Renogy Charge Controllers, two different input voltages

[Coloradojeep]

I have a Renogy 50 amp DC-DC MPPT (RDC50D1S) charge controller and a Renogy Rover 40 amp 12/24 volt MPPT (RVR-40) charge controller. On the DC-DC MPPT controller I can't go over 25 volts. I have 8x190 watt panels. I wan to wire the 40 amp controller 2s3p, giving me around 1100 watt, 24 volt input and the 50A DC MPPT controller 2p, giving me 380 watt, 12 volt input. Both of these wired to a single buss bar to charge my 400 amp hour battery bank. Do you see any issues with the two different voltage inputs? The charge controllers should output the same no matter the input, correct?

I like the DC-DC MPPT charge controller due to the fact it charges the starter battery when the house battery is full. I have this setup on a work van utilizing the 30 amp dc-dc mppt charge controller with 2x100 (2p) watt panels and a single 100 ah battery. It's been great and I want the same feature on our Skoolie.

 

[Albatross]

So most of your "12V" panels are actually going to be putting out something closer to the tune of 18V-20V maximum. Wiring them up in parallel could over-volt the input line on the charge controller.

But without knowing what your panels are, or seeing the tags on the back of them, it's impossible ot say for sure.

And a drawing of what you're thinking would make this a lot simpler.

 

[Coloradojeep]

The 40 amp charge controller max input IAs 100v while the 50 amp is 25v.

What are the suggested setups with 8 panels?

 

[Coloradojeep]

https://photos.google.com/share/AF1QipMnhzvUi991goCIT4CZVYtAuPRwd_afh_5Vi5prMD8VI-Wpyp4XNvF7a3TDvsHXMw?key=cEZ2VFlkMXNwdEUyOGxRMmNjV18tZDBqZzY0THpB

40 amp charge controller max input voltage is 100v
50 amp charge controller max input voltage is 25v

what are the suggested setups with 8 panels?

I hope my photo works.... been a while since I've used web forums.

 

[Jono14]

May need to split 4 and 4

If you load 6 panels up on one of the MPPT controllers, that will theoretically hit 1,140 Watts and reach a max of 89 amps (into a 12.8V battery). This is probably too much "over-panelling" for either the 40A or 50A unit and a lot of energy will be wasted from that 6 panel string.

If 4 panels are directed to each controller, the theoretical max 59A from MPPT controller to battery will likely stay under the 40A and 50A limits for most parts of most days.

For the 25V input limited SCC, you will have to use 4P to keep the Voc below that threshold. For the other SCC it may not matter a lot if you do 4P vs 2P2S (but check the Voc of the panels to see if 2x is OK for the 40A MPPT. Voltage % drop will be a little less and shading can get a little more problematic with 2P2S vs. 4P.

I agree with Albatross that if you post the 4 values from the panel sticker (Voc, Vmp, Isc, Imp) then advice can be a bit more specific.

To your original question, you are right that different input voltages to the two MPPT controllers will not matter and the output voltage will be the same when the units are connected to the same bus bars.