which gauge wire to use?

[Jay64]

I have a 48v 10ah lifebatt pack that has 10ga wire coming out of it. I was told the pack can do 100-120a continuous. From my understanding, 10ga is only good for about 30a. Is that correct? I was looking at a wire chart which suggested that for 100a, 4ga is recommended. Is that true? And, if that is true, then does it make much difference to have 10ga coming out of the pack, switch it to 4ga to run through the contactor to the controller, and then to the motor? I would think that the 10ga coming out of the pack would get extrememly hot.

 

[deardancer3]

some points to consider, my opinions:

Wire gauge charts are tools to help judge total resistance, voltage drop, safe operation.
The length of the run has a lot to do with what gauge to use. 6 inches of 10 gauge is not going to drop much voltage at 40 amps.

Taking us to another point, Battery capable of x AMPS, controller at Y amps, motor at z amps.

An ebike at 100 amps of 48 volts is over 6 HP, and would drain a 10 amp hour pack in about 5 to 6 minutes. this is not what is going to happen. Most ebikes are at about 1500 watts maximum sustained, 2000 watts peak. wiring that can sustain 30 amps should be fine.. but then you have to have some pretty darn good connectors.

If you plan on drag racing this, or are running a motorcycle, forget the above data though.

d

 

[Link]

I wouldn't worry at all. I was running 30A through several feet of 12ga without it heating up. Hell, the links between the batteries were only slightly warm, and they were 14ga.

I think you'll be fine. 60A continuously would probably be okay with 10ga. My DocWattson only has, what, 12ga on it and it's rated for peaks of 100A. 10ga is nearly double the cross sectional area of that.

 

[Jay64]

Thanks for the info. But once again, I will be drawing 100+amps continuously. I was told when I first bought it that the 10ga was ok, but I was talking to a guy that does remote control cars and stuff, and he also thought that 10ga was way too small for 100a.

 

[Lock]

But once again, I will be drawing 100+amps continuously.

But "continuously" doesn't mean 24/7... For most folks "continuous" means only for 1/2hr or 1-2 hrs max, correct?
Yer worried about yer solder dripping out of your connections? Or what? Consumed by worries about energy efficiency?
Watt does it matter really if your wire run is 14ga or 10ga? The EV car ppl tap about 0 gauge welding cable or whatever
If stuff doen't melt, are you not "good to go"?
Signed - Curious
tks
Lock

 

[Anonymous]

.

 

[TylerDurden]

Big wire can be a chore to manipulate, but it carries the goods. The less small gauge you have the better, you don't want your wires to get warm... replace at the origin if you can.

http://salestores.com/powerb28.html

 

[Anonymous]

.

 

[Jay64]

Yes, at the moment, the "continuous" will probably only be for about 5 or 6 minutes. And yes, if it doesn't melt, that's good for me. However, I do want to make sure it doesn't melt. I am not consumed by it, but I would like to make sure that I have things right before I melt out some very expensive parts. But at the same time, this is a test bike, and I am going to be having to push a LOT more then that for my "race" bike that I need to build in less then a year. As far as the kilowatts, I guess at the moment it would be about 4.8 kw. But I need to eventually build a VERY high kilowatt bike, about 45-80kw, so I need to get a good handle of everything now.

Well, I was thinking that I wouldn't bring it back down to 10ga at the motor and/or controller.

 

[Link]

For 100A I'd want to use something like 8ga. That should be a good balance between current carrying capability, price, and ease of installation.

I've got some 4ga audio wire, and, yes, it is "freaking huge" compared to what we're used to using. But, I've also got some SB-350s made for 2/0ga that I plan on using for my eventual motorcycle conversion. They're bigger than my entire palm.

 

[Jay64]

So 8ga would be capable of handling 100a without melting? The reason why I am asking this stuff is because the guy I was talking to said he had the insulation melt off the wiring before. Also, if I go with 8ga, would I be able to just have it switch to 8ga after it comes out of the battery pack, or should I try to replace the wire coming out of the pack with 8ga also? My plan is to build the ah of this particular build also, so I could be running upwards of maybe 20-30 minutes at a time at 100a.

 

[powermed]

Here's a good table that covers it. At the bottom is a calculator for voltage drop. http://www.powerstream.com/Wire_Size.htm

I've used a lot of very heavy gauge (as low as 4) for my electric boat, unexposed to sunlight audio cable is exceptional stuff and can be found cheap sometimes. It's also usually superflex - a lot of very fine wires. You'll need a professional crimper. A local battery store may do it for nothing.

 

[dogman dan]

If it's easy to make the connection make the wire fatter for sure. If it's too hard to manipulate, a pair of 10 guage wires would bend easier, and carry a lot of current.

 

[Jonathan]

Your wiring requirement is quite similar to what I used in my WWII Search Light (28VDC @ 100A cont).
I used 6 AWG welding cable (from CloudEV). These are typically rated at 115A, while the 4 AWG are rated at 150A continuous. Welding cable are usually made of 30 AWG or smaller strands which make them much more manageable.

What I used in my calculation is the Power Loss (heat) = Wire Resistance * Length * (continuous current of system)^2.
For 6 AWG it's 0.4023 mOhms/foot, and 4 AWG it's 0.2533 mOhms/foot. My system is about 5 feet with 100A continuous draw.
The total heat dissipated is about 20 Watts for 6 AWG and 13 Watts for 4 AWG respectively.

I also question the capability of your batteries. You're running it at 10C (continuously) for 100A. I would amp up that battery by a factor of 2x at least.

 

[vanilla ice]

http://www.partsexpress.com/webpage.cfm?FILTER=running+car+audio+power&FTR=running+car+audio+power&search_type=main&WebPage_ID=3&x=0&y=0

Not too badly priced 2 and 4ga. ..

 

[Jay64]

Ok, what would be the best way to transition from a 10 ga wire with anderson PP connections to a 6ga welding wire? I have a brute crimp tool for crimping large sized wire.

 

[Link]

Replace the Andersons on the 10ga with a higher amperage model to match what you put on the 6ga. Double up the 10ga as to make it fit right.

 

[Jay64]

Link, what type of connector do you use for your 4ga?

 

[Jonathan]

Jay, I would use Anderson SB120 connectors. And instead of crimping, I would use a 80W solder iron or torch to solder.
http://www.powerwerx.com/product.asp?ProdID=35858&CtgID=3578

 

[Link]

Link, what type of connector do you use for your 4ga?

Teh SB-175. An SB-120 will work, too, though, and be a little lighter/smaller.

 

[Jay64]

Apparently the 10ga wire WAS too small for this project. The insulation did melt and it burnt out my BMS. I guess it was a valid concern and not just a case of me being consumed by worries.

 

[miro13car]

Jay 64,
Do you have original LifeBatt HPS pack? It cannot be.
It must be home-made.
All LifeBatt packs have gold plated terminals with gold-plated bolts, washer.
There are no wires coming out of any LifeBatt battery.
Just look at LifebATT web site.
I have HPS 36V 10Ah pack and I am using AWG10, 2times 90cm lenght.
I draw 48A absolute max. for just 3-4 second under hard acceleration.
My Tidal Force controller will not allow for more.
Under 48A my WattsUp shows 35V which is blamed on like almost 2 meters of 10AWG wire FROM BATT TO CONTROLLER.
I checked WatssUp warms up very slightly /difficult to feel difference/ during going uphill for like 5 minutes at 10-11A drawn.
MC

 

[Jay64]

You don't have any wires coming out of your pack? How do you hook your pack up to the bike?
No, I do not have a pack from HPS. I believe my bike is pulling a lot more then 48a max, I think more like 100a continous, like mentioned above.

 

[johnrobholmes]

I would vote 6awg unless you want 4. It really depends on the length of wire too, but that has been covered.

 

[miro13car]

wires are terminated with ring connectors and connected to terminals.
All HPS packs from LifeBatt have gold plated termianls.
Even for short 100 bursts, for sure you shoud use bigger wire than AWG10.
Mc