This is the first part of a series of posts on comparing Welch Allyn products that will help incoming first year medical students learn about and select different medical instrument components to construct the right Welch Allyn diagnostic kit (otoscope and ophthalmoscope). The focus of this discussion is on Welch Allyn diagnostic kit handles and power sources, which house the battery and provide power for the otoscope or ophthalmoscope head. If you’re interested in the bottom-line short version, scroll to the bottom.
The easiest way to start is to say what you do NOT need, and that is the Welch Allyn Universal Desk Charger (seen right). These clunky things run upwards of $200 and represent the superfluous up-sell. The concept is good in theory, in that you can just drop your instruments into one of the holes to get it charged. As a med student on the wards, such a tactic is sub-optimal at best and a good way to get your gear stolen at worst. The actual handles have their own methods of charging which do not require this costly and unnecessary extension cord.
Now let’s turn to the real decision: Welch Allyn NiCad or Lithium
Lightsaber power handle. Each one has its pros and cons, but understanding your use of your Welch Allyn diagnostic kit as a med student is what should really determine your buying trend. Most med schools only require you to purchase and use personal diagnostic kits during the teaching of physical exam techniques in the preclinical years, with very rare use in specific clinics during third and fourth year of medical school. You should ascertain usage patterns at your med school to make sure you don’t jump at the high end model when it will only be used a handful of times for the entirety of your medical school training.
The Welch Allyn Nickel-Cadmium (NiCad) handle (shown left) is the baseline model that will serve as a cheaper but reliable power source. The NiCad battery inside can be recharged by plugging the handle directly into any wall socket. One of the biggest benefits of this power source over the Lithium below is that it can be converted to normal C-battery use. I have seen several med students forget to charge their handle, subsequently lose power in the middle of clinic, and then look really foolish for the rest of the day. With this model, having a couple of batteries in your bag means you can pop them in and keep going strong when the charge dies. This is especially ideal for developing countries with unpredictable electrical sources, should you decide to go abroad.
There are a couple of downsides to the NiCad battery. First, it is heavier than the Lithium handles. For most people, this is not significant and not an issue whatsoever. The only other consideration is that there are rumors (often times furthered by Welch Allyn representatives) that NiCad batteries in general may experience “charge memory” or “memory effect.” This refers to a historic observation that NiCad batteries will remember the point at which you charge them as “empty,” thus not utilizing the full capacity. Most modern observations of this effect require over 1000 charges and partial-discharges for this to actually take effect. Suffice it to say, I have never heard of any medical student or resident complain about their NiCad handle losing charge time, and this may possibly by a result of the overall infrequency of use. Many medical students can get through all of medical school on just one set of 2 C batteries in their diagnostic kit.
Next we have the “superior” (read: more expensive) option, the Lithium Ion battery powered Welch Allyn diagnostic kit handle. This is one of their up-sells, advertised as “twice the battery life with just half the weight.” It mostly speaks for itself, but there are a few considerations. Like the NiCad handle, it can be plugged into any electrical outlet via the hidden electrical AC plug within the handle. However this handle cannot be converted to use C batteries. In other words, when you run out of juice in this thing, you’re done until you can charge it in the wall again. Again, keep in mind that a full charge will get you pretty far, so weigh things based on your schools requirements. Another possibly-insignificant difference with this handle is that the green push-and-twist power button is on the side of the handle itself instead of on the top edge. There’s really no difference in ease of use.
In summary, the direct comparison is as follows:
|Approx. Price||Battery Life||Compare Weight||Recharge Options|
|Nickel Cadmium||$150||~60 minutes||less light||Wall Outlet or C Batteries|
|Lithium Ion||$300||~120 minutes||lighter||Wall Outlet only|
Still can’t decide? Let us help! Check all that apply:
|My med school requires infrequent usage of diagnostic kits.|
|Money is of no concern in the purchase of my instruments.|
|I have a habit of losing things easily.|
|I have a habit of forgetting to charge my cell phone.|
|I want to learn physical exam techniques using the absolute best equipment at my disposal.|
|I want to look like a jedi.|