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Balancing and Busbars


Ingo

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I've read a few posts on balancing and I actually bought two HA-02's from a forum member a while ago. I want to confirm the wiring before I add them to my battery bank. Below is a diagram from one of the posts that I modified to show my 48V battery bank with two sets of 48V ea. The suggestion in the diagram is to use one HA02. I have two of these so would wire them up one per string. Is that the preferred way?

Lastly, my installer wired my batteries without busbars. The cables run from my inverter to +/- on one string and then tap off from there to string two. This is obviously sub-optimal.  Where can I find something like below to  fix this? I don't plan on up-sizing the battery capacity anytime soon so the three post busbar would be perfect. Once the batteries are kaput I will look at Lithium or even Supercap by then.

Thanks,

Ingo

 

Balancer.png

Busbar.png

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Yes, I like them too, difficult to find in SA.

Me being tired of crimping and with solar wires and inverter all coming to the same point, I am seriously looking at these, from ACDC, on for Pos and one for Neg:

image.png.c92cc103213c1551a8277b96debc7d99.png

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21 hours ago, Ingo said:

 I actually bought two HA-02's from a forum member a while ago.

If that is the case than you could attached one HA-02 to one string and one HA-02 to the second string without the need for complicated wiring. I dispensed with fuses as the cable seems thick enough - you moving tens of  Watts between batteries.

 

22 hours ago, Ingo said:

Lastly, my installer wired my batteries without busbars. The cables run from my inverter to +/- on one string and then tap off from there to string two. This is obviously g

If you have 2 strings of batteries an acceptable solution is one could have the positive for the inverter tapping off the one string and the negative tapping of the other. If you total intra-connects of each string are equal in length and the two  inter-connects  between the two strings are the same length you should have a fairly balanced battery bank in terms of resistance of each string.

 

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39 minutes ago, Chris Hobson said:

If you have 2 strings of batteries an acceptable solution is one could have the positive for the inverter tapping off the one string and the negative tapping of the other. If you total intra-connects of each string are equal in length and the two  inter-connects  between the two strings are the same length you should have a fairly balanced battery bank in terms of resistance of each string.

That might save some money. I will measure it tonight to confirm.

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On 2018/09/30 at 4:30 PM, The Terrible Triplett said:

Yes, I like them too, difficult to find in SA.

Me being tired of crimping and with solar wires and inverter all coming to the same point, I am seriously looking at these, from ACDC, on for Pos and one for Neg:

image.png.c92cc103213c1551a8277b96debc7d99.png

Careful. It's rated for AC power, not DC. Might cause a fire. 

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19 hours ago, Chris Hobson said:

I dispensed with fuses as the cable seems thick enough - you moving tens of  Watts between batteries.

Such decisions should be made based on what would happen in a fault condition and not during normal operation. Imagine something inside the HA02 becomes damage, for example a mosfet blows up or suffers shoot-through and now you're passing 50A instead of the milliamps of the design. What you want is for something safe to burn out before something else (eg a piece of copper cable or the ha02 itself) bursts into flame.

I've made this mistake myself, too many times. Example: Timer switch for a geyser. Often I'd use a thinner black cable for the neutral side (because all the power is on the red wires, the neutral is just there for the switch to power itself). This is wrong, if something goes wrong inside the timer switch, that thin black wire will burn long before the breaker trips. You must then either put a fuse in the neutral line, or size the neutral line to take the full current of the breaker.

28 minutes ago, SilverNodashi said:

Careful. It's rated for AC power, not DC. Might cause a fire. 

AC vs DC makes no difference here. Where it makes a difference is in items means to break the circuit, such as breakers and fuses, because of the arcing potential of DC. In places where wires are simply connected together AC vs DC makes no difference, with one small exception: Arc-over gaps. If it is a combination item with positive and negative in the same component, you may have to consider whether the arc-over gap is large enough, and then again you have to compensate for the larger arc on DC. Terminal blocks like this should be fine.

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36 minutes ago, SilverNodashi said:

Careful. It's rated for AC power, not DC. Might cause a fire. 

Nope, it is a fancy busbar, rated for AC and DC.

But pray tell, how can a busbar, if rate correctly in terms of max volts / amps, be any different between AC and DC, being a piece of metal?

 

As I have flat busbars as battery cables, same as below, this is where I am going with these Erifllex idea.
image.png.5bb8b98fb253d81014997e72f0397806.png

 

That cool new fuse direct on the pole (see below) with the flexible busbar connected to it ... that is the thought ... still thinking it through.

Fuse has 2 poles:
1) Inverter connected direct via a 300amp fuse.
2) On pole 2, with the flexible busbar:
2.1) X amp fuse for the positive side of the panels, using the existing inline fuse for the negative side of the panels.
2.2) And then the Eriflex and be done with the blerrie bunch of wires that are all over the show. 

See, multiple controllers + VenusGX + BMV add to a lot of wires. Then connect all of this onto the movable battery box ... 

image.png.2527cf391c4eb9f444276aeeb7414533.png

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