Battery amperage measurement question

12 volt system, 6 100AH batteries.
Inverter connected across whole pack.
Plus at one end, positive the other.
Running a test load 1400W heater.
I get very different readings between each pair.
(Only measuring the plus at this point because I have to move a bunch of stuff to get to other cables)
62A, 45A, & 34A.
Shouldn’t they all be about the same?

Quite typical for six in a parallel stack. For best results equal length cables from each battery to a common bus should be used.

Here is some reading; http://www.smartgauge.co.uk/batt_con.html

Yes, what you are seeing is predictable.

Unbalanced Charging: It Is a Matter of Resistance

This works with banks of 2,4,8,16.... batteries, not 6.

One way of wiring 6 batteries is to use a pos and neg power post or busbar. All the battery neg posts are wired to the neg post with EQUAL length cables. Likewise for the pos side. This ensures equal resistance for each battery.

HTH;
John