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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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5V output on AAA Ni-Mh battery charger?

I bought a cheap Ni-Mh battery charger from Aliexpress to charge my rechargeable AA and AAA 1.2V batteries but before I plug them in, I checked the voltage on the charger terminals and it is reading ...
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55 views

DC Motor PWM Circuit Implementation

I'm a little new to this, so bear with me: I am working on a hobby-related project that involves the operation of two DC motors in parallel, powered by a NiMH battery. (Crappy circuit diagram ...
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46 views

Does replacing Li-ion accumulator with a pair of good quality AAA NiMH makes light shoes safer?

I bought my daughter a pair of light shoes (LED). Fortunately they broke down after 2 days and she's not wearing them anymore. After buying I realised that they probably have Li-ion accu inside. So I ...
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46 views

Is there a Single Component/Chip for Performing Low Voltage Cut-Off for a NiMH Battery?

I would like to build a circuit that uses a single Ni-MH AA Battery. My circuit can work well with the 1.2v that the battery supplies most of its discharging time, and I would like my circuit to stop ...
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113 views

What is the miminum voltage for series NiMH pack?

Suppose a pack of 8 AA NiMH cells are serially attached and its known NiMH cells should not go below 900mV per cell. Does this really mean the pack should not be discharged past 7.2v?
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139 views

Do NiMH demand balancing?

Is it fine to charge a pile of 8 2 Ah AA NiMH @ 11.6 V 0.5 A serially? They are from the same packaging and were bought only for use as an 8x pack - they were not used for anything else. Im not sure ...
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107 views

Step-up converter with Vin, Vout, GND

I want to use pololu step-up converter https://www.pololu.com/product/2836 in order to power a 5V device with two Ni-Mh batteries (1.3V each). It has only Vin, Vout and GND connectors. I've checked ...
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69 views

Electronic load battery testing - Honda NiMH batteries - Energy storage

I recently found a way to recondition used cylindrical NiMH batteries pretty well (typically those used in the Honda Insight series). However, I want to know whether the batteries will hold ...
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44 views

What would be a good replacement for a set of HR6 batteries?

I need to change this OEM set of batteries1 because they are not holding a charge any longer. I am not familiar with rechargeable batteries. My understanding is that I should be able to swap the OEM ...
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2answers
114 views

Can I replace a NIMH rechargeable pack with a resistor if I only want to run plugged in?

My kids have a pair of IKEA night lights ("spoka") where the internal battery packs have died. I'm debating replacing the batteries (3x AAA NIMH, marked 3.6V so in series) and have looked at this ...
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32 views

Charging NiMHs: about current fluctuation tolerance

While trying to make a DIY charging system on my bicycle -based on the hub dynamo- I have seen in action that Li-Ion batteries (typical 18650 ones) do not like charging current fluctuation at all. ...
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311 views

Algorithm to know NiMH battery level

Background I have a device with a NiMH battery. This is a portable device, so I need to know how much battery I have left at all times. To achieve this, I want to map the battery voltage to a ...
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68 views

USB NiMH charger keeps drawing same power forever?

If my USB charger for AA/AAA NiMH batteries by BTY charges a NiMH battery, the current (ampèrage) of charge only depends on the USB input voltage (usually 5V) and the battery manufacturer (input ...
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31 views

Can I power a DC fan from li ion to nimh?

I have a mini DC fan with a 2.5mm DC connector connected to a li ion battery provided by the manufacturer. The li iom battery pack have 4 speeds switch from 3.5V(1.3W) to 7.4V(8W). The question is ...
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88 views

DS2715 NI-MH Charge Controller Help

I am attempting to design a system that charges a 6 cell 1800 mAh NIMH R/C car battery wirelessly with the DS2715 charge controller by Maxim. I am trying to modify their linear charging design for a 6 ...
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33 views

NiMH battery Wh in and out

I'm trying to calculate the Wh I get out from a NiMH battery while discharging. Also, how much I'm putting in while charging. I have tried to multiply the voltage that I'm charging my battery with and ...
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65 views

Safe to replace just some cells in a NiMH battery pack?

The battery pack of my Roomba is made of 12 sub-C NiMH 1.2v cells; two of them are down to around 0.5v, and the Roomba won't work. Can I replace just these two cells with brand-new ones? Will this be ...
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3k 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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129 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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140 views

NiMH Smart Charging Circuit with Load-Share for Autonomous Robot

a couple of questions/issues for creating a NiMH smart charging circuit with load-sharing. Background I have a functional autonomous robot based on different MCU including Arduinos and a Raspberry ...
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300 views

Li-Ion battery modification to charge with Ni-MH charger

First of all, I have to say I know "Li-Ion batteries can not charge with NiMH charging". So this question about li-Ion battery modification. 1. I found a battery from China that consists of 2 serial ...
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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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334 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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489 views

LiPo or NiMH Batteries and Charge Controller

I’m a senior Electrical Engineer student and am working on a team capstone project where we need to use solar power to recharge a set of batteries.  Our little contraption design, a box carrier with a ...
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1answer
49 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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1answer
76 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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405 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
49 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
409 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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1answer
95 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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91 views

Few questions with charging NiMH batteries in series

I have read a few other posts about this topic. But I am no Electrical engineer. I do have a degree in Computer engineering, so that sort of helps. Ultimately I am trying to produce this project. ...
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1answer
34 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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43 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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1answer
629 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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1answer
991 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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1k 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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597 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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668 views

bq2002 IC set up for charging circuit

I want to set up a charging circuit with a bq2002 IC as below: VCC = 5V However I am not sure what the resistor values R3, R4 and RT should be. I've read thought the datasheet: http://www.ti.com/...
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1answer
223 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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2answers
588 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 ...
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2answers
141 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
424 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
107 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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2answers
518 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
315 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
247 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
288 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
64 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
73 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
327 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. ...