I am using a Bluetti Elite 100 V2 as a UPS and noticed repeated small charge/discharge cycles while the unit is permanently connected to AC input.
Setup:
AC load: ~19 W
USB-C load: ~15 W
Charging Mode: Silent
Bluetti App 2.3.29
Issue:
Even with stable AC input, the battery occasionally drops from 100% to 99% and the unit starts recharging. App readings often show AC Input ≈ AC Output, while the USB-C DC output seems to be supplied from the battery instead of AC passthrough.
Could you please confirm whether this behavior is expected for the Elite 100 V2 in UPS mode, or if there is a setting or firmware update that enables full pass-through for both AC and DC outputs?
Normal - my 100 v2 does as you describe. Pass through is only on the AC side of power output as far as I am aware.
That said - If the SOC is not at 100% your input supply will charge the Elite until it is full. Periodically, the “smarts” of the power station interogate the battery to make sure it is full by applying a small charge, then switching charge off when it senses 100%.
If you have a small DC load at the same time, this is supplied from the battery and also explains the slight drop in SOC. As it is a very low power event, the battery is not actually cycling and therefore doesn’t count in cycle life count.
I use an AC70 on my Fibre Optic input, WiFi Router and home security system in UPS mode. They are 25W total, all from AC power. (No DC loads) In this situation SOC remains stable at 100%, however, when I connect an almost flat Android Tab to the USB port, the slight fluctuation to 99% SOC occurs.
Thank you, @Mandp, for your info. You’re correct, I checked on several Bluetti stations, different models, on all - DC workload (at least USB connected) working on the station’s battery. Only one thing I want to check - workload connected to DC5521 ports (to power ONU/router), I think the result will be the same, but - just in case :-)
On this and similar sized power stations, all DC connections power from the internal battery and are independent of pass through AC charging. Other than a charge when SOC <100%.
It doesn’t matter if the voltage is 5VDC USB-A, 5-20VDC USB-C PD 100W (5-28 at 140W) or 12VDC cig socket or 5521 port. They all connect to the battery via transformer/regulator at their appropriate output voltage and are independent of the AC circuit, be they 120VAC U.S. or 240VAC AU - EURO.
I am also confident that a DC input, solar or other, does not operate as UPS. @BLUETTI_CARE might confirm my opinion.
Hi @tempal, Thank you for reaching out to us.
As @Mandp mentioned, this is a normal phenomenon.
When the power station is nearly fully charged, it will enter trickle charging mode—this is designed to avoid overcharging, which could damage the battery. Once fully charged, the power station will automatically stop charging and switch to discharging. When the power drops to a certain level, automatic charging will be reactivated.
The voltage of grid power is identical to that of AC loads, so pass-through charging is enabled. For DC loads, however, the current and voltage need to be converted by the inverter before charging, so power must be drawn from the battery.
