Bluetti / PowerOak AC200P low load inverter inefficiency, and terrible support

[lukerogers]

Hi, I recently purchased a PowerOak AC200P (UK model) and I’m experiencing some weirdness with the output at low wattages. I noticed that with low AC loads, the reported load is often much higher. I bought a wattmeter to verify the actual load on the device. For example, as you can see in the photo a 26W load is drawing 92W. Is this normal or expected? It seems better with higher loads, but this seems really inefficient at lower loads. The manual says it should be >88% efficient and even gives examples with a 20W LED lamp lasting 75-85 hours, which certainly couldn’t happen with the inefficiencies I’m seeing.

I used the wattmeter to measure the power drawn over an hour which should have equated to 2% battery loss, but I actually saw 5% battery loss, so it seems it’s not just a display issue.

I bought it on Amazon and have been in contact with PowerOak via Amazon. They’re fairly responsive, but I feel like I’m being taken for a ride. They’re dragging their heels and giving bogus answers. The latest was this:

Hi Luke, As we've consulted our technical staff, they suggested that the test results from a wattmeter is imprecise. As it can not calculate its power loss accurately considering its product conversion rate, line loss, standby power consumption, etc. By the way, we noticed that you plugged a device in a USB port, which is using DC output. And the AC load showed 92W is from the wattmeter. When plugging in the AC port with a wattmeter, the unit is also powering the device. Therefore, it's not accurate to test the unit with a wattmeter. Regards, Laura

Blaming the wattmeter seems like total BS to me. I only bought it because of the crazy numbers I was seeing in the first place! And why they’re bringing DC into this I don’t know, the DC seems fine.

I’m new to this, so I just wanted some reassurance that I can call them out on this. Also to say if you buy from PowerOak in the UK, don’t expect support to be helpful.

Thanks,
Luke

 

[740GLE]

The inverter has standby by losses, those losses are constant, thus if you have a small load 20w, the total draw on the battery will be higher, for your example 60-90w total load applied to the battery pack isn’t unheard of.

What were you charging via USB when you took the picture?

 

[JWLV]

I've seen several posts from different people regarding idle power draw from the Bluetti just being on. 50 watts is the number being throw around various posts and other forums. That would be approximately 1.2kwh per day.

 

[lukerogers]

The inverter has standby by losses, those losses are constant, thus if you have a small load 20w, the total draw on the battery will be higher, for your example 60-90w total load applied to the battery pack isn’t unheard of.

What were you charging via USB when you took the picture?

Hi, thanks for your response. I thought that might be the case, but as I said that’s counter to what the manual says. I also thought it’s what the support people would have said, but they seem insistent on blaming the wattmeter. I had plugged my phone into USB — I’d either unplugged it or it had fully charged by this point. I think it maxed out at 2W when charging, so it’s not making much difference to anything.

 

[lukerogers]

I've seen several posts from different people regarding idle power draw from the Bluetti just being on. 50 watts is the number being throw around various posts and other forums. That would be approximately 1.2kwh per day.

Is that consistent with other similar products? Presumably a decent inverter wouldn’t do that, right? Thanks.

 

[JWLV]

Is that consistent with other similar products? Presumably a decent inverter wouldn’t do that, right? Thanks.

I think 50w is rather high. I have a generic Chinese 1000w continuous / 2000w surge sine wave inverter that uses 24w when idle. Keep in mind that a higher wattage inverter will draw more power when idle.

 

[lukerogers]

I think 50w is rather high. I have a generic Chinese 1000w continuous / 2000w surge sine wave inverter that uses 24w when idle. Keep in mind that a higher wattage inverter will draw more power when idle.

Thanks. So for a 2000W inverter, maybe 50W idle usage isn’t that awful? I’m not sure why the support staff, including the “technical staff” are unaware of this. (For anyone else looking, this article is useful). Thank you both so much for your help.

Given that my usual load is only about 25W and seems to be at most about 70W, would it make sense to get say a 200W inverter and connect it to the DC output of the AC200? There’s a 12V/10A cigarette style output and another 12V/25A output that I think is an SA20 connector. Would that reduce the inefficiencies accordingly?

 

[Bvillebob]

My 4000 watt inverter draws about 18 watts of power, so yes, 50 watts is awful. It's definitely something to consider when shopping.

 

[lukerogers]

My 4000 watt inverter draws about 18 watts of power, so yes, 50 watts is awful. It's definitely something to consider when shopping.

Yes, I definitely would have appreciated if this information was more readily available too. 88% efficiency sounds good enough, but really that’s only peak efficiency if your load is exactly right.

I went ahead and bought a 300W pure sine wave inverter and connected it to the cigarette port. So far so good. The new inverter is only using about 5W when idle and it’s happily powering everything I need for 90% of the time. When I need a higher load, I can just turn on the Bluetti’s AC inverter and connect it to that. As I’m using this for an office, I work out that this is saving me about 1.5kWh per week.

Thanks again for all the help.
Luke

 

[leslens]

yes from what i read, this is a problem for low wattage with this model
lousy inverter

not a great use case for this model at low watts