Connect the charge controller leads to batteries or inverter??

[Elevation]

I was pondering if it would be better to connect the leads from the Victron MPPT charge controller to the input terminals of the Multiplus Instead of directly to the batteries? The question would the charge controller prove more power from the solar panels when a draw is occurring on the inverter?

 

[snoobler]

No. It's essentially the same thing except when you connect it to the inverter, you just have a longer wire run to the batteries. Hopefully, this isn't a big deal because you have beefy inverter power cables.

There is no intrinsic benefit to your proposal.

 

[HaldorEE]

My starter batteries are under the van, by the side door. Cables to the batteries are a lot shorter than to the alternator.

 

[HaldorEE]

I miss read your question. Snoobler has the correct answer.

Possible issue with what you are proposing is related to disconnects. I would want to be able to connect/disconnect each device individually from the primary DC power bus. How would you connect the Solar charge controller to the battery without the inverter or vise-versa?

 

[Elevation]

Snoobler is essentially right. However, I have observed that the Victron MPPT reads just the amount of watts that it is putting into the batteries and not the amount of watts being produced by the solar array. I will occasionally turn off the battery charger and slide the RV slide outs in and out to burn 12 volt power to see charge controller wattage output go up.
The thought was to try to get the charge controller to provide more wattage to the power inverter when it is needed as opposed to waiting for the batteries to be drained first.
I suspect there is little difference if any at all.
For HaldorEE, I have a 70 breaker / disconnect between the positive terminal of the Victron smart 150 / 60 MPPT and the batteries.

 

[snoobler]

Snoobler is essentially right. (1) However, I have observed that the Victron MPPT reads just the amount of watts that it is putting into the batteries and not the amount of watts being produced by the solar array. I will occasionally turn off the battery charger and slide the RV slide outs in and out to burn 12 volt power to see charge controller wattage output go up.
(2) The thought was to try to get the charge controller to provide more wattage to the power inverter when it is needed as opposed to waiting for the batteries to be drained first.
I suspect there is little difference if any at all.
For HaldorEE, I have a 70 breaker / disconnect between the positive terminal of the Victron smart 150 / 60 MPPT and the batteries.

(1) The number of watts coming out of the SCC is essentially the same as the PV array input. The only difference is efficiency losses. If the MPPT is outputting 100W, the panels are inputting 101-102W.

(2) They normally work as you desire.

You have a system with PV input, storage and DC out (even if it's an inverter producing AC - still a DC load).

The MPPT charges the battery according to the absorption voltage meets termination criteria and then it enters float. At that time, it will input as much power as possible to maintain the float voltage, so if a 300W load is applied to the battery, the MPPT will sense the battery voltage drop below float and add additional power to maintain float. This is of course limited by available solar power, but in the example, you'll get 300W more than you were before the load.

If you're seeing something different, you have something strange going on.

 

[Elevation]

Yessir, I agree. But it is obvious that when I intentionally create a load / drain the batteries the charge controller jumps from 50 to 60 watts up to 580W or 700W. So since the RV is sitting there in partial sunshine, the charge controller has available PV watts and is providing what is required. Again your right, it moves from float, to absorption, to bulk eventually. Basically doing it’s job... By the way the voltage stays around 34v to 37v most of the time.

 

[snoobler]

I'm just not following you.

Charging (order of charge states): Bulk, absorp, float.

If float can't be maintained due to too much load for the available solar and voltage drops to the re-bulk level, you'll repeat the bulk, absorp, float cycle as able.

Here's how my system works:

1. 52V float, PV system supplying
2. 1000W load, voltage dips
3. PV comes on supplying 1000W (assuming it's available)
4. 52V float maintained, 0 Ah of battery capacity consumed
5. 1000W removed
6. PV power reduces to that required to maintain 52V.

Note step 4, "0 Ah of battery capacity consumed"

Yours should be as above. If it's not, either something is wrong, or you just don't have sufficient solar to maintain battery voltage.

34 to 37V? Huh?