Review: ColdHeat Soldering Iron
The ColdHeat soldering iron has been touted in stores and advertisements as an end-all solution to one's soldering iron needs. And indeed, when one reads the features list, the ColdHeat is appealing: it only uses a few AA batteries, has a built-in white LED work light, and the tip heats up and cools down in only a few seconds. On paper, the ColdHeat beats not only other, portable soldering irons (most of which are butane-powered), but also traditional corded irons.
However, that's just on paper. As they say, looks can be deceiving. And in the case of the ColdHeat, unfortunately, they are deceiving indeed.
I picked up a ColdHeat at Radio Shack; I was looking for something that would heat up faster than the plain $8.19 25-Watt iron I'd been using. The ColdHeat, which was sold under the Radio Shack brand, cost $19.99 and included the iron, plastic carrying case, and chisel tip. Supply a few AA batteries, and you're good to go. I don't like working with chisel tips on soldering irons, as a lot of times they end up being too large when working with small components. So for $9.99, I picked up the conical tip for the ColdHeat.
Fig. 1. The ColdHeat in its carrying case.
An immediate problem I saw with the ColdHeat is the placement of the white LED light, meant to illuminate what you're working on. The problem with it is that they put it underneath the tip, instead of on top of it. This, therefore, pretty much makes the light useless, unless you use the iron upside-down.
Fig. 2. The ColdHeat's white LED light.
When I first opened the case, something didn't look quite right to me. First, the ColdHeat comes with a cap for the tip -- I had never seen an iron come with one. Also, the yellow sticker on the inside top of the case offered a warning: "The soldering tip is fragile. Please do not press hard."
The warning is very true. After I installed the batteries in the ColdHeat, I pulled out the chisel tip that it came with and swapped in the conical one. As a test, I tried soldering two wires together. With some work, I got them together. I then tried adding more solder to the joint, and in pressing down on it, part of the tip snapped off. It was no more pressure than I'd exert on a normal iron with a small pencil tip. Herein lies one of the fundamental flaws of the ColdHeat's "instant heat" technology -- the tips are not made of metal, but rather a soft ceramic.
Fig. 3. The ColdHeat tips are split down the middle and are made of a soft ceramic material.
The second flaw with the tip, that exacerbates the first flaw and also poses another problem altogether, is that the tips are split down the middle. The way the ColdHeat works is by passing an electrical current through the tip. When you press both halves of the tip to a conductive surface -- the solder or wire or whatever you're soldering -- it completes the circuit and causes the tip to heat up rapidly. However, because the tip is split, it reduces its strength. You need to use a very gentle touch when soldering with the ColdHeat, or else you'll be out $9.99 as I now am.
The other problem that the split tip causes is a nasty sparking when the circuit is completed. And it's not a single spark that's emitted when the circuit is completed; no, it's more of a continuous arcing.
Fig. 4. The ColdHeat's tip sparks and arcs when it completes the circuit to heat the tip.
It's hard to take a picture of the sparking/arcing, but the little bright spot next to one of the prongs of the tip above is one of the sparks. I don't know how much voltage and amperage the ColdHeat uses to heat the tip, but I'm seriously concerned about using it with anything ESD-sensitive. In fact, I'd go so far as to recommend that anyone who uses a ColdHeat use it for use on wires and connectors only. Do not use the ColdHeat on any kind of PCB.
Overall, the ColdHeat has a good concept -- a soldering iron that's completely portable, heats up and cools down fast, and uses standard batteries. Its execution is horrible, however. While the tip does heat up and cool down in about 5 seconds, the longer you use the ColdHeat the longer it takes for the tip to cool down. The tips wear quickly, and prone to breaking, are large (making detail work hard if not impossible), and expensive, and the overall technology behind how the ColdHeat works could potentially kill any ICs you work on.
Here are my pros, cons and overall rating for the ColdHeat:
Iron is relatively inexpensive ($20)
Uses standard AA batteries
Comes with carrying case
It solders, but not well (normal irons create joints smoothly)
White LED light misplaced
Tips are large, expensive ($10 each) and prone to breaking
Iron is potentially dangerous to ICs
Two out of five stars.
ColdHeat has struck a licensing deal with Weller, a well-known and respected soldering iron manufacturer. Weller will begin selling the ColdHeat under the Weller brand name. Keep in mind that Weller does not manufacture this version of the ColdHeat; as sold by Weller, it's just a normal ColdHeat that's been rebadged. So, don't buy the Weller version thinking it'll be better -- it's not.
The Weller iron is actually ColdHeat's new "Pro" model, not the model reviewed here. Please see Weller's post in the comments below. - Tom