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0
votes
3answers
69 views

Multiple source Smartphone charger pack

I am in no means a electrical engineer or student but i dabble. I have a project to make a BIG smartphone charger using multiple 1800mAH batteries. you can choose which cell to use and charge via a ...
0
votes
1answer
63 views

CR2032 alternative for higher current [closed]

I'm designing a small battery powered circuit which will draw around 50mA for a millisecond every couple of seconds. I was planning on using a CR2032 coin cell but have recently learned that a coin ...
0
votes
1answer
54 views

Can I replace D cell with AA cell in an electric train?

I have an electric train powered by 2 D cells. But they are quite cumbersome and I have only AA charger and a bunch of good quality AA rechargeable batteries. So I want to tweak my electric train and ...
1
vote
1answer
27 views

Inequal discharge across battery cell

I am looking into building my own battery management system, and I am beginning to understand the concerns of overcharging/discharging, overheating, and equal use of each of the cells. I am planning ...
0
votes
1answer
54 views

Parallel external supply to CR2450 coin battery

I have a temperature data logger which should be used within the time period of 1 year as according to the supplier the battery would be drained by this time. The logger has a program stored inside a ...
3
votes
3answers
781 views

Explosion in a battery

I recently joined a 9 volt cell and two 1.5 volt cells to get an output voltage of nearly 6 volt. For 15 minutes or so, the battery worked perfectly. It did not even show any sign of heating and in ...
14
votes
3answers
2k views

Lithium Coin Cell CR2032 battery specifications

I am using a CR2032 battery module to operate a BLE 4.1 module. The BLE radio for communication takes around 3.5ma to 5ma of current. But when I look at the datasheet of the battery (https://cdn-shop....
1
vote
1answer
243 views

What is the meaning of 25C?

I have a lipo battery of 11.1V,3s,5200mAH. What is the meaning of the 25C discharge current? How much current does it indicate? How do you interpret it?
-2
votes
1answer
318 views

Charging a 3.7 V with a 5V usb charger [closed]

For a project, I want to charge a lipo battery (3.7V @2000mah) with a 5V USB charger. I'm not into electronics, so I don't know if is viable to do that. So, can I charger a 3.7 battery with a 5V ...
0
votes
1answer
151 views

Powering a bbc micro:bit with coin cell batteries

Would it be possible to safely power the bbc micro:bit using coin cell batteries? Out of the box it requires x2 AAA batteries, although an earlier prototype did use cell batteries. I was wondering ...
3
votes
5answers
394 views

Testing Chinese CR2032 Li-ion Battery Capacity

I recently bought a lot of cheap CR2032 batteries from aliexpress. Since there is no manufacturer stated on the package or the batteries, I would like to know if these batteries really have 220 mAh or ...
0
votes
2answers
283 views

How to connect old 18650 different capacity cells as a 2S2P pack?

recently I've opened up a laptop battery pack and got 6 18650 cells and 2 of them were 0V and other 4 had 3.75V. so i fully charged them with a Imax b6 charger and discharged them at 1.0A to 3V and ...
0
votes
3answers
127 views

Will this OP AMP work for this application?

I designed the following circuit in CircuitLab. My question isn't about the whole thing, but rather about the TL081 Operation Amplifiers that circuitlab uses as a default(data sheet found here). ...
1
vote
2answers
60 views

LiPo/Li-Ion Cells in series max end-to-end voltage

I have wondered how many cells can be connected in series before issues may arise. I also wonder what specifications on the tech data sheet would allow you to decide which batteries are best for high ...
0
votes
2answers
96 views

Bike mobile charger

Hi, I've made a battery operated mobile charger using this circuit. I am able to charge the basic phones (with 2100mAh battery) with it. But the problem is, I couldn't charge any smart phones (with ...
0
votes
2answers
100 views

Ground Connection for circuit. [closed]

Here i am trying to light a single LED using a 1.5V battery. Forget About LED voltage rating. What i need here is , where will my ground connection go? what is the significance of that ground and how ...
0
votes
1answer
62 views

Re-attaching A Cable To A Circuitboard [closed]

I have a drone, but one of the cables connecting the battery to the circuit detached and I took it apart so I could have better acces to the circuit board. I know where the cable goes but my problem ...
0
votes
2answers
142 views

What can I replace copper with?

I and my friends were trying to make a salt water battery but we cannot find copper strips in our town so is there any other electrode that I can use to make our battery. We have aluminum foil (which ...
0
votes
1answer
64 views

Charging several phones in the field

There's an outdoor area I'm working on, and I want to build a small station where people can charge their phones. There's no access to house power in the area. I've looked into solar chargers, but ...
1
vote
1answer
63 views

Using/Substituting a Coin Cell Battery

I wish to run an MCU (for bluetooth to be specific) which commonly runs on a coin cell battery. I was wondering if it was possible to replace the regular CR2032 battery with the smaller and cheaper ...
4
votes
0answers
244 views

18650 LiFePO4 Cell UVP/OVP Under/Over Voltage Protection

The vast majority of existing ancillary protection IC's available (such as Seiko) are not compatible with LiFePO4 chemistry due to the lower operating voltage. And the few vendors selling iron-...
0
votes
2answers
84 views

Can a RC 7.2V 1300mAh Ni-Mh Pack be replaced by 6xAA 1300mAh Ni-MH in holder? [closed]

Can a RC 7.2V 1300mAh Ni-Mh Pack be replaced by 6xAA 1300mAh Ni-MH in holder ?
0
votes
1answer
73 views

Does one of the battery failure damages the UPS DC capacitor bank? [closed]

Last day i found the DC capacitor bank of the 300kva UPS was burst/damaged.Upon further inspection one of the battery in the battery bank found damaged .My doubt is whether the failure of battery can ...
3
votes
1answer
54 views

LiFePO4 lithium iron-phosphate cells - OK to dip?

I want to try epoxy-dipping a PCB with an 18650-sized LiFePO4 cell. This is for a low-power application and is slow-charged, so thermal is a non-issue. Before doing anything unforeseen dangerous, is ...
-2
votes
1answer
111 views

Equal charging of new and old battery [closed]

I am using four "12volt" batteries of 150 amp hour each, for a 24 volt solar backup system of ouyback things since four years. Now i add 4 new batteries of same capacity to increase the backup time ...
5
votes
2answers
555 views

5 year run time on small battery

I am working on a project that checks a sensor every 12 hours and reports the status via cellular modem to our server .. Power consumption is less than 1mA during sleep mode and spikes to 900mA ...
-1
votes
3answers
367 views

Why wont my 3volt LED light up with two 1.5volt Batteries?

I have two 1.5 Volt batteries, a Red 3V LED, and some cables. The batteries I have connected in series like +- +- From my studying I believe I should now have 3 ...
0
votes
1answer
148 views

12 Volt Solar Air conditionair

I saw a post on YouTube where somebody was able to make ice with a 90 watt solar panel, two 12 volt batteries, an ice maker (800 watt spikes) and 1000 watt DC-AC inverter. https://www.youtube.com/...
1
vote
2answers
1k views

How to charge an AGM battery fast?

I have a 12V, 200AH AGM battery. The maximum charging current recommended by the manufacturer is 50 amps. Now, I need to connect two AGM 12v batteries in series to connect to the input of my 24 volt ...
1
vote
1answer
101 views

How to calculate solar panel setup?

I have an equipment which draws 550W at a constant level, no peaks. I want to power this unit with solar cells only during the day when there is light using a simple car battery. Because I don't want ...
-3
votes
1answer
90 views

LM386 with power bank [closed]

I made a guitar amp using the LM386 and i power it with a power bank and a sparkfun usb breakout board but the power bank shuts down by itself after 20-30 seconds. I read it's because the circuit ...
0
votes
1answer
86 views

Discharge and Recharge of a battery [closed]

Under which value it is not recommendend to discharge a Li-Ion battery? How fully discharging battery affects a battery life? What happens if we leave a battery on charger, even battery is fully ...
0
votes
1answer
738 views

Laptop battery not working after replacing cells [closed]

I have a Sony VGP-BPS21A battery that I use to power my laptop. It is really old, like 5-6 years now and its cells have lost more than 50% of their capacity. As a new OEM is very expensive, hard to ...
0
votes
2answers
49 views

Use a li-ion battery at two different voltages

I scavenged a li-ion battery from a broken laptop. It is made of 6 Samsung ICR18650 cells (3.75V 2800mAh), parallels two by two so that the total pack is in fact the sum of 3 cells at 3.75V, so 11.25V ...
-5
votes
1answer
2k views

How many hours would a 38000 mAh powerbank will last? [closed]

i bought a 38000 mAh powerbank and to my surprise when I could only use it for a total of 6 hours and then I have to recharge it again. My battery's capacitu is 1 700 mAh. By the way I'm taking up ...
0
votes
2answers
321 views

Can someone explain the battery management schematic for the following robot?

This seems like a good start to build my own battery management system. Can someone explain how exactly is this circuit working? See link for full size image. Link to Full Size Image Link to Robot ...
0
votes
2answers
739 views

Estimate minimum discharge voltage in a laptop battery

The objective is to determine the best 18650 cells to replace the ones in my laptop battery. To do that, I need to know the minimum voltage the battery controller accepts before ordering the OS to ...
0
votes
1answer
1k views

How to turn-on laptop's battery pack after replacing cells? [closed]

After a few years of use, my battery pack finally died. The laptop doesn't even detect or try to charge the pack anymore. So I replaced the cells in the pack for new ones, but that didn't make it to ...
7
votes
6answers
10k views

How to calculate the maximum current a AA battery can deliver for a short period of time?

I want to measure the maximum current a AA battery (full charged) can deliver for a short period of time (let's say one second) I have in mind to do this with a multimeter : setup multimeter to ...
1
vote
1answer
210 views

If I have three button cells in series, and one of them dies, will the whole circuit still function at a lower voltage or will it stop flowing?

If I wire three button cell batteries in series, their voltages should be summed. Now, if a battery dies, let's say BAT3 for the sake of example, will the circuit ...
0
votes
2answers
14k views

What is a dead battery cell, what causes this to happen, and what are the implications?

Today I had a bit of car trouble where the culprit turned out to be the battery. I had driven my car just 5 minutes earlier without issue, but upon attempting to crank the vehicle it made a final ...
0
votes
1answer
77 views

DIY power 230v filament bulb off grid [closed]

I need to power a 230v bulb off the grid via solar power. Typically, I would have solar panels that charges some 12v dry/wet cells. These cells will have to supply an inverter that would power the ...
0
votes
2answers
278 views

avoid Li-Ion batteries explosion

As a student group project, we are going to use Li-Ion batteries to test our charging and balancing circuit. These batteries at risk of explosion. How should we avoid that danger? Is there any ...
0
votes
3answers
6k views

Replacing 18650 cells in laptop battery with greater capacity ones

My laptop battery died and I can't find a replacement (old laptop) so I'm going to need to replace myself the 18650 cells it has. It is an 8-cell battery (a series of 4 banks of 2), making the whole ...
0
votes
3answers
116 views

why does the model s use multiple batteries?

The Tesla Model S and NASA's Robonaut both use a battery pack that consists of an array of hundreds of battery cells. Why don't the engineers just create one giant cell?
0
votes
2answers
245 views

Fast rising voltage on lead acid battery while charging

I have a couple of 12V sealed lead-acid batteries, which I have to charge. But when I hook one of them on the charger at 12V/1A (the battery is 10Ah) the voltage from 12.6 drastically increases up to ...
5
votes
4answers
1k views

Developing BLE device. Questions

I am designing a bluetooth low energy device. It basically reads a sensor over I2C and collect data. You can check data in your phone whenever you want. I have two questions, one related with antennas ...
0
votes
2answers
477 views

Are BLE modules capable of working with a CR2032 battery? [duplicate]

I keep reading that the Bluetooth Low Energy modules are capable of working with a CR2032 battery for years, but their consumption is around 20mA and the max discharge of a CR2032 is around 3mA (200uA ...
7
votes
4answers
826 views

Connector Problem. How to conveniently connect with cell-phone LiPo batteries

Using a LiPo battery from sparkfun is easy as it comes with a molex connector on it. But how to conveniently connect to a LiPo battery taken from a cellphone? Soldering doesn't work on the exposed ...
-1
votes
1answer
85 views

Doubt regarding Combination of Cells

I was unsure of what the voltmeter would read: the terminal voltage of the top cell, or the voltage across the parallel combination of cells. I tried calculating both ways, but both give the same ...