Hummina Shadeeba
10 MW
what sizes are you using for how many amps?
https://www.rcgroups.com/forums/showatt.php?attachmentid=1214696&d=1173563160
https://www.rcgroups.com/forums/showatt.php?attachmentid=1214696&d=1173563160
Ampacity?
- Thread starter Hummina Shadeeba
- Start date
nutnspecial
10 MW
Wow that's a really comprehensive chart!
I use 10ga silicone for battery and have drawn 105 amps in the 16" run. My motor phase wires are stock/standard/non-silicone and only 12 or 14 gauge and have run up to 200 phase amps thru their similar length run. Neither gets noticably hot but I noticed some cracking of the phase wire jackets on the tight loops in the motor though.
I use about 5' of charger lead with about 15a. They are high quality speaker wire (of 14ga iirc). They get pretty warm during a full 1/2hr long charge. I think nice subwoofer wire would be a good application to any of the above. Or cheap old jumper cable.
I use 10ga silicone for battery and have drawn 105 amps in the 16" run. My motor phase wires are stock/standard/non-silicone and only 12 or 14 gauge and have run up to 200 phase amps thru their similar length run. Neither gets noticably hot but I noticed some cracking of the phase wire jackets on the tight loops in the motor though.
I use about 5' of charger lead with about 15a. They are high quality speaker wire (of 14ga iirc). They get pretty warm during a full 1/2hr long charge. I think nice subwoofer wire would be a good application to any of the above. Or cheap old jumper cable.
agniusm
1 MW
I find weird when people dig up stuff from RC and use that on bikes. All of the RC stuff is highly overrated. Motors, ESC's, batteries, connectors, cables.
Then cables melt, connectrs burn.
Ampacity, look here: http://www.powerstream.com/Wire_Size.htm
I was gonna use XT90 connector which is rated at 90A continues, friend did som tests with them and they might be good for 60A, better 50A continues.
So there you go, you want more reliable data, look elswhere than RC
Then cables melt, connectrs burn.
Ampacity, look here: http://www.powerstream.com/Wire_Size.htm
I was gonna use XT90 connector which is rated at 90A continues, friend did som tests with them and they might be good for 60A, better 50A continues.
So there you go, you want more reliable data, look elswhere than RC
nutnspecial
10 MW
I did think cabling was pretty standard across the board, but don't bother with plastic connections for amperage. Bullets are cheaper, simpler, and more effective imo, and not hard at all to solder with a torch.
edit// agnuism that link looks more like what I would use for AC wiring in a house, and doesn't have any wiring ratings besides awg.
edit// agnuism that link looks more like what I would use for AC wiring in a house, and doesn't have any wiring ratings besides awg.
MrDude_1
100 kW
You cant make generalizations either way. Bullet connectors and wire from the RC world is some of the best, and cheap. Controllers and motors however are almost universally overrated in the RC world.
Pretty much every RC advertised value is absolute peak.. not continuous.
Pretty much every RC advertised value is absolute peak.. not continuous.
agniusm
1 MW
I am not saying its crap. I am saying its overrated. Same plastic connectors have bullets in them and they ar good if not overdriven. The question is do you really pull 50 or 100A constantly?
On the site I linked is calculator which includes 48vdc so I asume its good for dc as well
I pulled around 3kw on a bench for some time and 10awg got very worm
On the site I linked is calculator which includes 48vdc so I asume its good for dc as well
I pulled around 3kw on a bench for some time and 10awg got very worm
SniperGaulois
10 kW
I'm curious if anyone has ditched copper altogether, because aluminium is more performant for the same weight of wire, and less expensive. what are the hassles of using aluminium?
nutnspecial
10 MW
I'm guessing size and flexibility? And in houses it's banned for anything other than the service entrance. I don't see it anywhere else. Connections are likely not as reliable.
________
Perhaps it's not for me to say, but OP authored a thread and only asked ONE question. . . .
________
Perhaps it's not for me to say, but OP authored a thread and only asked ONE question. . . .
dustNbone
10 kW
Aluminum doesn't take repeated bending well, it develops small cracks which become hot spots. In stranded wire it's not difficult to break entire strands through repeated flexing and even thermal cycling. It's best used in stationary applications, where it's bent once and then secured to some kind of structure.
Also you have to take special consideration when mating aluminum to brass or copper, to avoid oxidization. In the case of compression type connections (screw terminals, crimp ons) an antioxidant paste needs to be applied.
All in all I don't think it's suitable for anything subject to movement or shock/vibration. The weight of the conductors on most ebike applications I've seen is pretty minimal.
Answer to the original question, I use 10AWG stranded wire for my battery wires, total overkill for the 28A or so the BBS02 peaks out at. Continuous is less than 25, 12 or even 14AWG would probably be fine, arguably better as I'm not using a BMS and 14AWG would burn off alot quicker in the event of a short than 10AWG.
Also you have to take special consideration when mating aluminum to brass or copper, to avoid oxidization. In the case of compression type connections (screw terminals, crimp ons) an antioxidant paste needs to be applied.
All in all I don't think it's suitable for anything subject to movement or shock/vibration. The weight of the conductors on most ebike applications I've seen is pretty minimal.
Answer to the original question, I use 10AWG stranded wire for my battery wires, total overkill for the 28A or so the BBS02 peaks out at. Continuous is less than 25, 12 or even 14AWG would probably be fine, arguably better as I'm not using a BMS and 14AWG would burn off alot quicker in the event of a short than 10AWG.
Hillhater
100 TW
dustNbone said:
odd that it is used so successfully for nearly all main power distribution wires, swinging about up in the wind on those pylons ??
..But for our use, Aluminium is a bitch to solder compared to copper !
Hummina Shadeeba
10 MW
anyone have the formula on hand or in head for figuring the wattage lost to heat in a wire? copper preferably. based on wire resistance, length, and amps is all I think.
agniusm
1 MW
MrDude_1
100 kW
Punx0r said:
In otherwords.. copper is heavy. Aluminum is not a great conductor, but its the next element closest to copper that is cheap. So if you are going to string it up in the air, you can use aluminum thats larger, and accept the rest of the transfer losses..
On your bike, you have limited room, the wires are somewhat enclosed, and you want more power going to your motor, and less wasted as heat. So Copper is the best reasonably priced solution. If you wanted Silver or Gold wires, they would work even better, but they would be a tad bit expensive.
Matador
100 kW
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- Jun 29, 2016
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Hummina Shadeeba said:
P = dV x I (where P is power lost in heat as Watts, dV is the voltage drop in volts and I is the current going through the wire in amperes).
(the formula comes from P = V x I where V = R x I, so all in all... P = R x I^2)
Knowing the resistivity (in Ohm-meters) of the metal consitituting your wire, it's gauge (the sectional area in square meters) and the length of the wire used (in meters), you can calculate the resistance (in ohms) of that lenght of wire (see link to usefull 2 posts below).
Then knowing that resistance you just calculated, you can determine voltage drop at a given current by ohms law : dV = R x I.
From that voltage drop (dV), you can calculate power loss in heat (P) at any given current (I).
You can also directly use the formula P = R x I^2
For calculation exemples concerning how to calculate the resistance (R) of your wire, see my previous posts :
https://endless-sphere.com/forums/viewtopic.php?f=14&t=57810&start=150#p1213424 and https://endless-sphere.com/forums/viewtopic.php?f=14&t=57810&start=175#p1214787
But in summary, Resistance = Resistivity x lenght / cross-sectionnal area
NB : You can use AWG ampacity charts/tables like this one https://en.wikipedia.org/wiki/American_wire_gauge to determine which AWG gauge corresponds to which cross-sectionnal area (in mm2) in order to make you calculations for resistance values. Dont forget to convert mm2 units to square meters units (by dividing by 1000000).
For a list of resistivity values for different metal used as conductors, see the big table on this webpage here https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity
Matador
Matador
100 kW
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As you can see by resistivity values on the wikipedia, aluminium is also a great conductor, but indeed a bit more fragile.
Also aluminium can be a PITA to weld, necessitating special techniques (since aluminium oxidises as soon as it enters in contact with air, even more so when it is heated, aluminium oxide is fomed on the surface which prevent the weld from bonding. Also, aluminium melts at a very low temp for a metal wich make it delicate to work with).
Also aluminium can be a PITA to weld, necessitating special techniques (since aluminium oxidises as soon as it enters in contact with air, even more so when it is heated, aluminium oxide is fomed on the surface which prevent the weld from bonding. Also, aluminium melts at a very low temp for a metal wich make it delicate to work with).
agniusm
1 MW
We just need to wait for graphene wires and we will have another player. I don't see the point in using aluminium when there is copper. In weight, its only fraction when considering the whole system.
Hummina Shadeeba
10 MW
I didn't write them for a quote but looking around on the web for something that might be real gets this far :
http://motherboard.vice.com/read/a-cheap-graphene-upgrade-could-boost-computing-speeds-by-30-percent-2
Superconducting at room temp. That's the goal.
http://motherboard.vice.com/read/a-cheap-graphene-upgrade-could-boost-computing-speeds-by-30-percent-2
Superconducting at room temp. That's the goal.
sn0wchyld
100 kW
Hummina Shadeeba said:
whats CM/A represent? presumably some time value?
Hummina Shadeeba
10 MW
Matador Looking at the chart cross-sectional area doesn't parallel ampacity: the 5mm x
.1 is rated at 48 amps and the 10mm x .1 is 66. What's going on?
.1 is rated at 48 amps and the 10mm x .1 is 66. What's going on?
Matador
100 kW
- Joined
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Hummina Shadeeba said:
Ampacity, is not the same as Amps. Ampacity is not directly proportionnal to surface area.
You'll observe the same with copper wire (check it out here : http://www.powerstream.com/Wire_Size.htm)
You see that 11 AWG (4.17 mm2) is rated 47 amps, while 9 AWG (6.63 mm2) is rated 64 amps.
If it was a direct linear relationship between cross sectionnal area and ampacity, you could deduce that 9AWG (6.63mm2) would be rated for 75 amps, but it's not. It's only 64 amps according to http://www.powerstream.com/Wire_Size.htm
Rather than a direct relashionship, it seems like it's the inverse of ampacity (1/A) is proportionnal to resistance/meter
in other words the inverse ampacity (1/A) is proportionnal to cross sectionnal area.
Remember ampacity is not the same as amps. My guess is ampacity probably also takes the thermal dissipation capability of the metal into account.
Use powerstream chart to do a plot of 1/A in y-axis and Resistance/meter into x-axis and you'll see it appear. That will give you a linear relationship.
I am here by no means making a definition or an explanation of what Ampacity is. I'm just doing an empirical observation based on plotting the data on a graph... I get a straight line going through the plotted dots with a good linear regression coefficient (R2=0.999 or 0.997).
Hummina Shadeeba
10 MW
I still dont get it. a conductor resistance is proportional to it's cross-sectional, as is shown in the chart, so the wattage being wasted as heat and the voltage drop will parallel the resistance. the only variable is the surface area and that determines the ability to disipate that heat. A 5mm x .1mm sheet has half the surface area per amp through as a 10mm x .1mm sheet so why doesnt it have half the ampacity?
only variables are conductance/resistance, surface area, amps, and cross-sectional no?
only variables are conductance/resistance, surface area, amps, and cross-sectional no?
