Hello, All. I recently wired up a 12V-28V 20A 560W DC-DC converter as an alternate input to solar for my Blue SmartSolar MPPT 100/30. Works perfectly to charge my portable battery unit at full SmartSolar 30A output when connected to the 250A alternator in my vehicle, which can handily supply the ~32A converter draw expected for the ~426W input power reported by my SmartSolar 100/30.
When I tried testing my Blue Smart IP67 12/25 in Power Supply mode set at 14V and max 25A output, as input for the DC-DC converter, however, instead of supplying 25A and sitting there, it heads there and then resets to 0, then heads there again and resets to 0, repeatedly. I had hoped that it would supply as much as it could, that is, up to 25A reliably and sit there, stably, which it does when operating as a charger, despite my battery being able to accept up to 100A charge.
I guess it makes sense that the current /draw/ is the governing factor, which is why circuit fuses exist. Try to draw more than the circuit is rated for and the fuse/breaker blows. And I suspect that the BMS built into the battery must limit the current draw to whatever the charger is offering. But I'm not a power expert, and would welcome input.
Why does it (power draw and supply, and battery charging) work this way? How do the charger and battery negotiate the current rate, and why isn't the Blue Smart charger in PSU mode able to supply up to max but no more? A pointer to some useful reading or reference material would be great. Thanks.
