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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39 views

How to safely replace NiCD/NiMH with Li-ion in a small electric screwdriver? [duplicate]

I'd like to repair and re-use a small Bosch electric screwdriver. It currently has a battery of 3 small AA-type rechargables (unmarked cardboard wrapping) that has almost the same occupancy volume of ...
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166 views

How can I trickle charge NiMH batteries as part of an IOT controller?

I have built an IOT motor controller board that's powered by 4 AA NiMH batteries in series. I want to use a solar panel to trickle charge the batteries, but the voltage slowly decreases even when the ...
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810 views

Replacing NiMH with Li ion [duplicate]

I have a rechargeable vacuum cleaner with NiMH batteries, 1800mAh and 14.4 volts, 12 cells. The charger is 18v 200mA. The batteries have now died. Can I replace the batteries with 4 cell Li-ion in ...
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56 views

BQ2002, LM317 NiMH charging circuit. How to control the current output?

I have designed a charging circuit utilising the BQ2002 and LM317 for 2x 1.2V NiMH batteries, and it is to be charged using a 5V USB input, I need the output current to be between 550 mA and 1A. I ...
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72 views

Trickle charging 10NiMh in series with ~1W solar panel

I have been put onto a project that needs to be powered by a small (1-2W) solar panel trickle charging a battery pack. The product will be located on rooftops. We have reviewed similar products and ...
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1answer
46 views

Balance charging battery pack one-half at a time?

I'm trying to wrap my head around how I need to go about balancing charging a few NiMh battery packs. I'm using a HiTec x4 charger, which supports balancing charging up to 6 cells at a time. However, ...
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361 views

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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163 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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1answer
500 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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329 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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225 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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67 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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150 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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1answer
34 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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708 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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1answer
80 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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43 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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136 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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68 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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7k 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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217 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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39 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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473 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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53 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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91 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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704 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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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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696 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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102 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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38 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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48 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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973 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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2k 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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2k 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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749 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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319 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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888 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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192 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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527 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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122 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
921 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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508 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
362 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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417 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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71 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
99 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
516 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
491 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
2k 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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558 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 ...