Author Topic: Favorite Fluorescent Tube  (Read 13040 times)
wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #60 on: August 29, 2016, 08:55:28 PM » Author: wattMaster
I was talking about Medved's Powerfull Mega POlice flsahlight

2..3W is sorta possible on a NiMH, consideing that thir short circuit current is 10A or more, so internal resistance low respectively. But its still no less of awfull to actually count on that in a product design. The battery would not last long at all with such abuse (as in lifetime till battery is destroyed, not till it needs charging)
And it becomes worse when you see that the flashlight got bundled with a free alkaline battery, which is asking for trouble. And don't forget that you can try it out in the store, too.
Logged

SLS! (Stop LED Streetlights!)

Ash
Member
*****
Offline

View Posts
View Gallery


Re: Favorite Fluorescent Tube « Reply #61 on: August 29, 2016, 09:04:27 PM » Author: Ash
The trouble in using an Alkaline battery there is a waste of battery. Some alkalines have impressively low internal resistance too when new, so might even power the flashlight at quite high power, but not for long at all
Logged
wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #62 on: August 29, 2016, 09:07:19 PM » Author: wattMaster
The trouble in using an Alkaline battery there is a waste of battery. Some alkalines have impressively low internal resistance too when new, so might even power the flashlight at quite high power, but not for long at all
I even did a test with a NiCd AA (got it from a garden light) and within just a couple of minutes, it was very dim.
Logged

SLS! (Stop LED Streetlights!)

Ash
Member
*****
Offline

View Posts
View Gallery


Re: Favorite Fluorescent Tube « Reply #63 on: August 29, 2016, 09:24:19 PM » Author: Ash
The NiCd's from garden lights are the cheapest batteries made, as the demands there are very basic - low capacity and low discharge current

It may come down tothe voltage drop over discharge characteristic for those batteries. While for digital cameras and the like, the effort in modern NiMH battery design is to make the voltage drop over discharge as flat as possible (stay same voltage till the end andthen sharply drop), the cheap batteries go down in voltage quite a lot as they discharge
Logged
wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #64 on: August 29, 2016, 09:36:56 PM » Author: wattMaster
The NiCd's from garden lights are the cheapest batteries made, as the demands there are very basic - low capacity and low discharge current

It may come down tothe voltage drop over discharge characteristic for those batteries. While for digital cameras and the like, the effort in modern NiMH battery design is to make the voltage drop over discharge as flat as possible (stay same voltage till the end andthen sharply drop), the cheap batteries go down in voltage quite a lot as they discharge
That seems to be the case for all NiMH batteries, not just good ones.
Logged

SLS! (Stop LED Streetlights!)

Ash
Member
*****
Offline

View Posts
View Gallery


Re: Favorite Fluorescent Tube « Reply #65 on: August 29, 2016, 09:43:36 PM » Author: Ash
This have always been a design goal, but the better NiMH's achieve it better. Many devices complain on low battery or switch off while the battery is still quite full when the discharge characteristic is not flat enough. I think it is cause those devices were designed with Alkalines in mind, that have 1.5V to begin with vs 1.2V
Logged
wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #66 on: August 29, 2016, 09:45:38 PM » Author: wattMaster
This have always been a design goal, but the better NiMH's achieve it better. Many devices complain on low battery or switch off while the battery is still quite full when the discharge characteristic is not flat enough. I think it is cause those devices were designed with Alkalines in mind, that have 1.5V to begin with vs 1.2V
I have never needed to deal with that because all of my cameras use Li-ion batteries.
Logged

SLS! (Stop LED Streetlights!)

Ash
Member
*****
Offline

View Posts
View Gallery


Re: Favorite Fluorescent Tube « Reply #67 on: August 29, 2016, 10:00:39 PM » Author: Ash
I do, cause i prefer a camera with AA's and not some proprietary battery format
Logged
wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #68 on: August 29, 2016, 10:05:24 PM » Author: wattMaster
I do, cause i prefer a camera with AA's and not some proprietary battery format
At least you can buy aftermarket spares. How do they work?
Logged

SLS! (Stop LED Streetlights!)

Ash
Member
*****
Offline

View Posts
View Gallery


Re: Favorite Fluorescent Tube « Reply #69 on: August 29, 2016, 10:30:54 PM » Author: Ash
The NiMH's with flat discharge characteristic - Sanyo Eneloop work great, the cheaper with flat discharge characteristic - GP Recyko work fair too, good for what they cost. Have few batteries around and in the charger and you are set for quite extensive photo activity

The conventional NiMH's reach very soon the "low battery" warning and not long after that the point where the camera would just switch off and not want to come on

Camera is old, but i dont depend on the manufacturer to get new batteries whenever i want, and the batteries are at reasonable price as AA's are
Logged
Medved
Member
*****
Offline

Gender: Male
View Posts
View Gallery

Re: Favorite Fluorescent Tube « Reply #70 on: August 30, 2016, 05:14:58 AM » Author: Medved
The MH's do not like high currents, it tends to increase their internal resistance.
3W means nearly 3A, even for good quality AA cells that means a lifetime barely few 10's of charging/discharging cycles.
Note, the "Low self-discharge" types are not that good at high current, you will need the "power tool" type of cells (different composition; but that means higher selfdischarge and lower rated capacity for the given size)

The "garden light" NiCd's do not work well not just because they are of low quality or so. Even a high quality "garden light" cells wiil perform very bad with high power applications. The reason is, the "garden light" cells have to be designed to mainly swallow a lot of overcharge at high temperature. That means they need a huge margin for gas recycling and that means low capacity (600mAh is really the maximum attainable for a good garden light grade AA). At the same time the separator and the exact chemical composition of the electrolyte are tailored for the every day full charge/discharge cycle, what means a higher selfdischarge and higher internal resistance as consequences. For a daily charged/discharged solar light that is still OK, but not much use for other purposes.
A few years back NiMH cells appeared for that use, but their capacity is the same as NiCd (no apacity gain towards the NiCd, as the cell size is dominated by the features needed for the overcharge robustness; so just they do not contain the toxic Cd). However I do not know their lifetime rating.
The "garden light" service, with 1000 cycles that means just 3 years of service. Yet given the abuse (frequent overcharge at high temperature), reaching that is quite a miracle - and there are many cells that do that.
Logged

No more selfballasted c***

wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #71 on: August 30, 2016, 09:54:46 AM » Author: wattMaster
And you don't want Li-ion garden light batteries because Li-ion always doesn't like overcharging and high temps.
I wonder how we got here, from talking about fluorescent tubes.
Logged

SLS! (Stop LED Streetlights!)

Medved
Member
*****
Offline

Gender: Male
View Posts
View Gallery

Re: Favorite Fluorescent Tube « Reply #72 on: August 30, 2016, 11:56:32 AM » Author: Medved
And you don't want Li-ion garden light batteries because Li-ion always doesn't like overcharging and high temps.

Because LiIons have very low voltage temperature coefficient and because the charging does not generate any heat, it is quite easy to prevent an overcharge by just limiting the voltage (4.2V/cell for maximum capacity, 3.9V/cell for longer life).

With the NiMh is very difficult to get the information about the real state of charge, as the voltage tends to go down with higher temperature and the charging generates heat. I've seen once Braun shaver from the half 90's used a voltage regulation with build in thermal slope, so the charger electronic compensated the battery temperature, but I haven't seen anything similar ever since (apparently it was adjusted for a given battery, as when I replaced it after the original died, it didn't worked that well anymore).


I wonder how we got here, from talking about fluorescent tubes.

Fluorecent tubes -> LED's -> LED flashlights -> batteries...
Anyway, very frequently I ask such question (about the drifting discussion topic) after few hours talking with friends in a pub, but very rarely I was able to get the whole chain. But in all cases such question rise a new wave of laugh and caused the discussion to drift even further... :-D
Logged

No more selfballasted c***

wattMaster
Member
*****
Offline

Gender: Male
View Posts
View Gallery


WWW
Re: Favorite Fluorescent Tube « Reply #73 on: August 30, 2016, 04:24:09 PM » Author: wattMaster
It also seems like this tendency to drift off topic is less common with photos.
Logged

SLS! (Stop LED Streetlights!)

Print 
© 2005-2024 Lighting-Gallery.net | SMF 2.0.19 | SMF © 2021, Simple Machines | Terms and Policies