I have had AC300 and two B300 offgrid for over a year working fine charging off two PV420 panels primarily running a small fridge. Only twice has AC shut off, most recently with Helene ( and of course doesn’t turn on again) :-( So to get extended time during cloudy times I got a 3rd B300. It arrived at 50% charge. Other two were at full charge. The new one was added. AC300 still said 100% which I thought should have been 86%. Overnight it is now at 18% still on standby, sun shining and charging the other 2 which are at 74% and 84%. On bluetooth the only thing different is two charging have two joined circles next to parallel and the new one has like a crossed out lozenge icon. Are the order you connect the batteries from and to the two ports important? In the manual it shows 4 connected and I used part of that for my 3. Wanted to connect a PV420 directly to the battery but think Amp limit too high. Tried other B300 standby topics to no avail. Please help explain and solve standby.
To add, when the new 50% SOC battery was added and the other two were full, I had plenty of sun on the panels going nowhere.
A couple of things to check since the battery link symbol is not showing active. First, you can have a maximum of 2 batteries linked together on either of the AC300 battery ports (ie: you cannot have three batteries linked). The other is to make sure the cable between the new battery and the AC300 port or already connected B300 battery is fully plugged into the ports on each end, and that the slide switch on both ends is locked in.
That’s not true. You can also connect all 4 batteries one after the other to one connection on the AC300. Nevertheless, parallel connection is guaranteed and all batteries are recognized.
In my case, all batteries are on top of each other and the AC 300 is at the top.
However, the cables should be properly plugged in, locked and switched on.
That’s all in the operating instructions.
Thanks for the suggestions. I will check the plugs are fully inserted and locked next time i visit. I thought they were since its charge was being used. Did not understand the parallel icon. That means not properly connected?
I haven’t paid attention to that yet because everything works fine for me.
If a charge level indicator is shown in % SOC, the battery is working.
Check the cables again and swap them and their plugs.
It may be a contact problem.
But then an error message would appear on the display.
It sounds like there might be an issue with the new B300’s connection or compatibility with the AC300. Ensure that all batteries are correctly connected as per the manual, and consider resetting the system or checking for firmware updates for better integration.
Thanks. I’m going to check connections when I return late next week and even swap cables. I am assuming from responses that the somehow the communication isnt made and will be looking for the two linked circles showing? Noone has commented about battery connection order into and out of the two ports joining them together.
Hi @Cpf, I appreciate your interest in Bluetti.
Thanks to @hnymann, @Akel, and @abuislam for their input. Yes, please make sure the cables are properly connected and locked. When connecting three B300 batteries to the AC300, connect two on one port and one on the other port.
If this still doesn’t work, test by connecting the AC300 to a single new B300 battery. If that doesn’t work, try switching the connection cable. If the issue is with the cable, please contact customer service to arrange a replacement.
If you want to charge the B300 using a PV420, you’ll need a D050S adapter to charge through the 7909 DC input port.
I will try that but big effort to get ac300 directly connected to the new b300 due to how they are arranged and length of cord but I will first check good connections, then will swap cables to see if new one is faulty. Are the port numbers special ie ac300#1 connect to b300#1 then ac300#2 to second b300#2 then 3rd b300 from 2ndb300#2 port to #2?
No, it won’t matter which battery port is connected to what other battery port, and the AC300 is going to number the batteries according to it’s own scheme (which won’t match at all what you think it is… 
). And after it has numbered them then that number stays with the battery, even if you move their connections around in the future, so don’t worry much about that and just connect them as it works for you. Akel states you can connect more than two together from a single AC300 battery port, but that’s not what I remember or what Bluetti stated above. Feel free to try it and if that works then great, but if you continue to have the grey split circle icon on a battery, then make it a maximum of two per AC300 port. And do make sure the locks are slid all the way towards the plug end.
Hi @Cpf, Perhaps there was a misunderstanding in our explanation. The AC300 has two Battery Connection Ports.
Please connect one B300 to Battery Connection Port 1 of the AC300, then use the B300’s parallel port to connect a second B300. Finally, connect a third B300 to Battery Connection Port 2.
We suggest this to avoid having three B300s connected to one port of the AC300, while the other port has no batteries, which can cause SOC imbalance among the batteries. We hope customers can maintain symmetry by using both Battery Connection Ports for the batteries.
Thank you, @hnymann, for your detailed explanation.
I have them connected as a linked pair and a single to the AC300. Is there any best way to connect? AC300#1 to B300 #1 then from the B300#2 port to the second B300 port #1 or #2 for the linked pair? Then AC300#2 to B300#2 or #1 port or does none of this matter?
@hnymann This makes sense. So where it is plugged into is immaterial. My first two batteries were 2nd and 3rd on the AC300 display and my new one is now 1st!. Later next week when i get back there I’ll be checking the connections and cables…I hope that will fix everything.
Hi @Cpf, Thank you for getting back to us so quickly.
Yes, it is, please make sure the AC300’s 2 Battery Connection Ports connect 1 or 2 battery separately will be fine.
We are waiting for your feedback.
Solved! Thanks so much for the support. I am back on site with two original B300s at 100% and new one 0%. The first thing i did was mark my 3 cables to identify if my new one was faulty by swapping locations. They all appeared to be engaged. I then removed the new one and reconnected to the other battery and the new B300s other port. Still no luck. I then removed again and reversed and this time it clicked in positively and is now connected. AC300 showing 66% which it should. Looking forward to charging in tomorrow’s sun. Guess you can’t check you connections enough. Feel a fool but so glad i dont have anything to return.
So my 3 batteries are at 28% 42% 67%. I am getting 350W from my solar in the early morning sun and all 3 are on standby, none charging? Now a while later, the two highest % are on charge and the lowest not. Can anyone explain the priorites of the AC300 charging?
From my own observations with my AC300 system, the batteries, especially if they have differing hardware / software configurations, will charge and discharge at different rates and show the “charge / discharge” status differently as well. In my case I bought my original AC300 with two B300 batteries, and then on two occasions I bought another B300, and so I have four now. Sometimes when solar charging is low I will see that one will not say it’s charging while the others do. I believe that it is the BMS in the battery pack that indicates the charging condition, as well as the SoC, so I don’t worry too much about that when I’m not getting a lot of sun. Basically, my thought is that the different versions of BMS have differing threshold input or output current value before setting a charging or discharging status. It doesn’t mean that there is not some level of charging or discharging going on, just not enough to affect the “official” charging status of the battery.
@hnymann thanks. I will continue to watch when I am there. Have had continued cloudy weather so two ( one of which is the new one) have dwindled to 10% and have stayed there while the other is used and recieves what little solar charging I get. Can’t wait for a sunny period to get tham all fully charged especially the new one which arrived at 50% and has never gone up yet!