Nimh batteries

Started by Eder in sci.electronics.basics11 years ago 1 reply

I have bought some AA Nimh batteries and find that they are vary slightly bigger than standard alkalines. I'm talking about a millimetre or two...

I have bought some AA Nimh batteries and find that they are vary slightly bigger than standard alkalines. I'm talking about a millimetre or two and not much more, but it's enough to make them an extremely tight fit in devices that have two batteries stacked on top of each other. I was wondering whether anyone could recommend to me Nimh batteries that that don't have this problem of being sli...


How hot should NiMH's get in the charger

Started by Bearded Occam in sci.electronics.basics10 years ago 4 replies

New subscriber here. I have a set of Sony AA size NiMH's that are the original batteries which came with the charger. Upon charging for a...

New subscriber here. I have a set of Sony AA size NiMH's that are the original batteries which came with the charger. Upon charging for a couple hours, they are almost too hot to hold in my hand. Normal? Safe? Advice? Second question: Is there any reason to fear using other brands of NiMH's in the same charger?


dead unused NiMH AA cells

Started by Adam Funk in sci.electronics.basics2 years ago 6 replies

I recently opened a pack of NiMH AAs that I'd had lying around for a while, & some of them wouldn't charge at all. I tried putting them in the...

I recently opened a pack of NiMH AAs that I'd had lying around for a while, & some of them wouldn't charge at all. I tried putting them in the fancy German charger as well (I can't remember the model name, but it's the one that has discharge, test, & refresh modes) but it just showed "null" for them, as if they weren't even there. Is there some need to charge NiMH cells as soon as you buy ...


NiMH 1.2V charger

Started by Anonymous in sci.electronics.basics11 years ago 26 replies

I'm looking for a good design (with schematic) to charge single 1.2V NiMH batteries. Not two in series, not three or four in series:...

I'm looking for a good design (with schematic) to charge single 1.2V NiMH batteries. Not two in series, not three or four in series: individual batteries. Schematics of chargers which can handle 4 batteries in parallel (charging individually) would be appreciated too. I've got some NiMH batteries on the fritz, and I'd like to take care of them as much as possible. Dad had a Ray-o-Vac ...


Can I replace NiCad with NiMH?

Started by Mitch in sci.electronics.basics10 years ago 8 replies

I have some rechargable wireless headphones that I use on the treadmill. The NiCads have developed so much memory that they only last about 1/2...

I have some rechargable wireless headphones that I use on the treadmill. The NiCads have developed so much memory that they only last about 1/2 hour. Can I replace them with NiMH? Will the charging dock handle them the same?


Draining NiMH by using LED in flashlight?

Started by david in sci.electronics.basics6 years ago 5 replies

Is it true you an use an LED flashlight to drain an NiMH rechargeable AA cell to a suitable voltage in order to condition the cell? ISTR that...

Is it true you an use an LED flashlight to drain an NiMH rechargeable AA cell to a suitable voltage in order to condition the cell? ISTR that NiMHs should nto be drained to below 0.9 volts. Would an LED used in a typical flashlight stop drawing current once the voltage fell below 0.9 volts?


Maxim 712 NiMH Charger Cutoff Temperature

Started by Joe in sci.electronics.basics8 years ago 1 reply

I built a NiMH charger based on the Maxim 712 chip some time ago. I didn't implement the temperature cutoff part of the chip's capability, and...

I built a NiMH charger based on the Maxim 712 chip some time ago. I didn't implement the temperature cutoff part of the chip's capability, and now would like to do that. Here's the main question: How much above ambient temperature should the cutoff be? Thanks. --- Joe


Reviving 'dead' PP3 NiMH?

Started by Terry Pinnell in sci.electronics.basics2 years ago 6 replies

Some of my PP3s steadfastly refuse to recharge. Neither in my 'intelligent' nor basic chargers. Despite being years old, I'm reluctant to dump...

Some of my PP3s steadfastly refuse to recharge. Neither in my 'intelligent' nor basic chargers. Despite being years old, I'm reluctant to dump them. Any tips from others who have managed to bring these back into service please? -- Terry, East Grinstead, UK


# of batteries to cause polarity reversal

Started by Anonymous in sci.electronics.basics11 years ago 22 replies

If I have two NiMH batteries in series under a load, and one is weaker than the other, is it possible for the stronger one to force the...

If I have two NiMH batteries in series under a load, and one is weaker than the other, is it possible for the stronger one to force the weaker one to reverse polarity?


Soldering onto NiMH batteries?

Started by DeanB in sci.electronics.basics9 years ago 9 replies

Hello all, I've only done a little soldering before, but I want to rebuild a battery pack for my TI-59 calculator (which is basically 3...

Hello all, I've only done a little soldering before, but I want to rebuild a battery pack for my TI-59 calculator (which is basically 3 AA-sized batteries soldered together in series). Can I just solder directly onto the battery terminals? With a copper wire. Should I use flux? Will this overheat the battery and/or blow it up? Thanks for any tips!


Re: Soldering onto NiMH batteries?

Started by C. Nick Kruzer in sci.electronics.basics9 years ago 1 reply

Hi Kris, you wrote: > I'm a beginner, so sorry if this is a really basic > question, but, what is the advantage of > soldering them in,...

Hi Kris, you wrote: > I'm a beginner, so sorry if this is a really basic > question, but, what is the advantage of > soldering them in, rather than using a battery > holder? The cells I used were of a flatenned box-shape [90=B0 corners], (about 1cm=D72.5cm=D76cm) I think they might be called prism cells but they are not of a true geometric prism configuration. I don't know why they might b


Need 12v, 500mA for 10-12hrs- lightweight

Started by Jim Elbrecht in sci.electronics.basics10 years ago 8 replies

So my clock capacity tester has shown me that I've got a lot more bad batteries than good ones. So I'm in the market for some new...

So my clock capacity tester has shown me that I've got a lot more bad batteries than good ones. So I'm in the market for some new NiMH cells. I was going to use my wealth of AAs to run a wireless headset on my metal detector. The wireless system was designed for a car [12v - or should I call it 13.6?]. All I can find for specs on it is that it is rated at 500milli-Amps. It is a L...


NiMH charger recommendations?

Started by DaveC in sci.electronics.basics5 years ago 20 replies

First of all, this is a request for a *recommendation*, not a request for someone to do Google searches for me. - - - I need a charger for AA,...

First of all, this is a request for a *recommendation*, not a request for someone to do Google searches for me. - - - I need a charger for AA, AAA, and 9v batteries. Four of the AA or AAA at a time is OK. I see very few that support all these batteries (Maha makes a separate charger for 9v). Of those that do, not all use delta-V termination (or don't specify). Of those remaining th...


OT: cordless screwdriver

Started by Pimpom in sci.electronics.basics5 years ago 15 replies

Is anyone familiar with the cordless screwdriver in the link or a similar one? I'd like to know if using rechargeable 1.2V NiCd or NiMH cells...

Is anyone familiar with the cordless screwdriver in the link or a similar one? I'd like to know if using rechargeable 1.2V NiCd or NiMH cells instead of the specified 1.5V alkalines will result in a severely reduced torque. http://www.ebay.com/itm/Black-Decker-6-Volt-Alkaline-4-AA-Battery-Operated-Cordless-SCREWDRIVER- NEW-/251240800353?pt=Power_Tools&hash=item3a7f1e6061


Help me build a bicycle phone charger

Started by BikePilgrim in sci.electronics.basics10 years ago 18 replies

Hello, I recently built-up a front wheel for my bicycle that has a 6v/ 3.5w dynamo. These are designed to power headlamps, but I'd prefer...

Hello, I recently built-up a front wheel for my bicycle that has a 6v/ 3.5w dynamo. These are designed to power headlamps, but I'd prefer to store the electricity in a battery which could charge my phone. I believe iPhones charge on standard USB. My first question is about the battery. Of course, any cell or chemistry would do, but I'd like to use NiMH AA cells so that I could easily repla...


lm555 timer problem

Started by Cliff Hartle in sci.electronics.basics6 years ago 18 replies

I have a basic off the shelf astable timer circuit with the diode for less than 50% duty cycle thats on this...

I have a basic off the shelf astable timer circuit with the diode for less than 50% duty cycle thats on this page. http://www.doctronics.co.uk/555.htm#more_astables I hooked it up with 4 AAA NiMH batteries. I used an LED to get the resistors correct for the timing I need and it all works. I'm going to drive a relay with this circut so I hooked up a 5v reed relay with a protection d...


Battery Charger Temperature Cutoff

Started by Joe in sci.electronics.basics10 years ago 1 reply

I built a NiMH charger based on the Maxim 712 chip some time ago. I didn't implement the temperature cutoff part of the chip's capability, and...

I built a NiMH charger based on the Maxim 712 chip some time ago. I didn't implement the temperature cutoff part of the chip's capability, and now would like to do that. Here's the main question: How much above ambient temperature should the cutoff be? Thanks. --- Joe


Rechargable battery power

Started by Rod...@Hillhead in sci.electronics.basics11 years ago 3 replies

Hi, I have connected 5 new NiMh batteries in series, each is rated at 3800 mAH. When I connect a 10W, 6v halogen bulb to them it lasts about...

Hi, I have connected 5 new NiMh batteries in series, each is rated at 3800 mAH. When I connect a 10W, 6v halogen bulb to them it lasts about 2 hrs. I expected longer than this, calculating that the current should be 1.6 amps through the bulb, and the battery pack should have 5 x 3.8 Ahr = 19 Ahr. Should the bulb not last for 11.8 hrs, or am I doing something wrong? Rod


Battery discharger - will this work?

Started by George in sci.electronics.basics9 years ago 19 replies

The circut is here: http://drop.io/kuv9yi5 The idea is to discharge a NiMH AA cell at 500ma down to the point where the cell voltage is...

The circut is here: http://drop.io/kuv9yi5 The idea is to discharge a NiMH AA cell at 500ma down to the point where the cell voltage is 1V. I picked the specific parts because I already have them in my junque bin. The idea is that R1 is the sense resistor which should have a voltage across it of 0.25V if 500ma is passing through it. Op amp B controls the pass transistor such tha...


Rubbish camera batteries

Started by Periproct in sci.electronics.basics10 years ago 9 replies

My proprietary camera batteries don't last long when new and as I'm not a photography enthusiast I find, when the camera does come out, the...

My proprietary camera batteries don't last long when new and as I'm not a photography enthusiast I find, when the camera does come out, the batteries have discharged to the point of not taking a charge. My cunning plan is an external battery pack of standard (cheaper and higher capacity) NiMH. Trouble is I need a dummy battery of the correct shape and with contacts in the right place to...