Why you need a regulated 12v output

[svetz]

Great job Will!

 

[gnubie]

Yup, says it nicely indeed. Even if the load will run off lower voltage with the high current demanded compared to voltage any change in voltage, even minor, will result in a significant reduction in power delivered to the load.

 

[electric]

I wonder what kind of batteries are inside these small units. Based on unregulated voltage Will measured in the video I suspect they have NMC cells in 3S config? How else to explain these weird low voltages in what is supposedly a 12V product? NMC cells are terrible for 12V systems exactly for this reason, cell voltages don't allow for good voltage match with 12V nominal, i.e. 3S is too low, while 4S is too high. This is why LFP cells are the best choice for 12V applications in 4S config, which is almost a perfect match with AGM and other Lead Acid types. This is what allows LFP 12V batteries to become a "drop in" replacement for AGM. But with NMC you cannot do that, until you get to 24V and 48V systems, where you can match with 7S and 14S using NMC cells.
If you designed a solar storage box with 3S NMC battery, then you can forget about regulated 12V output, because you will have to regulate up, which means DC boost converter, which would be too expensive at a decent power level, rendering the whole design useless. At that point you might as well switch to LFP cells and don't need to regulate at all.