Questions regarding use of load terminals on Renogy MPPT controller

[wedge1020]

Hello!

I have a Renogy ROVER 40A MPPT controller (RNG-CTRL-RVR40-BT) currently running a 12V solar system at my off-grid cabin (400W of panels, 300Ah of battery).

With my current lead acid batteries pushing 5-6 years old, and notably performing less and less well with my usual loads, I am considering new batteries and upgrading to a 24v system.

The manual for the MPPT would seem to indicate that the load terminal provides 20A at what I assume to be system voltage (currently 12v). It also warns against connecting an inverter to the load terminal (instead to wire it inline to the battery, which is what I currently have).

I have a 1300W EcoFlow Delta with integrated inverter, and when charging from AC pulls up to 600W, but from solar up to 400W (amperage limit of 10A). Currently, I charge it through a 240W AC adapter plugged into my inverter, although I have from time to time plugged it directly into the solar panels (although in that case I lose out on so much of the power generated due to the 10A limit imposed by the Delta circuitry-- 12v 4 x 100W panels... on the ideal day the charge controller reads 33A). Either way, I charge the delta through its XT60 solar port (the 240W 24V/10A AC adapter, or the 120W 12V/10A best case direct from panels).

Question: is it unreasonable to consider powering the Delta through the load terminal on the MPPT controller? If the Delta limits itself at 10A, and the terminal provides 20A, I wouldn't be pushing any currently apparent limits (and would remove what seems to be an unnecessary DC -> AC -> DC conversion in the process).

This would free up my most pressing need for my current 12v 1200W inverter (really only used to plug in the AC adapter to charge the Delta).

Question #2: Should that not be an unreasonable course of action, I also have a DC fridge (Setpower RV45S) that runs in 12/24v, which from quick calculations wouldn't be pulling more than 5A in 24v operation. With the load terminal providing 20A, 10+5=15A, and 15A being less than 20A. If I split the connection to run to each of these devices, provided the sum total consumption of all involved devices doesn't exceed the available 240W, would that be in any way a bad idea?

General operation of my system is pretty much to keep my devices charged, and keep my foodstuffs cooled. My general need for AC is limited to wall warts converting to DC for various devices, and as-needed a 600W vacuum via AC (which is more than within the Delta's operating capacity). I'm aiming for minimal and operational.

Wondering if I can do without the standalone inverter and basically use my Delta more centrally for the occasional AC needs and USB power, while more fully making use of my Renogy MPPT charge controller to manage the larger battery bank.

 

[sunshine_eggo]

#1: Should work. Load terminal voltage IS the battery voltage, so it will vary with your battery voltage.

#2: The concern with the fridge is any surge current the motor might draw during start-up. Motor surges are typically 4-10X the run current. If it has "soft-start" or is "inverter" type, there is no surge.

 

[wedge1020]

#1: Should work. Load terminal voltage IS the battery voltage, so it will vary with your battery voltage.

Thank you for the confirmation. I found the wording in the manual not denying this, but also not as clear as I'd like.

And yes, I was running with the assumption the load was tied to the battery voltage, also good to know that is indeed the case.

#2: The concern with the fridge is any surge current the motor might draw during start-up. Motor surges are typically 4-10X the run current. If it has "soft-start" or is "inverter" type, there is no surge.

Noted. I will do some tests to look out for this, and proceed with this particular exploration from there. Considering it is marketed as a car/RV fridge, and I see as a general rule of thumb those tend to be fused for 10A current, I'd think it is probably a safer bet something towards the latter is the case (but, always worth checking and confirming nonetheless).

Thank you very much!

 

[MisterSandals]

And yes, I was running with the assumption the load was tied to the battery voltage, also good to know that is indeed the case.

My thought on this is why one would want to put to put the loads on the SCC? It just puts additional stress on this central piece of equipment unnecessarily. A connection to the battery, which is specifically designed to power loads, is quick and easy.

Did i miss something about the 12V inverter? Its a 24V system, no?

I'm confused (pre-coffee haze) but if its a matter of charging the Delta from 24V load terminal or from 24V battery, i'd do the battery every time.

 

[wedge1020]

My thought on this is why one would want to put to put the loads on the SCC? It just puts additional stress on this central piece of equipment unnecessarily. A connection to the battery, which is specifically designed to power loads, is quick and easy.

Did i miss something about the 12V inverter? Its a 24V system, no?

At present, 12V, but I am considering rewiring the panels and batteries for 24V at some point.

Generally just exploring my options, and making sure I'm not misinterpreting anything, or in this case, completely not considering viable options.

I'm confused (pre-coffee haze) but if its a matter of charging the Delta from 24V load terminal or from 24V battery, i'd do the battery every time.

You know... somehow I had blocked that out as an option. But you're right: it is all direct current, isn't it?

I guess I had black-boxed the battery as something not directly available, so it wasn't factoring into any of my considerations.

The Delta would have no problems handling whatever it is fed. And the fridge seemingly in a similar situation (it has settings for battery health).

Thank you, this gives me another, more flexible angle to explore.

 

[sunshine_eggo]

Noted. I will do some tests to look out for this, and proceed with this particular exploration from there. Considering it is marketed as a car/RV fridge, and I see as a general rule of thumb those tend to be fused for 10A current, I'd think it is probably a safer bet something towards the latter is the case (but, always worth checking and confirming nonetheless).

Fusing is only done for the continuous current and isn't a reliable means of estimating surge. Surge is not considered. Surge may only last milliseconds or at most a few seconds with a rapid taper. This duration is too short for the fuse/breaker to heat sufficiently to trigger it; however, the duration is long enough to cause the circuitry to register the overload and shut down.

 

[nilnil]

At present, 12V, but I am considering rewiring the panels and batteries for 24V at some point.

Generally just exploring my options, and making sure I'm not misinterpreting anything, or in this case, completely not considering viable options.



You know... somehow I had blocked that out as an option. But you're right: it is all direct current, isn't it?

I guess I had black-boxed the battery as something not directly available, so it wasn't factoring into any of my considerations.

The Delta would have no problems handling whatever it is fed. And the fridge seemingly in a similar situation (it has settings for battery health).

Thank you, this gives me another, more flexible angle to explore.

Did you hook up your EcoFlow battery to Load terminal?