Modifying a Micro-Heater for Rechargeable Cell Phone Battery Use

  • Thread starter Thread starter kylethedab
  • Start date Start date
  • Tags Tags
    Battery Cell
Click For Summary

Discussion Overview

The discussion revolves around modifying a micro-heater designed for AA batteries to operate with a rechargeable cell phone battery. Participants explore the safety, feasibility, and implications of using a Li-ion battery instead of NiMH batteries, as well as the electrical characteristics involved in such a modification.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant questions the safety of using a 3.7v Li-ion battery with the micro-heater, expressing concern about potential damage due to heating.
  • Another participant suggests that modifying the circuit with a resistor to adjust current may not be straightforward, emphasizing the relationship between voltage, current, and resistance.
  • There is a discussion about the implications of using higher voltage and lower current, with one participant stating that the heater's resistance will dictate the current drawn.
  • A participant points out that the energy capacity of the cell phone battery (3.4Wh) is lower than that of two AA NiMH batteries (approximately 2.4Wh), questioning the practicality of the modification.
  • Another participant humorously warns against the risks of using a Li-ion battery inappropriately, highlighting safety concerns.
  • Suggestions are made to consider alternative heating solutions, such as hand warmers, which may provide more energy than the proposed battery setup.

Areas of Agreement / Disagreement

Participants express differing views on the safety and feasibility of using a Li-ion battery for the micro-heater. There is no consensus on whether the modification is advisable, and multiple competing perspectives on the electrical principles involved are presented.

Contextual Notes

Participants note the importance of understanding the voltage and current ratings of the heater and the battery, as well as the implications of using different battery types. The discussion highlights the need for caution when modifying electrical devices.

Who May Find This Useful

Individuals interested in electronics, battery technology, and DIY modifications for heating devices may find this discussion relevant.

kylethedab
Messages
2
Reaction score
0
Hi! My brother has a small micro-heater that runs on a single AA battery. The battery life tends to be rather short so we started using rechargeable batteries. The rechargeable batteries are marked as 2000mAh and since they're AA and Nickel-metal Hydride I'm guessing they operate at 1.25v.

I want to mod it for use with a rechargeable cell phone battery. But I have a few questions about that.

1. The cell phone battery is marked as 3.7v, 930mAh, 3.4Wh and is a Li-ion battery. Is it safe to use a Li-ion battery? The NiMH batteries tend to heat up, will this damage the cell phone battery?

2. Assuming P=IV and V=IR hold true here, would I just have to add a resistor to decrease the current and send the same power to the heater? Is it really that easy?

3. Would there be any difference in sending a higher voltage and lower current to the heater if it receives the same power?

4. Given the cell phone battery is running with a higher resistance, would it last longer than two AA batteries? If its not, then this project isn't worth it.
 
Engineering news on Phys.org


88 views and no replies? :frown: Does anyone have any speculation on the answers?
 


kylethedab said:
88 views and no replies? :frown: Does anyone have any speculation on the answers?
What type of heater is it. I mean, what does it heat.

The short answer is no, it's probably is not a good idea to try and run that from anything too different from it's rated voltage, certainly not a phone battery. Post more details about the nature of the heater, especially it's voltage and current and/or power ratings.
 


Lithium batteries are brilliant but only when run as they are designed to. Steer clear unless you know what any particular battery is rated at and can present it with the right load.
BTW, you can't operate a simple heater with 'higher volts and lower current' because its resistance is what it is. More volts will give you more current (I=V/R)
Primary cells are actually pretty high capacity so they tend to last well - they just cost a bit to replace.
 


Your cell phone battery only has 3.4Wh. A 2000mAh AA NiMH battery has about 2.4 Wh. So why not use 2 NiMH batteries?
What do you want to use that heater for? You could also use a hand warmer.
http://en.wikipedia.org/wiki/Hand_warmer
A sodium acetate hand warmer weights usually 200g and releases 14 Wh of heat. More than 5 times the energy of a AA battery. A hand warmer powered by lighter fluid gives you even a lot more energy. Just a drop of lighter fluid releases more heat than a battery. (10Wh per ml)
 


You don't want his small brother setting fire to his pocket, do you? HAHA
 

Similar threads

The most suitable batteries for 4x5V motors 1.2A
  • · Replies 8 ·
Replies
8
Views
1K
How Can I Efficiently Build a Solar Phone Charger with Nimh and Lipo Batteries?
  • · Replies 5 ·
Replies
5
Views
2K
What Battery did Marty Cooper use in 1973?
  • · Replies 7 ·
Replies
7
Views
2K
How much current does a cell phone use?
  • · Replies 10 ·
Replies
10
Views
11K
Safe to charge a Lithium Battery with a Voltage Limit?
  • · Replies 2 ·
Replies
2
Views
2K
Could Connecting Two Cell Phone Batteries Charge A Camera Battery?
  • · Replies 10 ·
Replies
10
Views
5K
Build Solar USB Charger: Voltage & Current for Rechargeable Batteries
  • · Replies 11 ·
Replies
11
Views
5K
Creating a Cell Phone Charger from Batteries: Understanding the Process
  • · Replies 3 ·
Replies
3
Views
3K
Shopping advice: Solar battery charger and power supply
  • · Replies 5 ·
Replies
5
Views
2K
Seeking means of maximizing energy use from LiIon battery
  • · Replies 8 ·
Replies
8
Views
2K