How to create quick disconnect for parallel 48V batteries in golf cart straight to AIO inverter as battery storage?

[raurre]

Since there is a permanent battery bank attached to the inverters there's no need for a pre charged resistor. The inrush between the two battery banks is less than you would think and depends on the SOC difference between the two. Like I mentioned earlier, I can only speak to my own system. I only connect or disconnect it when the system is not under a large load. This is the system I am referring to Thread '4 MPP LV6548 / 30 kW EVE 304ah LiFePO4 battery/ 14 kW PV array' https://diysolarforum.com/threads/4-mpp-lv6548-30-kw-eve-304ah-lifepo4-battery-14-kw-pv-array.32343/

 

[robbob2112]

And do you check the relative state of charge before connecting? Or current after connecting?

 

[raurre]

I did when I first set up the system. I checked it with an fluke meter that measures in rush, watched the BMS and never had any faults or arcing. Now I just make sure the inverters are not under a large load.

 

[Zwy]

Maybe I am missing something here. Please type slowly so I can follow along.

I believe the OP wants to parallel the FLA in the golf cart and the lithium in the Polaris. Once the connection is made they are going to equalize in an angry hurry.

Not happening.

 

[zanydroid]

I did when I first set up the system. I checked it with a fluke meter that measures in rush, watched the BMS and never had any faults or arcing. Now I just make sure the inverters are not under a large load.

That doesn’t guard against the issues discussed here. Which arises on every connect. Inverters under large load affects the arcing potential when you disconnect (and if your switch is not rated to the battery pack then this is important)

So my vibe on this is, no engineered solution will parallel a separate 48V pack into a stationary pack without mediating electronics (EG: current regulation until the mobile pack catches up) or some notion of how each component is providing safety. I believe your procedure has some in-built assumptions like the SoC/pack voltage always being at a certain point.

(As such, I’ll probably dip out of this thread since the risk tolerance/engineering standards aren’t being super educational for my goals)

make sure the wires are all the size of your maximum possible current.

The tricky part of this that makes my engineer uncomfortable is that as you increase the size of the wires the current will also go up (lower resistance), which then increases the probability of tripping BMS.

Now, if there is enough resistance added on some components like busbar or fuseholder that can take the extra heat, maybe that helps protect the system.