I have 3 dual battery banks. All 3 are connected to j cameras since last week of October. On 2 of the cameras, I received error code 4. On one camera, it happens every 2 weeks or so. I reflashed 7_7 on both, replaced all 12 batteries on both, different sd cards on both, reseated the cords on both....still getting the error code every couple weeks...on one camera more so than the other. Neither camera have internal batteries. Sometimes report shows ext-1 ok for a day, then ext-2 for a few days, then offline. When I check them, error code is on.