Rechargeable Batteries Suck.

[Empath]

Power is expressed as volts times amps, or watts. The work done in any circuit is dependent on the power. The alkaline has the higher voltage, but the amperage at any instant is less than what the rechargeable can produce. When the alkaline is required to deliver more amps than it can deliver in a particular instant, you get a voltage drop from the alkaline cell. The rechargeable, while lower in voltage, delivers a higher current, or amperage, without the associated voltage drop. Powerwise, or in terms of watts, it has more capability at any particular instant.

Basically, the rechargeable can deliver it's power very quickly. The alkaline, while delivering more total power, does so a little at a time.

If a circuit doesn't require much current, but does require voltage, alkaline is fine. When the circuit requires high current, the rechargeable excells.

 

[JonSidneyB]

Thanks for that informative post.

 

[raggie33]

i understand now. i was always wondering how it worked

 

[Cougar_Allen]

The problem with the claims the manufacturers of alkaline batteries make is they are based on tests at LOW current draw. In a device that draws little current they will perform as advertised, but in a device that draws a lot of current (which includes some flashlights) performance is much worse than those advertising claims -- worse than rechargeables in every way. Even the voltage claim doesn't hold up under high current drain -- it'll drop way below 1.5 volts, below 1.2 volts in the first few seconds, and in a really high current application like a digital camera (or some modified flashlights) it'll soon drop so low it can't run the device at all.

"Shouldn't the size of the battery be more proprtionate to it's capacity??"

It would be, if they were all the same on the inside and the only difference were the size....

Re brands, if one brand were just plain better than the others, nobody would buy the others and they would go broke.

 

[Cougar_Allen]

Ya gotta type fast if you want to be the first to answer a question around here! /ubbthreads/images/graemlins/smile.gif

 

[asdalton]

As you draw more and more current from a battery, an increasing fraction of the battery's power is dissipated within the battery itself due to internal resistance, rather than being expended within the circuit. (However, the same amount of current goes through everything.) The practical consequence is that the battery heats up, and this heat is wasted energy.

This problem occurs in all batteries, but it is a worse problem in alkaline batteries than in NiCd or NiMH. For high current drains, a lower-capacity rechargeable battery can deliver more energy to the circuit than an alkaline battery can, even though the alkaline battery might release more energy. Much of the alkaline battery's energy is spent in heating itself up.

 

[gwbaltzell]

One of the simplest solutions is to use a bulb (lamp) for a 4 cell flashlight (torch for our British friends) in a 5 cell flashlight. Always kind of assumed this is why 5 cell flashlights existed! Voltage range becomes close.
New primary cells 4 * 1.55V = 6.2V
Charged secondary cell 5 * 1.35V = 6.25V
"Dead" primary cells 4 * 1.1V = 4.4V
Discharged secondary 5 * 0.9V = 4.5V

Notice that most bulbs design voltage is near the end of battery life, they are almost always overdriven and rated life means little.

See page 13 of pdf format catalog under "B-3 1/2 Bulb" for the ratings of many common bulbs. BTW, 4 F cells means the common 6V lantern battery.

As for "self life sucks", if you're not using the light every week then rechargeables are likely not the right choice.

 

[paulr]

Rechargeable consumer C cells have the same capacity as consumer D cells because they both have the same small sub-C battery inside. If you want a full capacity C or D cell, you have to get it from a specialty dealer. You can tell the difference immediately because a professional NiMH D cell weighs about 2x as much as a consumer one--and has over 3x the capacity.

 

[qarawol]

I have also disassembled consumer 'cheapy' rechargeable C cells and they contained a rechargeable 'AA' cell. It even used the same + tip for they are the same lenght.

As 'Empath' stated clearly... "a primary cell is manufactured as a means of producing electricity. Rechargeable cells are manufactured as a means of storing electricity".

All the Flashlights I use regularly, I use only rechargeables. They never really have time to sit.

During the daytime on the weekends, I carry a lithium battery powered Flashlight.

Enjoy...

 

[LEDite]

Re: Rechargeable Lithium-Ion Batteries

I use rechargable lithium-ion batteries in all my homebuilt UV & white lights.

They output 4.2 volts and hold their charge much better than Nicads or NiMh types. Watt density is better also.

You do have to charge them correctly, however.

 

[CM]

Re: Rechargeable Lithium-Ion Batteries

I have gone away from NiMH for the most part and have migrated to Li-Ions for my regulated 123 based lights. High performance lights use Lithiums and the conversion is rather simple for many lights. Charge retention is excellent, energy density is unequalled by NiMH. So you might want to reconsider your statement that rechargeables in general suck. Try the Pila's and you may change your mind.

CM

 

[greenLED]

You'll see some long-term savings if you use rechargeables! They're also relatively more friendly on the environment than regular cells (because they're not disposed as often). But again, it all depends on your application.

 

[paulr]

I've had some alkalines leak too. It seems to me that AAA's leak the most. I think I've seen AA's leak. I don't remember ever seeing C's or D's leak. Hot weather may also cause leakage. Most alkaline manufacturers will repair or replace anything damaged by leaking cells, but generally I've found I can just scrub off any leaked gunk and the item is fine.

Rechargeables are worth it if you use the item a lot. Running a cellular phone on alkalines and having to throw away another set of them every couple days would be ridiculous. It's the same way with police flashlights, which are used for several hours every single night. They get recharged every day and so shelf life is irrelevant. For an item that you leave in storage or only use once in a while, rechargeables don't really help that much and shelf life becomes an issue.

However, I do find that NiMH holds its charge (or say at least 50% of its charge) for at least 3 months. It's not like if you set the item on the shelf for 1 week, the batteries will be dead. So I have NiMH cells in my 2aa minimag, my GPS, etc., and charge them up when they need it. For long-term emergency lights, lithium is your best bet.

 

[Sub_Umbra]

[ QUOTE ]
paulr:
Rechargeable consumer C cells have the same capacity as consumer D cells because they both have the same small sub-C battery inside. If you want a full capacity C or D cell, you have to get it from a specialty dealer.

[/ QUOTE ]

Emphasis mine

That's wild. Do you have a link to one with full capacity C/D cells so I could look around?

Thanks

 

[Kiessling]

yeah ... rechargeables are for weenies /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/evilgrin07.gif /ubbthreads/images/graemlins/tongue.gif
finally someone found the courage to post it /ubbthreads/images/graemlins/smile.gif
and I will crawl back under my small rock now ... /ubbthreads/images/graemlins/wink.gif
bernhard

 

[SilverFox]

Hello Bernhard,

I think you need to find a larger rock to crawl under... and stay there!!!

I think rechargeable batteries are great.

Tom

 

[Kiessling]

/ubbthreads/images/graemlins/grin.gif
hotbeam tried to convert me and failed.
Charlie too.
I just do not like'em. I do not have the time nor the nerve to care for my batteries. My light needs to be ready when I need it. And once empty, battereis are disposed and not carried with me like empty rechargables. I do not want to worry about possible Li-Ion explosions. I do not want to worry about chargers, melting things and such.
Yeah ... did I say I do not like rechargeables? /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

... looking for a huge rock now ... /ubbthreads/images/graemlins/tongue.gif

bernhard

 

[BuddTX]

I am very new to rechargables (I do not own a set yet).

For years, the 1.2 volts of rechargables vs the 1.5 volts for alkalines, had me fooled. I always said that I could afford alkaline batteries, and they give .3 volts more, per battery than rechargables, right?

Well, I am just finding out, that alkaline batteries have a very high resistance to them, whereas the rechargables have a very low resistance.

this means, that in a multiple battery configuration, your effective TOTAL volts should be actuall HIGHER with the rechargables, than with the alkalines.

Also, rechargables are better for high drain devices.

But you are right, shelf life sucks. I think I read somewhere that it was 5% loss per week on rechargables.

People in the know, please correct any information that I have given that might be less than accurate.

 

[CM]

Explosions? What explosions? If you take reasonable care of them, the risk is nil. I use my battery powered toys A LOT and for me, it makes sense to use rechargeables. True, disposables are ready to go but you always have to have spares since the one in your light may have only 10% left in them (you can't keep them "topped off"). I rotate my rechargeables so that the one in the pipe is always backed up by a spare and the one in the pipe always gets topped off so that both sets are almost always 100% ready to go. Primary lithiums are relagated to backup emergency.

 

[SilverFox]

Hello BuddTX,

Here is a chart that should help you understand the self discharge concept. This represents a 1% self discharge rate. My cells are less than that at about 0.66%. I have been using my cells for a little over a year now. I believe it is possible to have an increase in the self discharge rate as the cell ages. I do not have numbers to go with that, but the advertised rate is usually given between 1%-1.5%.

You can see that in 70 days they are at 50% capacity, and drop to 25% in 139 days. As long as you remember to recharge them every 6 months or so, you should not have problems.

Tom