We put this portable soldering iron to the test to see how reliable a Li-ion powered iron can be.
Over the years, the team here at DIYODE have used a great many soldering irons, so Altronics’ new USB-rechargeable, Lithium Ion-powered soldering iron, the Iroda Pro-25L, caused some interest. Familiar with the usual electric and gas-powered offerings, and even with some experience with irons designed to run off car batteries, we were quite curious to see how this new iron compared. Can a battery really do the job of providing so much energy? Soldering irons are energy converters, and they are not wildy efficient. This means that the amount of energy on the input side needs to be significant.
WHY USE BATTERY POWER?
Battery power achieves two things. There are situations where a cordless soldering iron is necessary. Gas soldering irons get around this problem, but have issues as well. The exhaust gas can burn things, and fumes are an issue. Piezo igniters are fragile, when they’re even fitted, and gas irons can have inconsistent temperatures. Battery powered irons eliminate these issues, but up until the advent of lithium iron technology, were impractical.
On opening the package, the iron appeared to be no less bulky than a medium-level gas iron, and around the same size as a 40W electric iron, albeit a little longer. It is bigger than the pencil of a 40W soldering station, but is a comfortable fit in the hand. That, of course, depends on the size of your hands. All this gels well with the stated power of 30W. It is around the same weight as comparable sized gas irons that I am used to, and although I have used many, there are many more on the market, so this may or may not be a useful indicator.
The power switch sits on top near the finger end of the handle area. Unlike a gas iron, however, you don’t just slide the switch and ignite the Pro-25L. It has a button in the middle of the switch which must be held down to operate it. This makes deciding how to hold the iron less straightforward, as you can see from the images. Eventually, I settled on a pencil-like grip with my index finger on the button, but ultimately, this will depend on both user preference and the dynamics of the job at hand.
The tip on the Pro-25L is interchangeable, although Altronics only list one replacement tip, a conical tip which appears in product photos to be slightly narrower than the supplied tip. Changing tips is achieved by unscrewing a plastic nut, which gives a degree of heatproofing. I was able to remove and replace the tip even after around ten minutes of soldering with it. Immediately above the retaining nut is another knurled plastic section, this one bonded to the tip shaft. Rotating this section rotates the whole tip. The usefulness of that is lost on a conical tip, but it enables chisel tips to be rotated to suit the job.
Inside the retaining nut are the electrical contacts. The centre contact is solid and connects to the middle of the tip core, while the other contact is a concentric spring around the outside, connected somewhere out of sight. The centre contact matches with a brass plate which appears folded over for a little bit of elasticity in the connection, while the spring makes contact with the rolled end of a brass sleeve.
Next to this at the end of the body is a white LED, which serves two purposes. It does add light to dark workspaces. Although it does not throw much light, it is enough for the job. Its other role is to indicate that the heat button is actually being pressed, particularly useful if your preferred grip has the button underneath.
An end cap is provided, which serves to protect the tip from physical damage, as well as allowing the hot tip to be covered. The cap has a good clearance from the tip for this purpose. It also holds the power switch back, in the ‘off’ position.
The other end of the body contains a micro-USB port for charging the internal battery. This port does not have a cover, so care will need to be taken across the life of the tool to prevent this from accumulating debris that will make inserting the plug difficult. At the same end, on the side of the body, is a charging indicator LED, which lights red when charging, and green when charged. The manufacturer states 3.5 hours for a full charge. With the supplied metre-long micro-USB cable, the iron happily charged within the stated time frame from a USB hub connected to a PC.
The packaging claims that the Pro-25L will reach working temperature in eight seconds, run for forty-five minutes, and heat up to 600°C. No word on whether or not the run-time is a continuous figure or for an average forty-five minute soldering session load, with the requisite pauses while other things happen. These are the claims we wanted to put to the test.
From cold, the iron consistently averaged seventeen seconds for the time taken between the heat button being pressed, and the tip melting 60/40 lead/tin, 0.71mm rosin-cored solder. This was an average of five cycles, with the iron returning to room temperature every time.
However, with a timed one-minute pause, things change. A stopwatch timed from when the power button was released, as though the iron was being laid on the bench while components were inserted in a board, to when the button was pressed again to heat the tip. Under these circumstances, the iron averaged five seconds to working temperature for the same solder as above.
Measuring the temperature of the tip proved more of a challenge. It seems that non-contact thermometers are not up to the job, as their measurement area, even close up, takes in too much to be accurate. Readings of 94°C were common for a tip that was melting solder. A thermocouple wrapped to the tip with tinned copper wire yielded an initial reading of 576°C.
When bench testing this iron, it ran for well over an hour in an off/on duty cycle as a normal iron would be used. In other words, letting go of the button and putting the iron down to make new connections, insert components, twist wires, and the like.
For a run-time test, the Pro-25L was clamped to the metal frame of the workbench, the thermocouple still attached, and the power button taped down. Initial temperature was the same 576°C above. After fifteen minutes, the tip temperature was 540°C. At thirty minutes, the tip temperature had dropped, but only to 468°C, still a hot soldering temperature. At thirty-five minutes the tip read 438°C, and at forty minutes, 383°C. At forty-three minutes, the LED turned off and the tip temperature started to drop rapidly. Not a bad effort, really. Please note that this test destroyed the tip, as it is designed to have heat leave it into the job, and to be cleaned regularly. Sitting idle at maximum temperature is destructive to any soldering iron tip.
Of course, these things mean little if the tool can’t do its job. The supplied tip is of a general purpose size. It is similar to that found on a 25W mains powered soldering iron. As such, it will never be soldering SMDs, but it should happily work a circuit board such as the one we tested on. That turned out not to be the case. The iron was able to be manipulated to access all connections, even when all the resistors had been inserted at once. The challenge, however, was the shape of the tip. Instead of the straight-sided cone that normal tips have, the end of the supplied tip is in fact rather rounded and snub-nosed. This made contacting both the PCB pad and component leg at the same time difficult.
Additionally, it became apparent that the power button does not have to be held down the entire time. The tip retains enough heat to allow you to let go, and holding the button on actually heats up the tip too much. We were seeing burning on the board, and rosin core evaporating before it could do its job. Care is needed to manually regulate tip temperature.
The tip is big enough to solder wire as well. Our test used some 7.5A/18AWG wire first, then 15A/15AWG, then 25A/12AWG. 25 amp wire was a bit optimistic, and the equivalent mains iron would struggle too.
Soldering the 18AWG wire was a doddle. So much so that too much heat was applied without noticing. The insulation began to melt, while the solder flowed very well and flooded the join evenly. This join took around ten seconds.
When it came time for the 15AWG wire, the iron came into its own. It was able to add enough heat so that solder applied beside the iron and around the join melted and flowed, and only at the end did the insulation become visibly soft. The join, with the iron applied already up to temperature, took around twenty seconds.
Soldering the 12AWG wire was successful, but moderately so. Initially, the iron struggled to add enough heat to allow solder to melt when applied beside the tip. Eventually, it did, but flow was not ideal. Solder was wicking away instead of flowing around the join. Eventually, moving the iron tip frequently around the join and adding solder in many places did the job. Less than perfect but still satisfactory. This operation took nearly one minute.
WHAT DO WE THINK?
All up, the Iroda Pro-25L from Altronics is an effective and versatile tool that is very capable of doing the jobs that it was intended to do. Like any tool, this iron has its limitations. However, when used in its intended general purpose role, it performs comfortably and exceeds our expectations. While only adequate for circuit board work, cordless irons generally spend their time joining wires and terminals, and in this role, the Pro-25L is a solid and user-friendly option.
Iroda PRO25L Lithium Ion Soldering Iron available at Altronics: