Thanks for the help guys.
I think
@MisterSandals and
@FilterGuy hit the nail on the head.
I did checks again with different loads and the current is always almost half that of the eFlex Batteries. I suspect it's because the Fortress eFlex batteries use an EV battery relay on the BMS to engage the power while the EG4 uses Mosfets. It is either that or the EG4 batteries internal resistance really sucks!
I did a thermal image and let me apologize in advance for not centering the temp on the hottest spot but there was only a 2deg C difference at the hottest point which is the LED at the Top Right which measured 27c. The two second warmest parts are the Terminals on the 250A breaker which was about 26C. You can see 5 wires on the bottom one and that is coming from the 4 batteries plus one small wire that goes to my Precharge resistor near the LED. The Top Terminal is where the 2/0 cable goes to the Inverter. On the left is the 4 Terminal 600A Victron Busbar.
BTW EG4 Battery terminals are totally cool at 24c. I will not bother posting a picture because there is no temp variations between the cool front panel and terminals.
Same measurement with the house being powered at around 3.5Kw.
20Amps from each eFlex Battery and 11 Amps from the EG4.
I now have mixed feelings about buying this battery.
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