AC300: Is the Fusion AC Input Cable really needed?

I asked this in a reply on another topic but got no responses so I’ll make it a topic by itself.

Bluetti warns users not to use the original AC charging cables to charge AC300’s when they are connected in the split-phase mode. Their picture of the forbidden configuration shows power for both AC300’s coming from L1.

Their picture of the permitted connection with the special cable shows one AC300 powered from L1 and the other from L2.

Because Bluetti doesn’t sell the cable they say is required, users have made their own. From both their descriptions and the diagram above it seems as if the only thing the special cable does is ensure that one AC300 gets its power from L1 and the other from L2. Does the cable do anything else?

If that’s the case can’t the same function be accomplished by powering the two AC300’s from two outlets from opposite sides of the main panel using the standard AC charging cables? That would save having to install a 240V outlet and having to purchase (or make) a special cable.

You are correct. You can built you own using an L14-30r 240v outlet and by putting a y-adapter for each Leg to go to a different AC300.

I have a series on this topic. I’ll take you through understanding the original cables and then making your own. You can start here on video #1 :

Video #2 : verifying your outlets for split phase:

You are correct in your statement about using two different legs of the 240 volt circuit. That is what I did and it is working fine. Now you need to ask yourself, what do I need the 240 volts plug for? For the hot water heater? For the Air Conditioner ? In both cases the AC300 will not last very long and will be unreliable for all the other circuits that are plugged into the same battery power.
Now what am I using the 240 volt plug for? WATER I have a well that runs off of 240 volt pump and when the Electric company fails to provide power, I do not have water. So I disconnected the water pump wires from the circuit box and put a 4 prong plug on it and built a 4 prong receptacle from the circuit box. Now I can run my water from AC or Bluetti Fusion box.

Thanks. That’s a wonderful series of videos!

If I could clarify how your reply relates to my question -

You’ve shown how to build the equivalent of Bluetti’s nonexistent dual 30A “Fusion AC Input Cable”. It requires purchasing two $79 single 30A cables, a Y-adapter cable, and the two TT30 plugs. And of course you need to install another 240V outlet so you can plug in the assembly.

But if you’re willing to limit your AC charging to 15A on each unit - and you indicated in video #3 that you were only interested in AC charging at 1 or 2 amps - couldn’t you just use the free 15A 120V AC charging cables included with each AC300 and connect them to standard 15A 120V outlets that are on opposite phases? You’d save hundreds of dollars and lots of work. Of course as you point out in video #2.1 about powering stand-alone AC300’s, you’d need to be sure that you didn’t have other loads on those two circuits that would eat into their 15A capacities. (Or you could set the AC300s’ max input current down to a 10A and still have other small loads on the circuits.)

Like you, I’d only need a minor amount of AC charging, if any. I’d certainly prefer to do it with the cables that came with my system if I could. I hope someone will tell me if there’s some important factor I’m missing here.

Thanks again for your extremely thorough and clear videos. I’d seen links to them in other posts but because I was more interested in using the cables I have than buying and/or fabricating new ones I hadn’t watched them until now.

I’m in a similar situation to yours with 240V loads. The only one I care about in an extended grid outage is my well pump. I’ve got one AC300 and I’m trying to decide whether to get a second one and connect them with a P030A so that I can run the pump.

I’ve speculated in a different topic whether that Bluetti system can handle the pump’s surge amps. It’s a ¾HP pump and draws 9A continuous with a 35A surge. Apparently you’re not having any problems. Have you measured your surge amps or do you see a surge rating in the pump’s literature? Do you know its horsepower rating?

As you can see by my starting this topic, I’m trying to look at all the aspects of running the dual system.

I have it set-up to connect it if the power goes out, but I have not tried using the Bluetti battery power because I do not want to burn up the pump if it fails. Call me Chicken. What I have done is dig another well 100’ down and put a solar water pump in that well. The pump runs on 24 volt solar panel 350 watts. Here is the link:

It has been working for the past year without any problem except freezing that I am fixing now.