Bus Bar Sizes - Leaf Cell 48v Pack

zurkeyon

zurkeyon

Member
Joined
Oct 4, 2018
Messages
53
Hello,

I am getting ready to start assembling my pack.

Today I got some 1/8" Thick copper strips, about 3/4" wide.

How many pieces will I need to use for interconnects?

Do I really need to go to 1/4 Inch Thickness on the copper?

Or am I ok at 1/8 Inch?

Thanks!
 
I don't think anyone can answer those questions without knowing what your cell layout will be, and what current you'll be expecting to draw.
 
Sean said:
I don't think anyone can answer those questions without knowing what your cell layout will be, and what current you'll be expecting to draw.
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4p7s Pack setup.

All the breakers are 30 Amp in the Combiner Box

The Main Breaker from Battery to Inverter is 150 Amps.

So, if I understand that breaker correctly, it should prevent my system from drawing more than 150 Amps out of the pack at any one time.

But I expect an average draw of 20-75 amps.

Thanks, Sorry.

:)

(I'd like them to be thick enough to tolerate 200 Amp for brief periods. Just in case)
 
Ismashed copper pipe in a bench vise. I think it was 3\8". But like Sean says it depends on your peak amps being pulled.
 
A 150A breaker is nominal at 150A. that means it should be able to withstand 150A for ever kind of. You can push that to 300A during shorter times! So you need to dimension the Breaker to be the weakest point. Can your batteries give out 300A? Can your busbar do that to?
 
zurkeyon said:
How many pieces will I need to use for interconnects?
Click to expand...

So we've established you know what the electrical layout of the cells will be, and I'm assuming you know what thephysical layout ofthe cells will be ..... im wondering why you can't answer the above question yourself ?



daromer said:
A 150A breaker is nominal at 150A. that means it should be able to withstand 150A for ever kind of. You can push that to 300A during shorter times!
Click to expand...

I'd expect a 150A breaker to trip rather quickly if it had 300A though it, very very quickly.
 
Ok,

So I am looking at a lot of info online on the leaf Cells themselves.

Not all of it entirely accurate or trustworthy.

The C Rating of the cells themselves is hard to find.

This is the info I am able to find at present on the cells themselves.
http://www.hybridautocenter.com/HAC...me=58ah-nissan-leaf-battery-module&Itemid=605

Shows a 240a to 540a Peak discharge. As these are EV cells, I would expect this.

So, I also found this table.
https://www.copper.org/applications/electrical/busbar/busbar_ampacities.html

Which shows that at 1/8" by 3/4" in normal temp conditions, I should be able to get 212-215 Amps through that.

IF I am looking at and understanding all this correctly, as well as what was stated about the breaker, I should be doubling these to 1/4" thick for 400-ish Amps.

To be SUPER safe about it.

Correct?
 
Depends if the breaker is fast or slow blow. For e medium breaker it can last 2-10 seconds. Im not sure that is quick :D But once again totally depends on the breaker and people tend to think that the rated ampere is where it breaks suddenly but thats not true. If you want it to break at exactly set current you need electronics doing it.


For instance i have 16A main breakers here. They are normal rated. I run 25A through them without problems for 20 minutes or so at a time :p Thats just how they work and im to cheap to get 25A put in place (They are my main breakers so its normal here)
 
You need to be designing the interconnects and protection based on the expected current draw ofthe equipment, and the loading you intend to connect to it - not the manufacturers maximum cell limits.
 
A stack of 7 Leaf modules will need 6 short bus bars, assuming you have 3 with + on the left side and 4 with + on the right side. Or vise versa.
 
Is there a way to determine this (Max Value) from the inverter I am using?

As in, can I from the specs, figure out what the MAX amp draw the inverter is capable of creating?

I would assume if overloaded it will shut off anyway.

I am just trying to determine how to find that upper AMP limit, and get above it by a safe bit. 100 Amps or so.

My inverter is:
https://www.aimscorp.net/6000-watt-...er-charger-48-volt-dc-to-120-240-volt-ac.html
 
Are you the same person who mentioned they'd got 30+ years of electronics experience the other day ?

You should be able to read a spec sheet.
 
Amp * Volts = Watts
Inverter is 6000W, so, Watts / Volts = Amps
 
That inverter can do 500A easy during max draw for 20 seconds! That is ALOT
 
Korishan said:
Amp * Volts = Watts
Inverter is 6000W, so, Watts / Volts = Amps
Click to expand...

So 125 Amps nominal.

Thank you!

It would seem that 2 of these Strips, would combine for a total of about 430 Amps max.

More than enough for my meager use.

I only have x2 thirty amp breakers in the panel in my office, with a 100amp main disconnect at the top of the panel.

There is very little going in there.

15watt t5 LED lights x6
Small AC Unit - https://www.frigidaire.com/Home-Comfort/Air-Conditioning/Window-Mounted-AC/FFRA0522U1/
Infrequent use of my Air compressor. https://www.homedepot.com/p/Husky-20-Gal-175-PSI-Portable-Electric-Air-Compressor-C201H/206189626
And a Small Fridge. Either an RV Fridge, or an Energy Star Dorm Fridge. (The more expensive kind at about 300kw / year )

With about 3100 Watts at 77v Solar Coming in to the system.

I'm thinking this is good.
 
When calculating dont forget to that you need to calculate for lowest Voltage and thats around 40VDC for that unit.

Then you need to add the efficiency losses. So 6kW would be around 6600W on battery side
6600/40 = 165A nominal!

Edit: Also beware of that when starting hungry appliances you will go above several times. For instance a motor that starts can easy pull 5-10x the current during the start so you take that in account. This does though not affect concurrent useage much and the breakers will work just fine.
 
Sean said:
Are you the same person who mentioned they'd got 30+ years of electronics experience the other day ?

You should be able to read a spec sheet.
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Sean.... If you don't have anything to contribute that isn't negative BS.

Then don't.

Others here are more than willing.

I've been in IT for going on 30 years. Yes.

I have been building customelectronics and tinkering with 3d printers for about 15 years.

These systems did NOT require such a detailed understanding of AMPS / WATTS

You typically just plug that stuff in....

So, be serious and stop trying to look smart.

Its just making you look like an ass...

Honestly.

I appreciate the answers / help you have provided.

But when you type stuff like this, it cheapens the acts.

Help or don't. Its a choice.

Your peanut gallery comments are rude and unnecessary.


Not all of us are electrical engineers by trade, but still enjoy LIVING and being in one piece.

Knowledge is power.

IF I am asking the WRONG questions, then try being helpful and show me the RIGHT questions.

All, I'm saying.

Peace.
 
Dude, I don't spoon feed answers, I've previously given you more than enough help and pointers for you to have been able to answer all of the questions you've asked in this thread.

Stop being lazy, do your own research.
 
Stop it. Rudeness have nothing here to be at all. I removed all 3 posts. Lets continue to talk facts and rest should not be on this forum.
 
daromer said:
Stop it. Rudeness have nothing here to be at all. I removed all 3 posts. Lets continue to talk facts and rest should not be on this forum.
Click to expand...

Yes. I understand. And Agree.

I'm just looking for information and as an amateur in battery building, Trying to keep myself SAFE as I learn.

Thank You.
 
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