AC200Max 48VDC Brick into PV input charging

Hi! I have hooked up a power supply in picture through an XT90 - > Aviation connector into PV input of the Bluetti AC200 Max:

The switch in the power supply kicks in 15 seconds after plugging, ramps up to 700 or so watts into the Bluetti PV input and then shuts off in a couple seconds, presumably by the AC200Max’s command. After a minute, the cycle repeats.

What I am limited by here? What causes this behaviour? I tried both DC input modes. My battery is 90% charged.


I have the impression that it is not the AC200max which makes the solar input safe by cutting off the power supply, but it is your power supply which goes into safety (because it is too hot?) because 700W it’s still a lot even if it says that the power supply can go up to 880W (which surprises me a little given the size). To test this hypothesis, connect a voltmeter to the DC outputs of your power supply while the AC200max is charging if possible, (otherwise just after it cuts out, unplug the XT90 … to quickly measure the voltage on the DC output of your power supply) if there is no voltage (or a very much lower voltage than 50V) , it’s your power supply that’s too hot…and has shut itself down until it has cooled sufficiently, and then it will work again.

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Hi! Thanks for the suggestions. There is an interesting observation towards the theory that it is AC200Max that’s shutting off the input:
If I connect both T500 to the wall charge input and the DC charger into PV input, Bluetti shuts off both charging inputs when the DC charger ramps up. After this, both chargers no longer supply charge unless I reconnect them.

@achernikov According to the parameters of the charger you provided, set the DC input source to Others, it should work. Have you tried connecting 7909 input port?

Hello. I’ve Tried Setting DC input source to Others, but it still works the same way: Charger kicks on after 15 seconds, ramps up and switches off.
If I connect a T500 charger to 7909 input port at the same time, both chargers shut off and Bluetti does not receive charge. from either of the ports.

I think Bluetti suggests you connect your power supply to the DC7909 input (like for your T500) with an XT90 > DC7909 adapter cable (it can be found on aliexpress, I bought one).

I agree with you, the power supply from the T500 is also cut, it seems to be the AC200max which has gone into safety mode… (it could still be a problem on your power supply: overvoltage for example ). Do you have error/anomaly messages on your AC200Max?

I wish there were error/fault messages, but there is nothing that could confirm any of the theories :melting_face:
Theoretically, if DC7909 Wall charger port is rated at 8A max, it should only pull 58.8V x 8A of power. If the charger works in this scenario, then it’s the charger that trips when Bluetti pulls 15A via Solar input port.
However, there are things worth nothing:

  1. I think DC input source “Other” only accepts 8A. However, it still trips and turns off
  2. Wall charger input is a direct connection to the battery (I think), so I must scratch my head very well before shoving something

What I noticed is that in DC input mode set to “Other” and to “PV” the charging power ramps up to 780-ish watts in both cases.

In AC200Max manual, it says max input current is 15A. Other Bluetti replies I’ve read say that the current needs to be at least 15A to accept charge. Which again does not makes sense as T500 charger outputs 8A 58.8V and Bluetti recommends using it for dual charging. Now I am confused :)

Already there is a problem that we do not understand, because your observation that the power supply cuts off both for the solar input but also at the same time for the t500 on the dc7909, the synchronicity of the two cuts shows that It was the ac200max that cut out, I was hoping for an error message then, but without messages it will be complex.

However, I can answer your other questions to keep you from going down the wrong path:
The solar input only limits the intensity to 8A if the power supply voltage is lower than approximately 30v, because in this case the ac200max thinks that you are plugged into a cigarette lighter socket (12/24v) and to respect the standard, it limits to 8A.In your case, like the charger has a voltage of around fifty volts, the ac200max does not limit the intensity to 8A… Hence the 780W that you saw. Furthermore, when you set “other” instead of “PV”, it just deactivates the mppt (which optimizes solar production). So normal that in both cases you see a power of more than 780w.

“Other Bluetti replies I’ve read say that the current needs to be at least 15A to accept charge”… It’s a wrong assertion… This morning it was raining, the sky was gray, my solar panels barely provided 40w for 50-60 volts to my ac200max… That’s less than 1A, it recharge very slowly my ac200max.
Otherwise, I can confirm that you can accumulate 900w on the solar input and 500w on the DC7909 input, this allows the AC200max to be recharged very quickly!

I guess it’s your power supply that’s the problem. If you don’t have a voltmeter or oscilloscope, do the following test: connect your power supply to the solar input and click on the solar panel icon or on the car on the screen (it depends if you have it configured in “pv” or “others”). Normally, you should see the power (w) supplying your ac200max as well as the voltage (v) . Be patient, stay in front of the screen and monitor the voltage to see if just before it cuts you don’t see a surge…

Hi! Thanks, that’s all super helpful.
There is no surge in the dc input meter on the Bluetti. I assume, the charger cuts off when Bluetti tries to pull 15A from it?
I can try replacing it with a 20A rated PSU of the same voltage.
However, one thing that I am curious about:
How does t500 to dc input work then? How does AC200Max not try pulling 15 Amps from t500 and subsequently trippiing it? Is there a handshake or something else?
Or am I looking into the wrong direction?

If I had to play Mr. Spock or Mr. Holmes, I would say that it’s either your power supply or the ac200max that has a problem.
-either you know someone who has another ac200max and you go to them with your power supply, and you test and if it also cuts out, there is a good chance that it is your power supply which has a problem. If, on the other hand, it works on his ac200max, but not on your ac200max, it’s yours that has a problem.
-your proposal to test with another power supply of more than 780w also allows us to sort things out: if it works, it is your first power supply which has a problem… On the other hand, if it cuts out again, there is chances are it’s your ac200max that has a problem.

You ask a lot of questions about the dc7909 input and the t500… This makes me doubt on one point: does it cut out when you plug your charger alone into the solar input? (the t500 adapter is not connected to the dc7909 of your ac200max) or is it only when your power supply and the t500 are connected at the same time to your ac200max that the problem occurs?

To answer your question, for me the solar input and the dc7909 input are on 2 different circuits, with different max intensities. At some point, the two must still come together to reach the battery cells.

Just to add I have a 12-48 DC-DC 20A on the PV input of my AC200 Max and that’s flawless, charges at 700w.
I think the power supply is where I would look first.
Do you have the meters to measure voltage and current during the first minute of charging?

Yes, it cuts off with either being alone in the aviation port or with a neighbour t500 connected to AC charging port.

I am going to try a 20A charger first and then it depends. I have a friend with an ac200p :)

20A is probably the key here… gotta try the 20A charger.

There is only 5 seconds of charging, not a minute :D

I think so too. manufacturers are sometimes optimistic about the performance of their product, when they say 15A and 880w (!) it can in reality be 20 to 30% less… look at the bluetti t500, it is only 500w and the size it takes, certainly as big or even bigger than your charger…

Hello. I have tried replacing it with another charger now rated at 20 Amps and AC200Max cuts the charging off after it reaches 750Watts again. The same thing on PV and on “Other” mode. Interesting thing is that both times when charger is connected, there is a 30 second delay until AC200Max starts drawing power from it and I suspect it is AC200MAX that cuts off the charging as well.
Considering the fact that it cuts all charging (the AC wall charger stops charging too), could that be a bug in the BMS software? Are there any workarounds about this?


To clarify - there is no power supply on the photo. Never was. It is some lithium battery charger that google knows nothing about (AIYON).
Being a battery charger, it will try to force [supposedly] CC/CV/end-of-charge logic on any connected equipment.

Just to ensure that there is no problem with the reported SOC, could you monitor BMS values from the ‘secret’ BMS screen? (main screen/Data/Bms/ then fast click 5-10 times using plastic tip on the top left corner).
Charge should end when any cell voltage reaches 3.60V.

Hi there. Yeah that makes more sense. Being a 48V Li-ion charger it most likely shuts itself off when it sees 53.1 battery voltage.
That screen shows Pack1 Voltage of 53.1 and each cell is 3.31V
I might need a dumb power supply then, I assume?

‘shuts itself off when it sees 53.1 battery voltage.’
Chinese engineers use ‘lithium’ as a synonym for ‘LiFePO4’. That AIYONG charger should shut when reaching 58.8V and charging current lower - who knows? 1A? 2A?

If that ‘secret’ BMS screen doesn’t show any cell voltage close to 3.6V when you connect the charger and it is cut off, then it is not BMS that is responsible to cutting off.
I’ve seen reviews people successfully using e-bike chargers like 48V 6A to charge AC200Max, so I’ve no idea what is going on. Try using 48V 20A LED power source to see if charging will be ok.

P.S. When I got my AC200Max I considered buying some PSU on Aliexpress cause 4+ hours charging time doesn’t fit but ended up buying another T500. For peace of mind - when buying cheap, I never know how it will turn out.

Thanks. I’ll give it another test while charging and reading the BMS screen.
I have tested this charger with D050S and it works fine, charing through it with 450-480 Watts.

This is a question which is sort of related to this thread.
What happens if you connect solar panels to the DC Input port of the AC200MAX and don’t select PV but leave it on Other.
Then what happens if you connect a T500 Charger to the DC Inport port of the AC200MAX and don’t select Other but leave it on PV.
Thanks for any guidance.