Stenlight S7 Headlamp Review
Twin 3w Luxeon Headlamp from
www.excellentstuff.co.uk
Price £199 for Lamp, Battery and Charger
Overview
The Stenlight S7 is a compact metallic headlamp produced in the United States for the Caving/Exploring market. It's based on not one, but two 3w Luxeon LEDs - but is it any good? Read on to find out.
The Lamp Build
The first thing to hit me as I unpacked the demo unit was the shockingly small size of the lamp. It is barely larger than a Petzl MyoXP and weighs very little. It is machined out of a solid block of aluminium - the only headlamp I know of to be built in this way rather than out of moulded plastic.
On the back is the standard spade fitting which will fit most helmets designed to take a lamp. This spade fitting has a tensioner to hold it in the helmet socket, which does its job so well that it is an effort to get the lamp off should you need to. The spade fitting also has that all important hinge so that the lamp can be aimed up or down to suit the user. It's amazing what a difference that makes, many lamps (E.G. the Oldham) don't have this simple feature which can encourage incorrect wearing of the helmet to obtain a preferable light angle.
Also on the back of the lamp is the five position mode switch (Off, Low, Medium, High, Turbo). The switch on many lamps is the weak point of the system but not on the Stenlight. Firstly the switch is magnetic to prevent water/dirt ingress. It is also made out of sheet steel and I expect trying to break it would be very difficult indeed. It moves between the modes by rotating it around the lamp and I must say it feels like a Landrover Series 1 gear-stick. No flimsy calculator-grade buttons here, the tactile Clunk-Click movement is a true delight and poses no problems to operate even whilst wearing gloves. It doesn't look or feel at all cheap and nasty (because it is neither).
On the front is a metal bezel holding in (with a rubber seal) the front plastic cover. Beneath this are the two 3w Luxeon LEDs, arranged next to each other like little eyes. In practice I found the plastic front a little easy to scratch if abused, but replacements are available cheaply from the manufacturers website.
The lamp is waterproof but not to diving standards. The manufacturer states that it is fine for getting drenched in typical caving situations (climbing waterfalls etc) and also for submerging under the odd sump but for proper diving applications look elsewhere. It is not certified gas-proof either so it is unsuitable for explosive environments. If you are into mountain biking there is a handlebar bracket under development so you will also be able to use it for your late night trailing.
The Stenlight S7 (left) next to an Oldham Caplamp
The casing for the Stenlight S7 is solid as a rock and has been crafted like a piece of jewellery. I defy anyone to break one without using heavy plant machinery.
The cable into the lamp is not as chunky as Oldham type cables and the grommets are not receptive to being whacked against sharp rocks. Bear in mind this lamp was intended for use with helmet mounted batteries and therefore the cable doesn't need to be as tough as found on an Oldham. The cable is still more than adequate and will not cause you problems if you do not abuse it.
The cable is attached to the battery via small plastic plugs. They push together and will pull apart if sharply tugged, rather than locking and potentially damaging the cable/lamp/battery if you get it caught on a rock whilst abseiling etc.
The Light Source
The Stenlight is unusual for having two rather than one LED's and they are both used at the same time and at the same power level. These are both forward-shining 3w Luxeons, each fitted with its own interchangeable lens. One is set to 5 degrees for a tight beam and the other at 15 degrees for a wider spill. Other variants are available from 99p including 25 and 50 degrees to suit the users personal preference.
These in turn are driven by a temperature controlled regulator circuit that is happy to accept any incoming voltage from 7.2v to 18v. It will take a minimum of 6v but at the sacrifice of the highest power level, so 7.2v is required for full output. On Turbo mode the regulator will drive the Luxeons as hard as it can, delivering an awesome 7 watts output. At this light level the lamp will heat up very quickly and reduce its output to cope with the heat, averaging around 4 to 5 watts output long term. The lower power settings are 0.1 watts, 0.6 watts and 2 watts.
The Stenlight Battery
The Lithium-Ion battery
The Stenlight S7 is also available with a small rechargeable Lithium-Ion battery, intended to be mounted on the back of the helmet using the supplied 3M Twin Lock Fastener strips. These do the job just fine without needing to modify the helmet in any way. If you did not already know, Lithium-Ion is the top battery technology available for size and weight to capacity ratio, which is why they are used on mobile phones and laptop computers. Not many headlamps come with Lithium-Ion batteries and the battery is indeed physically very small and light.
The Stenlight Battery (left) next to an Oldham
Type T battery
It holds 2300mah at 7.2v, or 16.6 watt-hours. This will drive the lamp on full output for between 3 and 5 hours, or 7 to 8 hours on the 2 watt setting. Go down to 0.6 watts and you get over 24 hours of light between recharges. You can of course buy and carry more batteries if you wish. Stensat are considering releasing a larger 6000mah (43 watt-hours) cell which would more than double the available burn time.
The Stenlight Battery Charger (left) next to an
Oldham Twin Battery Charger
If you buy the Lithium-Ion battery you will of course also need the charger. This like the battery is very small and light and will provide a full charge in 3-4 hours. The charger, thankfully, will work off our 240v mains (the mains voltage in the US is 110v) but the power lead does come with a US plug on it. The power lead at the charger end is a standard euro-type figure8 connector. Chances are you already have one of these leads at home powering something else like a stereo, printer etc. They can be obtained cheaply from hardware stores or online or simply cut off the US plug and put a British one on there (assuming you are able to safely do the rewire).
The Stenlight with its Lithium-Ion battery
A final point to mention is that the Stenlight can come with a cheap adapter for a 9V PP3 battery (which would deplete very quickly) or a battery case for 6 AA cells. Neither are sealed boxes and just hold the batteries so presumably are only intended for emergency use. The six AA cells (if installed with 2500mah rechargeable AA's) would provide 18 watt-hours, which is more than that of the Lithium-Ion battery.
Using your Own Battery
If the Lithium-Ion battery solution does not appeal, you can always rig up your own - Stensat do sell the plugs separately as a kit for this purpose. The bad news is that your battery must be at least 7.2 volts for the lamp to achieve full brightness and with less than 6 volts it will not light at all. So if you were hoping to rig up your Oldham or Speleo FX battery to it - forget it, it won't work.
A battery could be put together cheaply using a 12v Sealed Lead Acid unit (ideally at least 4.5ah capacity), obtainable from eBay with a basic charger for about the price of a round of drinks. Mounting it reliably to your waist will be challenging.
Alternatively consider a big Ni-Mh battery pack designed for use in remote-control cars. These are available in a range of voltages including 7.2v, 8.4v, 9.6v and 12v (any of which will do). They can come in decent capacities and are not very expensive even with a good charger. Again, waist mounting them will be entertaining but not impossible. Or try to assemble a box to hold at least six regular batteries (AA's, C's, or even D's).
You might be able to use an existing Oldham or Speleo FX battery with some sort of inline step-up transformer to double the voltage. The Oldham T6 battery is 4 volts, but provides nearly 100 watt-hours giving it five times the capacity of Stenlights Lithium-Ion cell. Rigging two Oldham batteries in series would give you 8 volts (fine for the Stenlight) and an absurd 200 watt-hours (almost) capacity, but chances are you would loose an inch in body height on every trip with so much weight around your waist.
Comparisons with Other Headlamps
So how does it measure up with some other product offerings on the market? With the help of a friend (thanks Ferret) I took the Stenlight down a local mine with several other lamps, a tripod and a camera. The aim was to provide an accurate real-life comparison of the Stenlights output versus several others. I did this by positioning the camera on a tripod looking down a randomly chosen tunnel and placing my friend to one side looking down it. The camera settings were exactly the same for each shot (Daylight Balance, ISO200, 8sec, F2.6, 24mm), and my friend was not allowed to move between exposures. The same picture was taken with the same settings just using the different lamps, which I swapped on his helmet ready for the next shot.
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Stenlight
S7 Very bright and penetrating beam of medium spread, providing clear white illumination. |
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Oldham
Caplamp with 1w EverLED Upgrade A very narrow and tight beam which actually threw further than all other lamps on test, but with a weak spread. |
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Oldham
Caplamp with Retro2 Upgrade (2x1w Luxeons) Nice, wide and even illumination but lacking the long range |
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Speleo
Technics Nova3 (single 3w Luxeon) Very close to the Stenlights output, but not quite as bright and not quite as wide. Impressive given that it only has one Luxeon rather than the Stenlights two. |
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Petzl
Zoom (2.5w Halogen) Provided as an interesting comparison light. Zooms remain a very popular cheap'n'cheerful headlamp for climbing and underground use. As can be seen, it falls far behind the other lamps and the light is very yellow and uneven due to the filament bulb. |
The Stenlight in Use
I spent about 30 hours underground with this lamp to give it a really good test. Activities undertaken with it included abseiling vertical drops, climbing mountains of scree, slipping through tight spaces and wandering through vast chambers hundreds of feet across. In all applications the lamp performed beautifully and was certainly brighter than the headlamps my various companions were sporting. In fact, at time of writing, it is the brightest headlamp I have ever seen.
There was nothing at the very 'wide' end of the beam, which caused a bit of stumbling as I find I get on better with very wide lights. This is just personal preference and I can very cheaply change the lenses to wider ones if I so choose. Some of my companions were using high-end lamps based on single 3w Luxeons (E.G. the Nova3) and it was surprising how close they came. The Stenlight was certainly brighter but not twice as bright. This is presumably because of the thermal controller running the LEDs at a more leisurely pace to prevent them from overheating, rather than driving them flat out reducing their life span.
But the Stenlight is not just about being bright - it is the whole package. It is very small, very strong, well made and looks great.
Overall Verdict
The Stenlights price puts it at the top of the market - it is not cheap. If you bought the lamp, charger and two batteries this would set you back 360 dollars, or around 190 British pounds at time of writing. Then add the import duty etc and it has put a respectable dent in your wallet. Having said that, its value for money all depends on how often you go underground. If you only dabble on the odd trip, then certainly the Stenlight is extravagant. But if you are underground a lot and spend good money on fuel and accommodation driving around the country visiting new mines and caves, then the cost of the lamp does not seem so high. Your light is going to show you what there is to see and inset the memories you will take back with you. Is there any point in driving hundreds of miles and staying in fancy B&B's to visit mines you can not even see properly once you are inside? Not really. Your lamp is everything underground. You will only ever see what your lamp can show you, so if you are going to get a lot of use out of it, then the Stenlight is a serious lamp to think about.
If your budget is lower you could always try and rig up your own battery or buy the kit to run it off AA's. The lamp alone with the AA battery kit would set you back 250 dollars or 133 pounds (at time of writing) plus the import taxes, giving a lower cost of ownership especially if you have got a load of good Ni-Mh AA's at home with a charger already.
Looking down a tunnel with the Stenlight S7
My only real negative point with the product is the lack of battery options. The Lithium-Ion battery is great but 3 to 5 hours burn time is just not enough - a full days exploring for me can easily run to 12 hours. It is all very well just carrying more batteries but sometimes that is not convenient, especially if you are in a wetsuit carrying only a tackle bag. Where would you carry them safely? In some waterproof pouch I suppose - but it is not ideal. Personally I prefer to put my lamp on at the start of the day and not have to worry about it until I am leaving. A battery change halfway down a 500 foot shaft abseil would not be much fun.
The situation would be greatly eased if it could connect to various other manufacturers waist-mounted batteries but it can't because of the high voltage requirement. So your options are simply to buy and carry multiple Lithium-Ion cells, or build your own battery entirely. I think it is a shame after buying such a nice headlamp to have to resort to bodging up a DIY battery out of Lego or whatever you would use - not a problem if you are an engineer but for the rest of us it is not so easy. A chain is no stronger than its weakest link.
This was emphasised during one of my test trips; As it was a full day trip I had taped together two 6v sealed lead acid batteries to give 12v (enough for the Stenlight) and was using that as my power source. Because I could not attach them to my waist I put them in my backpack. Fine - except I could not take my pack off. Upon arriving at the mine in the morning I realised I had forgotten the short length of wire to go between the two batteries. Hunting around the site I found an old bit of steel fencing and broke some off to tie it between the terminals. This worked fine, except the connection was a little loose. But I would stay close to my friends so if it went out suddenly I could use their light to fix it. Four hours underground, I ducked into a side passage to pay a visit whilst my companions went on. Sure enough, after they had gone way out of sight onto another floor, I was suddenly in the pitch black. My spare torch was in my bag (never a good idea) and there was little I could do but sigh and wait for my friends to come back to find me. I know all of this was just me being unprepared rather than anything I could blame the Stenlight for. But it did drive home to me that it does not matter how good your headlamp is, your battery has to be solid too (so if you do make you own, do a better job than I did). My point is that with a fancy high-end product like the Stenlight, it would be nice to buy a complete solution that does not leave anything else you have to worry about, I.E. how to power it properly all day.
Having raised the issue with them, they put the point across that Turbo mode is very bright and full-day users should stick to the lower power modes (like the 2 watt). This would still provide ample light and the battery would therefore last a lot longer. Fair point - but my counter argument to this is that if you are forced to spend all day working on a low light output, be it still sufficient or not, you may as well have just brought a cheaper lamp in the first place. We explorers are all light-mad anyway, we want to dazzle our friends and make them feel inferior!
My niggle with the battery is hardly a show stopper. If Stensat do release the 6000mah version of the battery, so much the better. I would have liked to have seen the lamp offered with a nicely made waist-mounted cell, I think it is crying out for one. In the mean time, carrying a number of Lithium-Ion cells is no great problem and the freedom of movement afforded by a head-mounted battery is a real bonus and probably worth the few mid-trip battery changes anyway.
The Stenlight is indeed a fantastic light of the utmost quality and I can certainly recommend it. It comes at a high price but you are getting a whole lot of lamp for your money. By my estimation it will last a lot longer than a cheaper made equivalent that may need replacing in a couple of years. If you are in the market for a damn good lamp, give the Stenlight serious consideration.
My sincere thanks got to Stensat Group for providing me with a demo unit and lots of helpful information!