Questions tagged [nimh]

A nickel–metal hydride battery (NiMH) battery is a type of rechargeable battery. They have a better energy density than nickel–cadmium batteries (NiCd or NiCad) and have largely replaced them in many applications.

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15k views

Can I charge a NiCd battery with a NiMH charger?

I have an old NiCd RC battery pack. It was not used for at least ten years but when I tried to charge it with the old charger I was suprised to see it still had some capacity. Now I just went and ...
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358 views

NiMH Batteries and Fuel Gauge

I'm currently trying to figure out the best way to make use of my gas gauge LTC2943-1 in conjunction with my pack of NiMH batteries. I am aware that voltage alone is not a sufficient measure of the ...
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165 views

Any deleterious effect from very strong, close magnets on NiMH cells over time?

This question probably isn't a perfect fit for this SE, but I did find this question: Will placing a strong magnet near my electric skateboard Li-Ion Battery pack damage or discharge it? This is a ...
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1k views

Can NiMH batteries charge at cold temperatures?

While I am aware of the risk associated with charging Li-ion below 0 °C and that the charge acceptance for a NiMH battery decreases with rising temperature, I am finding conflicting information ...
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64 views

Replacing 10 AAA NiMH 1.2A batteries with 6, 9v Lithium 1.2A batteries

A vacuum that ran on 10 AAA NiMH batteries in series (15.6v at 1.2A) is nearly dead. I attempted to replace with 6, EBL 9v 1.2A batteries Lithium... bought off a the internet. I connected them such ...
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107 views

Ebike battery not charging after cell change from Ni-Cd to high capacity Ni-MH

I recently replaced the cells in my ebike which consisted of 20 Ni-CD Size D (1.2V) 4,000mAh with 20 Ni-Mh Size D (1.2V) 10,000mAh batteries. Before installation, I charged up each battery to ensure ...
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2answers
884 views

Can a diode prevent backwards current flow from a constant current source?

I'm trying to make a AA battery replacement battery for a vintage computer because its actual battery has gone bad. Its of the NiMH type and I'm pretty sure those are charged with a constant current. ...
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1answer
51 views

Ni-Mh batteries, low capacity better performance?

When we take appart cordless things like drills, vacuum cleaners, telephones..., they often use small capacity (like 700 mAh) Ni-Mh cells. I've always thought that it was because of cost reduction, ...
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1answer
1k views

How to make Li-Ion mimic NiMH voltages

I'm trying to replace the old NiMH Roomba battery with a bunch of 18650s recycled from old laptops. Lucky enough Roomba uses 12s NiMH battery, that operates in voltage range 12-18V, and has quite ...
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134 views

Why do different batteries of the same voltage have different results and which battery would i choose?

I want a power a homemade robot that uses an arduino and 4 small dc motors and a few sensors. Ive used pp3 energizer 9v batteries to power it in the past and they worked well, i used 9v again after ...
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1answer
52 views

multiple Nimh vs dry cell

Greetings. I have this problem. I have a telephone that requires 3 AAA cells. I installed 3 AAA dry cells. it works good. LCD display is very sharp and bright. But then i thought. one day that the ...
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49 views

Protect device from losing power when to much current is drawn

I use an EVX 3014 RC ESC (BEC provides 5V & 1.5amps) and I'm worried that to much of the current will be drawn to the motors that not enough of it will be available to the raspberry pi computer (...
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2k views

Charging 6 NiMH batteries in series via solar

I'm currently working on a project in which a Atmega328 is powered by 6AA NiMH batteries in series (7.5v, 2000MaH). It is in sleep mode most of the time, except to turn a servo a couple times a day, ...
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3k views

Is it ok to use a 10 years old set of NiMH rechargeable AA batteries? [closed]

I've just found my 10 year old pack of rechargeable NiMH AA and AAA batteries. The AAA ones are completely blown with a dark powder all over their positive terminals. The AA ones look fine when ...
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4k views

Balancing NiMh batteries in series over a long term

I'd like to place two NiMh batteries in series to drive a string of single LEDs. I can charge them simply at C/20 or so and the output will be intermittant so the batteries will never reach half ...
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1answer
1k views

Mosfet is getting hot in switching circuit

I've built a NiMh battery charger (6-cell battery, 7.2v, 3000Mah) using DS2715. Input is 12v. Here is the schematic: For Q1 I used IRF9540N For Q3 I used IRLB8721PbF L1 is a 47uF ferrite choke R7 (...
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1answer
479 views

NiMh switch-mode charger for 6-cell NiMh

I've built a charger for my batter (NiMh 6-cell 7.2v) using MAX712 IC. The problem I'm facing is that it's in a linear mode which requires either a huge heatsink or a heatsink with a fan (9W). See ...
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2k views

MAX712 charging circuit - diode gets too hot

I've built a charger for my 7.2v 3000mAh battery using MAX712 IC. Here is the datasheet: http://pdfserv.maximintegrated.com/en/ds/1666.pdf This is the schematic of my charger: It's almost a schematic ...
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226 views

Crude LM7809 9V NiMH charger

I want to charge my 9V NiMH cell with a LM7809. The problem is that I want to limit the current output to 20mA or 30mA. How can I limit the current output from that voltage regulator with simple ...
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2answers
667 views

do mAh on batteries (for home-use - nerf) make a difference? [duplicate]

I was wondering if the mAh on an battery pack is important or relevant, so you would recognize a difference? Little bit Off-Topic: I've read a lot about "Nerf voltage mods" where modders change the ...
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1answer
148 views

Questions on rechargeable battery pack configuration and calculations

I'm looking at making a battery pack for a medical device (CPAP) that would allow its use while camping. I'll tell you what I need and then what I'm planning. What I need: 24v at 3.75 amps DC ...
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1k views

Recharging NiMH cells after long period (18 months) of self discharge

I have seen information supplied with branded NiMH cells (e.g. Duracell) saying "do not leave cells for more than 6 months without recharging." I have some AA size cells which were fully charged ...
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1answer
856 views

Parallel battery supply

I want to parallel connect 4 x AA NiMH batteries rated each at 1.2V, along with 4 x 1N4001 simple diodes to prevent unwanted current flow (recharging) between batteries. The electric circuit is: ...
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2answers
699 views

Can I safely replace rechargable NiMH batteries with consumer-grade ones?

I have a cordless handheld vacuum cleaner (Electrolux Rapid ZB4103) which is powered by 3 rechargeable AA NiMH batteries (1.2V 1300mAh) connected in series and stacked (glued?) in a pyramid to fit ...
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1answer
837 views

Can I charge Ni-MH battery with modem power supply?

I bought a 8.4V 3800mAh Ni-MH battery from eBay. Unfortunately, its charger is not working. I searched about charging Ni-MH batteries on the web. Can I charge this battery with TP-Link power supply ...
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1answer
74 views

Can NiMH type AA battery charger be used for other types like AAA, C, or D (all NiMH)? [closed]

As the title states, I would like to know if a battery charger for AA NiMH batteries could be used to charge also AAA, C and D battery types (all of which also of NiMH type). I am aware of that ...
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1answer
159 views

At what currents should NI-MH batteries be charged?

So I bought one of those cool chinese battery chargers that can charge any type of battery and in a lot of sizes. By default it charges it at 500 mA but i can be set up to 2000 mA. Is it safe to ...
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1answer
1k views

Need help with a simple solar battery charger

I need some help with a circuit that I'm trying to build for an engineering class. We are making these solar cars to practice soldering, and most people just used solar but I want to make it better. ...
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3answers
741 views

Is there an IC that can charge multiple NiMH batteries at once?

I'm building a battery charger that can charge multiple batteries at a time, and I'm currently looking at Linear Tech's LTC4011 IC, but I think it can only change once battery at a time (a single ...
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1answer
3k views

NiMH battery voltage drop under load

I have a 8.4V, 5000mAh NiMH hump pack running 2 PC cooling fans, each of which draws ~5A. When I turned on the system (battery voltage ~9V), the fans ran fine for a moment, but then the voltage ...
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936 views

What does it mean that NiMH batteries do not have a “float voltage”?

I am working on a project that requires a very tiny amount of power and will be used fairly infrequently for short periods. As such, I'd like to experiment with making it entirely self-contained by ...
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1answer
102 views

NiMH battery charger - purchased module or homemade? [closed]

I would like to get to a cheap way of charging NiMH batteries. Are there any suitable modules that could one purchase or should I rather focus on creating one at home? What are the pros and cons of ...
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6k views

Can I swap a USB power sources for a 3-AAA battery source?

I'm putting some battery-powered lights into a boat, and I have the following question: I bought a bunch of cheapo LED lights, as pictured: They run on 3 AAA batteries. They work fine using 1.2V ...
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4answers
4k views

Why Led lights with 3 AA batteries and not in pairs? [closed]

Im trying to purchase some lamp powered by batteries, I want to use the typical 2100 mAh AA rechargeable 1.2V batteries to avoid purchasing tons and tons of one use AA simple batteries. I already ...
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309 views

NiMH battery at 660mV, is it trash or good?

An AAA battery of type NiMH is only at 660mV (unloaded). Can it still be charged and used or should I throw it away*? Some more details: The battery comes in a 2 pack. The other battery has about 1....
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2k views

Charge NiMH using TP4056

Is it possible to charge 3x NiMH AA (eneloops) in series with a TP4056 module? I know that TP4056 will automatically cut off charging when Li-ion reaches 4.2v. So 3x 1.2v Ni-MH = 3.6v, TP4056 ...
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842 views

How to protect single cell Ni-MH battery (overcurrent, undervoltage, overtemperature, etc.) during discharge?

Story I am designing a boost converter for a battery powered board. I am planning to use single Ni-MH battery. The needed output voltage is 3V3. The device will be in deep sleep mode (drawing few ...
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1answer
206 views

Light LEDs with NIMH Batteries

I need to drive a 3 W LED (Forward voltage 12 V, Forward current 0.2 to 0.3 A) using NiMH Batteries( 1.2 V, 2700 mAh ). As the supply voltage should exceed the forward voltage of the LED, I am ...
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1answer
253 views

Ni-MH battery voltage [duplicate]

I have a battery pack of 8 Ni-MH 2400 mAh cells connected to a load that draws ~700 mAh (a Raspberry Pi Zero, display, WiFi dongle, USB hub, and a wireless keyboard dongle). I want to add a led that ...
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9k views

Lithium charge module on NiMh batteries [closed]

Can I use a lithium charge module on NiMh batteries? The charge module has 2 led, one for charging and one for full that I would really like to use with my NiMh batteries.
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6k views

Leaving NiMH and LI-ION powered devices (toothbrush) at charging station [closed]

So I have 2 sonic toothbrushes, one powered by NiMH the other by Li-ion batteries (waterpik & philips). The base stations (with charger in them) look so convenient and just lure me to store ...
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2answers
2k views

Is it possible and safe to charge a NiMH battery with this circuit?

I am trying to design a circuit to charge NiMH battery packs from 2.4V to 9.6V and also single cells. From what I have read about charging NiMH batteries, it seems that all that needs to be done is to ...
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4answers
232 views

Is it okay to use these kind of batteries with this holder (pictures inside)

I have the pictured battery with 1.2 v .. It does not look like regular AA batteries on both ends. My questions: 1) Is it fine to put the batteries in the holder although it does not fit (the ...
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1answer
190 views

Does it matter what the input voltage is to a DC/DC step-up converter?

I have a converter that outputs 5v and 1 amp. The input voltage can be 2.5-6 volts. Does it matter as long as it is in the range? Also, will the current draw from the batteries differ if I change the ...
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116 views

Can I feed a 5V boost converter with 4xNiMH cells?

The spec page of my DC-DC boost converter (couldn't find a datasheet) says ”the input voltage should be kept below the output voltage”. And 4x the nominal 1.2V from an NiMH cell is below my 5V output ...
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1answer
728 views

LM317 to charge a NImh battery from usb [closed]

Hi want to charge my 4000 mAh 1.2V nimh cell battery simply, I do not use them very often. So I wanted to plug this kind of voltage regulator which I think is like that : https://en.wikipedia.org/...
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2answers
2k views

Overcharged NiMh batteries + Servo

I have 2 NiMh batteries 3500mAh 7.2V. However, first one have 7.58V(it increases each time Im measuring it) and second one have 8.37V. Can this be the reason why 5x servos are doing unexpected ...
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1answer
281 views

Battery voltage increasing while measuring (NiMH)

I was going through conditioning for a NiMH battery pack (12 x 1.2V, 1500mAh cell) and decided to check the cell voltages. I noticed that the measured voltage, with a multimeter, increased over time. ...
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407 views

Convert SLA laptop battery to NIMH

I have an old laptop that uses a SLA Battery and I'm wondering what sort of circuit would be need to convert the charging circuit for NiMH Cells. Many manufacturers were able to do some time ago but ...
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1answer
193 views

do I need overvoltage protection with 4.8V NI-MH pack?

I plan to run an avr like attiny + led strip with 5V supply. The whole thing can draw up to 15A at 5V. To avoid heating problem stepdown and other regulator problem, I've choosen a pack of 4 * 1.2V ...