AC300 No AC after drained batteries

AC300’s with 4xB300s each. Set to operate as standard UPS
Scenario: Utility power off → batteries kick in → batteries drained → all is off…-> utility comes back on. Utility power is not routed back through AC300 outlets !!! How come ?

Hi @BigApple , Since the UPS situation you described has the machine shut down after the battery is depleted, our machine has to be turned on manually after it is shut down.
It can only be turned on automatically if there is PV input.

So if the Utility power comes back on… it does nothing ? it wont recharge itself either as it is completely non functional ? only if i have Solar.? so using this as a UPS with Utility power only is limited as you have to be home to turn it back on ? I have devices that turn itself back on when the power gets restored … why would you not make these units one of them as they seem to need it… Or at least have it passthrough the Utility power when the unit is off this way at least the power is back for the house when the unit is off. it seems to make things worse rather then help.

Hi @BigApple , When the battery is depleted and the utility power is restored, you need to turn on the machine by yourself.
Unless you connect the solar panel, there is PV input to make the machine turn on automatically.

As an owner of both AC300 and AC500 this seems very odd to me as well, but wouldn’t it be simple to connect a DC power supply to the AC300’s PV input? Power it from your grid so that when utility power is restored the AC300 thinks it’s seeing PV input?

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Any good UPS would restore power to the load and charge the UPS battery after a prolonged power outage that caused the UPS battery to be drained empty. The fact that the AC300 does not do this means that it cannot function as fully-fledged UPS.


My advise: Buy a pure sine-wave UPS from a reliable UPS manufacturer like APC and Eaton and use that as UPS. Keep your Bluetti as backup battery or solar power station. Then you can have best of two worlds. It will result in much less parasitic power drain as well. The AC300 is not an efficient UPS. In this way, you have the option to (manually) turn on your AC300 and plug your UPS into it when there is a power outage. And when nobody is home, the UPS battery will drain in 20 minutes or so and the load will automatically resume operation when the power outage is over.

Exactly. Works. I use a dc charger for that reason as well as to avoid the neutral bonding issue on AC.