How to Perform a Burn Test

[grouchyturtle]

I want to do a burn test on my canister, to see just how much burn time I can really get out of it.

I'd assume that I'd want to keep it submerged in water for the test, to keep it from overheating.

Also, as far as I know HIDs don't slowly dim when the battery runs out of juice. They just have cut out abruptly. I've hear that running the battery completely down, though, isn't the greatest thing for the battery, bulb, and ballast. Is any of that true?

Basically how would I go about doing this test?

 

[ChrisA]

Assuming you are correct about it not being good to let the battery actually run dry.
(I don't know that answer as it depends on the type of battery, the voltage
regulator electronics and so on)

But here is a way to estimate the burn time without letting it burn out:

Run the light fora half hour then take out the battery and measure the voltage
run for another 30 minutesr and measure again. do this for a while and
then plot the voltage over time on a graph. (or let your spreadsheet
program make the plot)

Next step is guess at what battery voltage the light would fail. (or measure
ths if you have a variable voltage power supply handy.)
and to estimate when the batery would reach that voltage based on shape
of plotted curve

Actually I don't think running the battery out is that bad. If anything charging
a not fully discharged NiCd is bad for it.

One more thing. As the batteries age the burn time will go down so
any test you do now will not apply after some time was passed.

I want to do a burn test on my canister, to see just how much burn time I can really get out of it.

I'd assume that I'd want to keep it submerged in water for the test, to keep it from overheating.

Also, as far as I know HIDs don't slowly dim when the battery runs out of juice. They just have cut out abruptly. I've hear that running the battery completely down, though, isn't the greatest thing for the battery, bulb, and ballast. Is any of that true?

Basically how would I go about doing this test?

 

[willydiver]

I want to do a burn test on my canister, to see just how much burn time I can really get out of it.

I'd assume that I'd want to keep it submerged in water for the test, to keep it from overheating.

Also, as far as I know HIDs don't slowly dim when the battery runs out of juice. They just have cut out abruptly. I've hear that running the battery completely down, though, isn't the greatest thing for the battery, bulb, and ballast. Is any of that true?

Basically how would I go about doing this test?

A few years ago, I downloaded a dive light manual from Dive Rite (diverite.com) that showed you how to do a burn test. It also discussed battery charging and life. Email them and see if you can still get the .pdf download.

WD

 

[crpntr133]

Another way would be to get a ceramic capacitor of the same value that the bulb pulls. Hook up the capacitor and a voltmeter to the battery and let it rip. Time it, plot or what ever you want to determine the final time. Fore warning the resistor will get hot so don't touch it.
Most will probably say that it isn't a good idea to fully drain batteries, long story.

 

[grouchyturtle]

Actually I don't think running the battery out is that bad. If anything charging a not fully discharged NiCd is bad for it.

It's a NiMH battery, and as far as I understand letting it burn out completely isn't bad for the battery. I've heard that this isn't the greatest thing for an HID bulb and ballast, though.

 

[grouchyturtle]

A few years ago, I downloaded a dive light manual from Dive Rite (diverite.com) that showed you how to do a burn test. It also discussed battery charging and life. Email them and see if you can still get the .pdf download.

WD

Doesn't have that info in any of their current light manuals. Just sent an email, we'll see.