Battery Indicator Question

This is just a curiosity question (as opposed to an important one ) but what is a possible explanation for my battery indicator operating as follows?

My BD Storm has a battery indicator. After the battery capacity drops below 75% it changes from a green indicator light to an orange one (and then to a red one at 25% and below).

When I turn the spot beam on the indicator light is now orange (was green until recently) however when I turn the flood beam on it is still showing green.

What does the mode the headlamp is in have to do with battery capacity?

Not knowing anything about the Storm, I presume that when you go from spot to flood, you're switching spot off and flood on, and not having both on?

If so, then I'd guess that the spot beam draws more power, so the voltage sag under load is greater. As such when you turn on the spot beam you're just under that 75% mark, but when you go to the flood then it's drawing less power, so the voltage under load rises just that tiny bit more so that it's above the 75% mark.

If you're going from spot to spot and flood... I dunno then. :shrug:

gcbryan said:

This is just a curiosity question (as opposed to an important one ) but what is a possible explanation for my battery indicator operating as follows?

My BD Storm has a battery indicator. After the battery capacity drops below 75% it changes from a green indicator light to an orange one (and then to a red one at 25% and below).

When I turn the spot beam on the indicator light is now orange (was green until recently) however when I turn the flood beam on it is still showing green.

What does the mode the headlamp is in have to do with battery capacity?

Click to expand...

Not familiar with that particular headlamp, so this is an educated guess.

That indicator light indicates not battery capacity, but rather battery voltage.

Spot mode likely pulls more current than flood mode, causing battery voltage to sag more in spot mode than it sags when in flood mode.

You get the orange light in spot mode because the voltage sags below some arbitrary value that is built in to the comparator circuit that controls the indicator LED.

But flood mode doesn't pull the battery voltage below that arbitary value, so you still get the green light.

Battery voltage under load may be a useful thing to know, but its correlation with battery capacity isn't exact. Also, that correlation will vary greatly from one battery type to another.

Alakaline, lithium, NiMh all have different characteristics of battery voltage under load versus remaining battery capacity.

.

Good responses and I'm sure that's the answer. I did think about that and when I turned it on spot (and yes it's either spot or flood and not both) while the indicator light was still on I ramping the output all the way to low but the orange light was still on.

I guess the explanation for that could be that once the indicator light is triggered on start up it doesn't reread the voltage for the few seconds that it stays on.