Loud popping noise

I’ve heard approx 4 LOUD popping noises coming from my bluetti 1500. Should I be concerned?

Very hard to say without any information from you regarding the circumstances. Was the unit off, on, under load and if so what? Temperature, outside or inside or any information at all that would enable someone to give you a reasonable response to the question?

It was inside my bus conversion. It had gotten down to 12 degrees the night before, no or limited heat inside the bus. I heard the popping after I had turned on the bus to warm up. It’s working fine now… got an error code of E021. But it seems to be charging ok now via solar and shore power.

The error code E021 states:
“E021 Charging protection of
battery protection board
Wait for the temperature to return to an
acceptable temperature and then start

So with your information you gave stating that it was 12 degrees with limited or no heat, you are attempting to operate your Bluetti EB1500 outside of its environmental limits. You did not state if you were atempting to charge, but I assume so since you got the error code 021 which is basically saying…Its too cold and can’t charge. The popping most likely was the expansion of parts outside or inside the unit when they were warming up just like when a house creaks when it gets warm.

I found this info by doing a google search for the operators manal for the EB1500…

Operating Temperature: 0-40°C …0 degrees C is 32 degrees farenheight which you were considerably below. Here is some additional cold temp info also contained in the manual…

Cold Weather
Cold weather can influence battery capacity. In sub-zero temperature (<0°C), you may
be able to discharge the product, but you should not charge it. Otherwise, the battery of
the product would be greatly damaged and the capacity may not even be recovered.
Low temperature charging protection: When the product is charged at a temperature
below 0°C, it will shut off and stop charging itself automatically. The product will reboot
and start charging itself when the temperature rise to above 10°C.
Low temperature discharging protection: If the product is discharged at a temperature
of -20°C, it will turn off. The product will reboot and turn on output when the temperature
rise to above -10°C.