097 BMS Temperature abnormal - AC500 with B300S

I have my system in the garage, where the Temperature is +5 degrees celcius now. As soon as I connect AC-input to grid, the AC500 shows this Error and will not charge. The spec says, it will work down to -20 degrees, so something is wrong. I let it run to give it time to heat up, but no Change. All software is up to Date. What to do?

Does the spec state the unit will produce power at -20 or that it will also charge at that temp. All the units will discharge power at a lower temp than you are able to recharge at.

The AC500 User Manual (available on bluettipower.com) shows on page 10:
Discharging Temperature: -4-104℉ (-20-40℃)
Charging Temperature: -4-104℉ (-20-40℃)
So at +5 Celcius the unit should work easily. I thought, I had read that the B300S has a build in heater, but anyway - my unit will not charge!

Mine did that once when the temp got down to the upper 40’sF in my garage. I put a space heater near it for a few hours to warm the general area up and its worked fine since then without the heater but I don’t think the garage has gotten that cold since then either. Mine has a B300S and a B300 battery.

@southside Hi, this can be caused by low battery temperature. We recommend you move AC500 to a warmer place. After AC500 gets back to a higher temperature, you can try to charge it. If it does not work, please contact our after-sales team.

Actually page 10 of the user manual states for the B300S (Discharge…-20 to 40C) and (Charge…0 to 40C) as the operating parameters of the battery. There is a third spec in the same group noted as (Storage…-20 to 40C) that you may have confused as the charge temp. Since you were at 5C and you have no charging (within 5 degrees of the lowest limit to allow charging) I would assume that either the battery is colder than 5 degrees above the minimum or the thermometers are not accurate to that degree. Warm it up a little and you should be good to go. It does take quite awhile to warm the internal battery temps, so be patient.

The B300S (but not the B300) is supposed to contain a heater to assist with low temp charging. (From Bluetti…“B300S has a built-in heating module that automatically pre-heats the battery pack at low temperatures, enabling low-temperature charging in environments as low as -20°C. Widen the use environment of the power supply”) I do not however know if this is a user selectable function and it may be off. Attached is the B300S manual that I found:


1 Like

@southside I agree with Scott here. Give it some time in a warmer environment and it should be good to go.

Thanks for your answers. In my post I was refering to the AC500 User Manual, which is as shown. For me it’s very surprising to see, that the B300S has a charging range 0-40 Celsius, because this limits the use of the AC500 to this range!
However , in the B300S Manual I found the following on page 11:
Note: When connecting B300S with the T500 adapter or AC500 to the grid, B300S is able
to self-heat and get charged even at -4°F/-20°C.

→ I connect AC500 to the grid, so it should work.
Today the temperature was +7 C (exactly), so even without the heater ist should work, but I got the 097 BMS - Error again. Next days will be warmer, so we will see…
But I fear, something is wrong here.

1 Like

Since the AC500 has no battery and the battery is the limiting factor with regard to temperature, the actual temp of the battery is key in this situation. In either case, I would simply warm up the battery itself (snuggle with it for 12 hours if no other way) and see if normal charging occurs.

Nothing new here. Temperature today was +9 C and will not change much the next days. This is spring in southern Germany :wink:

Tonight, I had the B300S in the house to warm it up. Then, in the morning back to the garage, connected and it worked. The unit charged by AC grid and by PV.
Next night will be cold again and we will see if it works tomorrow.

Don’t forget, it takes a long time to warm up a cold battery.

The next night, the unit was connected to the grid. In the cold morning it was working fine and charging from PV (PV priority mode). I thought, the internal heater made this possible.
Then the very next night, the unit was not connected to the grid (by intention). In the next cold morning it was also working without error and charging from PV. I don’t understand why - the internal heater is supposed to work only when grid is connected?!
The good thing is, the system is now working as expected…

My understanding is the heater only works when connected to the grid.

I think you are right.
The next night without Connection to Grit, ended in error 097 again. I then connected to grid and started discharging the unit with 2000 watts on the AC output. After 15 minutes the error disappeared.

Conclusion: in cold nights, make shure that AC is connected.