anyone try this with a phone

[garman]

My cordless phone is about 4 years old maybe older. Battery failed I opened the casing around the battery and found 3 AA NiCad batteries. I decided to use NiMh batteries instead. After soldering all three together in series and sealing the battery case with tape. I plugged the new battery to my phone. Works, makes sense battery still has a charge. Drained battery and recharged overnight, no leaks. Turned my phone on. Worked like a charm.
My ??? is, will this damage the battery/charger in the long run, since I am using a NiCad charger for NiMh batteries.
Right now I am testing to see how long the talk time and standy time has increase/decreased. My old NiCads were 3.6v/800mAh and the new NiMh are 3.6v/1400mAh. -cheers

[Capmaster]

NiCd batteries were bad for having a memory effect. Unless you discharged it all the way before recharging it, it would remember that spot and would lose capacity after a while, only discharging to thqt same point the next time. MiMH batteries are basically the same, but environmentally friendlier because they have no cadmium. They also don't have as much of a memory for charge. Both perform better when they're charged at a constant current for the amount of time that's figured by Time=(MA-H/charge current)*1.333 approx. The charging current is usually 1 to 10% of the mA-H rating. For example, if it's rated 1400 mA-H, you usually charge with from 14 to 140 mA for the amount of time from the formula.

Neither battery likes to be float-charged like a car battery. On the other hand, lithium-ion batteries prefer to be float-charged, like lead-acid batteries. They prefer to be charged using constant-voltage or a pulsating voltage, instead of constant-current, like NiCd or NiMH.

Bottom line: the NiMH batteries are so similar to NiCd, they should actually work better in the same application, provided that they're being charged at a high enough rate. But damage usually occurs when the charging rate is higher than the rating, not lower. Since your NiCd batteries were 800 mA-H and the NiMH are 1400, chances are the charging rate is on the low side for the batteries. The charger was designed for NiCd after all. Being on the low side should help prolong the life.

I think they'll work fine and probably outlast NiCd batteries

[garman]

Why bother go to batteryuniversity.com when I could just plug you for info. Thanks. About lithium ion/polymer My only gripe, I do believe the have a shelf life of 5 years. The day they come out of the manufacturer is they day they start ticking away like a time bomb. No matter how well you take care of them they will eventually kick the bucket around the five year life span. Not sure if this was done by design or just the way the technology evolved. Me personally, I believe that manufactures design things to last a certain time and then puff it dies time to buy a new one. Just like todays cars, tv's whatever. No corporation likes to have anything last for long periods of time. NO FUTURE PROFIT! A movie called something like "TUCKER" anyway watch it you'll get my point. -garman

[Capmaster]

Why bother go to batteryuniversity.com when I could just plug you for info. Thanks. About lithium ion/polymer My only gripe, I do believe the have a shelf life of 5 years. The day they come out of the manufacturer is they day they start ticking away like a time bomb. No matter how well you take care of them they will eventually kick the bucket around the five year life span. Not sure if this was done by design or just the way the technology evolved. Me personally, I believe that manufactures design things to last a certain time and then puff it dies time to buy a new one. Just like todays cars, tv's whatever. No corporation likes to have anything last for long periods of time. NO FUTURE PROFIT! A movie called something like "TUCKER" anyway watch it you'll get my point. -garman

Sorry. It was on the wordy side. This is too, but it explains my interest in battery technology.

I had to become an instant expert on batteries for a project at work years ago. I worked in the B61-7 SIP Division. I work for a DOE weapons lab.

I was tasked to design a self-powered device that was to ride in the tail of a B61 bomb for an upcoming rocket-sled test. The test would cost about $100,000 so there was no option for the device failing

The device would be an in-between timer to add delay to the B61 after the release from the rocket sled. It had to store energy from the bomb's thermal batteries and apply it to its own thermal batteries. The power source had to retain a programmed time, and fire the thermal batteries at the precise time so the bomb wouldn't go sailing into the Isleta Indian Reservation , and if all went well the parachute would deploy and the bomb would land on a 120ft by 120 ft concrete pad. If it missed the pad and landed in the dirt the test would be a waste since it was meant to simulate low-alt release and landing on a hard surface. The bomb would be traveling in excess of mach 1.

It absolutely could not lose the program for hours of power-on time. The available volume was very limited too. The enclosure was predetermined in shape and weight limit. The added handicap was that it had to operate at -65 degrees F since it was a cold test

I researched all the current batteries available, as well as some experimental batteries being developed by my company. NiCd and NiMH batteries were among the 20 or 30 types I was considering at first.

The cold ruled out an aqueous electrolyte. That ruled out Lithium Thionyl Chloride. Rechargeables were eliminated because there were none with a high enough power density. I ended up using Lithium-Sulfur-Dioxide batteries - an exotic with a huge power density. The downside - if shorted out they tended to explode and burn.

I spent weeks characterizing the battery discharge profiles at varying loads at various temperatures. That's what sold me on the LiSO2 batteries.

I encapsulated the assembly in polyurethane foam, about 10 lb/ cu ft. I actually built a backup unit too, and designed and built a ground controller for programming it.

Another concern was the fact that since I was using CMOS for the logic circuitry, I had to worry about induced voltages. The rocket sled travels so fast along the track, any residual magnetism in the tracks could induce voltages.

Also, the earth's magnetic lines could also induce voltages, causing errors. So I ended up completely surrounding it with a .040" mu-metal shield inside the aluminum enclosure.

It worked like a charm. The bomb landed about 10 feet shy of center and slid the length of the pad. Perfect!

The next morning I came into my office and on the blackboard were these huge block letters a fellow engineer had written but hadn't signed:

"Kevin - 1
Dragons - 0"



That was a very good day

[garman]

Need to remind myself to drain you for info on batteries. Now that I know, how long do think the auto industry will start mass producing cars that can drive for long periods without recharging and make them cost friendly. I just bought a car 2 years ago, and I normally keep them for 10 years. Do you think they'll be ready to go. -garman

[pacmania_2001]

My cat's breath smells like cat food.

[Tool Man]

My cat's breath smells like cat food.

Beautifull

[smearbrick1]

I work for a DOE weapons lab.

Department of Education weapons lab?

[yoda313]

I work for a DOE weapons lab.

Department of Education weapons lab?

Hello,

Yeah! Wear do you think the teachers get those chalk missiles???

Kevin

[Doramius]

They already are in the works of mixing Hydogen gas to fuel mixtures to extend the gas mileage. It's been proven that it can store and dispense safely and is very inexpensive to create.

The downside with Combustion engines is you really can't make a powerful engine that won't break down over time using materials currently here on earth. It is known that an engine could be created to burn gas completely without requiring and exhaust. All gasses would burn completely and turn into energy. However, we can't create something to contain heat of that magnitude in something as small as a regular vehicle. You're basically creating a combustion close or identical to the sun. The next closest thing is nuclear. However, nuclear would not be combustion. It would be a reactive current of electricity. Electric cars are heavy (and most current ones are extremely expensive to have maintenence). I'm also not sure about stability if the vehicle ever was in a severe accident.

We can create vehicles that can last a long time though. Many car maufacturers are starting to find out that people will still buy new cars, regardless of wether their previous one will last 30-50 years. Some people like the newer styles and want different power capabilities. I think the ideal for most people is to have a basic engine and frame that is extremely durable, and be able to go someplace and have a new body, or various options added, changed, or removed.

[sacajaweeda]

I have an old cordless phone (one of the really old ones with the extending metal antennae that looks like one of those old handy-talkie things from WWII). It has this really peculiar thing that it does, which is it's saving grace and the only reason I still own it. If you plug everything in - base, phone line, etc - then turn on the handset and unplug the power cord from the base unit, the dial tone goes away, but if anybody is using a cordless phone in about a two block radius I can pick it up on my handset. I can scan with the channel button and find several different convos going at any given time, and it's really wierd because I can hear the people on the phone just as clear as if I called them (well, them and whoever they are talking to) but they can't hear me at all.

[Cobra]

Is there not a law against that?

Makes me glad I'm on a much more secure DECT system...

[sacajaweeda]

I'm sure there probably is.

[sacajaweeda]

I've got a CB radio that can do neat stuff, too.

[Doramius]

It's obviously picking up analog cellular signals. Digital is encoded so you can't do that. I'm surprised people are still using analog Cells.

[Capmaster]

I work for a DOE weapons lab.

Department of Education weapons lab?

Yes. We're using nukes on the kids now. It's just part of our "Just Say Glow" program.

Do you think they'll be ready to go. -garman

Not as long as the oil lobby is as strong as it is :P

[Roundabout]

I've always wondered why they don't use LiIon batteries in cordless phones, so you don't have the memory effect problem. Never thought to ask when I was at Sony, but there must be a reason, maybe current or voltage problems?

All I know is, my cordless phone goes thru batteries fast, the NiCad batteries don't like being recharged when they're partially discharged. I keep telling my wife to wait till the battery is dead before putting it back on the base, but she always forgets... leading to more bad batteries.

Thank God, I laid in a supply of new ones before I left the company...

[Doramius]

My phone has NiMh. Do Lithium batteries Recharge? I just though they held constant power longer. I always liked Lithium batteries because they gave full power until they were totally dead, and they lasted a looong time.

[Dr. DOS]

Bottom line: the NiMH batteries are so similar to NiCd, they should actually work better in the same application, provided that they're being charged at a high enough rate. But damage usually occurs when the charging rate is higher than the rating, not lower. Since your NiCd batteries were 800 mA-H and the NiMH are 1400, chances are the charging rate is on the low side for the batteries. The charger was designed for NiCd after all. Being on the low side should help prolong the life.

I have a NiCD/NiMH charger at home for a set of NiMH batteries for my dig camera. On occassion rugrat #1 flips the switch on the charge to charge my MH's at a CD rate.... batteries charge fine and stay rather cool to the touch vs MH charging which is a little faster and the batteries then get smoking hot. So what Cap says makes sense...

[Roundabout]

My phone has NiMh. Do Lithium batteries Recharge? I just though they held constant power longer. I always liked Lithium batteries because they gave full power until they were totally dead, and they lasted a looong time.

Doramius,

Yeah, as far as I know, LiIon batteries do recharge. This is what is standard in cell phones. They last a long time and don't have any memory effect at all (that I'm aware of).

You might be thinking about Lithium (not LiIon) batteries that are used in some photo applications that are not rechargeable. Two different beasts.

I've looked around, but I can't seem to find any cordless phones that use LiIon batteries. Maybe I can modify my Nokia cell battery to work in my Sony cordless phone? I have to check the voltage, etc.

Maybe Cap can chime in, if he knows if it's possible to use this battery technology with the NiCad type recharger...I sure don't know.

[Capmaster]

My phone has NiMh. Do Lithium batteries Recharge? I just though they held constant power longer. I always liked Lithium batteries because they gave full power until they were totally dead, and they lasted a looong time.

Doramius,

Yeah, as far as I know, LiIon batteries do recharge. This is what is standard in cell phones. They last a long time and don't have any memory effect at all (that I'm aware of).

You might be thinking about Lithium (not LiIon) batteries that are used in some photo applications that are not rechargeable. Two different beasts.

I've looked around, but I can't seem to find any cordless phones that use LiIon batteries. Maybe I can modify my Nokia cell battery to work in my Sony cordless phone? I have to check the voltage, etc.

Maybe Cap can chime in, if he knows if it's possible to use this battery technology with the NiCad type recharger...I sure don't know.

The two systems aren't compatible. NiCd battery chargers, at least the decent ones, use constant current to charge. If the charge rate is ...say ...50 mA it'll maintain that current until the charge is done ...usually 14 - 16 hours if charged properly.

NiMH are similar. Their chemistry dictates a constant-current charge. Both NiCd and NiMH suffer memory effects, although NiMH is slightly better in this regard.

Lithium Ion is a high power density chemistry that utilizes a very reactive metal - lithium. Usually the more reactive the chemistry, the higher the power density ...like lead-acid, which uses sulfuric acid ...very reactive, and a decent energy density. Very good for high-current loads.

The nickel-based chemistries are also good for relatively high currents, but they have their drawbacks. The non-rechargeable lithium batteries are not as good for high currents, but have insanely high shelf lives and don't suffer from much self-discharge from their internal impedances and leakages, like many other battery types. That's why they're the choice for watches. They last years under low loads.

The reason is because internally, the cathode of the battery actually grows a protective layer over itself when current isn't being drawn. This makes the self-discharge impedance virtually infinite for all intents and purposes. The drawback is that when you start using it after it's been on the shelf for a while, there will be a voltage drop at the output for a period of minutes to hours depending on the current - higher current means less time that the voltage dips. This isn't a big issue for watches because they draw a tiny amount of current constantly ..with occasional higher currents needed for backlights and alarms.

The highly efficient lithium-ion battery chargers take advantage of a behavior of the chemistry that allows it to be quickly charged if you use a pulsating voltage without generating excessive internal heat - a battery killer. You can charge it with constant voltage or pulsating voltage.

You should not use a nickel-based battery charger for lithium-ion batteries. They try to maintain constant current regardless of the battery's voltage, and they will harm the battery by generating heat, and in turn cause internal warpage, with a severe drop in efficiency and a drop in internal impedance. The battery will self-discharge rapidly and it won't hold a charge. It'll be toast.

By the same token, don't ever use a lithium-ion-based charger on a NiCd battery. The currents will be excessive and will probably destroy the battery and the charger

Helpful facts: Non-rechargeable lithium batteries usually have a characteristic cell voltage of 3V. Lead acid is 2V. Zinc-carbon is 1.5V, alkaline is 1.6V, NiCd and NiMH are 1.2V. Batteries with multiple cells, like a 9V battery will be a multiple of cell voltages since they're in series. A 9V could be three 3V lithiums, or six 1.5V alkaline cells.

This concludes today's class: Batteries 102

[Doramius]

Someone told be you can add a capacitor, PnP transistor, and a resistor in a small circuit to make a conversion for certain rechargable batteries to be used in a NiMH charger (and not NiCd). I don't know what the parts ratings, but that probably varies depending on what the charge rating or battery type is. Do you know what I'm trying to explain Cap or have you heard of this?

[Roundabout]

Cap,

Wow. Thanks for the information. See, that's what I like about electronics - there's always more to learn. I know a lot about certain areas of electronics, since that's all I've done all my life, but I never researched battery technology. I'm a newbie when it comes to that. I'm aware of the different types of batteries and what they do, and I figured that it wouldn't be possible to interchange them, that's why I asked.

Maybe with some circuit modifications, it would be possible to make the charge circuit of the telephone base be compatible with the LiIon battery, but it sounds like more trouble than it's worth.

Maybe someone will make a cordless phone that uses that type of battery. Anyone know of any out there right now? I haven't been able to find any as yet. I think it would be nice, as the battery in my cordless seems to go dead all the time just when I need it. I know better than to put it on the base when it's halfway discharged, so I try to wait till it's pretty low on charge to recharge it. It would be a lot better if I could just recharge it anytime, just like the cell phone. You just start charging it when you want, you don't have to wait for it to go dead first.

I'll be sure to ask you when I want to know anything about batteries! You've obviously spent a lot of time on the subject