# backchannel: doubling down on the Renogy

My instinct here is that the gentleman made a rash claim, got called on it, and is now Just Saying Stuff without regard to the documentation or how solar MPPT charging actually works.

Well, they were talking about voltage there..... That's a different animal than Amps.

The documentation talks about the ability of solar to hold (or not) a given setpoint on its own.  The setpoints are expressed in volts.   That is normal.

It sounds like they are saying if solar can't produce the 19V it should (regardless of the AMPS), we'll defer to the alternator who tops out around 15V or so.

No, it does not sound like that.   Let’s review the actual text:

They are saying that if the solar can hold the setpoint (“constant voltage charge stage”) then charging will be by solar only (up to 50A as stated elsewhere in the manual).

If solar cannot hold the setpoint and the engine is running then both solar and alternator charging will be used (“supplementing”), up to 25A on each side.  Alternator voltage is DC-DC upconverted as needed, though I’m not sure why you want to charge in excess of 15v.

3.1: If the solar is attached and producing anything (EDIT: above 19V),

Panel voltage is not a part of the decision, only the ability of solar charging to hold a given voltage setpoint.

we will accept whatever it produces, exclusively.

I am starting to suspect deliberate misunderstanding.

• If solar can hold the setpoint, solar carries the load.

• If solar cannot hold the setpoint then alternator charging is introduced (“supplementing”)

3.3: If solar isn't producing anything above 19V,

Again, panel voltage is immaterial

we'll (begrudgingly) use the alternator, however, since the solar is not producing,

It is producing, just not enough to hold the setpoint.  If it were not producing  then the alternator would deliver up to 50A because there’d only be one charging source.

we can't possibly produce more than 25A from the alternator.

Clearly refuted in the manual.

We will, however, continue to add these two maximum numbers together and LOL as you guys debate it on Reddit. :D

Again, deliberate misunderstanding.  When both sides are contributing each leg can contribute up to 25A.  That is a max of 50A.

It's f*cking marketing. And it's aimed at the entry market, which makes it despicable to me.

This part is technical documentation, not marketing.  Someone has an axe to grind, and it misleads newbies.

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