chargers usually have a fuse, protecting the charger and the mains power. 
Ok that makes much more sense to me. @b264 you’re referring to just fusing the charging board/port side correct?
I usually put the fuse on the negative line, but yes. Either one.
Yes, just the charge jack on the board.
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Do some BMS have a built in fuse? This seems common sense for charge only ones given they already know what rate they’re charging. I imagine all battery makers would want to include this to protect their packs.
No BMS I have ever seen is “charge-only”
They just have very low discharge rates like 10A or less, and we don’t use that port.
“Charge-only” is more how you wire it up and not how the BMS is made.
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As i don’t want to cut my batteries leads, if i put bullet connectors where the blue arrows are is there any downside to this or reason not to?
and is this correct loopkey? one side goes direct to battery and the other to the vesc.
Charger cable would be soldered onto the vesc wire and then in a bullet connector
Edit: I’m aware the wiring colours don’t match up but i don’t see that as a concern for this
More places for shorts and disconnects and loss of power due to resistance. Use big bullets.
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Am I better off cutting the battery wire and just going with an XT-90?
It’s 4 mm bullet already so if better to use big bullets i’d need to change that anyway
These are the types of questions we all ponder for days.
4mm is not that big. 5.5mm or bigger will have better retention. If you can use shrouded bananas like XT150 even better, but XT150 are chunky.
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The XT90S with the green stripe needs to be the loopkey. Put the male (without the green stripe) on the board. Also put a fuse on your charge port negative line.
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keep seeing mixed opinions about this - does it really matter if it’s the loop or on the board?
Yes, it matters.
There are many reasons, 3 of which are
- If you accidentally don’t push it in all the way and ride, the broken part that you have to replace is the “key” and not the “board” (the burnt resistor will be in the easily-replaceable key)
- It’s easier to mount because you can JB Weld right to it instead of trying to leave exactly a 0.75mm gap all around it
- Your stuff is compatible with everyone else’s stuff if, for example, you misplaced your loop key or needed another one or someone was giving one away for free
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Counters 
- the elecrifeid parts are male and easy to short
- the more expensive/special part is the easily lost part
- uh need a third point… looks prettier mouned to your board
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Ok, Devil’s Advocate. There are cons to doing it that way, but overall you want the male part on the board 
Just look at 10 builds and you’ll see 9 are that way 
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gotcha, ill try one of each then
I’ve thought about it a lot for my build… Which side to mount to the board.
Burning out the resistor probably would suck if you have it permanently mounted to the board and permanently wired in. Best to find a way to securely mount a female XT-90S that’s easily removable.
I just went with bullet connectors and an M4 bolt that pinches a printed clamp. Very secure, and with a couple turns of the Allen wrenches I carry everywhere, I can disconnect the XT-90S from the board by unplugging the bullet connectors.
I feel much safer too potentially having exposed female side than two male pins in a wide opening incase my daughter just so happens to one day find the board and start poking around with her saliva fingers and I forget to cover it.
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Your daughter’s safe either way
Also
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What thiccnes is this copper rod?
10AWG
Hmmm… what in milimiters? 4mm? 3mm?