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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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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2answers
58 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
35 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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2answers
158 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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113 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
315 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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237 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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1answer
174 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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1answer
57 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
133 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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529 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
77 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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2answers
38 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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1answer
113 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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34 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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1answer
66 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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2answers
5k 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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1answer
175 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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37 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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3answers
420 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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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
80 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
593 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
575 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
99 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
35 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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1answer
47 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
850 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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1k 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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2answers
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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1answer
683 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
270 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
731 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
171 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
490 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
114 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
745 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
413 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
293 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
355 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
70 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
84 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
408 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
413 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
1k 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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1answer
505 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
95 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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3answers
3k 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 ...
