When a 45a converter/charger drops from 14.6v bulk to 13.6v abs, and that 45a drops to 19a, does that mean it's deceitful to call it a 45a charger?
Likewise, if a 30a solar controller passes thru 30a at 13v, but only 27.85a at 14v, is it deceitful to call it a 30a controller?
You're right, I don't get it.
I just went thru some mppt solar notes, and Vbatt remained well under 14v for several hours, so I fail to see what a fixed 14v has to do with anything? During that particular charge, panel power stayed below it's rated output for the most part, (it was a partly cloudy day, in the mid 70's), however, even when panel power had maxed out their wattage, and amps to bank increased considerably, Vbatt still remained well below 14v, (13.4v as a matter of fact), while the bank was still heavily depleted.
My bank has no problem accepting 45a at less than 13.2v, at 70% soc. So it should go without saying, if ~13.1v is enough pressure to pump 45a into the 30% dod bank, then it would take even less pressure to pump in 30a.
That day, at 12:45pm, I saw 22.5a controller output at 13.4 Vbatt. That's 301.5w. Prorated to 390w, that's 29.1a. But if the two 140w panels can put out 7% over their rating, why couldn't three 130w panels? So prorated to 417w, that's 31.12a. And on a cooler day, mppt controller output would be even higher than that.
Now, let's imagine the bank was at 50% dod, is it not fair to say 417w divided by less than 13.4v = more than 31.2a ??? But the 130w panels are rated at only 7.57a Imp... so how can the controller put out more than 3x 7.57a? Because it's an mppt controller, and that's what mppt controllers do... except some clip the extra amps, while other get burned up.
So I fail to see how the Tracers 390w/30a rating is deceitful in any way. To say it will never see 30a at 390w goes against everything I've learned about battery acceptance, charge rates, kirchoff's law, etc., etc.
390w / 13 Vbatt = 30a... the numbers don't lie. And solar charges at a relatively low charge rate, (except for rather large systems), and therefore Vbatt remains lower than it would at a higher C-rate. And the lower the soc, the lower the Vbatt required to sustain those 30 amps. There is just no way around these simple truths.
