4AA VS 4D bulb question

mykall said:

I have a question about incan. bulbs rated for 4D cells as opposed to
4AA. I use these cheap automatic motion sensing lights in my hallways
so that I don't have to flip lights on and off all the time (and possibly leave them on).

Anyway they take either 4AA cells or the optional 6V wall adapter. I have been using nimh cells in them for about 2 years with good results. Each of the 3 units came with a couple of spare bulbs which I"m now out of . I went to several stores to see if I could find one of these screw based 4.8V (not sure how many "A") bulbs. The closest thing I could find was one at ACE Hardware rated for 4 "D" cells. When put in the unit the bulb will come on and after about 3-4 seconds starts flashing.

Is this the wrong amp rating? It does appear quite a bit brighter than the original though. Since 4D and 4AA are both 6V is there a difference besides just capacity?


Thanks
MB

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DonShock said:

You might want to consider these 4 cell screw base LED replacement bulbs. They're a little pricey in comparison to incandescent bulbs, but you would only have to replace them once. LED bulbs also tend to make batteries last longer (2-5 times as long is claimed) and are also whiter that the yellowish light given off by the incandescents.
http://www.led-replacement.com/ls407.html

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RoyJ said:

No, there's no difference between 4AA and 4D. You just bought a "flasher" bulb, that's all! I made the same mistake before.

Look closely at the bulb, it's not a continuous filament, but has a metal plate contact. When the metal plates heat up they'll seperate and then cool off and touch eachother again. They're meant to flash.

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Handlobraesing said:

Actually there is a difference between AA and D rated bulbs. Look at the current rating. AA rated ones are usually 0.25-0.5A range while the D rated ones are 0.5 to 0.85A range and they're usually 4.7 to 4.8v rated.

an AA lamp with Ds is fine, but if you use a higher current D rated lamp with AAs, the batteries will go dead fast. Alkaline does not like high current draw. They can deliver 2900mAh at C/120 rate, but usable capacity loss is apparent at as low as C/30 rate. At C/5 to C/10 rate, expect to get about half the rated capacity and even less for higher load.

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mykall said:

I have a question about incan. bulbs rated for 4D cells as opposed to
4AA. I use these cheap automatic motion sensing lights in my hallways
so that I don't have to flip lights on and off all the time (and possibly leave them on).

Anyway they take either 4AA cells or the optional 6V wall adapter. I have been using nimh cells in them for about 2 years with good results. Each of the 3 units came with a couple of spare bulbs which I"m now out of . I went to several stores to see if I could find one of these screw based 4.8V (not sure how many "A") bulbs. The closest thing I could find was one at ACE Hardware rated for 4 "D" cells. When put in the unit the bulb will come on and after about 3-4 seconds starts flashing.

Is this the wrong amp rating? It does appear quite a bit brighter than the original though. Since 4D and 4AA are both 6V is there a difference besides just capacity?


Thanks
MB

Click to expand...

Handlobraesing said:

an AA lamp with Ds is fine, but if you use a higher current D rated lamp with AAs, the batteries will go dead fast.

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eebowler said:

I had the impression that if you use a bulb designed for a 2AA flashlight with 2D cells, it would blow instantly. eg the minimag 2AA bulb.

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Handlobraesing said:

an AA lamp with Ds is fine, but if you use a higher current D rated lamp with AAs, the batteries will go dead fast. Alkaline does not like high current draw. They can deliver 2900mAh at C/120 rate, but usable capacity loss is apparent at as low as C/30 rate. At C/5 to C/10 rate, expect to get about half the rated capacity and even less for higher load.

Click to expand...