question

Warwick Bruce Chapman avatar image
Warwick Bruce Chapman asked

Double Check Battery Balancer Wiring

Please confirm that my wiring on left for my bank works.

Trying to work out if my green, orange and blue lines (and single red and black lines) match what the manual suggests. The series and midpoints links don’t allow connecting midway on cable, so I placed on one side. For red and black, use same terminals as inverter.

1, 2 and 3 (blue) are the 3 battery balancers.

battery chargingBattery Balancer
1566166897710.png (637.6 KiB)
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

3 Answers
wkirby avatar image
wkirby answered ·

I have studied this and it seems correct to me.

EDIT:
I should add that, in this configuration with mid point inter links between banks (the vertical black wires in the Victron drawing), you need to follow the theme and have the positive and negative wires coming from the end of each bank of equal length. Have these wires meet at a common point like a bus bar.
Basically follow the Victron diagram for the end connections each of equal length.

Taking positive from one bank and negative from the other is perfect when you do not have mid point links.

13 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

Thank you.

The mid point links x 3 are all of equal length and gauge (same gauge as series links).

The two parallel links joining the positive and negative sides of each bank are the same length and the same gauge as the rest of the link described above.

To confirm, the midpoint links are the same length as one another, the series links all the same length as one another and the two parallel links (one + and one -) are the same length as one another. All of these are the same gauge.

Even the two links into the Inverter are the same length (though I believe this is not necessary).

HOWEVER, there is no bus bar. I would have to cut each of the parallel links midway and introduce a busbar on each side to meet this requirement, right? Then my black and red links in my diagram on the left (of identical length) would need to connect to the bus bars?

What would happen if I did not do this and wired the battery balancers into the positive from one bank and negative from the other?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

Hi @warwick

Yes, you could cut the dotted connections and connect halfway, or have equal length cables from both banks to the next connection point (positive to the fuse, negative to shunt or directly to inverter)

For safety, if using double cables, please also add the dotted connections to prevent big currents if one of the cables has a problem.

Most inverters have dual battery connections so you can use two 'thinner' cables instead of one big one.

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hey Daniel

Thank you for the reply.

Below is a representation of the system is it is right now (before we connect the battery balancers). The green midpoint links have been added in to make the bank ready for the balancers.:

0 Likes 0 ·
1566246368969.png (139.1 KiB)
1566244464803.png (22.4 KiB)
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

Hi @warwick

Nothing wrong with that (without the green connections), but under load (charging / discharging) there will be a voltage shift between the two banks, due to the way it is wired.

This is no problem, but if you want to connect balancers, the batteries need to be at the same level.


0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

What do you mean the same level?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

The top bank will be at a higher level than the bottom one wile charging, the bottom one at a higher level when discharging.

This is due to the longer positive / negative cables.

(I'm sorry I don't know how to explain this better, but with the green connections in place, without proper wiring to pos / neg connections of the banks, things will go wrong)

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Ok, but what if I make the black and red connections to be battery balancers the same length? I have actually already cut an connected those two cables to the battery balancers, and they are the same length to the millimetre.

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

Hi @warwick

It's not the connections to the battery balancers that are the problem.

It's the main wiring from battery to the next point. this has to be the same length on both positive and negative connections, as per the Victron diagram on the right in your original post.

Where do you have the battery fuses connected?


0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Balancers are mounted and ready to be wired. I just need to understand what must be done to ensure the batteries are "at the same level".

I am ready to introduce bus bars at whatever point you suggest. Do I understand that this should be exactly midway along the dashed parallel links - ie. I must cut those cables midway and introduce busbars? And then when I add MPPTs, they connect to same busbars?

There is a single 125A Mega Fuse on the positive battery lead:



0 Likes 0 ·
1568016861666.png (1.0 MiB)
1568016930533.png (1.2 MiB)
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

Hi @warwick

It's very simple: if one of the positive posts has a longer wire = more resistance, it will be at a different voltage than the other.
The same goes for the Negative post.
if you then connect the interconnect cables, you'll introduce a lot of problems.

call it a busbar, call it a connection point, just make sure the wiring to both banks is exactly the same from a point where they come together.

If you're not sure, please get an electrician / installer involved.

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

This is like a dark science to any installer or electrician I have consulted. I've been told, 'It doesn't matter', 'You don't need those balancers'.

I've done Victron training myself, and I do not think it is as simple as referring it to an electrician (who mostly have no clue about DC) or an installer (who, in my experience are drowning in the complexity of the Victron product environment and the fuzziness of electrickery).

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Ps. When you say positive posts, you mean these two, right?


I assume the same applies to the opposite negative posts because they add up for resistance of the entire charging circuit?

0 Likes 0 ·
1568018896198.png (146.1 KiB)
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Also, please note that I updated the above post at the same time as you replied.

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @warwick

Nothing black magic about voltages, just draw a diagram and see for yourself:for ease of explaining, 1 v voltage drop over the longer connections, and you have a 1v voltage difference between the two strings.


Use the green wires and forget the blue connections, and your done:


2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Warwick Bruce Chapman avatar image
Warwick Bruce Chapman answered ·

Hi Daniel

I have done the following:

I've put batteries 1 & 4 in each bank right next to one another so the cable runs to the bus bars are short. I've added busbars. I've moved the inverter to connect from the busbar instead of the battery.

All four of the dashed cables to the bus bars are the same length as one another. All the yellow serial links are the same length as one another.

If you may, please confirm:

1. this is the same as your diagram above;

2. the balancer wiring is right: Do I need to cut the midpoint links halfway and put the balancer wires at the middle of the midpoint links?

Warwick



battery-bank-30.png (54.8 KiB)
13 comments
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Hi @warwick

Why are you complicating things so much by not taking the system negative from the most right side batteries?

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Because of the spacing I have to work with - batteries are to the right of the equipment because of gassing if they were below:

Everything is on the left side - want to reduce the amount of cable.

Ps. I know this is messy. I am making progress every week to getting it cleaned up. When I started it was just the batteries and the MultiPlus II.

It now has 12 panels and 2 x 150/35 and bus bars:

Balancers and midpoint links removed for now until I know how best to wire them.

See at: https://vrm.victronenergy.com/installation/34733

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Warwick Bruce Chapman commented ·

Hey @Daniël Boekel (Victron Energy Staff) does that answer your question.


Let's assume I am happy that the battery wiring is all OK, I just want to know about the optimal midpoint configuration.


Should I cut the current midpoint cables at their centre point for the wires from the battery balancers to join or can they just go to the terminal on one side?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

you don't have to cut the midpoint cables.

My question was why the complicated cable runs, that makes it very hard to read your picture.

Why not like this?:


0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

I answered this two days ago:

0 Likes 0 ·
1573563891305.png (1.7 MiB)
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

But it makes for an unreadable diagram ;)

So yes you can connect it like that, but the diagram is one I'm not going to unravel...

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Perfectly understood. And it makes a lot of sense to have an easy to understand layout.

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

@Daniël Boekel (Victron Energy Staff) if you say "you don't have to cut the midpoint cables." then does that mean I can connect to a terminal at either end of the cable eg. the upper bank end of the midpoint cable?

0 Likes 0 ·
Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Warwick Bruce Chapman commented ·

@warwick

Yes.

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Ok. Will connect it up like that then.

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Daniel


This is connected. The Battery Balancers seem to be off. I have nothing on their LEDs to suggest that they are on and working properly...


I will start a new thread on this. No need to reply here.


Thank you again for all the input on this.


Warwick

0 Likes 0 ·
Warwick Bruce Chapman avatar image Warwick Bruce Chapman Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Yup, I guess I thought something would still flash or otherwise feedback to indicate signs of life.

0 Likes 0 ·

Related Resources

VictronConnect VE.Bus charging manual  

Additional resources still need to be added for this topic