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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Selecting a charge time for a NiMH charger at 1C

I'm building a solar charger for an Energizer 8.4 V, 175 mAh NiMH battery with a MAX713. The solar panel is 15.4 V, 200 mA. If I charge them at 1C (175 mA), would it be better to set the charge time ...
488 Studios's user avatar
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2 answers
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NiMH battery charging problem

I have a battery (8 cells in series, NiMH AA cells (1.2 V to 1.3 V), 1300 mAh per cell). Cells used- https://www.amazon.in/Rechargeable-NiMH-2300-Peak-Power/dp/B01MF8HUKO https://www.amazon.in/...
funtastic rdj's user avatar
2 votes
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What happens when charging a pair of AA NiMH batteries where one might be emptier than the other? [closed]

When there are multiple AA NiMH batteries that have been stored some time after being charged (so that they will be at hand if needed) and I want to charge them a little more, there appears a problem ...
ispiro's user avatar
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Properly Charging NiMH Batteries that Have been Stored for Too Long

For a Robotics Project, I've purchased two equal NiMH batteries, seven months ago. PRODUCT = NiMH Battery 12V 3000mAh XT30 Connector [MH-FC] 20A Fuse 12-20 LINK TO PRODUCT = LINK There is no ...
Diego Alves's user avatar
2 votes
1 answer
48 views

Two NiMH AA batteries powering servo circuit

My project has an ESP32 C3 and 9g servo. It has to be mobile, thus battery powered. Due to space constraints, I can’t use 4 AA batteries even though that would be ideal. I would like to use two NiMH ...
cjb567's user avatar
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Refined -dV termination method for charging NiMH batteries

In a radio control forum I have read the following statement: The minus delta V bump that is indicative of end-of-charge is much less pronounced in NiMH than NiCad, and it is very temperature ...
Julia's user avatar
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2 votes
2 answers
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Turning off a solar panel with a GPIO

This is one of those problems that seemed super simple at first but, after simulating, appears to be tricker than I expected, at least for my wannabe-EE brain. The circuit I'm working with looks ...
Robert Quattlebaum's user avatar
2 votes
1 answer
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Criteria to see if a battery was over-discharged in the case of Li-ion cells and NiMH batteries

Consider a Li-ion pouch battery from an RC model. Is there any reliable way to determine by measurement if the battery was in a over-discharged state in the past. (In particular I am looking for ...
martin's user avatar
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Can you use just a battery monitor for charging? (instead of a charging specific ic as well) [closed]

Would a fuel gauge IC that also monitors voltage and temperature be enough for monitoring a NiMH battery during charging and discharging? Charging ICs monitor just voltage and temperature so I think ...
Matthew3302's user avatar
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How do you measure capacity without a constant current? (coulomb counting?)

What would be the most accurate (but not too expensive) method to find the capacity of NiMH battery cells when you are not able to use a constant current? Would using coulomb counting work or is that ...
Matthew3302's user avatar
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Buck converter/ NiMH charger circuit review

I'm going to be charging an embedded NiMH battery and I'd like to use a switching charger to minimize heat production. For various reasons, I haven't found an off-the-shelf charger IC that would work ...
Andrew Mowry's user avatar
2 votes
2 answers
90 views

LED driver as constant current source for NiMH charging

LED drivers seem like an easy and cheap way to provide a constant current source for NiMH charging, but most need a sense resistor between the load and ground, which won't work when charging a cell in ...
Andrew Mowry's user avatar
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1 answer
81 views

How much power do I need to charge 12 V 800 mAh NiMH battery

I have a cordless drill with a 12 V 800 mAh NiMH battery. Somehow I lost its charger. I tried to charge the battery with another 12 V 1 A power supply, but it did not charge. So, how much voltage and ...
Johnykutty's user avatar
1 vote
2 answers
73 views

Do battery cells in a series have the same C-rate?

If I wired up four NiMH battery cells from the same manufacturer in a series to power a load would the current and voltage from them continue to be split evenly or would it need an IC to monitor the ...
Matthew3302's user avatar
2 votes
0 answers
79 views

Why are NiMH batteries venting with <200mA load?

I have built a custom NiMH battery pack/charger/controller that has two 2000mAh batteries wired in series. It has a boost converter that outputs 5V to a USB connector through a 500mA fuse. It seems to ...
inc's user avatar
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Charging 2S Li-ion battery with charger designed for 6S NiMH

Can I replace 6 NiMH batteries in series (7.2 V discharged, 8.4 V charged) with a 2S Li-ion battery pack (7.4 V discharged, 8.4 V charged), using the same charger, with close monitoring and multiple ...
ortegacomputacion's user avatar
1 vote
1 answer
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How to calculate clipper new battery charging time

I'm replacing batteries on a hair clipper following this tutorial. New batteries have higher capacity than the original ones : old batteries : 2x BYD AAA NiMH 1.2V 600 mAh new batteries : 2x Eneloop ...
Vince's user avatar
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NiMH battery under-charging

I can see there I’d so much information on the net about charging NiMH batteries and so many forum discussions on it that I am a reticent to start another in fear of the stock answers that are already ...
N Hughes's user avatar
1 vote
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230 views

Do NIMH batteries have a shelf life?

I have some 15 year old NIMH batteries which were not touched for 10 years. I tried charging them with a peak charger and they didn't hold a charge. I'm wondering if they died via age or some other ...
FourierFlux's user avatar
2 votes
4 answers
138 views

What causes an imbalanced battery discharge? Does it indicate a problem?

I've got a project that uses two AAA batteries in series (no center tap.) I've been using eneloop NiMH batteries. It seems like often if I let the system run until the batteries cut out, one is ...
Nick U.'s user avatar
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Using low self-discharge NiMH for a portable power station?

Portable power stations - the large type with AC outlets - typically utilize lithium-ion or lithium iron phosphate (LiFePO4) chemistries. I haven't found any which use NiMH. LiFePO4 batteries are ...
cluelesscoder's user avatar
1 vote
6 answers
1k views

Voltage of AA rechargeable batteries suddenly drops

I am having problems with rechargeable AA Ni-MH batteries. We are using 6 AA Ni-MH rechargeable batteries to power our device, but after about an hour of usage suddenly one of the batteries' voltage ...
Jeet Sodagar's user avatar
10 votes
2 answers
3k views

Can I indefinitely "trickle" charge NiMH batteries with a constant current?

[Note: Various answers to other questions address this, but I cannot find another question focused on just this. This is my attempt to create a definitive place for answers to this. [If at all ...
cjs's user avatar
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Automatic NiMH battery charger circuit

I found this circuit on the web and I'm trying to charge a 1.2 V Ni-MH battery. The problem is that the circuit outputs 2.5 V (no load). Which elements should I change in this circuit? What is the ...
Hosin Safari's user avatar
1 vote
3 answers
374 views

Can I low-rate charge (constant current) NiMH cells in parallel?

I'm building a simple constant-current charger (intended to charge at C/10 or less) for consumer NiMH cells (AA batteries). This is intended to help extend the life of some of my older cells that no ...
cjs's user avatar
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Battery charger OR topology

Is there some type of simple topology that can work in the situation shown in the schematic? This is a simplified version of what I want to do. The charger current and enabling will be MCU controlled....
Erik Friesen's user avatar
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Convert 6 V motor to run on 4.8 V

I have an electric pencil sharpener that has a motor that seem to be intended to run on 6 V (4 x 1.5 V alkaline batteries). What are my options to make it function with 4 rechargeable NiMH batteries (...
norq's user avatar
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Limit battery charging current with simple resistor?

I'm designing a device with a small (400 mAh) NiMH battery with integrated charging from USB. I realise that as I have an MCU it makes sense to control the charging in software rather than worry about ...
Andrew Mowry's user avatar
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Backfeeding boost converter

I'm designing a circuit that can be powered by either USB or a single NiMH cell. The NiMH will be boosted to 3.3V, and then an LDO will reduce both that and the USB 5V to 3.1V. I've attached a quick ...
Andrew Mowry's user avatar
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108 views

Charging NiMH cells which are welded together—safe?

I am attempting to recondition sticks (groups of cells in series) of NiMH batteries from a Honda Accord Hybrid Battery. The cells in question are nominally 1.2V cells with a capacity of 6500mAh. There ...
FawltyPlay's user avatar
5 votes
3 answers
1k views

Rechargable batteries vs alkaline

The instructions on these two devices (A flashlight and handheld radio) say not to use rechargeable batteries. Will using rechargeable NiMH batteries damage these devices or just cause them to ...
105's user avatar
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1 answer
544 views

Can a 9.6V Ni-MH battery be charged by unregulated 9V adaptor with 13.5V output?

I am analyzing this Ni-MH charger circuit: The charger is an unregulated power supply with 9 volts DC output. The original battery is unknown but it is Ni-CD and someone told me he used Ni-MH 9....
Jtl's user avatar
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NiMH or Li-Ion for a 5v <1A powered device for a kid?

I'm building a small device based on ESP32 and powered by a 5V power supply (looks like <1A even when speakers are playing). I want to power it on batteries and it seems that everyone does Li-Ion ...
Zach Moshe's user avatar
2 votes
2 answers
1k views

Using NiMH batteries with dumb charger designed for NiCd?

I'm attempting to revive a very old calculator that was designed to use NiCd batteries (no clue about capacity). These batteries act both as a power source but also as a voltage regulator. Charger is ...
P. N.'s user avatar
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3 votes
2 answers
1k views

High voltage when charging NiMH battery?

So, I have a number of high-capacity, Amazon AA NiMH batteries with unknown health and charge cycles. They’ve been in use for quite sometime and continue to work well for my purposes. I have been ...
Appleoddity's user avatar
0 votes
3 answers
517 views

NiMH reverse charged cells

I have a NiMH battery pack that I would like to balance (charge discharge for 3 cycles.) I am doing a low charge/discharge current of 0.5 A while the battery capacity is 5 Ah. Since the pack consists ...
Shadi Ghabboun's user avatar
2 votes
4 answers
393 views

Is it safe to use this arrangement of charging NiMH batteries in series and then using them in parallel?

I have built a solar charger that charges 6 AA NiMH rechargeable batteries in series using a constant current source at a little under C/10. That part is fine. I want to use the batteries to power a 3 ...
Mark Highton Ridley's user avatar
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0 answers
85 views

Solar charger module for two NiMH in series

I have two 2450mAh NiMH batteries to be used to power an IOT project outdoors. I would like to charge the batteries with a solar panel, 5V, 1W. I have come across this module for which specs for 2 ...
Ranjith's user avatar
1 vote
2 answers
356 views

NiMH battery charging rate vs life

I'm looking at the product info of a NiMH AA battery brand. It says these batteries last up to 2100 recharges while charged as per IEC 61951-2 2011, but they last for only 600 times if recharged using ...
Ananth Pattabiraman's user avatar
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0 answers
785 views

DIY power bank with NiMH batteries

I want to do a DIY power bank with NiMH batteries, like this example... But I have 6 NiMH batteries with 2600 mAh and 1.2 V. I want to use a 18650 PCB LCD but they are designed for Li-ion 18650 ...
Dani's user avatar
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681 views

Is it possible to revive a NiMH cell with low capacity

I have a bunch of 2100 mAh NiMH cells that have been lying around for many years (probably about 8 years). They still had 1.2-1.3 V when I recently took them out of the drawer, but when I tried to do ...
denmike's user avatar
0 votes
2 answers
175 views

NiMH battery management

This follows on from a post I made about my front door (link at bottom of this post). In essence I have a door with a 12 V motor in it, which is activated by a 12 V pulse. The power supply is only ...
jules_bike's user avatar
-1 votes
2 answers
683 views

How can I charge a NiMH cell with a 5 V, 2 A adapter

How can I charge a NiMH cell (1.2 V, 600 mAh) with a 5 V, 2 A adapter? Can I use a resistor in series, and if so, what value?
Sasi Kumar's user avatar
0 votes
1 answer
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Having battery cells in parallel does increase autonomy ? (My load is a constant power load. DC/DC)

I have 4 AA alkaline cells and I'm trying to figure out which is the best cell configuration to achieve maximum autonomy with constant power load. I understand that if your load is a constant current ...
user67441's user avatar
0 votes
1 answer
87 views

Battery pack for very slow charging of USB device

I have a GPS device that has too small of a battery pack (300 mAh) and only lasts a month or so - I want something that can last 6 mo to a year. It can recharge from a USB connection, but only draws ...
David Ljung Madison Stellar's user avatar
1 vote
2 answers
168 views

Do I need NiMH discharge protection when load is only LEDs

I'm powering a bunch of LEDs using 3 NiMH cells in series. I don't think I need worry about deep discharge protection as the LEDs will switch off when the voltage drops below their forward voltage. ...
Mark Highton Ridley's user avatar
0 votes
1 answer
118 views

LTC4060 NiMH charger 1A

I'm designing a charger for 2 series NiMH batteries. After some research I came across the LTC4060. What I don't understand about this IC is how it is able to charge 1A over the small 0.25mm trace ...
Joggem's user avatar
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USB-C breakout board, using V and G with a NiMH charger am I doing this wrong?

I’m pretty new to electronics so trying to find my way around. I’ve purchased this breakout USB-C: https://www.amazon.co.uk/Chenyang-24pin-Female-Socket-Connector/dp/B00VJ944V2 And this NiMH battery ...
Stephen Jenkins's user avatar
4 votes
2 answers
3k views

What is the minimum safe voltage for NiMH batteries, if at all?

Is there a minimum voltage below which a NiMH battery shouldn't be discharged to? One of the contributors on this website writes 800 mV is where you definitely want to stop to avoid damage. There is ...
apadana's user avatar
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0 votes
2 answers
109 views

What is the purpose of this thing on NiMH rechargeable batteries ? Can't figure out what this component is or its purpose

What is the purpose of this thing on NiMH rechargeable batteries? I can't figure out what this component is or what it is for. I'm trying to change the batteries in a Hoover automated vacuum cleaner. ...
Mike_Ivan's user avatar