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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42 views

NiMH battery discharged to 0V

I have a 90's handheld CB that I'm powering using 10x1.2V NiMH cells all in series. Because these cells are rather old (at least 8 years), when I got a low voltage warning, I decided to measure all ...
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Convert Ni-Mh charger's connector from cigarette lighter to USB

I recently purchased a very basic airpump to inflate a mattress. As we will be taking this mattress to a camping trip on a motorbike, we wont have a car cig-ligther socket (12V), only USB 5V. This is ...
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53 views

Charging or replacing old battery pack without burning house down

A wealthy neighbor passed down the most awesome toy ever for us to give our son under the Christmas tree, but it's got no charger. And I have no idea if the battery pack inside works. That pack is ...
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41 views

NiMH Battery Indefinite Charging

Can I indefinitely charge NiMH batteries through a current source that limits just below the battery voltage? More specifically, the battery is a 400mAh 14.4V pack and the supply is 15V but after a ...
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51 views

Measurement of internal resistance of a battery

I found two circuits online of almost same approach to measure internal resistance of a battery. Both the methods excite the battery at 50Hz using a square wave and AC voltage drop is measured across ...
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29 views

Repair/Rebuild NiMh battery pack?

2 years ago, bought a name brand cordless VSR drill motor with a 12 V battery pack for only $20. (I realize now, it was on clearance, as Manufacturer moved to a line of 20 V interchangeables...so it ...
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32 views

NiMH discharge protection and MCU powering

I would like to power an ESP32 devkit board with four NiMH AA batteries. The ESP32 board has an AMS1117 voltage regulator. It has a dropout voltage of 1V. The output voltage is 3.3 Volts so my ...
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81 views

Question about mixing battery sizes and quantities

Ok. I have searched everywhere and can't find a definite answer on this: My first question, Is, Can you mix 2 lithium batteries of different sizes together? (Like mixing an 18650 lithium battery with ...
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48 views

NiMH battery pack charging circuit using Solar panel [Help]

Recently I have been working on a NiMH battery pack (7.2V / 2100mAh) charging circuit powered by a 12V solar panel. With some research I found charging NiMH takes different forms by measuring change ...
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40 views

Replacing Nimh battery to Li-ion in hybrid cars

is it a good idea to replace a Nimh battery in hybrid car (like prius model 2012) to Li-ion battery without any problems.
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99 views

Buck converter without inductor in a NiMH charger (Zilog AN0259 application note)

After doing some reading online, it seems that you can't really build a step-down converter with only a filtering capacitor and without an inductor, because the losses occuring during charging of the ...
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58 views

Can I use a lithium charger for a bluetooth speaker with a NiMH battery? [closed]

I have a BlueAnt bt blast bluetooth speaker that I need a new charger for. It says DC 12V on the back by the power supply. I checked the manual and this speaker has a NiMH rechargeable battery. Can I ...
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29 views

Overvolting brushed motors by 0.2V

For RC models, I own several brushed motors which are intended to operate at 7,2V. According to my previous tests, they usually take 25 amps, 30 being the absolute maximum. To divide by two the weight ...
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26 views

Battery status monitoring of 1 cell NiMh battery powered embedded device

I am developing an embedded device (integrated RF controller) using 1 cell NiMh battery of 1.2 volt. I am figuring out ways to estimate the remaining battery capacity of the system. I have come across ...
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111 views

A voltage controlled switch for a single NiMH cell

I'm developing a small project that contains one AAA NiMH battery that is charged via USB with a MAX DS2711 IC. The output of the battery is connected to a TPS61006 to boost the ~0.9 - 1.3v cell ...
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69 views

Help needed with resistor value for charging NiMH batteries

I have an old calculator which contains 4 2/3 AA NiCd batteries in series. These batteries are very old and need replacing, so I'm going to replace them with 4 2/3 AA NiMH batteries in series, which ...
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34 views

Determine 9V NiMH battery cell count

I have a bunch of 9V NiMH rechargeable batteries. I also have an adjustable CC/CV charger and to have battery fully charged with that I need to know the correct stop voltage. I have read that 9V pack ...
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95 views

parallel connecting 24v 1500mah NIMH battery packs and how to charge

After several of searches on the internet for information about charging NIMH batteriers, i feel the need for some clarification. I've gotten my hands on a bunch of battery packs. Each battery pack is ...
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20 views

Maxim DS2710 CTEST resistor value

I'm designing a 1x NiMH cell USB rechargeable bicycle light for fun. I'm using the Maxim DS2710 to charge the NiMH cell. I'm currently at the IC's impedance-test threshold selection stage (datasheet ...
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50 views

Can I change laptop's RTC and backup battery with generic Ni-MH?

I got old laptop for a good price. After some inspection, I noticed that backup battery and RTC battery are already gone bad, and seems can't hold charge. I've checked eBay for replacements, but only ...
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Power Jack part number for YAESU FT 23R battery pack?

I am planning to design a small USB powered charger for the battery pack used with the radio YAESU FT 23R. I have been searching for the correct name / part number of the power jack connector shown in ...
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83 views

Vacuum cleaner charging works only with the original adapter - why?

I have this old robotic vacuum cleaner that I got cheap and was using for a while: https://www.youtube.com/watch?v=nvj8BmijDn4 (not my video) Now however the charging adapter broke and I've been ...
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Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)?

Looking around Amazon, it seems that different types of batteries are measured differently: Does anyone know why? Li-ion are measured in mWh 1200mWh ALTIZURE (Cheap-Os) 3200mWh Deleepow 3000mWh ...
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65 views

Why are Alkaline, NiMH, and Li-ion AA measured differently (mAh, mWh, etc)? [duplicate]

Looking around Amazon, it seems that different types of batteries are measured differently: Does anyone know why? Li-ion are measured in mWh 1200mWh Cheap-Os 3200mWh Deleepow 3000mWh AmpTorrent ...
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1answer
60 views

NiMH charging circuit using 24V

I am trying to make a charging circuit to charge 2 NiMH batteries via trickle charging with 0.015A (15mA) I have used a current regulator and basically J1 is connected to the source of 24V DC and J2 ...
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158 views

How bad would it be for a NiMH battery or/compared to a Lithium-ion battery in a device to sit unused for years?

I have a Sonicare toothbrush which has Lithium-ion battery and a body hair trimmer that has a NiMH battery. I have charged the Sonicare once or twice without ever using it, just to stop it go to 0% ...
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114 views

Nickel battery balancer

TLDR: The question is about retrofitting a balancer to the Ni-MH battery of an existing appliance (that doesn't trickle charge the battery), preferably in the way that will not require frequent access ...
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48 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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445 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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5k 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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123 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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85 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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1k 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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282 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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1k 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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458 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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298 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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136 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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223 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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36 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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1k 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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112 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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46 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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220 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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75 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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13k 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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317 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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101 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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909 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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61 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 ...