diy solar

diy solar

Battery Cable question.....

T

Transam

New Member
Joined
Oct 21, 2019
Messages
76
Starting my system.....
The inverter is a 48V system... so... here is the picture...

8 BANKS of batteries (AGM Deep cycle) Each bank... 4 batts in series to get my 48v.
then a total of 8 BANKS all paralleled (32 batts total)
Each batt is 120ah

what should I use for Jumpers ? 2/0 ? or AWG2 ?
and the Main leads (parallel leads to inverter... Same 2/0 or AWG2 ? or 1/0 ??

Any advice would be appreciated !

Also fyi bank is maybe 4-6' from inverter 48V input.

thanks in advance.
 
Hello,

I think you should size your wires according to the predicted consumption. I think you should check what's the max current of your charger/mppt and size your wiring according to this value. I'm fairly new here, so I would suggest you to wait for a more experienced answer.
About the jumpers and main leads, I suggest you use the same size for both.

My project also utilizes 48V, only that I have a single 110Ah bank yet!
Best regards
 
The batteries will supply whatever amperage is demanded of them.
Wires and fuses or breakers are sized to the demand.
If you have a 1000watt inverter tied to it, it only needs a 20 amp breaker and wire, so 12, or 10 would be fine.
If you have a 20,000 watt inverter, that changes to a 417 amp load... so, the wire needs to increase to handle the flow of watts.
 
I will use this image from one of my past posts in
"Solar Equipment Reviews and Technical Support;
Wire/Connectors/Junction Boxes;
Wire distance"

1571742434663.png

Hope this helps.
 
Thanks for the input ! :)....

So my inverter is a 5000 watt inverter... (as my orig post........ I have 32 120ah batteries (agm sealed)...)
so this will give me about 960ah

It was suggested to me to use 4AWG to series all batts (4 12v batts) and then run the + to a total of 8 50A DC Breakers (aka there is 8 BANKS of batts.... 4 x 12v batts=48v)...

Then out of the + breakers to a THICK SOLID Copper bus bar..... run the - all 8 leads also to their own bus bar.... then RUN 1/0 cable off the BUS BARS to the inverter....

I just wanna make sure I dont have a Chernobyl happen !

Supervstech said:
The batteries will supply whatever amperage is demanded of them.
Wires and fuses or breakers are sized to the demand.
If you have a 1000watt inverter tied to it, it only needs a 20 amp breaker and wire, so 12, or 10 would be fine.
If you have a 20,000 watt inverter, that changes to a 417 amp load... so, the wire needs to increase to handle the flow of watts.
Click to expand...
 
If you used the entire 5000w potential of the inverter, a 4g wire would work, but I'd go a bit heavier to cover up to a 6000w surge (I like to plan high).
 
How about 50 amps from the batteries to the inverter for a short distance (like 2 feet)? I had used this chart that recommends 6 AWG, but other charts are more lenient.
DC_wire_selection_chartlg.jpg
 
The series of 4 should have a max load of 50 amps (because it's behind a 50a breaker), so 4 gauge should be fine there. I like the bus bar idea...
 
thanks for the fast reply ! :)

Im glad I can use 4awg for battery to battery !

I think at the end of EACH String of batts the wire may be 3ISH feet....(all so they can run to the bus bar)

Bus bars im gunna use are THICK.... CDA 110 COPPER 1/2" thick by 1.5"wide by 12 long.... which should do 1000aH :)

then from the BUS BAR to the inverter 2' MAX of 1/0 wire....


between bat to batt... I think 8ish inches....

On Surge... this inverter is the house... so Im guessing Only surges may or will be window AC's (and maybe fridge) the fridge is brand new so pretty efficient :)

On a AC Window unit... surge of the compressor starting up.. maybe 5 seconds... 10 secs max....guessing :)

Do you think it all sounds good ?


Rider said:
If you used the entire 5000w potential of the inverter, a 4g wire would work, but I'd go a bit heavier to cover up to a 6000w surge (I like to plan high).
Click to expand...
 
Transam said:
Thanks for the input ! :)....

So my inverter is a 5000 watt inverter... (as my orig post........ I have 32 120ah batteries (agm sealed)...)
so this will give me about 960ah

It was suggested to me to use 4AWG to series all batts (4 12v batts) and then run the + to a total of 8 50A DC Breakers (aka there is 8 BANKS of batts.... 4 x 12v batts=48v)...

Then out of the + breakers to a THICK SOLID Copper bus bar..... run the - all 8 leads also to their own bus bar.... then RUN 1/0 cable off the BUS BARS to the inverter....

I just wanna make sure I dont have a Chernobyl happen !
Click to expand...

well, a 105amp draw or more from the battery at 5Kw... #4is a tad shy unless it is a short wire. #2is rated for 130a, so a safer size. Between batteries smaller size can be used, but from the bank to the inverter, I would use #2 on a 5Kw inverter load.
 
Transam said:
thanks for the fast reply ! :)

Im glad I can use 4awg for battery to battery !

I think at the end of EACH String of batts the wire may be 3ISH feet....(all so they can run to the bus bar)

Bus bars im gunna use are THICK.... CDA 110 COPPER 1/2" thick by 1.5"wide by 12 long.... which should do 1000aH :)

then from the BUS BAR to the inverter 2' MAX of 1/0 wire....


between bat to batt... I think 8ish inches....

On Surge... this inverter is the house... so Im guessing Only surges may or will be window AC's (and maybe fridge) the fridge is brand new so pretty efficient :)

On a AC Window unit... surge of the compressor starting up.. maybe 5 seconds... 10 secs max....guessing :)

Do you think it all sounds good ?
Click to expand...
1000Amps, not Ahour! Huge difference... Ah is a rating of time demand... a 10 amp load over 100 hours is 1000Ah... or 100 amps over 10 hours, or 1000Amps over 1 hour...
 
Yea I was going to use 4awg from Batt + to batt - (for the SERIES Part)

Then the - and + from each bank (4awg) to each bus bar... then 1/0 to the inverter (2') away....

Should I maybe use 2AWG from EACH bank to the bus bar ? (im also putting a 50A DC Breaker on each bank..)

Supervstech said:
well, a 105amp draw or more from the battery at 5Kw... #4is a tad shy unless it is a short wire. #2is rated for 130a, so a safer size. Between batteries smaller size can be used, but from the bank to the inverter, I would use #2 on a 5Kw inverter load.
Click to expand...
 
Transam said:
Do you think it all sounds good ?
Click to expand...
Supervstech said:
well, a 105amp draw or more from the battery at 5Kw... #4is a tad shy unless it is a short wire. #2is rated for 130a, so a safer size. Between batteries smaller size can be used, but from the bank to the inverter, I would use #2 on a 5Kw inverter load.
Click to expand...
I think most of us are in agreement that a #4 within battery groups is good, but #2 should be used to connect the banks together and to run to the inverter.
 
Ohh lol Im not well versed in the 1000ah/kw type of stuff :) haha Im told the Copper is thick enough to handle that many batts connected :)


So maybe I should use 2AWG to go from EACH + and - OFF Of each batt bank up to the BUS Bars ? then 1/0 from bus bars to the inverter ? (2' away) ?
does that sound good ?

although EACH + off EACH Batt bank will go into a 50A DC Breaker... I just dont know if the DC Breaker can take in a 2/0 cable....
its these breakers...
 
Oh, if you are connecting the 48v banks to a buss bar, and setting up 50 amp fuses, then #6 is fine to the bar from the bank, just use #2 to feed the inverter.
 
Awesome ! thanks for the info ! yea each bank's + *8 banks total) will run into thier OWN 50A breaker (I wanted to use the 4awg)
DISTANCE from BANKs to BREAKER will be maybe 2 or 3' for EACH BANK(4awg).... then out of BREAKERS (the +) to the BUS BAR... maybe 1.5-2'...

Then Id go from the BUS BAR to the inverter.... (2' MAX with 1/0)....

BTW I appreciate everyones help !!! :)

Supervstech said:
Oh, if you are connecting the 48v banks to a buss bar, and setting up 50 amp fuses, then #6 is fine to the bar from the bank, just use #2 to feed the inverter.
Click to expand...
 
Supervstech said:
Oh, if you are connecting the 48v banks to a buss bar, and setting up 50 amp fuses, then #6 is fine to the bar from the bank, just use #2 to feed the inverter.
Click to expand...
Yes. I keep overlooking that he's going to implement the 50A breakers. No need to go higher than #6.
 
Transam said:
Then Id go from the BUS BAR to the inverter.... (2' MAX with 1/0)....
Click to expand...
No need to go bigger than #2. The bigger the wire, the more expensive, the harder to work with, the bigger the connector lugs.....etc. A #2 wire is good for 130amps. At 6000w max potential, divide by 48VDC is 125Amps. Doubt you'll hit 6000W long enough to warrant bigger wire before the inverter shuts down.
 
Awesome,,, glad my 4awg will work for all (cept from busbar to inverter)...

took me a while to find them breakers (that are regular type wall breakers)... I wanted it all to be nice... found a nice breaker box for them breakers to.... googled and googled and found out they are called RAIL Breakers.. and go in a box like this : https://www.amazon.com/gp/product/B07S94Z7CF/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

I didnt want the cheesy little flip breakers (cause I have 8 banks).. and didnt want 1 gigantic fuse or 8 small ones....

I way lucked out.,... on batts... I got 2-3 yr old 120ah agm 12v batts...only discharges once really.. and mostly at float... 90/ea batt
came out of a data center... so also always AC'd./...these: OSI Batteries - EnerSys DataSafe 12HX505-FR Battery 12v 506W Sealed Rechargeable
so I prolly went overboard and bought 32 of em haha

But my elec bill is 1500-1700KWH a month... and its unfortunately a commercial meter and bull averages $550/mo
 
A WAY big thanks on the suggestion of 2awg.... !!
I 10000% agree 1/0 is difficult and costs more ;(

as ive been wiring my electrical breaker box up... ive been keeping a eye on what outlets are on which bus in the breaker bar... as not to overload appx more than 2300 watts per leg... (my inverter does 240) so 2 120 legs... I dont use any 240v stuff at all....) Not sure what the SURGE Rating on my inverter is... havent looked lol..... But its the 5KW inverter version of the 2400watt inverter that will did a vid on a month ago (appx)_

Rider said:
No need to go bigger than #2. The bigger the wire, the more expensive, the harder to work with, the bigger the connector lugs.....etc. A #2 wire is good for 130amps. At 6000w max potential, divide by 48VDC is 125Amps. Doubt you'll hit 6000W long enough to warrant bigger wire before the inverter shuts down.
Click to expand...
 
You must log in or register to reply here.

Similar threads

W
EG4 18kpv Battery Brand
Replies
4
Views
246
Quattrohead
Quattrohead
D
Combining 2 48v battery banks with 1 inverter
Replies
1
Views
192
timselectric
T
Cuemaker
Multiple Battery Banks
Replies
4
Views
240
Cuemaker
Cuemaker
Excpta
48v bank wiring for MPPT / inverter
Replies
6
Views
234
sunshine_eggo
sunshine_eggo
J
Sol ark 15k charging issues
Replies
7
Views
501
myles
myles
Back
Top