New 'Explorer' Caving Lamp
Explorer Lamps of Burnley have redesigned their caving lamp package, taking into account comments from users of the previous version and those obtained at last year's BCRA Conference. The new version is more directly competitive with the FX 2.
The new cell is basically as before except that the built-in charger is now sealed into the plastic housing rather than being a screw-on extra. This means that it is now non-serviceable but it has enabled the manufacturers to reduce the overall size to 150mm x 80mm x 50mm and the weight to 1kg. The headset supplied is no longer the "Oldham" type; this has been replaced by a "Ceag" unit. The belt loops have also been redesigned.
It is claimed that the lamp is almost indestructible and will give 10 hours continuous light on main beam for 5-600 recharge cycles. The built-in charge circuit contains a protection device to prevent overcharging. The cell can be charged continuously without being drained.
The new price is £69.95 for the complete unit, including a lead for charging from a 12v source (ie. car cigar lighter socket). A mains charger unit is also available. Details from:
John Blackburn
Explorer Lamps
16, Tiverton Drive
Burnley, Lancs Tel. 0282 54032
Addendum
The manufacturers assure me that the former propensity of the new design to explode was due to an unnotified change in the design of the cells used in constructing the lamps and a suitable pressure relief system will be built into future models.
Allan Ockenden
The Virtues Of NiCad Cells
Chris Fry
About seven years ago, when I first made contact with Croydon Caving Club, I had little idea about what equipment to purchase. Like many of our members I started my underground capers in the Surrey mines under the wing of Ron Smith. As all that was necessary at that time was a good lamp, helmet and old clothes it was logical that the first item of proper caving kit I should buy was a lamp. Asking those around me what the best lighting source would be, Ron replied that the 20 Amp hour NiCad cells sold by Caving Supplies were probably the best around, especially if fitted into an Oldham case with a new Oldham headset - if I could spare about £40. I took his advice and have never regretted that decision.
During those seven years of use I have never experienced any problems with leakage of electrolyte or suffered any light failure other than due to poor electrical contact caused by gradual corrosion of contacts within the headset. I have however found over the years that I have had to regularly (approx. every 18 months) shorten and strip back the cable at the cells as electrolytic action seems to take place here and the conductors themselves gradually corrode and become brittle. I am led to believe that this is due to using the standard cable intended for use with the Oldham lead acid unit and would be interested to hear any more on this topic.
During May this year I noticed that the performance of the unit was slightly below that to which I am accustomed and began a full overhaul. It soon became clear that I had some contact problems again. I also realised that I had already shortened the cable to the point where it was only just practical for me - and I am only 5'7". Fortunately I had a spare new Oldham headset and cable and made the switch. Unfortunately I was not careful enough in checking the polarity of the headset, I gave the cells 2.5v/l amp for 24 hours the wrong way!! At the end of this period, not realising my mistake, I checked that the lamp had charged and set about bench-testing it (which I do regularly) to check its condition. I was alarmed to see the beam dim away to nothing after about 2 minutes. Once I realised the error I had almost resigned myself to having to purchase a new power source but thought I had nothing to lose by re-charging at the correct polarity for a further day and set about doing this immediately. I have since been able to bench test the cell with a 1 Amp bulb for 19 hours, fractionally down on previous performance. Try matching that performance and resilience with a lead-acid unit and bear in mind that during 7 years I have never even replaced or topped up the electrolyte.
Incidentally old Croydon members may remember Phil Brown (Caving Supplies) trying to sell these same 20ah cells in Croydon for £1 by each extolling their virtues, but hardly anyone seemed to believe him. Now they are virtually unobtainable and advertised at £2.95 each (2 required) and the price of the combination I bought in 1980 is £6.50.