I am the proud owner of a Bluetti AC200P. It’s a nice unit, but it won’t power on or charge.
When I pressed the power button, the green light surrounding it would flash 3 times - then go right back off. When I plugged in the charger, its indicator light did not turn red. The unit showed no response.
I contacted Bluetti support, but they were not much help diagnosing it. They said it needs a new charger, for $150. I had already tested the charger - 56V coming out of it. I opted not to waste $150 and began diagnostics. A lot of you guys probably already know all this stuff, but this was a fun journey so I thought I would post my findings for anyone else trying to figure this out.
I disassembled the unit down to the battery and BMS. I plugged everything back in, but in a way where I could peek in to see the BMS. I hit the power button, I saw the green LED on the BMS. Then I heard a click, and the BMS shut back off.
From what I can see, this is a 16S10P (16 series, 10 parallel) battery. This means there are 160 batteries, split into 10 groups of 16 cells each. Each 16 cell group is wired in series, producing 48V nominal. And then all 10 groups were wired in parallel.
I checked the raw battery voltage at these terminals, it showed 53V. That ruled out over-discharge:
Next I checked the individual cell series using these pins. All were within 0.02V of one another, so that ruled out unbalanced cells:
Next I checked the voltage on the BMS output for the few seconds it was powered on, it showed 0V:
The click before shutdown made me think a component is shutting this BMS down, probably for safety reasons. I figured this could be the thermal sensors or a shorted output. Thermal sensors are here:
I opted to check the BMS output for a shirt first. The cables ends themselves didn’t show continuity. Then I checked the battery input on the power inverter board. Bingo! 0 ohm resistance:
I carefully looked over the inverter board, considering a DIY repair. I would probably have to desolder all the MOSFETS, gates and other things and check them individually. Even if I find the bad ones, they might just burn out again if I miss the actual root problem. Plus I’d have to fight through all this funky glue that’s holding it together. I opted not to go this route.
Armed (proudly) with my diagnosis, I contacted Bluetti support again. Lois was very nice, but knew nothing technical. She again insisted the charger was bad. I pushed back on this with my findings, and she brought someone else into the email chain - I assume a technician.
He tried to sell me a new charger again, I said no thank you. He informed me that I was welcome to ship the unit in for repair, at my expense. I said I already have it apart, and I know the part I need - and asked him to sell me the part. He said they don’t sell repair parts, they’d have to service it themselves. I asked how much it would cost to replace this board, he said he didn’t know - they’d have to diagnose it when it arrives and then give me a price.
Bluetti’s solution to this problem is to have me spend $100 or so on shipping costs just to find out how much it would cost me to fix this unit. Since the charger alone is $150, I have to assume the repair would have cost a minimum of $300 plus shipping.
This is my reason for refusing to do so: I can spend upwards of $400 (just my guesstimate) for a repair on this unit that has a limited lifespan remaining on the battery. Once the battery goes bad, all of this expensive, proprietary, one-off circuitry (that I’m paying to replace) is now worthless to me.
I looked at this box of parts and took inventory:
- Box itself - battery fits nicely, has a nice set of AC/DC/USB plugs and boards that may be reusable, nice fan slots up top
- Battery - still putting out voltage and still in balance
- BMS - I think it communicates via some kind of CAN bus design that I have no interest in reverse engineering, but it may still be reusable for the safe charge/discharge of the battery pack
- Power inverter - proprietary, and burned out anyway
- LCD & mainboard - proprietary and reliant on CAN bus, likely not reusable
I opted to rebuild the box with my own parts - non-proprietary parts that belong to me and can be reused on the next build or project. I will detail my progress on that journey in my next post.
