Utilizing MPPT DC Output vs Charger/Batteries

[TheArgobus]

I have a 60 amp AIMS Power MPPT charge controller and it has two outputs: the charger output and a DC power output. The charger output is connected directly to my master battery switch (on my DC control panel), such that it will always charge the batteries even if the switch is off.



Is there any reason to use the DC power output of the MPPT instead of the charger output I have set up? Does anyone have that attached to anything? Like lights, or AC, or anything funky?

[john61ct]

DC power output is for controlling loads, like a PSU.

As opposed to the Absorb then Float profile of a charger.

Usually the only reason to use the former rather than tapping into the loads buss off your battery, is a "battery protect" LVC so those loads don't pull the bank SoC too low.

Sometimes timer control, e.g. streetlights.

But beware limited ampacity rating.

Note your charge output should really go directly to the battery posts to get accurate voltage reading.

[TheArgobus]

I think I was missing the core concept here...


After some further investigation, it appears that I am supposed to wire the MPPT's "Battery" output directly to the batteries, and the MPPT's "DC Load" output to the DC Control Panel (with the master battery switch, circuit breakers, etc...).


I'm going to email AIMS Power to make sure I'm understanding it right, but in any case is that what most folks with MPPTs are doing?

[john61ct]

Yes, as I explained.

What you called the "charger output" should be the same as what you are now calling "Battery" output right?

As I said the "DC power" output, you now calling "DC Load", is completely optional

may limit the amps used too much

might only work with certain load types (e.g. inductive).

Most people ignore that, and just distribute power directly from the bank's busses.

Good luck getting help from AIMS. . .

[dzl_]

I'm only familiar with the load output on Victron controllers, so everything below is based on what I know about them, some or all may apply to your aims controller.



One advantage of separate outputs for battery and loads is low voltage disconnect. With a LiFePO4 system, this is probably redundant, as your BMS can handle this as well.



But this doesn't make the feature useless, it can be used creatively in any way you can think to utilize it. Maybe you have an icemaker or a hotwater heater that you only want to run when the batteries are >80% charged for instance.


In the case of the Victron, there are various other things that this enables, there are several algorithms or adaptive settings that can be used on the load side. But I don't know much beyond that.