For a project that just needed some antisparks wired in and a few bolts, it has been a long three months and 4 redesigns of various parts… and i still havnt done the bolts and also blew up/ set fire to / generally destroyed, the antisparks…
Ive decided to firstly install a loop key while i plan the antispark future, going to install the enclosure penetrations for the switches now to make life a little easier down the track when i put them in… for now its the loop key which is mapped but not fully soldered in yet… i am agonising ove where to put the loop key through the enclosure and its giving me the shits… the issue really is the design of everyrhing else didnt have that in mind so im gunna have to srrip it all out and do more enclosure fitting…
I do have a question… the bms to negative cable, i should run that and connect into the negative AFTER the loop key or BEFORE the loop key, Id assumed after initially but now im not so sure… also, can i use something like this for the bms to negative connection
FWIW i’ve killed a battery leaving the l00p key plugged in after a ride. Voltage alarms (as present in products like the robogochi) are super useful in this regard
Yep, aware of the dangers, it will have the antisparks installed later on then the loop key forms a redundency cercuit breaker if my switches be bitches
Thats a good question. Im gunna take Discharge for $200 jimmy, thats how i understand it anyway, the green goes off to the charging cable, the blue was involved in the antispark fiasco… first build man so still trying to wrap my head around various bits of it.
I think most of us bypass discharge including me. So, I don’t know for sure but I’d imagine it shouldn’t matter on order, as the loop key will just break the circuit.
Actually thinking about it if you’re doing discharge then that cable is your battery negative right? So it shouldn’t be a part of the loop key. I think loop key just breaks the positive connection.
@zero_ads does it matter which breaks the circuit? I didn’t think it would make a difference and have done all my planning based on dropping the LK into the Batt. Neg… ??
I just remember reading do it on the positive line but I don’t know if it’s a hard rule. At the same time I think most of the AS in QS8s and XT90s are on the positive side right? So you’d want those to slow down the in rush of current, therefore having it on the positive side. Or does that happen regardless
Water is often used as an analogy for current, but that wouldnt work in this case. If there’s a choke point anywhere in the system, everything slows down. Doesnt matter where the resistor is.
Evan makes a good point so, in theory it should not matter as long as your loopkey has the resistor then it will slow the in rush. Makes sense to me.
In a nutshell, the advantage of having it is that it protects your battery, but if you ever say brake/accelerate hard enough to beyond the limits of your BMS’s amperage rating you run the risk of losing power. So, most would rather damage the battery a little bit than run the risk of crashing at a bad time. Most recently I think @haven had a bad crash due to this.
Discharge is better handled within the vesc/vesc setting arena, where you can specify based on your pack config, not the hard window specified by the BMS.
Another reason is that a BMS that can handle 80A is a lot bigger and more expensive than the 20A ones we employ and bypass.
Yeah, I was running 50a per side thru my 60a LLT BMS. Worked fine for a while, but one night I floored it up a hill just enough that it must’ve gone over the limit, and it cut out. My knee still ain’t the same…
Thanx for that. It’s reduced my workload of things i need to do and now. I dont need anymore chances of eating shit than i currently have so its a bit of a no brainer.
