rlhess
Enlightened
Hi, I managed to run across several (bought one) Energizer 2-tube folding fluorescent lanterns today.
It has two 4W tubes and runs on 4 D cells. You can switch on one or both tubes (can't alternate which tube runs so if you're using it a lot on one tube, it might be worthwhile every battery change or two to swap tubes).
It CLAIMS (I just got it) to run for 40 hours with one tube and 20 hours with two tubes.
One tube (at one foot) gave me about 8 cd and two tubes peaked at about 13 cd.
Since this is pretty even illumination over a broad range, I would estimate perhaps 0.7 * pi * 11 or about 24 lumens output. Not bad for alleged 20 hours burn time.
Let's do the calcs for burn time.
18AH to 0.8V (or so) and 8W at 6V is about 1.33A so I don't believe the burn time. As the voltage drops the light will, too OR the current will go up.
Perhaps they're starving the tubes?
Yup...both tubes about 0.68A or 4W for both tubes and 0.37A or 2.2W for one tube (assuming no significant voltage drop from 6V).
Those current drains do match the run times one would expect--and it's not even asking it to go to 0.8V.
Two tubes work at 0.5A and 4.5V which is a fair indication of how far you can easily go down in voltage and they were still quite bright. Two tubes were very dim but would still work at 3.0V. At 3.0V the two tubes also draw 0.5A.
Cheers,
Richard
It has two 4W tubes and runs on 4 D cells. You can switch on one or both tubes (can't alternate which tube runs so if you're using it a lot on one tube, it might be worthwhile every battery change or two to swap tubes).
It CLAIMS (I just got it) to run for 40 hours with one tube and 20 hours with two tubes.
One tube (at one foot) gave me about 8 cd and two tubes peaked at about 13 cd.
Since this is pretty even illumination over a broad range, I would estimate perhaps 0.7 * pi * 11 or about 24 lumens output. Not bad for alleged 20 hours burn time.
Let's do the calcs for burn time.
18AH to 0.8V (or so) and 8W at 6V is about 1.33A so I don't believe the burn time. As the voltage drops the light will, too OR the current will go up.
Perhaps they're starving the tubes?
Yup...both tubes about 0.68A or 4W for both tubes and 0.37A or 2.2W for one tube (assuming no significant voltage drop from 6V).
Those current drains do match the run times one would expect--and it's not even asking it to go to 0.8V.
Two tubes work at 0.5A and 4.5V which is a fair indication of how far you can easily go down in voltage and they were still quite bright. Two tubes were very dim but would still work at 3.0V. At 3.0V the two tubes also draw 0.5A.
Cheers,
Richard