AC500 + B300S Will not charge from Power Cord

Hello,
My AC500+B300S is not charging via an AC Cord plugged into an extension cord and a household socket. I’ve had intermittent problems with this. Sometimes it charges just fine and over the past week it will not charge. I’ve tried unplugging all cords, plugging back in, I’ve tried a different extension cord, outlet, etc. I’m getting so frustrated with this. I had it plugged in all day the other day–it was at 23% to start–ahead of a storm to make sure it would be charged fully in case I needed to run the sump pumps for flooding and it never charged. Tried again yesterday and today–now at 12%–to no avail. There has been no sun to try to charge it via solar the past week.

@llewella Please refer to the responses in this thread to see if they are helpful. If the issue remains unresolved, please let me know.

@cyn791,
Thank you for the reply. I am unclear on what you mean by “what devices are you carrying?” or how to ensure the frequency is the same as the AC500? Frequency on what? The firmware is updated to the latest. There are no error codes. AC output voltage is normal. I do not know how to measure the AC output using a multimeter. I am simply trying to charge the AC500&B300S via AC outlet and it will not charge. I’ve charged it fine hundreds of times via the exact same outlet, etc. It has been sporadically doing this; one time it won’t charge and the next few times it is fine. I have tried everything I can think of including a different outlet, a different extension cord, etc.

Hi @llewella

Please check, if AC charging is enabled for the unit and try to activate “grid adapt mode”

greetings
Erik

Where do I check if AC charging is enabled? I cannot find this option and have never needed to use it. Next, it appears I need a password to activate “grid adapt mode.” Where do I get the password?
Thank you.

Hi @llewella

the password can be provided by @BLUETTI or @BLUETTI_CARE

Grid charging only can be enabled/disabled when you select a custom UPS mode.

greetings
Erik

The password is eight eights (88888888). Please update both the APP and the firmware to the latest versions to activate it.

Update: The system was again plugged into AC wall outlet all day. The temperature outside was 63 degrees and 67 degrees inside the van. I left the door open to be sure warm air got inside. I had an electric heater sitting near it as well. There was also some sun today (to charge via solar). It has been at 1% all day and shows nothing coming in to PV or AC input for charging. I am now trying to charge the battery via solar (directly plugging into the B300S) but it is overcast now and only about an hour before sunset.
I don’t know what else to try. Should I try the factory reset? This setup has worked flawlessly until about a month or two ago. It is very well taken care of and hasn’t been moved or in the elements since installing it in my build. I guess it did get cold enough for it not to charge, though I thought the B300S was heated so that shouldn’t be a problem. But it has been above freezing for several days now and was in the 60s today.


Earlier this morning I posted this: Well, it appears that I did have an error. A035 Charing Low-Temperature Protection. The thing is that I didn’t have this problem when it was single-digit temperatures and I thought the B300S avoided the low-temperature issue. It is milder temperatures the past week and we will see what happens today (highs in the 50s). This is installed in a van build (ambulance). I am currently not traveling and have the luxury of plugging in to house power to charge. I did not have this issue last winter. I’ve never had to enable AC charging (I still can’t seem to find this option but I will play with it some more–I have to get to work. I usually simply plug it in and it starts charging. Thank you all so much for trying to help me.

What is your UPS mode set to? (Tap the icon on the APP in the upper right.) Look for “Working Mode.” Also at the bottom of the APP is “Advanced Settings.” You can set the max grid input current. You’ll need that code if you want to draw more than the recommended current draw. Normally, houses have 15 amp circuit breakers.
.
Mine is set to PV Priority and at 30% SOC. This means than the AC500 will switch from solar to grid power if the SOC falls below 30%. It will switch back to solar when the B300s gets above 30%. You can set this from 0% to 100%.
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One other thing, is the Grid icon on the right of the APP green or grey. It should be lit green if you’re plugged into a wall socket, even if you’re not drawing grid power.

UPS mode is Standard
Max grid input is at 15 amps
The Grid icon on the right is orange on mine with the others greyed out.

UPDATE: 2/4/25 11:30 AM
I went out to begin loading to leave in a few days and it was charged to 100%!!! I assume it was via AC as there is no sun today. I am so relieved but would really like to know how I can avoid the problem in the future. This unit is my lifeline.

Hi @BLUETTI,
The issue has not been resolved. I had thought maybe it needed warmed up to charge (even though the B300S is supposed to self-heat). It was in the 60s F yesterday. I even plugged in a heater near it. Plugged into AC and solar all day (several days in a row now) and it will not charge. Forcast is all rain today so plugging into the battery directly to charge via solar is not an option. I do not know what else to do but I really need my power system as I am leaving for work (and will be living in the van again) in a few days. Thanks for any help.

Hi @llewella, We believe this issue is indeed related to the environmental temperature. Even if it doesn’t drop to freezing, it can still significantly affect the charging and discharging speed. We recommend making sure the RV is well-insulated to protect against the cold.


Additionally, could you check the extension cord and home power strip? Please provide your AC500’s SN code and current firmware version.


You also mentioned earlier that the Max grid input is set to 15 amps—could you try lowering it a bit and see if that helps?


Thanks to @Selfmadestrom and @St8kout for their attention and feedback on this matter.

1 Like

Hi. The RV is well-insulated and I also use a thermal blanket when I am not living in the RV/not using the unit.
The extension cord is a 10/3 severe weather cord.
The max grid input was on 10 amps and I just upped it to 15 amps while trouble shooting to see if it would help. I have never changed it previously.
I can provide the SN and firmware version in the AM. The firmware was just updated.

Hi @llewella, We would like to know if the indicator light on the adapter is on.

When charging the AC, please click the Adapter icon and check if the input voltage of the adapter is normal. If you have a multimeter, it would be helpful to test the output voltage of the adapter as well.

Also, is the AC200MAX showing any error codes?

Maybe I can help with this issue. I have Ac500 and B300s located in my Garage, where the temp ist now down to Zero degrees celcius. What I have seen is:
When you get A035 Low temp error, the ac500 will Stop charging from solar and AC input. Even so it IS supposed to Heat the battery it will not do so. The only way to come over this is to warm up the battery well over 10 degrees celcius. Then the error disappears and the system operates normallY. I think,this happend to you.

When the system shows the A035 Error, I thougt, connect it to AC and it will Heat up the battery. But it does definitely not. This is what you have seen and I think, this is a Software Problem, that could be cured by bluetti.

So, in a cold Environment it is important to have AC Always connected,so the system can start heating when necessary. If Not and the battery cools down, you get the Error and you are lost.
When the system starts heating, it consumes very Low power on the AC input, around 1 Watt. You can Not See it in the AC500, but measure it externally.
The system does Not Heat from the battery nor solar input, only from AC.

Hope this helps.

Thank you so much for your comment. I mostly leave it plugged in while somewhere with access but at times, like last week when it was very cold, I unplugged the bluettii to plug in my engine heater block for a few hours and because I was at 70% battery, thought it would still heat the battery. I was wrong. I’ll have to plug in an electric heater.
I wonder if a heat pad under the battery would help or hurt?
I thought the B300S would solve the problem of cold temps but, as we have seen, it doesn’t.
A bit frustrating and disappointing.
Thanks again for your help!

Hi.
The icon for AC input was orange and others grayed out. It was animated as well but no input, just dots. I don’t know how to test voltage. I actually do have a multimeter but do not know how to use it. I’ll have to learn I guess. Most of the time, however, I am running off solar without access to AC plugin. I see the new DC power charger available and this would be very helpful, but out of my price range.
Also, this is not an AC200MAX, this is an AC500 and B300S.

Hi @llewella, The AC500 + B300S does indeed have a self-heating function, but it only activates when charging via AC or solar power and the power reaches a certain threshold.
Additionally, if the temperature of the B300S battery is already below 0°C, it must warm up to 10°C before normal charging can resume. This is to prevent potential damage to the battery’s lifespan caused by charging in low temperatures, so we’ve implemented this protective measure.


When you mentioned, “It was animated as well but no input, just dots,” I believe you’re referring to no DC input. This could mean the DC input voltage is too low, thus preventing successful charging.


Apologies for mixing up the model earlier, and thank you for the correction.