Hi guys, I have a wire harness that's getting very hot. Today on the ride in to work I smelled something burning and zipped open my battery bag and saw that it had started melting a bit of the foam I keep around the sides. Obviously the harness was getting insulated and trapping the heat so I'm contemplating on how to best fix it. I'll remove the foam from around the sides, especially so that the wires can get some air. I was also thinking of cutting a hole in the back and keeping the front open to let the air through. A buddy suggested maybe building a heat sync out of aluminum sheets, basically a battery box, but wanted to see what you guys think. The wire between the battery and the fuse is okay, but the positive between the fuse and my plug to my controller was the one getting hot. It melted the soldier I used to weld it to the connector holding the fuse which is inside the black cylinder in the pic. I have 30a 250V fuses on a yescomusa generic 1000W kit
Getting HOT
- Thread starter mythprod
- Start date
dnmun
1 PW
i think we told you before to cut out the fuse and solder the wire together there. maybe it was another guy. if you have a BMS then you do not need the fuse. the BMS will open the circuit if it shorts.
Sure I can solder them together. Will that help with my heat issue? When I read what you wrote it made me wonder if I had a bad solder job and that's why it was overheating (in addition to it being over insulated by the foam). If there's any truth to that then it should get a bit better when I lose the fuse.
dnmun
1 PW
it is the crimp connection inside the fuse holder that is causing the heat. if you used enuff current it would just melt down into a pile of plastic around the fuse. but you only use about 15A now. if it was 30A then it woulda already gone.
you can use larger wire if you wanna, but the problem is just the fuse holder and since a fuse is not needed if your BMS is functional then you can cut it out and solder the leads together.
that is what the BMS does, it is a super fast circuit breaker when the output is shorted.
you can use larger wire if you wanna, but the problem is just the fuse holder and since a fuse is not needed if your BMS is functional then you can cut it out and solder the leads together.
that is what the BMS does, it is a super fast circuit breaker when the output is shorted.
Great thanks for the info, I'll definitely lose the fuse. The wire harness also has a fuse and it's easier to get to (winds up in the side pocket of my battery bag) so even if I lose this one I'll still have one in addition to the BMS like you said, so I should be covered. I'll let you know how it goes
cal3thousand
10 MW
Also, what's the size of that wiring to the battery?
thinner wire or longer wire = greater resistance = more heat
thinner wire or longer wire = greater resistance = more heat
dogman dan
1 PW
Yes the heat is definitely coming from a bad connection. Good connection and the heat goes away. However, having flammable stuff packed around your plugs and connections is not a good idea. If you solder it, it will never get loose so that doesn't count.
But since any plug can develop a problem, don't smother them with foam. Keep it fire resistant around the plugs.
But since any plug can develop a problem, don't smother them with foam. Keep it fire resistant around the plugs.
wesnewell
100 GW
If you're using the original wiring from controller to battery, replace it and the fuse type. The fuse holder is crap. The wiring should be minimum 12awg. IIRC, the original was a lot smaller than that on the part from the 3 prong connector to the fuse and battery. Walmart sells a 12awg ATC blade fuse holder for $1.28 when I bought mine that I use in line with my 10awg wiring. Throw in a 40A fuse and you'll be fine.
Thanks guys.
From the battery the wire is thicker AWG (not sure exactly what size) and short, probably only 3-4 in. and it doesn't seem to be a problem. The wire from the connection to the plug (that the controller plugs into) is thinner and longer, probably a size down AWG from the batt cable is my guess. I'm going to lose the fuse and solder the two cables together and tape down the soldered part with electrical tape and lose the foam so it's not insulated. I'll also keep the bag open so more air can get in there (losing the foam will help with this). Hopefully after I do that I can get rid of my heat issues.
From the battery the wire is thicker AWG (not sure exactly what size) and short, probably only 3-4 in. and it doesn't seem to be a problem. The wire from the connection to the plug (that the controller plugs into) is thinner and longer, probably a size down AWG from the batt cable is my guess. I'm going to lose the fuse and solder the two cables together and tape down the soldered part with electrical tape and lose the foam so it's not insulated. I'll also keep the bag open so more air can get in there (losing the foam will help with this). Hopefully after I do that I can get rid of my heat issues.
if the wire is sized correctly and the connections are good, I don't think the wires would need "air" cooling
just a thought from an old electrical engineer, but, an ebike noob
edit: and, if you do require "air" cooling, you are running a risky set up, be careful
just a thought from an old electrical engineer, but, an ebike noob
edit: and, if you do require "air" cooling, you are running a risky set up, be careful
Since you have discoloration/melt/burn marks from the heat, then you know *exactly* where the heat is coming from. Wherever those marks are the worst is the source of the heat, assumign they are right up against the wiring.
With the fuseholder, if the marks are worst just to either end of it, then that should show the source of the heat is inside the fuseholder itself, assuming the fuseholder is against the foam where the marks are.
If you have what looks like a single continuous wire that is by itself against the foam and it has a hotspot mark at some point, then wherever that mark is probably means the wires are not continuous inside the insulation. Either the wire maker overlapped strands inside the insulation to make a continuous wire (I've seen this several times with Chinese ebike stuff so far, though not with high-current battery wires yet), or some of the wire strands are broken inside the insulation there, usually from being bent at a sharp angle and then vibrated, or a pulling-load.
With the fuseholder, if the marks are worst just to either end of it, then that should show the source of the heat is inside the fuseholder itself, assuming the fuseholder is against the foam where the marks are.
If you have what looks like a single continuous wire that is by itself against the foam and it has a hotspot mark at some point, then wherever that mark is probably means the wires are not continuous inside the insulation. Either the wire maker overlapped strands inside the insulation to make a continuous wire (I've seen this several times with Chinese ebike stuff so far, though not with high-current battery wires yet), or some of the wire strands are broken inside the insulation there, usually from being bent at a sharp angle and then vibrated, or a pulling-load.
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