Permanent install of Pre-charge resistor on DIY battery bank

[solarHandyman]

I noticed in tear down videos of the EG4 and Jakipier batteries that the EG4 has a pre-charge resistor permanently installed. Does anyone know how these are wired in a permanent installation? I'm planning building to build a battery bank of multiple 48v16s groups of LiFePO4 cells wired to a central set of bush bars, with large breakers for each inverter (EG4 6548s) in the system, and smaller DIN rail breakers for each 16s group. Basically I want to make my own EG4 batteries in larger capacities. Is the precharge reisistor something one can leave permanently installed on each batter group? Is it wired in series on the positive output before the on-off DIN rail breaker? The videos I've seen of Will using a pre-charge resistor are on the more simple side and just used for the initial connection to protect a BMS and an inverter from the in-rush current (a good thing). I'm scared under heavy loads when the system is charging and discharging a pre-charge resistor would melt. I'd like to be able to turn off and on the battery breakers without having to disconnect and pre-charge with a resistor prior to restarting the battery bank. On my current build I've definitely thrown some "good" sparks flipping the breakers back on after doing maintenance.

 

[Browse]

You would need a switch to activate the bypass resistor, then remove it from the circuit.

 

[SparkyJJO]

I think those have the limiting resistor in parallel with the switch. Personally I don't like it because then "off" is not really fully off.

 

[LeoThomson]

Technically you can put in a pre-charge resister parallel to the cable and leave it in place after you connect the cable, it won't do any harm.

I personally wouldn't do that because it is messy and it might be confusing to others as you will have plenty of wires all over the place and you have to remember to disconnect an extra wire. But it can be done.

 

[Danke]

My Push Button Pre-Charger Install for the SW 4024 Inverter

Up until Last week I had never heard of pre-charging a larger inverter before connecting the battery cables. I just lived with the spark. But I was watching a "Will" video about a DIY LFP build and saw that he used a resistor before connecting the Positive Terminal. This peaked my...

diysolarforum.com

 

[solarHandyman]

Thanks everyone for the replies!

 

[gubbernl]

I just read this post.
I put the resistor with a momentary 15A switch in parallel to the breaker installed in each 16S bank.
From the Off position: press the switch for a couple of seconds, then turn on the breaker and release the switch.