of one battery and the ground connected to the negative terminal of the other battery. But, as an electronics engineer for over 35 years, I can assure you that unless you're using undersized cables to parallel your batteries, it makes absolutely no difference whatsoever. Similarly, unless you're using undersized cables to connect your batteries, then a few inches, or even a foot or 2 difference in those cable lengths will also make no difference.

If you're using appropriately sized cables then there will be more resistance in the connections than the cables themselves. There will actually be more difference between the internal resistance of the batteries than there is in your joining cables.

If the cables connecting your batteries are getting more than barely warm, then they're too small or you have dirty/poor connections.

Dougwe · Chief one feather

Mmmm, Steve, I have + - coming from my regulator in O/H cupboard above batteries which is how the sparky fitted out the van. From the reg to battery 1 both + - connected. From that I have changed from thin cable to heavy duty battery cable in parallel and both equal length at 8". After testing it all not that long ago I didn't notice any heat on the cables or terminals.

Since all that I have fitted another Reg that a portable Solar Panel I rigged up to if needed, from that reg cable connects alao to battery 1. From Battery 2 I have run cable to a Anderson plug inside van for a 300w Inverter to plug into when I need that. All seems to be working OK.

As I said I hadn't heard of "Balanced Wiring". I now have. Thanks for the info.

Ondabeach · Senior Member

Everything you described sounds good as gold brother smile

Woody n Sue · Guru

Thank you ondabeach yes you are correct and I should have looked closer and gave it more thought as I did know this in future I will try to engage brain before the keyboard
I'll go to the noughty room now

Ondabeach · Senior Member

Woody, if you're coming to the naughty room, can you bring me a beer biggrin

Dougwe · Chief one feather

Just cos ya woz nice to me Steve, there are two beers hidden behind the water jug in the naughty room fridge. I left them there when I was allowed out the other day for my next visit but you are welcome to them. I will smuggle more in on my next visit.

Enjoy.

KevKim37 · Senior Member

Just to add more confusion have a look at these Battery Wiring layouts mainly used for Heavy Draw set ups. I had our 4 AGM's set up as per the 4th diagram and they worked great.

www.smartgauge.co.uk/batt.con_html

Woody n Sue · Guru

Certainly ondabeach would you like a heavy or a light

Baz421 · Guru

It sure does make a difference when connecting batteries + and - input/output.

Battery performance and longevity is effected.

This is but one website that explains it easily, and from years of experience it is true. I flattened and shortened my boat battery life (3X12V) in parallel by NOT using the correct methodology. Cost me $ so lesson learnt the hard way.

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

Woody n Sue · Guru

Baz421 an excellent article actually makes sense to my simple mind not something I have ever had to do hook up 3 or more batteries but I can see the logic behind the article
Excellent post
For that you get a "get out of the naughty room for free card" from me , should you ever need it

Ondabeach · Senior Member

As the smartgauge site points out, there's a lot more resistance in poor connections than in the connecting cables, that's where the bulk of the losses are occurring in his examples. In fact, 90% of the resistance according to his own figures are in the connections, not the cables. And seriously, if they're the best connections he can make, I wouldn't trust him to replace the batteries in my flashlight.

His results are misleading because he's using worst case scenarios to amplify the losses to try and prove a point.

If you were experiencing the kinds of power losses due to the connection resistances he's talking about, the terminals would be getting hot in very short order.

The 'horrific' math involved is really quite straight forward, there are only a couple of formulae used which you can find in the link below, along with explanations of how to apply them.

http://electronics.stackexchange.com/questions/58700/how-to-calculate-voltage-drop-over-and-power-loss-in-wires

If you have crappy connections like he's using, then you're losing power no matter how you wire your batts. That's why I keep emphasising the use of heavy cables and making good connections.

Once I get my dual house batts set up in my bus, I'll take all the relevant voltage and current readings with both connection methods and demonstrate in practice that he's just like the guys that promote nitrogen in passenger vehicle tyres... full of gas biggrin

Doug, I'd already downed those 2 beers you had stashed, cheers for the appetisers wink

Woody, make it a 6 pack of Peroni Bro... let's party biggrin

Stratman77 · Senior Member

Well, I never! Thanks to baz41, I now have an understanding of battery balance wiring theory and why - in multiple battery, heavy load situations - how they are wired together and what they are wired with has a great impact on their life and performance. I also feel that the vast majority of van battery installations would be fine as long as the cables were as heavy as possible (the Smartguage site talks about cable with a cross-sectional area of 35 square mm which is an awful lot of copper), the cables all the same length and as short as possible, and wired as per the diagram from Joe50. I am so happy that I can manage with just a single battery!

The Doo crew · Senior Member

35mm squared a lot of copper?? I definitely went overkill on my 24v set up then. All battery leads between 4 12v battery's, inverter & main breaker are 75mm square, balanced wiring & no voltage drop issues even when pulling big amps for short periods off the inverter, the extra 10kg's of weight was well worth it.

Upgraded most of the house wiring in the last refit as it was FAR too small to work effectively, prior owner complained of dimming lights & flat battery's as just something that was normal. The solar was struggling to work as the cables from the panels were half of the required size, turn the tap on & the pump would cause the telly to turn off, when we did some volt drop tests it just confirmed the manufacturers didn't understand what was required for it to work properly, built down to a price not up to a standard unfortunately.

Peter_n_Margaret · Guru

Dougwe wrote:
Just read in another thread and "Balanced Wiring" was mentioned.
Simply put....What does it mean please someone I understand two batteries being wired in paralal but never heard of the above.

Depends on the context, but it is also used to refer to how multiple batteries are connected into a single bank.

It is important that each battery sees the same "load", especially when loads get higher. This can be achieved by using very heavy cables or by using a wiring pattern that ensures the loads are balanced.

The link below explains the common alternatives. I use option 3 which is sometimes called a "Star" connection.

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

Cheers,

Peter

EDIT.......Sorry Baz421, just noticed you posted a link to that site earlier in the thread..........Thanks.......

-- Edited by Peter_n_Margaret on Sunday 28th of June 2015 07:08:32 PM

-- Edited by Peter_n_Margaret on Sunday 28th of June 2015 07:09:02 PM

Phil C · Guru

OK you lot... the naughty room is getting full, time for me to get parole..

BTW I drank those 3 stubbies Dougwe left behind

My comments on this thread.

We would assemble our own aircraft NiCAD batteries for some aircraft and have to use links of solid metal of the same size and resistance (in milli ohms) to join them up. Frankly I have never heard of balanced wiring outside of audio applications.

Cheers