I have discovered a problem with my EP500s. I have been using my EP500s independently to run some appliances in Time Control UPS mode. The appliances drain about 10% of the battery each day, then the EP500s recharge from the grid using the A/C cables. I was using the second set of A/C cables Bluetti sent me and recently switched to the third set. I just found that when there is an A/C output load, the A/C input is drawing power outside my charging window. I tested one EP500 with a 1078W load on the A/C output and measured 729W input power with a Kill-a-Watt, but the A/C input on the EP500 screen stays at 0 Watts. If I unplug the A/C input cable, the UPS continues to supply output power. When I remove the load the input power goes to 0.
I have a pair of EP500s running independently, one I have not updated, but the above test was done before and after updating the firmware on the other. No difference. The 1000W+ load was just for testing and surprised me with more than 700W input draw. My normal operation is around 100W load, less than 70W continuous input from the grid, 500W+ when recharging the battery during the Time Control window.
I expected that the unit would only draw power to recharge the battery within the Time Control window. Instead it is drawing power all the time, and uses battery capacity, then recharges the batteries on schedule.
Does anyone know what is going on? I don’t think Time Control UPS mode should be drawing power whenever there is a load.
Is anybody using their EP500s for time-shifting? Bluetti watched my videos and said that using power all the time is normal. If I put a heavy load (1200W+) the input power draw can be over 1000W. This can only partially help with time-of-use power.
The EP500 screen and app never show the power being pulled from the grid outside of the time window, but I used multiple external devices to verify that power is being used. I found that only the A/C cables do this The cable marked “GEN” does not take power when I don’t want it to. With the GEN cable the power draw is 0W outside the time window and ~550W inside the window for battery recharging. This also causes the battery to drain much more between charges.
I will try your suggestion today and post an update.
I have the charge time set to later in the day, so the battery does not charge in TCUPS mode. With a 70W light bulb attached I have 74W output and about 64 W input in TCUPS mode. When I switch back to Standard UPS mode the battery starts charging regardless of the SOC settings. In Online Standard UPS the input is about 570W and in Offline Standard UPS mode the input is 640W. That seems backwards to me so I checked it twice, Offline adds the battery charge plus about 90% of the load value, and Online mode is just the battery charge current. Either way the battery charges if it is less than 100% even if it is above the top SOC setting.
Back in TCUPS mode the load causes a current draw of about 90% of the output load. The battery only charges within the time and SOC windows. This only happens with the multiple A/C cables provided. Using the GEN cable on the A/C input fixes what I see as a problem. I plan to check the differences between the GEN and A/C cables.
The A/C and GEN cables have three-prong plugs, of course, and five-sockets on the EP-500 end. If you number the sockets 1 thru 5 clockwise from the top, the A/C cables supply power on pins 1 and 2, with ground on 3. The GEN cable keeps ground on 3, but power is delivered on sockets 4 and 5. So, the EP-500 works differently depending on which pins have power. I don’t know why they did it this way, maybe different tolerances on the GEN inputs.
I prefer the way the GEN cable makes the EP500 perform, so I am using the one GEN cable for now. I will try to convert one of the A/C cables, but it may require a special insertion tool.
I got some better light on the aviation connectors (EP500 end) and they are numbered left to right, then top to bottom. The a/c cables have power on 2 and 4, and the GEN cable has power on 1 and 3. Both use 5 for ground.
I guess I am just talking to myself here, but in case anybody cares: I converted an A/C cable to a GEN cable by moving the power wires to pins 1 and 3. Now my EP500s truly only use power when I want them to.
The connector comes apart by unscrewing the cable clamp, then the shell from the body. The wires are soldered to the pins, so it is simple (but fiddly) to unsolder the wires and move them to new pins.