Question about Maglites and Parasitic Drain?

[CobraMagnum]

Hello, everyone. I'll make this brief. Before I begin, I have two separate questions and, if possible, I would be appreciatie if someone would take time to answer each. Thanks in advance.

More than three years ago, I purchased a Maglite ML50L 611 Lumen LED flashlight, which requires 3 C-cell batteries. The light has seen moderate use, and it is primarily used on the medium and eco modes (at least recently).

Although the light functions very well and is in excellent condition from what I can tell, the last two times that I've had to replace the batteries, which I am estimating were about 6 months apart (between the first time and the second time), it seemed like I didn't receive anywhere near the runtime which is advertised for this light, which is 16 hours on high mode. Although it could be a misinterpretation of how long I've been using it, I don't think either time that I received even close to 16 hours of accumulated runtime.

Question 1) Could my Maglite be experiencing a parasitic drain issue, and if so, would that be causing sooner-than-expected battery replacement?

Question 2) When the Maglite is not in use, does it help to unscrew the tailcap, and if so, should I even take the batteries out of it completely? Or just unscrew the cap?

Hope you all have an excellent day!

 

[hsa]

It does have parasitic drain for sure and can be avoided by unscrewing the tail cap a quarter to half turn. After doing that make sure it doesn't come on when you press the switch. Also you should put a UCl lens in it from Flashlight lens.com. It is a really good flashlight. One of my favorites.

 

[bykfixer]

^^ What he said ^^
I loosen the tailcap with the light turned on and when it turns off the drain is halted.

 

[drewtiger13]

Hello, everyone. I'll make this brief. Before I begin, I have two separate questions and, if possible, I would be appreciatie if someone would take time to answer each. Thanks in advance.

More than three years ago, I purchased a Maglite ML50L 611 Lumen LED flashlight, which requires 3 C-cell batteries. The light has seen moderate use, and it is primarily used on the medium and eco modes (at least recently).

Although the light functions very well and is in excellent condition from what I can tell, the last two times that I've had to replace the batteries, which I am estimating were about 6 months apart (between the first time and the second time), it seemed like I didn't receive anywhere near the runtime which is advertised for this light, which is 16 hours on high mode. Although it could be a misinterpretation of how long I've been using it, I don't think either time that I received even close to 16 hours of accumulated runtime.

Question 1) Could my Maglite be experiencing a parasitic drain issue, and if so, would that be causing sooner-than-expected battery replacement?

Question 2) When the Maglite is not in use, does it help to unscrew the tailcap, and if so, should I even take the batteries out of it completely? Or just unscrew the cap?

Hope you all have an excellent day!

1. Possibly. What rechargeable batteries are you using? Have you tried a fresh set of rechargeable batteries? This should make clear if your problem is circuitry, batteries, or both. If it appears to be primarily the light rather than the batteries, be prepared to get a new light. The solid state components in modern lights are great in many ways, but often don't last as long as old school lights, and not as easily or cheap to repair. And a sudden increase in drain of the scale you describe is a certain sign of impending failure.
2. I wouldn't worry about the cap unless it's not lasting a single shift. Then I would do it only as long as it took to get a new flashlight

 

[CobraMagnum]

1. Possibly. What rechargeable batteries are you using? Have you tried a fresh set of rechargeable batteries? This should make clear if your problem is circuitry, batteries, or both. If it appears to be primarily the light rather than the batteries, be prepared to get a new light. The solid state components in modern lights are great in many ways, but often don't last as long as old school lights, and not as easily or cheap to repair. And a sudden increase in drain of the scale you describe is a certain sign of impending failure.
2. I wouldn't worry about the cap unless it's not lasting a single shift. Then I would do it only as long as it took to get a new flashlight

Let me first take the time to thank you for your response. It's appreciated. However, just to clarify: the Maglite ML50L that I'm using is a 3 C-cell flashlight. It does not use rechargeable batteries. I made that clear in the initial post. It requires 3 standard C-cell batteries, not rechargeable. This light hasn't been used nearly enough to warrant any kind of impending failure, and Maglite is typically known for a reliable product, typically. I've only had to change the batteries 3 times, but for a long time it wasn't seeing any use whatsoever. I don't know what's typical for the runtime on lights like this. I just noticed that my perceived runtime didn't seem to be consistent with the advertising on the pacakage.

 

[Lynx_Arc]

If you are looking at the ANSI runtimes then you have to know that ANSI runtimes are not what you think they are.
Here in the forum before ANSI ratings were implemented most lights were measured down to 50% of the output for runtime, ANSI measures down to 10% which if a light isn't regulate or doesn't use rechargeables which tend to hold a higher steadier voltage then runtime will likely start out high and slowly dim to nothing. A light rated at 300 lumens may actually step down after awhile to 150 lumens or less then slowly over time drop to 30 lumens and the measurement is stopped. In other words a light that says 300 lumens and claims 10 hours runtime likely is going to have a lot of that under 150 lumens and you could find it running at 50 lumens for hours even before reaching 30.
One has to actually see runtime graphs or measure current at the rated output, looking at charts that tell the batteries capacity at that current draw and taking into account the capacity of the battery, estimate the runtime.
There are lights that are regulated, likely your alkaleak based light isn't.

 

[hsa]

@CobraMagnum, the ML50l does a very good job with the alkaline cells, it was designed to maximize the alkaline chemistry. If you follow the lockout procedure outlined above you will be happy with it's performance again. I use eneloop pros in eneloop aa to c adapters in mine and it works out just fine. There is nothing defective about your flashlight. Lots of flashlights have parasitic drain. It is a shame that it is like that but it often comes with 'e' switches.

 

[bykfixer]

There are lights that are regulated, likely your alkaleak based light isn't.

Just curious:
Why did you say that?

 

[Poppy]

Just curious:
Why did you say that?

I can't answer for him, but my thought was the same.
Maglites have historically had long runtimes based on the use of alkaline cells, and that they drop voltage very rapidly. The lower the voltage, the less the LED pulls in Amperes, and the longer that battery can produce current. The problem is that the lower the voltage, the lower the output of the LED in lumens. So as an example:

The Cree XPL2 LED requires a little over an amp to get to 611 lumens.
a "C" cell can't supply a full amp for more than 3 hours.
See HKJ's chart.

Test of Panasonic Pro Power C

Follow the blue line in the graph for 1 amp

If one wants to get 16 hours from a "C" cell battery, he needs to pull less than 0.1 amp because it can only run for about 9 hours at 0.1 amp... see the cart below

If you look at the chart below, taken from the Cree XPL2 datasheet

https://cree-led.com/media/documents/dsxpl2.pdf

You can see that at about 0.1 amp, the LED will put out less than 10% of it's 1 amp output which is about 420 lumens and that equates to about 42 lumens output.

In the FAQ for this light

ML50L LED 3-Cell C

Are you looking for a dependable flashlight you can rely on during work, camping, or emergencies? Look no further than the ML50L C-Cell LED. This flashlight boasts an Eco mode that allows up to 184 hours of usage time, making it an excellent choice for extended periods of use. Its "Quick-Click"...

maglite.com

They make this statement:
All of our published ANSI-standard performance data (Light Output, Beam Distance, Peak Beam Candlepower and Run Time) are based on testing with alkaline batteries; and when we ship these flashlights with batteries, the batteries we include with them are alkaline. We do this because the designs of these flashlights are optimized for use with (non-rechargeable) alkaline batteries.

Alkaline AAA, AA, C and D batteries standardly have a nominal output of 1.5 volts. NiMH rechargeable batteries in these sizes typically have a somewhat lower nominal output (1.2 volts). Also, the discharge curves of NiMH batteries typically differ from those of alkaline batteries – so the two battery types may behave differently under load.

Since alkalines start at a higher voltage they will give a higher lumen output than NIMH cells, BUT since they drop voltage rather quickly, that increased output is short lived. The discharge curve for NIMH cells is much flatter under load, so once the alkaline cell's voltage drops below the 1.2 volts of the NIMH cell, the NIMH will maintain a higher voltage and higher LED lumen output until it is nearly completely depleted. Remember that at a higher voltage the LED will draw more amperage, and the higher the amperage drain, the more rapidly the battery will become depleted.

So in short, in an unregulated light, the lumen output will follow the discharge curve of the battery. A "C" cell does not have the capacity to deliver 611 lumens, but for a short period of time, and to get within ANSI specs for 16 hours, many of those hours would be under 100 lumens.

 

[Lynx_Arc]

I think Poppy hit the nail on the head. Alkaleak based lights often use the high internal resistance of the chemistry to throttle output such that often unusefully long runtimes are achieved. It wasn't as bad in the past when LEDs couldn't handle high enough currents to load batteries down more than they could handle but now we have lights that can for a short time put out a lot of lumens and too often manufacturers are listing this short term new battery output on their lights. We see lights that are insanely bright for a few minutes then fall off output like a brick in a deep puddle and a light possibly claiming to be 500 lumens spends most of its run time like Poppy said around or below 100 lumens. Since the advent of LEDs that can take even 2-3 amps of current for awhile alkaleaks are definitely unable to handle this need for but a short initial burst. If the burst is long enough to suffice for the (lousy thought about) ANSI ratings it can sucker people into thinking that the light is going to actually be a light saber for a long time instead of a blinding light that fades quickly into a candle.

We even have light makers do similarly with rechargeables. They list their lights as having a very high output and the turbo modes as they are called are unsastainable for most lights they likely either are throttle back by a timer or by a temperature sensor or the battery itself caves under the extreme power requirements.

I almost always try to find reviews that show runtime graphs as they are about the only thing that you can get reality about lights these days. Even lights that are using lithium ion do drop output under high current loads and the way they drop current varies greatly and it can be dramatic and unexpected. In other words don't blindly trust manufacturers to tell you what you think is the truth too often they are interested in selling you something. Personally I think only the lowest mode on a light should dim to nothing the rest should be regulated.

 

[xxo]

Interesting information. The only thing I don't understand is why Mag puts these (3 cell):



or these (2 cell):



in direct drive lights?



pics and vid credits - Old Lumens (RIP).

 

[Poppy]

I don't know if they are direct drive or not. I couldn't find any output/time graphs either.
Nor do I know enough about electronics to recognize items in the pictures you posted above. The two cell light might have a higher output, but again shorter run time if there is a boost circuit. On the other hand, the 3 cell light might have a longer runtime at lower output if there is a buck driver in it.

At any rate, those components that you pictured above are in the least necessary so that either light can accomodate:

• Multi-mode electronic switch allowing the user to quickly toggle between the five available modes

 

[bykfixer]

Yay! Charts and graphs.

Maglite ML products are thermal regulated to step down to either 75% or 50% depending on the model after 12 to 15 minutes, again depending on the model. After that a power save mode begins a slow decline if using alkaline cells due to the nature of said alkaline. In the case of using NIMH fuel they hold pretty steady at the 50-75% until the voltage drops to below a minimum point and at that point output drops fairly quickly. Again based on the characteristics of the battery.

You can find an old review by Robyn on the ML100, which uses the same or similar regulation circuitry as the 25, 50, 125, 150, and 300.

Maglite typically builds the 2 cell versions to hold regulations better while sacrificing the runtime and 3 cell tend to draw down the battery slower for increased runtime.

All ML products use an electronic switch. Maglite changed how they anodize the tail end of ML products to allow the user to cut the circuit between uses. In the case of the ML25 it can also be used as the on/off switch or hi/lo (in the 2 cell gen 2) instead of the front end.

 

[Lynx_Arc]

Likely the 2 cell circuit is a boost circuit as I see what looks like an inductor in the upper left corner. The 3 cell I don't see an inductor it may just be a linear regulator and with digital switching and thermal sensing you need a circuit board.

 

[xxo]

Yay! Charts and graphs.

Maglite ML products are thermal regulated to step down to either 75% or 50% depending on the model after 12 to 15 minutes, again depending on the model. After that a power save mode begins a slow decline if using alkaline cells due to the nature of said alkaline. In the case of using NIMH fuel they hold pretty steady at the 50-75% until the voltage drops to below a minimum point and at that point output drops fairly quickly. Again based on the characteristics of the battery.

You can find an old review by Robyn on the ML100, which uses the same or similar regulation circuitry as the 25, 50, 125, 150, and 300.

Maglite typically builds the 2 cell versions to hold regulations better while sacrificing the runtime and 3 cell tend to draw down the battery slower for increased runtime.

All ML products use an electronic switch. Maglite changed how they anodize the tail end of ML products to allow the user to cut the circuit between uses. In the case of the ML25 it can also be used as the on/off switch or hi/lo (in the 2 cell gen 2) instead of the front end.

Here's Robbin's review of the ML125 -

Maglite ML125 Rechargeable LED Flashlight Review - LED-Resource

www.led-resource.com

running on NiMH it has a timed step down to about 75% (with some fluctuation, likely due to thermal regulation) and stays at this level until the battery is dead at about the 5 hour mark. Alkalines can't keep up and drop out of regulation almost from the start, but don't hit the 10% level until around 24 hrs. of run time.

Bottom line - if you want the highest output in high mode you need to run NiMH's ( or Li-ions), though total run time to 10% will be less than alkalines.

 

[vicv]

Besides what else has been mentioned, it depends on your use. When have you ever used your flashlight by turning it on and leaving it until he batteries die. You use it 5minutes here. 3 minutes there. And so you're not taking that times stepped down and the light it always coming on full power as long as the batteries can support it. So you'll never get the marketed runtime as it's more often brighter if I'm getting it across properly.
These lights do have some parasitic drain but it's not that bad. You can cut it off though if you want.
Also to the op, you seemed upset people didn't understand you were using alkaline. Just because the light is designed for alkalines doesn't mean you're using them. I have the same light and I'm using AA recharables in C adapters. Can also use AA lithium's in those adapters. Or C sized recharables. So asking what rechargeable cells you were using was a reasonable question. Especially as alkaline batteries are terrible in every known way except as a throwing weapon