200L AA Voltage?

[mesasone]

I recently ordered a pair of the Dinotte 200L AAs during the last sale. I noticed that the battery pack is marked for 1.5V AAs (Disposable), which NiMH rechargables are typically 1.2v. So, I'm wondering... would I be able to add a fifth 1.2v NiMH rechargable in series to get 6v, and get an increase in brightness compared to 4.8v? Anybody compared brightness on these things running rechargables vs disposables?

Also, can you overvolt an LED? Say, go as far as to add in a sixth battery in series to increase it up to 7.2v? That would be especially useful if you wanted to build a Li-on battery pack out of two 12 aH 3.7v cells. Get the best of both worlds - great run times, and the ability to use AAs when needed. And still cheaper than the dual Li-on set from Dinotte.

[znomit]

NiMH run around 1.3 - 1.1v for most of their discharge cycle. They are 1.4-1.5v when freshly charged, but they drop quickly to 1.3 and then slowly down to 1.1, not much left after that.
So 5 cells will give a peak voltage of 7-7.5v. Might be too much. Email dinotte and ask.

Alkaline disposables tend to drop more smoothly but you get more total power out of a NiMH (might not be true for expensive lithium disposables).

An LED needs around 3.5v... there is a driver circuit in there that takes the battery current/voltage and converts it onto appropriate current/voltage for the LED (called a constant current driver). Ideally changing the battery voltage wont change things on the LED side of the circuit... but there is a range over what it will operate at. A lot of drivers need an input of at least 1v more than the LED. If the battery voltage is higher than the LED voltage its called a buck driver, if lower its called a boost. There are drivers that do both.

Some lights (ayups) just use a resistor in series with the LEDs. In this case changing the battery voltage will change the led brighness.

[n4zou]

They are using a standard battery holder so it would be marked for standard disposable batteries but the light is designed and comes with rechargeable batteries. Ignore the markings on the battery holder. If the LED driver circuit is just a resistor you can't add more voltage as this would cause in increase in current across the LED. This would shorten it's life and could cause a color change. If it's using a real current regulating circuit adding a second battery is not going to do much of anything except cause the regulator to convert more power into heat to regulate current flow. It would be safe to parallel a second battery holder doubling your burn time. If you want some extra battery holders here you go.
http://www.mouser.com/Search/ProductDetail.aspx?qs=5P%252byv4k1rSHWBYH6PnGGUA%3d%3d