Ac200Max and B300 problem. Need help!


I have the Ac200Max paired with the B300 battery.
The issue I’m having is when the AC200Max hits 100% regardless of the B300 charge state the Solar charging turns off.

so the overall with both batteries can be Max 100% B300 94% Overall level 92% and the solar charging turns off.

I’ve depleted both batteries to 0% and charged them back up with no luck. I’ve also charged them both to 100% and
sometimes when connected they discharge at the same time and this is great. Because then the Ac200Max gets to 99% and starts to charge.

I made a youtube video with the issue and the link is below. I need my system to always be at 100% since I use this system not for backup but to power my tiny house.

Interesting. So if the AC200Max is 100% it doesn’t charge even when the connected batteries are not totally full. In your video, they are pretty close to full, how far down does the system let the connected battery drain before the AC200Max starts to drain and reenable charging? If they are not off more than a few % then this isn’t too big of a deal. But if the B300 can drain to say 90% before it starts recharging then it is bad.

I’ve seen the max at 100% and the b300 in the mid 80s and the solar still hadn’t kicked in.

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Hi @andrew6103,

Sorry for the inconvenience.
Pls discharge the AC200MAX and make sure the SOC of the AC200MAX is lower than B300’s. And then try again to charge them at the same time.

This only fixes the issue temporarily. As soon as you use the system and drain it. when the solar kicks in it charge the Ac200Max to 100% first and leave the B300 around the low 90%. Then discharge off the B300 first.

It seems strange that Bluetti would not configure the AC200Max/AC300 to prioritize charging the exterior battery bank (whether B300 or B230) ahead of the internal battery bank. Charging simultaneously but keeping the external battery bank 5% or so percent ahead of the internal. But I am kind of new to the whole concept so maybe there is something I am missing.

Yes, its odd. Your suggestion would definitely fix the issue. I hope they can fix this with a firmware patch. I received a lot so great email from bluetti about this. The b230 might not be an issue but the B300 Def is.

That is good to know. I was planning on ordering one or two B300s, but maybe I’ll wait till the charging issues is sorted out. If a person is loosing out on 10% of charge/capacity because of this issue, it would be cheaper to just go with the B230. A little less capacity but ability to charge to 100%.
Also good to hear you are getting feedback from Bluetti support… I emailed Bluetti about the SOC indicator acting weirdly (AC200Max) and have yet to hear back.

I spoke with bluetti tech support on the phone. They said there going to look into the issue and possibly fix it with a patch. They are supposed to update me next week.

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FYI, I have a 200Max with 2x B230 batteries. It does not have this issue. It always charges the B230’s full before hitting 100% on the Max itself. Perhaps the larger capacity of the B300’s have something to do with it. It needs to calculate a different charge rate for B300 as it has a larger capacity to keep charging balanced between the Max and the batteries compared to B230 which has the same capacity as the AC200Max itself. I am pretty sure that’s the issue. Needs updated firmware to be fixed.


Good news everyone,
Bluetti called me and told me they found the issue and assured me it will be fixed on the next app update coming out in two weeks. Really pleased with this news!


Hi there,
I know this isn’t related to your charging issue but I thought you may know the answer to my question as you have a AC200 max & B300 combination. Does the cord supplied with the B300 allow you to put the AC 200 max on top of the B300 or does it need to be side by side ?.

The cable has enough slack in it to stack or you can attach side by side.

Thanks andrew6103 for your lightning fast reply - appreciated

I do hope your problem gets fixed fairly sharpish. I’ve just bought a B300 to go with my AC200MAX. Sounds like mine may do the same as yours when it arrives.

They already fixed this issue with a firmware update through the app.

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That’s great news to hear.

Just attached a b300 to my Ac200max and have the same issue. Once the Ac200max reaches full charge it stops charging the b300. Connected with BLUETTI app and chose firmware update which says the Ac200max firmware is current. No option to update the b300 firmware.

Currently have charged both fully and using both down to 0%.

The above posts suggest this was solved by a firmware update, can anyone advise.

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Following response from support to explain how the charging works .

Hi there,

Thanks for contacting us.

If you want to charge B300 and AC200MAX to 100% automatically, please plug the T500 to the B300, and then connect B300 to AC200MAX.

Please see the charging ways of AC200MAX+B230(B300), I hope it will help.

Kind regards,

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After charging back up from 0% on both using Solar connected to AC200MAX got 100% on Ac200max and 91% on b300 when charging stopped (still sunny). Plugged in ac power to b300 and after about a minute it reset to 100%.

Assume b300 was not properly calibrated and has now reset its self to correct 100%.