djac5700,
Re: rechargeable batteries in the C8 eLED:
The short answer; if you are going to use the light infrequently (say, once a month or less) then Alkalines are probably your best choice. For frequent use (once a week or more) rechargeables will probably save you money in the long run. If you do go with rechargeables, I would not recommend the UK battery. It is a custom pack made from 2200mA NiCad cells. NiMh batteries in C size are typically more than twice that capacity (4500mA) and will probably cost you less.
Check out
www.amondotech.com for good prices on NiMh batteries and smart chargers.
The long answer:
For infrequent use Alkalines may be a more convenient option. One drawback to rechargeables is that they have limited shelf life. If you charge up NiMh or NiCad batteries then put them away for a month you will find that they are depleated when you go to use them. NiMh and NiCad batteries lose from 1% to 5% of their charge a day in storage (depending on temperature, humidity, etc.).
The advantage to rechargeables (besides their obvious rechargeability) is that they have a flatter discharge curve (less voltage drop for more consistant light outptut and color temp) and more current capability. If you try and pull a couple of amps load from an Alkaline its voltage can drop up to 50% (from 1.5v to only 0.75v). NiMh & NiCad rechargeables can typically deliver several amps with little or no voltage drop.
Alkalines actually have more stored power than rechargeables. For example, the Energizer E2 Alkaline has over 9000mA (milliamp) capacity, while most NiMh C cells only have 4500mA (the best are 5000) and NiCads only run around 2200mA. The problem is, under high current demands an Alkaline's voltage drops so much that they often become unuseable before their power is depleted. Alkalines are designed to output only small amounts of power over a very long time and don't do well when the device demands large amounts of power. This is why lower capacity rechargeables last longer in high current demand devices like digital cameras and high power lights.
So how does all this relate to the lights we are talking about?
The UK Light Cannon LC100: The LC uses a short arc metal halide lamp that requires a series of high voltage pulses to "strike" the lamp (start it up). This is kind of like the starter in your car. A weak battery can still run your lights, radio, etc. but can't start your car because the starter requires loads of power. The LC will often fail to strike on partially depleted Alkalines because they can't deliver the required surge current. While nearly depleted rechargeables can still deliver several amps of current for a short time.
The C4 & C8 eLED use electronic reglation to deliver the required power to the LED light engine. Regulation circuits trade voltage for current, so...
The C4 eLED uses 4 batteries for a total of 6v (fresh Alkalines), but the 5W Luxeon LED requires around 7v so the regulation has to boost the power and this means it will actually drow
more current than the LED needs.
The C8 eLED uses 8 batteries, so the regulation circuit has to drop power to the LED, and will actually draw
less current than the LED needs. This is what makes the C8 eLED a good candidate for Alkalines. In this particular light the current draw is low enough that Alkalines actually perform pretty well.
Sorry this answer got so long and involved. Hope you find some useful info in here.
Aloha, iG
), and sometimes you don't really need so much light if you want to experience the serenity of a night dive.
