AC200MAC - Customize DC (Car-Charging) Voltages


Bought the AC200Max, because it would accept DC-chage from 12-24V - or so I thoughts.
I have a Battery Bank with nominal 18V, which on occasion should be used to charge the Bluetti. But it won’t charge.
Now I read in the manual, that it accepts 11,5-14V, and 23-29V only. All this makes sense to prevent Deep Discharge on Lead-Acid. And with that it will not accept a charge from my battery, since it’s too low from the 24V-perspective of the box.

All the specs make clear, that the limitation lies in the Software, not the hardware. A simple setting.
How can I change the Values, so that the Box will accept 16-20V, so 16V would be my DeepDischarge Shutoff for the external Battery Bank? Is there an advanced menu, or how can this be accomplished?

I know, the Box will accept a charge from my Battery Bank, if DC-Input-Source is set to “PV”, instead of “Others” (for 12/24V). This however is not my first choice, because the Box then will draw 15A from the charger-Battery, which I find too much. I much rather would like to see a charge rate with 8 Amps for this setup. So I either need the Voltage thresholds changes, as described above, or the Max Charging current - somewhere in the software.

@BLUETTI_CARE Any help/support available?

@Basti_D I’m sorry it can’t be solved by a firmware upgrade. I suggest that you can buy a D050S to increase the voltage.


@Basti_D Welcome to the Community!

Thank you for the reply.

Can you tell me, when the Box falls back from PV-Charge to Car-Mode? As mentiones above, the Box did accept 18Amp on PV-Mode. Did try something else with the same Batteries, and all of a sudden, the Box falls back to CarMode and stops charging alltogether. (Details mentioned here What is the PV charging trigger voltage? - #12 by Basti_D)

@Basti_D May I know the SN and the version details of your AC200MAX? We can push a firmware that optimizes automatic recognition.

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That sounds great.
In the app I find the following.

ARM 4008.03
DSP 4005.07
BMS 1017.03

That’s not including the SN (not shown in the App). Should I put the SN here in the public? I’d rather provide it by different means.

While we speak about Firmare update: The box does not show AC power draw if it’s low (roughly everything below 100W is shown as Zero) Any chance to improve that, since with these “little” power PowerBanks (2kW), it’s making a major difference for the overall runtime if the draw is 10/30/70W as an example. So it would be very useful to see the actual power draw on AC, even if it’s below 100W.

@Basti_D You can message me in private. We need the SN number then the firmware can be pushed. You can check the SN number on the display (as attached).


All right. The Firmware upgrade is letting me charge (in PV-mode). Great!

It is charging with 10 Amps (only).

With that I have some questions:
1st: Did you on purpose limit from 15Amp (as stated in the manual) down to 10?
2nd: Could it be increased to 15Amp, as my setup gladly delivers that amount.
3rd: Will this affect PV to be down to 10A also, if it’s utilized?

And a final question in regards to the AC-load shown on the Display: What is the smallest load it does show? Didn’t find that information in the manual (yet).

@Admin: Coud you please correct a typo in the title of the original/first Post? “DV” must be “DC”.
After that this request here could very well be deleted. Thank you.

@Basti_D 1. If you choose PV mode, the current will be limited to 15A, if others, 8A.
2. No. It can’t be set and reach 15A. The MAX PV input of AC200MAX is 900W. If 4 pieces of 18V battery are connected in series, 18V415A=1080W.
3. No. The firmware optimizes automatic recognition.
AC-load shown on the Display: Over 70W.

In regards to #2: PV mode is chosen, and it*s limiting the charge to (only) 10A. The Makita Batteries are parallel, so the spectrum of 16-20V remains. With 15A, there should be close to 300W input. But max charging Wattage seen was just below 200W, and as expected is getting lower as the Makita Battery voltage drops, always maintaining pretty much 10A. So I wonder, why just 10A?, because as you mentioned and I was aware of: Car mode is limited to 8A, and PV mode should deliver 15A. So why am I only seeing 10Amp?
In regards to #3: 70W - Ok. I have an ice maker, which according to a plugin-Watt-meter continuously draws 0,7A@230V, and 97W (with a PF of only 0,6) - the Bluetti shows zero W, and at the same time will loose almost 10% Battery capacity in one hour. With that load, I assume the Watt-meter on the Bluetti-Display should show something… I guess I can try another Watt-meter to confirm the values, but on the other side, the battery drainage confirms 100W or more…
By the way in regards to #2: While the Makita Batteries charge with up top 200W and the ice maker is running, the Bluetty Battery hardly gains any percentage after an hour (I’ve seen 1%). This also confirms much more power draw than the 70W threshold for the display, and the Display still shows Zero AC-Watt.

@Basti_D 1. Did you connect the batteries in series? Please connect them in series to test. Please check the max output current of your battery.
2. You can buy a multimeter to measure. The starting power of the ice maker can be 3-5 times of the constant power.

And I think that there is no measurement method can be completely accurate. The value shown on the screen is the apparent power (S).

While I can’t answer the “why” I can confirm this is expected behavior. Jeff Hagen did some lab tests (and I independently confirmed just now on my AC200Max) that the AC200Max limits its PV charge current as follows:

From 12-29V up to 8.3A
From 30-145V up to 15A

You’d need to boost your voltage to at least 30V (say, using a DC-DC step up boost converter) to get your AC200Max to pull the full 15A in PV input mode.

Good information. Thank you.