AA NiMh @ 3.5 Amps?

I have the Energizer 2300ma AA Nimh batteries and was wondering if I can get away with battering them with the WA 01111-U, a 3.35 A /ubbthreads/images/graemlins/mad.gif bulb at 6 volts nominal. This will be wired into my headlamp as my "throw and go" option, meaning that it will only be used for 1-5 minutes maximum at a time to spot distant objects while hiking. I hope this will work - if it doesn't, I'll be doomed to using bulbs in the 2A class. Too ambitious? I tried the Sanyo and Energizer websites, but found nothing specific to my question.

You need to test it out - the voltage unter load should be in the 1V to 1,1V max area so I would suggest you try 6 cells to get the 6V needed. Most NiMhs are rated for max 2C discharge but will drop voltage significantly above 1C.

Klaus

Unfortunately, four cells is pretty much the upper limit for my headlamp. More than that would result in too much buk and weight on my skull. I believe the cutoff voltage for these cells is 1v. What happens if this high current draw forces a drop to terminal voltage? Battery damage? If the V drop under load is so severe that the lamp is effectively derated, then I'd probably be better off w/ a 2A or so bulb. Could you enlighten me regarding 2C - can't remember how to covert to amps or power.

at http://data.energizer.com/datasheets/library/rechargeables/consumer/nimh/nh15.pdf there is a chart showing voltages and runtimes at different current draws... it has a voltage of 1.25 volts at low current draws and at 1C (2.3A) it shows the voltage at about 1.2 volts and runtime is not really effected, so 1C is fine. however at 2C the voltage is only about 1 volt and it only gives around 20mins runtime... dont know how accurate the graphs are but it shows the batteries dont really like 2C, but they will handle it, if you dont mind the voltage dropoff and the crap runtime, but the fact that they even have a 2C graph on their probably suggests that the batteries wont instantly die when put under that stress /ubbthreads/images/graemlins/smile.gif

having said that maybe 6 cells is the go instead of 5?

If you can´t use 6 cells for the high draw forget it - you´ll get more light using a 2A bulb then - "C" is the capacity of the cells so 2C is 4A when the cells has 2A.

Klaus

Well, it might be worth some benchtop experimentation. According the to datasheet, performance is still robust @ 2.3A with voltage hovering near 1.22V. Come to think of it, anything beyond 200 lumens would likely be wasted as sidespill by the 1" Surefire e2e bezel and reflector, although I may try to retrofit a reflector (elliptical) made specifically for projection.

Here's your data:

http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Board=ElectroLumens&Number=587617&page=0&view=collapsed&sb=5&o=14&fpart=1

Wilkey

Thanks, good post. You even have the 401 charger like myself.