Hot power cord..

[montyjcm]

Hey everybody,

So, I am sorry if this is the wrong section, or if I am being a complete neophyte. But you guys are the most knowledgeable out there.. so here it goes.

I was just charging my lipos a few minutes ago, and I noticed that the power cord to my power supply was hot, very hot actually. I whipped out my little infrared temp gauge, and it read up to 125 degrees! Granted, the emissivity setting on the temp gauge probably wasn't setup correctly to read a thin right, but let's say 120+/-5. This seemed pretty high to me. Especially since everything else in the circuit was relatively cool.

Duh.. my setup: Power Supply: Power Cube- 20 amps at 12v
http://cgi.ebay.com/12-Volt-DC-20-Am...3%3A1|294%3A50
Charger: Turnigy Accucell 8150 (8s, 150w max on the circuit)
Batteries: 2, SPC 8000mah 20c charging in series at 7.0amps (max for the charger)

So.. this setup puts me at about 100 watts for 14.8v * 7amps. Of course thats not considering power loss and the increased power consumption when the packs are closer to full, but this is still under what the power supply can supply.. for lack of a better word.

I should note that the cord only remained hot during the cc part of the charge, not the cv part. The cord is also about 3ft long I believe and made of copper. Perfectly normal looking imo.

So, should I be worried? I have never noticed this before, but then again, I have never bothered to check. This charger/ps combo has worked well for me with about 20 or so charge cycles on it. Could I have a bad wire, creating a lot of resistance?

Thanks for the help, everyone!!

[MetalMan]

Time for a little math...
Let's say charger/PS efficiency comes out to 70%, it should be something like that. 100watts / 0.70 = 143watts into the power supply. 143watts / 120V (into the PS, assuming you're in the US) = 1.19amps. The individual wires can't be more than probably 16ga. 3ft. of 16ga. wire has a resistance of about 0.0123ohms.

Power losses due to heat: P=I^2*R, so P=(1.19 * 1.19) * 0.0123 = 0.017watts dissipated as heat along the entire length of wire. Even if the wire were only 1in. long that shouldn't be enough to heat it up... To me it seems there's something wrong, have you inspected the exterior of the cord for the entire length?

Of course, if the wire is even 18ga. the power lost to heat would still be less than 0.03watts for 3ft. which is still nothing.

[BrianG]

Yep, I posted something along these lines a while back: http://www.rc-monster.com/forum/showthread.php?t=3969

[MetalMan]

Brian, he's saying the power cord to the power supply is getting hot. Not something that should normally be replaced.

[BrianG]

Wow, that wire should NOT get hot at all. A little over 1A could easily be handled by even 24GA wire, and power cords typically use 16-18GA.

[montyjcm]

Yeah.. that's what I thought. It's pretty substantial wire... I am guessing something is wrong with it. I am going to try and get a replacement and see if that fixes it. Like I said, nothing else seems too hot.