jimw1960
10 kW
Zombie, Amen, brother. Precisely the point.
jimw1960 said:Zombie, Amen, brother. Precisely the point.
jimw1960 said:You just don't learn, do you? It is not just voltage drop, but heat management you need to worry about at 50 amps and higher. The video showed that heat generated in the wire is proportional to the current. It was not a dead short, it was a controlled current supply. You are trying to say that wire could handle the current if something else was in the system. That is just plain wrong!!!! Amps is amps. wire has resitance. resistance causes heat in proportion to the square of the current and if you don't understand what that means you should just hold your tongue and admit you don't know.
wesnewell said:The video is what it is. It proves that a 5' 12 awg wire heats up considerably with 130A pumped directly across it. It would heat up a lot faster with only 2 feet. Now make that wire 1000' long and do the same test. Think you'll see smoke there? Not likely, ....
LFP, so what are the merits of making the piss weak wire that comes off of these motors shorter?
wesnewell said:The video is what it is. It proves that a 5' 12 awg wire heats up considerably with 130A pumped directly across it. It would heat up a lot faster with only 2 feet. Now make that wire 1000' long and do the same test. Think you'll see smoke there? Not likely, as the energy would be dispersed over a much larger area that would dissipate the heat better. How many feet of wire in a hub motors windings?
Why is everyone dodging the questions of wire sizes using 50A controllers in ebike applications, which was the original subject? Do you think 12 awg wire is not large enough for this? I'm using 16 awg in my setup and the wires never even get warm. Of course I don't short them across the battery either.
I'm really not confused about any of this, but I do have one question. I've got a 14s lipo battery and I've got 3' (6' total) 14 awg from battery to controller. My controller maxes out at 31A. Phase wires to motor are 6' 16 awg. What would I gain by replacing the 14 awg wire with 8 awg? I estimate about .5v. That's not really much of an incentive. Going from 12 awg to 8 awg with a 50A controller would be about the same .5v gain. Stll not much of an incentive. Any comments?zombiess said:wesnewell said:The video is what it is. It proves that a 5' 12 awg wire heats up considerably with 130A pumped directly across it. It would heat up a lot faster with only 2 feet. Now make that wire 1000' long and do the same test. Think you'll see smoke there? Not likely, as the energy would be dispersed over a much larger area that would dissipate the heat better. How many feet of wire in a hub motors windings?
Why is everyone dodging the questions of wire sizes using 50A controllers in ebike applications, which was the original subject? Do you think 12 awg wire is not large enough for this? I'm using 16 awg in my setup and the wires never even get warm. Of course I don't short them across the battery either.
Please read my post with the math, it should help you understand the concept you are confused about.
When you say 50A controllers are you talking about delivering 50A continuous right? If you want to deliver 50A continuous I would suggest 8 gauge wire since it's relatively small, flexible, pretty easy to work with and cheap. Most people only peak at 50amps on their setups, but it really depends on the motor and terrain. The general rule is use as large a conductor as reasonable and keep the lengths as short as possible.
I'm really not confused about any of this, but I do have one question. I've got a 14s lipo battery and I've got 3' (6' total) 14 awg from battery to controller. My controller maxes out at 31A. Phase wires to motor are 6' 16 awg. What would I gain by replacing the 14 awg wire with 8 awg? I estimate about .5v. That's not really much of an incentive. Going from 12 awg to 8 awg with a 50A controller would be about the same .5v gain. Stll not much of an incentive. Any comments?
Copper busbars. Solder your matching connectors to the copper and plug you battery discharge leads onto them. One output connector for each busbar. (Well that's how I'm doing it)wojtek said:...What is the best, cleanest way to connect 10x 8awg wires together into single wire? What is your experiences and best practice for that?
gtadmin said:Copper busbars. Solder your matching connectors to the copper and plug you battery discharge leads onto them. One output connector for each busbar. (Well that's how I'm doing it)wojtek said:...What is the best, cleanest way to connect 10x 8awg wires together into single wire? What is your experiences and best practice for that?
Not really. I'm just trying to get to a practical answer as related to the original question. 12 awg with 50A controller. I still contend that it is more than adequate for several reasons. What I'd really like to know is how long at 50A it would take to melt the insulation in a free air environment. Voltage drop compared to using 8 awg is minimal and not really a concern. With a 50A controller, it's unlikely that anyone would be drawing 50A continuously to begin with, but taking that as worse case, using a 50AH battery pack, continuous would never exceed 1 hour. I think a more practical example would be using a 25AH pack making the time 30 min.. Next, lets consider the size of wire used by the controller. Unless the controller uses 10 awg wire or larger, it makes no sense to use anything larger than 12 awg to the controller unless you have your battery pack on a trailer or something where voltage drop would be excessive. Next concern is the motor itself. What will happen to it after 30 minutes of 50A continuous to it. With a 48v system, that's 2400W into what size motor, with what size wire windings. Is 2400W for 30 minutes straight going to burn up the motor. I don't know, but I think it would burn up a lot of them. Maybe this doesn't matter to a lot of people, but it does to me. All this makes perfect sense to me why 12awg is adequate for a 50A controller on an ebike.liveforphysics said:He is trolling us guys. Nobody could be so stupid (unless he is a master-electrician).
How about running it at 50A with a fan blowing on the wire. Unless you have a large fan, there's no way to simulate the airflow it would get on a bike going 30mph, but it would be more realistic results. Thanks.liveforphysics said:I will run the test again. This time on my just-unboxed super bad-ass Amrel 8-50 supply with Kelvin outputs. This power supply is so sick I'm just drooling looking at it, waiting for something to smoke with it.
Alan B said:In Luke's previous second 50A experiment the wire temperature was rising, so 50A is enough to heat the wire to "soft insulation" stage where he stopped.
Sorta ... but I was thinking like AussieJester's or my unfinished oneswojtek said:gtadmin said:Copper busbars. Solder your matching connectors to the copper and plug you battery discharge leads onto them. One output connector for each busbar. (Well that's how I'm doing it)wojtek said:...What is the best, cleanest way to connect 10x 8awg wires together into single wire? What is your experiences and best practice for that?
something like that?
http://bluesea.com/viewresource/74