So Bluetti says the B230 Battery is not compatible with the EB3A.
What if you plug one of the 12V/10A DC out of the B230 to the PV in of the EB3A?
Theoretically you would get 120W of power transfer (say at night while camping and not able to use a solar panel).
So 2+ hours to recharge the EB3A while using up some portion of the B230 charge (what, 268Wh - 300Wh?) so it might last for a week+.
What is the efficiency of DC out from the B230 and DC in of the EB3A?
Also, to get tricky, is there a gadget that can take the two 12V/10A DC outs of the B230, combine them in parallel to feed 24V/8.5A into the EB3A at the max 200W DC input of the EB3A?
You can do that, of course. When Bluetti says it’s not compatible it’s referring to being able to fully use the B230 with the EB3A which includes charging it. Your only option to charge the B230 using your EB3A is with a T500 AC adapter which will incur inverter losses. With the AC200P/Max you can charge the battery directly via DC solar without having to first covert it to AC.
I don’t know the exact efficiency figures for the B230 but the EB3A has at least 75% efficiency with DC output above 20W according to Jeff Hagen from the Bluetti Facebook group. It had a max of 86.2% efficiency at 60W DC output.
I don’t know of a gadget that will combine DC outputs from that battery. The B230 only has one 12V DC car outlet output anyway.
Bluetti seems to use “Compatible” to shut down any use at all (with those devices), possibly so people wont complain when not “Everything” works such as charging the external battery (without using charging brick).
So DC out (at 60W) is only 86.2% efficient? That still seems low. Disappointing. I wonder what the full 12V10A (120W) value is.
I was misremembering about the B230 having dual DC5521 outputs like the EB3A/EB70S.
But if you have 2 batteries, i think there might be some way to combine the outputs from 2 * 12V/10A in serial to a single 24V/10A (which the PV input would only draw 8.5A) kind of like combining 2 solar panels in serial for double the voltage.
It just seemed like an way to add extra battery storage for the smaller units like the EB3A/EB70S/EB55.
The marketing dept have to decide on a yes/no compatibility label for each battery. There is no in-between, even though we know perfectly well that the cigarette lighter 12V output can feed the EB3A this doesn’t meet the threshold of being “compatible” for sales and marketing purposes. The B230/B300 batteries were never designed to formally extend the battery life of EB3A/EB55/EB70 units via the principle interface, the P090D battery extension port and cable, and thus aren’t labeled as compatible.
A crude analogy is that cars aren’t “compatible” with train tracks but it’s not impossible to drive on them, albeit in a very limited fashion at much slower speeds.
To your question, 125W DC output efficiency was 78.61% on Jeff Hagen’s EB3A.
My experience with my EB3A ignores input voltages less than about 13.4vdc. Around that voltage threshold the EB3A starts charging according to the input watt meter. Although I haven’t tried it nor know anything about the battery but I would presume if the voltage was below the 13.4v it would not share power. Please let me know what you discover.
You can also build or purchase a step up DC to DC convertor. It is much easier to buy one. I have an EB150 and it requires a minimum input voltage of 16V. I bought a DC to DC convertor that has adjustable voltage and current. Essentially, it works kinda like a CV/CC charger if you set it up correctly. You can control the power input by adjusting the voltage and current as desired. It works great and cost me about $20 instead of $200 for a D050S.