Is this the correct way to parallel batteries?

[jim furlong]

Remember that the cables going to the inverter needs to carry twice as much current as the cables between the batteries. If your intent is to add more batteries in the future do not continue to connect in this manner. Instead use a star configuration with all positive battery terminals connected to a common positive bus bar, and same for the negative terminals. Then heavier cables from the busbars to the inverter and charge controller. Breaker (+) and ammeter(-) go in series with those heavier cables.

Thx for that bit of info. I should get in to the habit of using bus bars... I currently just have the batteries in parallel with a positive connection going to the all in one inverter/charger (mpp solar lv6548) from one battery and the negative lead going to the inverter from the other battery

I do notice that the current between the 2 batteries is different 7.3A on positive and 12.4 A on the negative. How ever the current going to the inverter from the batteries is equal on both leads 20.5A
Why is this ? I think they should be much more equal

Any thoughts on that would be greatly appreciated

 

[KBWaldron]

Thx for that bit of info. I should get in to the habit of using bus bars... I currently just have the batteries in parallel with a positive connection going to the all in one inverter/charger (mpp solar lv6548) from one battery and the negative lead going to the inverter from the other battery

I do notice that the current between the 2 batteries is different 7.3A on positive and 12.4 A on the negative. How ever the current going to the inverter from the batteries is equal on both leads 20.5A
Why is this ? I think they should be much more equalView attachment 38825

Any thoughts on that would be greatly appreciated

I see from your picture that you did provide heavier cables for the battery to rest of system, so you did recognize the need for higher current capacity there.
I suspect you are not measuring equivalent current on negative and positive sides. How are you measuring current? You would need to disconnect the cable and insert your meter or use a clamp on meter. The former would introduce the potential for different connection resistances. Both the thinner cables should be seeing the same current.
One other possible cause could be one or more insufficiently tightened connections, or differences in contact area on the connections. Check to see if any of the connections is hot or warmer than the others. If you see oozing around your heat shrink this is a good indication of an insufficient connection.
I suspect a bit of both, since the difference is almost double.

 

[jim furlong]

I see from your picture that you did provide heavier cables for the battery to rest of system, so you did recognize the need for higher current capacity there.
I suspect you are not measuring equivalent current on negative and positive sides. How are you measuring current? You would need to disconnect the cable and insert your meter or use a clamp on meter. The former would introduce the potential for different connection resistances. Both the thinner cables should be seeing the same current.
One other possible cause could be one or more insufficiently tightened connections, or differences in contact area on the connections. Check to see if any of the connections is hot or warmer than the others. If you see oozing around your heat shrink this is a good indication of an insufficient connection.
I suspect a bit of both, since the difference is almost double.

I'm measuring with a clamp on meter. I originally suspected this connection point as it doesn't seem as properly cropped as the others