Question

This is probably a really stupid question but I am new to flashlights and Google does not produce an answer...
I am familiar with overall run time/output charts and how the light output drops if the light is constantly on due to heat.. But my question is, if my battery level is, say, low to medium, would I still be able to get full lumen brightness if I needed to use it? Or would my output be similar to the line I see on the charts? For example, if I have a 500 lumen light and I've used my light over a period of a few weeks so it's about 50% full, would my initial lumen output be 500 lumens when I turned it on? Or would I only be able to get 200ish?
Thanks for bearing with me, I appreciate any help!

it will depend on the light and how it is driven. Some will have perfect regulation where the output is flat until the battery is near exhausted. Others will have declining output.

The best thing to google for is "selfbuilt".

As stated, how it is (or isn't) regulated makes a big difference, as does battery chemistry. Alkaline batteries will not likely produce high outputs for very long, whereas ni-mh and lithium based batteries will provide more power at higher current levels, keeping your lights brighter for longer.

Also keep in mind that many lights have a High or Turbo mode. Due to heat, these are often timed. Example: A manufacture may advertise a light as 1000 lumen on High or Turbo and 300 on medium. That High/Turbo may only be for a preprogrammed time. Some are are 30 seconds, others 90 seconds or so. These times can vary wildly by lights. However, after the said time, the light will automatically step down to a lower output. This of course is different with all lights. This is all designed to protect from heat damage to led or electronics.

A few manufactures make lights that can run on High or Turbo until the cell is depleted. Or some custom lights are direct drive.

So to summarize, when you look at lights and read X amount of lumen on High or Turbo, always ask: For how long? This step down feature can obviously have a impact on how long your battery (or led lol) will last.

You may have already known all this, but it is a great question you posted and others who find this thread may no already know. Just wanted to give you more food for thought.

Welcome to the forum.

Thanks for the great feedback! Lots of good info. So would the amount of lumens I would be able to get follow those runtime/output charts? I was assuming that the only reason the output dropped was due to heat build up. If my batteries are not brand new, like half or less full, and I needed full lumens for a minute or so, would most lights give that to me?
Also, if it depends on the light and how it's designed, what information should I look for to tell me that? I have been looking at surefire and fenix lights but have only looked at the charts that tell me what they do if left on high continuously, and haven't found anything about being turned on high with a lower battery.

MattyT said:

Thanks for the great feedback! .... If my batteries are not brand new, like half or less full, and I needed full lumens for a minute or so, would most lights give that to me?
Also, if it depends on the light and how it's designed, what information should I look for to tell me that? ....

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Yes, it does depend on the light and how it's designed.

The information you want is called "regulation" ... eg, flat regulation, stepped regulation, semi-regulated, direct drive (unregulated) , etc, etc.

It is not always readily available information, however, but is occasionally discussed in these forums.

For being turned on High with a low battery: Many lights have what is called regulation. The electronics (driver) keeps the light output constant until the battery reaches a predefined threshold. So "basically" you have a High output until battery gets to a certain point. Then the light will either shut off completely, start blinking, or step down to the lowest level. The Surefire will drop down to the low mode. Thus giving you enough light to finish up with or whatever.

Going a step further. If you were to put a weak cell in a SF light it would likely only turn on in a low output. Or go high for just a blink of a eye, then stay in low.

That help you any?

That was great help! I will look for more info on regulation. So basically it sounds like surefire lights would give me a long time to access momentary high mode, until the batteries get really low, then it will be obvious that they need changing? As in a quick drop down to empty? Instead of high only with fresh batteries, and mid lumen output for most of the battery life cycle

Be sure to check out EagleTac and ArmyTek lights. Pretty sure MOST of there lights run 100% until the battery gets weak then they step down. This is assuming the lights are getting adequate ventilation, either by air or if you are holding them. They do have protection built in for excessive heat. I say if you are holding them, because when you do, your hand actually helps cool the light down.

Fenix, enough said.

MattyT. I have seen this question other places. Seems like we tun in the same circles. Just wanted to say Hello.

Eagle

MattyT said:

That was great help! I will look for more info on regulation. So basically it sounds like surefire lights would give me a long time to access momentary high mode, until the batteries get really low, then it will be obvious that they need changing? As in a quick drop down to empty? Instead of high only with fresh batteries, and mid lumen output for most of the battery life cycle

Click to expand...

It may be useful to get some runtime charts in here. Below are two from Selfbuilt's review of the Zebralight SC5. That might not be a flashlight that interests you, but the charts serve well to demonstrate what is being discussed here.

selfbuilt said:

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In the first chart, focus on the magenta lines. Those show the step-downs used by the Zebralight. Notice how you get plenty of runtime on the lower levels. Except for the first few minutes on H1, the Zebralight features flat regulation when running on standard Eneloops.

The other flashlights shown in the chart also do well on Eneloops. For the most part, they stay flat until the batteries run low. After that output tails off in a direct-drive-like pattern. This means those flashlights will dim slowly. If you notice that, there is no problem of getting stuck without a light. Unfortunately, it may take a while for you to notice the dimming.

I can tell you from experience, the step-downs used by Zebralight are jarring. You cannot fail to notice them.

selfbuilt said:

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The Zebralight holds its flat regulation on alkaline, albeit, with very little runtime on high. A couple of the other flashlights do okay. All the rest fall into direct-drive almost immediately.

WarRaven said:

Fenix, enough said.

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Fenix flashlights frequently feature some of the best regulation in the business: flat, with stair-case-like step-downs. Other models are flat with a nice direct-drive tail. I have read comments by Selfbuilt saying that Fenix drivers are typically very efficient.

(How are we doing for alliteration? :ironic: Okay, not so well. What's our score on tongue twisters? :shakehead)

Not many missed there KIL, that was hard to say in my head lol.

Thanks KeepingItLight! I've seen those charts and he does amazing work! So would that chart show my where my output would be at any point in the life cycle? If I wanted high with batteries that weren't fresh would I only be on one of the stair steps? Or does that chart only apply for leaving the light on high until the battery dies?

MattyT said:

So would that chart show my where my output would be at any point in the life cycle? If I wanted high with batteries that weren't fresh would I only be on one of the stair steps? Or does that chart only apply for leaving the light on high until the battery dies?

Click to expand...

Pretty much the former. The chart shows where output would be at any point in the life cycle.

When you power off, and allow your battery to rest, it can recover some of its voltage. When you turn your flashlight back on, therefore, you may get the higher output again (briefly), depending exactly how depleted your battery is. But that won't last for long.

Ok thanks that is very helpful! So basically each light is different and I could probably find one with a chart that shows a longer time in high mode before stepping down, if I wanted? I remember seeing a chart a couple days ago on a light, a surefire fury I believe, that had about 45 minutes on or near high lumens before making a gradual downward decline. Sounds like that might be something I'm looking for. I had no idea lights were so different and detailed! Love it!

MattyT said:

Ok thanks that is very helpful! So basically each light is different and I could probably find one with a chart that shows a longer time in high mode before stepping down, if I wanted? I remember seeing a chart a couple days ago on a light, a surefire fury I believe, that had about 45 minutes on or near high lumens before making a gradual downward decline. Sounds like that might be something I'm looking for. I had no idea lights were so different and detailed! Love it!

Click to expand...

You got it! Runtime charts reveal quite a lot about a flashlight.

Perhaps it is time for you to start a thread in the Recommend Me a Light For... forum. If you do, be sure to describe the ways you plan to use your light. Explain what you are trying to see. It's amazing how many knowledgeable people there are around here.

Enjoy!

Ok great thanks KeepingItLight! I really appreciate your help and patience!