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Question about Dc2DC connection with solar on the same bus.

jbnalley

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Sep 8, 2022
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17
I am trying to properly connect devices within the same container. Hopefully I have given enough information to answer the question.

I have the following I am working on: (sorry for the detail, but didn’t want to miss anything that might get asked)

  • Blue Smart IP22 12/30
  • Smart Solar MPPT 100 /20
  • DC2DC 12|12|18
  • Phoenix 12 | 800
  • 160ah battery /~2000watt
The goal is to move this box between different cars and a camper. The only time there would be a combination of power inputs is during driving and Camping in the camper.

  • Camper = Shore + Solar
  • Car = DC2DC + Solar
  • I can't think of a time where all three are running simultaneous but if they are all in the same box there is that potential, so I want to plan for it.
DC2DC connection:

Alternator connection to DC2DC is 4 AWG high strand pure copper cable the car with the longest wiring connection to the rear is 18 feet (36 for both + and -) It uses a 50a Anderson connector which will attach to a short set of cables (8 awg) 3 foot (6 foot both + and -) into the container through another set of Anderson connections. (Less than 1' on the inside of the container, also 8 Awg) to the DC2DC charger.

MPPT connection:

Total length of wires (10awg) including all the 2S 2P is 30 feet. up and into the PV input on the MPPT. 4 50 watt panels in 4s 2p (cars) and 2 120 watt panels 2s2p on the camper.

Inverter Connection:

The inverter will be able to pull power from that same main bus connection (using 8 awg cable between the main bus and inverter input). While all three devices potentially charge. However, the inverter output is separate from any of the DC bus or connections and will run through a GFCI outlet.

Main bus + connection:

According to the BMS specs on the battery It can charge or discharge at 200A. I do not plan for any discharge or charge of more than 100a for any length of time. This is attached to a 200ah lithium (LifePO4) home build battery I picked up from a friend who built it. (It has ~600 cycles on it so it’s tested well and still basically new)

The battery will be within 5 feet of the box (cables that connect it will be 4awg so max distance from battery to the main bus connection is 20 feet including the short runs to any loads.)

Between the main bus and the battery is a 100amp ANL fuse. (Located inside the container)

All lines off the main bus connecting the MPPT, DC2DC, and IP22 are 10 awg high stranded pure copper.

Load Connection:

Max DC load draw will be 45 amps based on how I have it fused from a blue sea 100-amp 6 circuit blade and no single fuse is over 15 amps. This will get its power from the main power bus bar

Assuming all wires and fuses are properly sized for the power:

Question:


Can I allow MPPT battery output, DC2DC output and Shore IP22 to send output to the same bus without harming the devices or the battery?

The bus is a 250a bus and would have all 4 devices connected. (This includes the inverter's input / draw connection and a connection to the BlueSea so DC power could also draw a load from the main bus) inverter output is into a GFCI outlet so that I am not overly concerned about.



(If my wire sizing or fuse sizing is off, you can comment on that, but my main question is related to the bus and having all devices connected to the same one internally)
 
Last edited:
This doesn't explicitly answer your question, but it should allow you to draw your own conclusion:

 
This doesn't explicitly answer your question, but it should allow you to draw your own conclusion:

Thank you for the quick response.
 
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