Connecting Several Batteries in Parallel using 4 AWG

[Peter Evans]

Hello All!

Setting up a basic 40 panel system with three separate 10 Kw inverters and (14) 5Kw batteries.

The battery manual shows they can be set in parallel and the batteries themselves have two inputs each for positive and negative. The batteries came with 4 AWG cabling to connect each battery to bussbars.

It also shows connecting the batteries from battery to battery in parallel using a different pair of 4 AWG wire that they also sent me with the battery purchase.

It seems to me that when you get to the 5th battery you are exceeding the ampere capacity of 4 AWG wire and the gauge would have to increase as you added battery after battery until you reached the maximum draw from the inverter, say limited to 250 amps.

So while the manual shows them accumulating 16 batteries in a long string of parallel connections wiring then going to the inverter, it seems like an error in the manual has occurred.

My current plan (see picture) is to connect four batteries in parallel (each with there own wires to a 300 amp buss bar (4 buss bars total) with one inverter connected to each buss bar.

So My Question: Is there something I am not understanding about amperage that would somehow allow the entire string of 14 batteries to be connected in parallel, battery to battery with 4 AWG wire drawing 250 amps as shown in the manual, or is the manual completely broken?

Thanks in advance for the help

 

[timselectric]

or is the manual completely broken?

This

 

[BentleyJ]

4AWG is rated for 85Amps + or - depending on which ampacity chart and temp column you use.

The 300A Bus Bars to connect the 4 batteries to each inverter is definitely the way to go. I would recommend Welding Cable since the fine strands make it much more flexible. 4Awg from each battery to the bus bar since this will be 50 to 60A. Between the bus bars and the inverter, 2/0 welding cable since it may be carrying the full 200+ Amps the inverter is capable of using.

Its not completely clear if the inverters are stacked or are operating independently and serving individual breaker panels. In the latter case the loads will be different between the inverters so the battery cross tie cables need to have low resistance so each set of 4 batteries will transfer current between themselves and more or less stay at the same state of charge. 4AWG or even 2 AWG cable would be recommended.

 

[Peter Evans]

Thanks, that's what I thought. I had diagrammed mine before looking at the manual and when they sent me the wires to connect battery to battery and with secondary connections to allow both parallel to each other AND to a buss bar I was not sure what was what :D

 

[Peter Evans]

4AWG is rated for 85Amps + or - depending on which ampacity chart and temp column you use.

The 300A Bus Bars to connect the 4 batteries to each inverter is definitely the way to go. I would recommend Welding Cable since the fine strands make it much more flexible. 4Awg from each battery to the bus bar since this will be 50 to 60A. Between the bus bars and the inverter, 2/0 welding cable since it may be carrying the full 200+ Amps the inverter is capable of using.

Its not completely clear if the inverters are stacked or are operating independently and serving individual breaker panels. In the latter case the loads will be different between the inverters so the battery cross tie cables need to have low resistance so each set of 4 batteries will transfer current between themselves and more or less stay at the same state of charge. 4AWG or even 2 AWG cable would be recommended.

Thank you for the reply, I am going to use 0000 between the buss bars and the same from the buss bars to each inverter as I am going for .25% voltage drop (power loss). Looks like that manual is gonna result in someone snapping terminals off of batteries of they start drawing for an 18 kw inverter at 350 amps.

 

[Peter Evans]

Thanks, that's what I thought. I had diagrammed mine before looking at the manual and when they sent me the wires to connect battery to battery and with secondary connections to allow both parallel to each other AND to a buss bar I was not sure what was what :D

The inverters are independent of each other, each connected to it's own buss and each running off-grid to three independent circuits. One inverter for Car Charging, one for A/C and Electric Heat, and one for a subpanel.