I purchased a 200AH Amperetime battery about a month ago and am very confused by what I'm seeing in the charge and discharge cycles. I have a shunt installed (https://www.amazon.com/dp/B08BCDCH1X?psc=1&ref=ppx_yo2_tab_ap_product_details). I am running all of the loads through a Renogy 200w pure sine inverter and charging with a Renogy Rover 40A MPPT controller and 4x 100w monocrystalline Renogy panels.
I decided to see how long the battery would supply power under normal use without any charge going in so I applied various loads to the battery, coffee pot, clothes iron, small refrigerator, led table lamp, and a box fan. When the BMS hit the low voltage cutoff, my battery monitor (shunt) showed 67.5 AH total had come out of the battery. I was puzzled but assumed that maybe it had not been at 100% SOC like I had thought it was so I disconnected the load from the battery and let it charge for a few days. The charge controller showed that 77AH went in on day 1, 77AH again on day 2, 15AH on day 3, and 44AH on day 4, for a total of 213AH input over the 4 days.
Now the battery showed 14.4v and the charge controller was showing 0 amps so I decided to do another test, this time without using the larger loads. This time I only ran 2 box fans on high, the dorm fridge, and a desktop computer. The average draw shown by the battery monitor was around 7 amps. After 2 hours I ran the numbers shown on the monitor and calculated that it would take around 30 hours to completely discharge the battery. That would happen late in the evening of the next day. Sadly, I awoke to the sound of the low voltage alarm of the inverter at about 4am. When the BMS shut the battery down, the monitor only showed 68AH had been used. Do I have a bad battery, or is my shunt not showing correct numbers? Or possibly, do I have a bad battery AND my Renogy controller is showing inaccurate numbers? Should a fridge, a pair of fans, and a desktop computer completely discharge my 200AH battery in 11 hours?
I decided to see how long the battery would supply power under normal use without any charge going in so I applied various loads to the battery, coffee pot, clothes iron, small refrigerator, led table lamp, and a box fan. When the BMS hit the low voltage cutoff, my battery monitor (shunt) showed 67.5 AH total had come out of the battery. I was puzzled but assumed that maybe it had not been at 100% SOC like I had thought it was so I disconnected the load from the battery and let it charge for a few days. The charge controller showed that 77AH went in on day 1, 77AH again on day 2, 15AH on day 3, and 44AH on day 4, for a total of 213AH input over the 4 days.
Now the battery showed 14.4v and the charge controller was showing 0 amps so I decided to do another test, this time without using the larger loads. This time I only ran 2 box fans on high, the dorm fridge, and a desktop computer. The average draw shown by the battery monitor was around 7 amps. After 2 hours I ran the numbers shown on the monitor and calculated that it would take around 30 hours to completely discharge the battery. That would happen late in the evening of the next day. Sadly, I awoke to the sound of the low voltage alarm of the inverter at about 4am. When the BMS shut the battery down, the monitor only showed 68AH had been used. Do I have a bad battery, or is my shunt not showing correct numbers? Or possibly, do I have a bad battery AND my Renogy controller is showing inaccurate numbers? Should a fridge, a pair of fans, and a desktop computer completely discharge my 200AH battery in 11 hours?
