Painfully boring technical question re. rear lights and rechargeable batteries

[presta]

In which case the lights would be fake.

So you're no longer

puzzled about that assumption the batteries are fine

then?

If the battery is lasting for 3-4 hours at 250mA, then that's a capacity of about 750-1000mAh, regardless of whether the load is a lamp or anything else, and regardless of whether it's faulty or not.

Note to those who are still insisting that the battery is faulty:
It's not possible to be precise about the exact battery life being obtained unless there's an equally precise measurement of the run time, and it's not possible to say whether the manufacturer's quoted capacity is being met unless the measurement's done under the load, temperature, and end point conditions specified by the manufacturer.

It should also be noted by anyone who wants to nit-pick about the exact capacity that the measurement will depend on whether you use a constant current, constant resistance, or constant power load, and that the lamp itself (faulty or otherwise) isn't necessarily any of these.

 

[albion]

I missed the battery draw quote. So now, obviously, it is thus the manufacturer of the light is fibbing, or the op has erred in the multimeter interpretation, or the lights are fake.

 

[fossyant]

I missed the battery draw quote. So now, obviously, it is thus the manufacturer of the light is fibbing, or the op has erred in the multimeter interpretation, or the lights are fake.

Or this thread is boring and pointless. Just charge the batteries more often.

 

[Ajax Bay]

Or this thread is boring and pointless. Just charge the batteries more often.

OP 'loves' their Moon Pulsar COB rear light which on highest brightness steady is advertised as 43 hours running time.
Runs on two AAA batteries and OP prefers rechargeable and can't bear the thought of inserting two 'normal' AAAs in and leaving the light on and seeing how long it runs for.
The fake Panasonic Eneloops pair he wibbles over only give 3-4 hours after they've been 'fully charged'. These are 'nearly new' but bought a year ago. The (fake) packaging (I shared) says "up to 950mAh" as opposed to proper Panasonic ones which are "900mAh".
I suggest these fake batteries are only taking a partial charge giving them "up to" XXXmAh. If the OP is getting only a tenth of the advertised run time (Moon is a reputable make and they'll be testing with Alkalines) then the fake battery capacity is maybe <200mAh.
Or Moon are overstating the run time a rider might typically get. That can be tested by: inserting two 'normal' AAAs in and leaving the light on and seeing how long it runs for. Asda get Which's recommendation for quality reliable AAAs: that's where I get mine.

However my tiny but powerful USB charged Sigma Nugget ii light takes the main strain and also has a wedge so it points horizontally when attached to the seat tube. That gives me 5+ hours (mix of low and flashing) which covers me unless it's an overnighter. If the latter, an hour on the power bank and rely on my other (or during a control stop) will see me through.

 

[albion]

Like me, you missed the multimeter test bit.
Fake lights might substitute the expensive LEDS for very inefficient cheap LEDS.

 

[Mike Ayling]

Or this thread is boring and pointless. Just charge the batteries more often.

Agree and agree.

 

[Ajax Bay]

After some time spent like a lobotimised monkey trying to pilot a spacecraft, . . . couple of current draw tests with the meter in series . . . . :
Mode 2 / 25lm: 0.25A / 250mA / 0.72W at 2.85v
So, if we consider the mode 2 figures as that's the setting the batteries were tested on, this suggests that over the 3hrs from fully charged that the light remained illuminated, it consumed 3x0.25= 0.75Ah or around 79% of the two cell's rated value of 950mAh each..?

I missed the battery draw quote. So now, obviously, it is thus the manufacturer of the light is fibbing, or the op has erred in the multimeter interpretation, or the lights are fake.

False product claim
OR
OP multimeter operation fail
OR
Fake lights @wafter where did you get the three you own from?

Or this thread is boring and pointless. Just charge the batteries more often.

Fossy - looks like you missed the bit in the OP: "anyone with the capacity [edit: and interest] to understand this stuff offer any thoughts please?" Incapacity?

Like me, you missed the multimeter test bit.
Fake lights might substitute the expensive LEDS for very inefficient cheap LEDS.

Thank you. If the OP's multimeter test was valid, the batteries, albeit clearly fakes, would seem to have about the capacity claimed "up to 950mAh).

 

[wafter]

Much thanks to those of you who sought to answer the questions I was asking - especially @presta 👍

Less thanks to those whose contributions helped make the thread somewhat akin to bobbing for anti-depressants in a pool of cold, lumpy cat sick..