10, 12, or 14 cells for MR16s?
- Thread starter apete2
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Depending on bulb wattage, bulb life, battery capability and total set up resistance, you may need to go up to 16 cells.
mdocod
Flashaholic
16 cells for most 2000 hour bulbs is pretty brilliant, I've gone as high as 18 cells on some 2000hr MR-16s but many will fail at this drive level (measured over 21V at the pins with eneloops and over 120W total power on a 12V50W2000hr rated Westinghouse brand MR16)...
Rather than replace your power supply with a huge expensive conversion, have you considered just switching to a different bulb?
Not sure what wattage class you are looking for but check out EFN 75W (64615) 50hr, EFP 100W (64627) 50hr, 64629 for slightly longer life (~500 hrs)...
Those should run on your 12V SLA with brilliant output by comparison to the long-life bulbs. Worth a try at least.
-Eric
Rather than replace your power supply with a huge expensive conversion, have you considered just switching to a different bulb?
Not sure what wattage class you are looking for but check out EFN 75W (64615) 50hr, EFP 100W (64627) 50hr, 64629 for slightly longer life (~500 hrs)...
Those should run on your 12V SLA with brilliant output by comparison to the long-life bulbs. Worth a try at least.
-Eric
i didnt know they had bulbs that high, I have been using phillips 50w spot and 20w flood from stores, i could try that
i wonder if 16 large cells would decrese the life too much compared to 16 aas, i dont want AAs since I want to get at least 45 min
i wonder if 16 large cells would decrese the life too much compared to 16 aas, i dont want AAs since I want to get at least 45 min
mdocod
Flashaholic
Keep in mind that as you over-drive, you are going to reach higher wattage anyways.
A 50W long-life halogen driven to ~19.2V from 16 cells will actually run at about 100W.
You might have a look at these charts to get a better feel for bulb overdriving behavior.
http://www.candlepowerforums.com/vb/showthread.php?t=179748
Check out the westinghouse 4743, which would be very much like the bulb in a 20W MR-16 long-life.
The 3 Hikari bulbs listed are also good examples of long-life halogens like what's found in MR-16s....
The Osram 64625 is worth a look to see an example of a "short-life" bulb design. Which reaches much higher output at rated voltage, and doesn't need as much over-driving to be really screaming.
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14 cells may be the way to go if you need some reliable bulb life on the table on the long-life halogens.
-Eric
A 50W long-life halogen driven to ~19.2V from 16 cells will actually run at about 100W.
You might have a look at these charts to get a better feel for bulb overdriving behavior.
http://www.candlepowerforums.com/vb/showthread.php?t=179748
Check out the westinghouse 4743, which would be very much like the bulb in a 20W MR-16 long-life.
The 3 Hikari bulbs listed are also good examples of long-life halogens like what's found in MR-16s....
The Osram 64625 is worth a look to see an example of a "short-life" bulb design. Which reaches much higher output at rated voltage, and doesn't need as much over-driving to be really screaming.
-----------
14 cells may be the way to go if you need some reliable bulb life on the table on the long-life halogens.
-Eric
LumenHound
Flashlight Enthusiast
The EFP 100 watt bulb works well on SLA batteries that are 7 Ah or larger. It's nice and white down to 10.75 volts.
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