-Keith Conover, M.D., FACEP
Version 0.25, August 10, 2002
At one point, my hospital’s disaster committee realized that it needed some caches of portable lights in case of complete power failure. There are commercial-quality lights available for this purpose, but they’re pretty expensive for what you get, use rechargeable NiCd (nickel-cadmium) batteries with all their attendant problems. And so I thought that the caving, cave rescue, mountain rescue, and mountaineering community knew quite a bit about lighting for emergency conditions, and that we might be able to do better. I sent an email out to those I know in these fields, and got lots of good ideas – some of which conflict, of course – but close enough that there seemed to be a fair consensus. This is not an exhaustive survey of the topic of handheld (or head-worn) lighting, but is an executive summary for those not experienced with the field. (My apologies to all of my advisors whose advice has been mangled and strangled and made to fit into this brief format.[i],[ii],[iii],[iv],[v])
So let’s start by asking why these lights are really needed. People will need them for personal tasks, such as working on paperwork at a desk, or working on a patient, which generally require both hands and relatively bright area lighting (not just a narrow spotlight), and for this, headlamps are clearly superior. But people also will need them for area lighting, such as at a nursing station. So there are really two types of lights that are needed.
1. If the power goes off entirely, despite generators and backup generators, the outage will generally be short, a few hours at most. And those who need lights need lights now. And so the lights should be easy to use (no complicated controls), and usable right out of the box, or with minimal preparation that requires no instruction or reading of instructions. And these power outages won’t happen very often, so the light need to have a long shelf-life.
2. On the other hand, if there is a massive disaster, the lights may need to be used for a long time – days, weeks, even months. So the lights should last for a long time, and replacement batteries (and bulbs) should be available from common sources, i.e., no proprietary batteries. And some sort of bulb that doesn’t require replacement, basically ever, would be nice: the new high-brightness LEDs or fluorescent tubes.
Related to the above “massive disaster” scenario, it would make much more sense to have a number of smaller caches throughout the hospital, so if one cache is destroyed, the others are still available (the “don’t put all your eggs in one basket” principle). This principle was endorsed by many reviewers, and fits the principle that disaster systems should be robust, that is, it should not be possible for a single failure (like destruction of the main light cache) to incapacitate the system.
It would be possible to buy bombproof commercial-quality lights – but for the same amount of money, we could get many more less-expensive but still high-quality lights. And cheap commercial-quality lights use NiCd batteries that die quickly and require lots of maintenance if you want them to work, use incandescent bulbs that burn out regularly, and aren’t all that good for the uses described above. And, given Murphy’s laws, having more means that, even if a few don’t work, we’re more likely to have the light that we need. And since many of these climber/caver/camper lights are in wide circulation, they are of generally high reliability – I’m not sure that commercial-quality lights are really any better, given they get much less “real use” testing by the public (and what is a better test than cave or mountain rescue?)
As more than one reviewer noted, having written instructions on each box, including a tag with when batteries are due to be rotated out, as well as a plastic security lock on each box, makes a lot of sense. Certainly having “Emergency Lighting” in bold letters on the outside of the box would make a lot of sense, too.
There are three types of bulbs commonly available for small portable lights: incandescent lightbulbs (including halogen bulbs), fluorescent tubes, and LEDs. Incandescent bulbs are the standard, but they have limited life (a problem in the “massive disaster” scenario). In a disaster, finding replacement bulbs could be a big problem, even if they’re stored in the cache (“OK, who remembers where that box is now?”) Fluorescent tubes are much less fragile, more efficient, and last much longer, though not as bright. The new high-brightness LEDs are efficient, extremely long-lasting, and almost indestructible, although still relatively expensive. For headlights, an array of high-brightness LEDs – 3 or more – is becoming more and more the standard in the outdoor community, often but not always with backup halogen lightbulbs for situations requiring high brightness and focused beams.
I personally use a bombproof hdssystems.com ActionLight 24-LED array with a single D lithium as my primary headlight, with a 4-AA cell Princeton Tec 40 halogen light on the side of my helmet for high-brightness when needed. For above-ground use for backpacking, I use a Petzl Duo light (incandescent bright light, LED dim light in the same housing.)
For LED lights, the battery orientation is critical, and it was suggested by one reviewer that some bright paint (nail polish?) be used to mark the + end of where each battery is supposed to go.
As far as batteries, I’m completely convinced of the superiority of disposable lithium cells.
· They have a 10-25+ year shelf life.
· They rarely corrode through.
· They work in extreme heat and cold with little change in their power output.
· They last two or more times longer than similar alkaline cells.
· They are much lighter than alkaline cells, which is important for headlights.
· They degrade gracefully and slowly in voltage as they wear out.
· They can be replaced by widely-available alkaline or even carbon-zinc cells if needed in an ongoing disaster situation.
Eveready Energizer disposable lithium AA cells are available in several drugstores in the Pittsburgh area, and are relatively inexpensive. These use a 1.5V technology and thus are a one-for-one replacement for AA alkalines. They are available from WalMart for about $10 for 4 ($2.50 each), or from www.walmart.com for about $12.50 including postage for a 4-pack, as of summer 2002. They are also precisely the same size as “standard” AA cells. (Some 3.0V AA lithium cells are slightly larger than “standard” AA cells and won’t fit in some lights.)
Lithium D cells are available from a variety of suppliers but not in retail outlets like drugstores. And, all of the lithium D cells currently available are 3V cells, which require the use of one dummy cell for each D cell – not an insurmountable problem but a complication that is best avoided if possible.
Li-SO2 batteries are generally thought by most to be the best form of 3.0V D cells, and ones with short-circuit protection are available from Henry at www.hdssystems.com. The short-circuit protection means that, if short-circuited, these cells will not vent SO2 gas, and thus these cells are considered non-hazardous, unlike other lithium D cells. As of July 2002, these cells are available in bulk at the following prices:
40 to 99 batteries: $14.25 each
100 to 200 batteries: $13.30 each
40 to 99 dummy cells: $7.50 each
100 to 200 dummy cells: $7.00 each
While this is expensive for batteries, I think it makes excellent sense to spend the money for these D-cells for hospital disaster light use. These batteries will operate a fluorescent lantern for days and have a shelf-life measured in decades rather than years – the savings, both in terms of not replacing lights, and not having to use expensive employee time for maintenance, make this expense a good investment that will provide longterm savings.
Rechargeable batteries make sense for lights that are used on an almost daily basis. NiCd batteries can be made to work if you coddle them, but even for the handheld radio that I use almost daily, I’ve had problems with NiCd batteries dying on a regular basis, so I switched to NiMH batteries – they recharge many more times than NiCd batteries, and don’t have the memory problems of NiCd batteries. Nonetheless, for rare usage, disposable batteries have much fewer things to go wrong (charger wires being damaged or loose, for example) and I recommend against any form of rechargeable battery, as much as I like NiMh batteries for daily use.
Keeping a “brick” of AA or D alkalines in each box as a backup makes great sense – these can be rotated out and replaced every few years. AA cells in particular are widely used in hospital pagers and this could be part of providing AA cells for pagers.
Some had suggested hand-pumped generator lights (e.g., http://www.navstore.com/forever.asp). And these might be useful if the power grid is gone forever and there is no gas for the hospital’s generators, but in such cases, hospitals aren’t likely to be going concerns anyway. So more convenient light sources make more sense.
I think the ideal lights would be as follows:
· an array of 3 or more high-brightness LEDs
· in a flashlight body or headlight body that is easily handheld,, and that takes 4 AA lithium cells (4 AA lithiums are light enough that having them on your head for a long time won’t cause neck strain or headache, at least not for most people)
· with a headstrap that allows it to be used as a headlight or as a handheld flashlight.
· Such lights are available from a variety of suppliers including www.karstsports.com, www.rei.com, www.caves.org/imo.
I have tested (= played around with) several lights that seemed possibly suitable and concluded the following:
· Princeton TEC Impact: I’ve used a headstrap-mounted Princeton TEC 4-AA halogen light for work around the house, so I was interested in the Princeton Tec Impact light, which uses a single large, high-brightness LED. However, when I got one, I found that, due to the lens in front of the LED, the light beam is so narrow that it is not very useful for working right in front of you, the primary use for headlights in a hospital disaster situation. Gave up on this one for our use (but nice to keep in the bedroom for personal emergency use as, unlike the MiniMag that I used to keep there, my 3-year old daughter can’t drop it 30 times and make the bulb die.)
· Princeton TEC Matrix: this is a 3-LED headlamp that uses 2-AA cells. Nice, but the light isn’t as bright as with larger arrays of LEDs. ($40 + $5 for 2 AA lithiums). Available from www.karstsports.com, www.caves.org/imo, and other sources.
· Lightwave 2000 LED flashlight: this can be mounted in the JakStrap II headstrap to make a fair headlamp. It has an array of 4 LEDs, and uses 3 AA cells, so it will last longer and is a bit brighter than the Princeton TEC Matrix, but isn’t quite as sturdy. ($30 + $7.50 for 3 AA lithiums + $6 for a JakStrap II headstrap = $43.50). Available from www.karstsports.com, www.caves.org/imo, and other sources.
· Lightwave 2000 Illuminator Headlamp: this is a dedicated headlight version of the Lightwave 2000 flashlight, also with 4 LEDs and takes 3 AA cells. ($36 + $7.50 for 3 AA lithiums = $43.50). Available from www.karstsports.com, www.caves.org/imo, and other sources.
· Mountain Green “8 LED headlamp” ($25 + $10 for 4 AA lithiums = $35) This is a Chinese import that uses 8 LEDs and takes 4 AA lithium cells. It is moderately solid construction, but the latex headstrap is far inferior to the headstrap of the Lightwave Illuminator or Princeton TEC Matrix headlamps. Bright, inexpensive. Available from www.cabelas.com
As of the time of my writing this (July 2002) I think the best deal is the Lightwave Illuminator 2000 headlight. There are certainly more rugged headlights available, but this one is rugged enough for the expected, use, is bright enough, light enough, and when a bunch of them are stored with lithium cells in them, they are all likely to work years later when pulled out of the box. At $43.50 each including batteries, they aren’t all that cheap, but they will do the job well.
I will be getting a Lightwave Illuminator 2000 headlight and have some people in the hospital try it vs. the Mountain Green headlight and see how much the strap, number of LEDs and other design features matter to the intended users.
· a lamp with two or better four fluorescent tubes, or two U tubes (each U tube is as bright as two straight tubes, but with double power consumption as well).
· runs on 8 AA cells or D cells – however have found none that are big and bright enough that run on AA cells.
Coleman (www.coleman.com) makes a variety of battery-powered fluorescent lanterns, and also has a discount web-based direct purchase program.
They offer the Electric Northstar Lantern (42 watts, $45, less with the discount program, + $45 for 3 lithium D cells, and $22.50 for three dummy cells = $112.50, will burn for about 24 hours).
Another is the Energizer Folding Fluorescent Lantern from www.rei.com, (19 watts, $18 + $30 for two lithium D cells and $15 for two dummy D cells = $63, will burn for about 48 hours). I did get one of these, and it seems like an excellent design for the intended use. Unlike the Coleman lanterns, which for marketing and brand-identification reasons are made to look like Coleman gas lanterns, this is designed in an excellent and functional way for a fluorescent-battery lantern.
It’s not rugged enough for caving or rescue, but would be fine sitting at a nurses’ station. It uses two fluorescent tubes, and can be held as a hand-lantern with the light going in one direction only, or the section with the fluorescent tubes can be rotated up to provide area lighting. There are no controls except for the rotating section with the tubes (which has a permanent reminder that it can be flipped up – good!) and a large, well-marked “off-low-high” switch. Unless I find something better that runs on AA cells (no luck so far) I will recommend this light. Although not as bright as the brightest of the Coleman battery lanterns, it is quite bright when both tubes are lit, is about half the price of the Coleman top-of-the-line lantern, and burns about twice as long.
The Energizer is my recommendation for emergency area lighting.
[i] Some suggested hats with lights on them: but in many situations, we have to wear scrub hats, so another hat on top of this would be difficult.
[ii] Some suggested the Petzl Tikka or similar lights that use 3 AAA cells – but these won’t work with disposable lithiums, and the advantages of disposable lithium cells overwhelm the attractiveness of these lights.
[iii] Some suggested Cyalume or similar glow sticks – but the light from these isn’t enough for most medical tasks, including patient care or writing or reading.
[iv] Some suggested hand-cranked generator lights. For our uses, I don’t think these are appropriate, people are too busy to crank the lights.
[v] Some suggested computer-style UPSs attached to lights, and commercial lead-acid sealed-cell lights that automatically come on with a power outage might be a nice backup for a hospital to install, but that’s really outside the scope of what’s discussed in this paper.