Here is a lead acid battery charger circuit using IC LM317. The IC here provides the correct charging voltage for the battery. A battery must be charged with 1/10 its Ah value. This charging circuit is designed based on this fact. The charging current for the battery is controlled by Q1,R1,R4 and R5. Potentiometer R5 can be used to set the charging current. As the battery gets charged the the current through R1 increases.
Lead Acid Battery Charger Circuit – [Link]
Making LED devices portable can be a little bulky due to the batteries. The Joule Thief solves that, by boosting a single AA battery’s voltage to a high enough level to light a LED. Check it out.
Joule Thief – use LEDs with only one AA battery! - [Link]
This project is used for charging sealed lead-acid batteries with a solar panel in small and portable applications. The charger will stop charging once a pre-set voltage (temperature compensated) has been reached, and resume charging when the voltage has dropped off. The load is disconnected when the battery voltage drops below 11V and reconnected when it gets back to 12.5V.
Solar charger for lead-acid batteries - [Link]
This article discuss how to make your own LiIon batteries using obsolete Li-Ion pack able to power a robot. The overall cost is about 10$ to build a 14.4V 2.2Ah Li-ion pack. Read about the procedure on the link below.
Making your own lithium-ion batteries – [Link]
This is a 9V power supply which will work even on power failure. It uses a rechargeable battery and regulators. A transformer with 15-0-15 AC volts output is required.
Battery Backup Supply – [Link]
This project is a tiny, lightweight LiPo battery voltage monitor/alarm system based on PIC microcontroller. [via]
This simple PIC project includes a simple A-to-D application that measures the voltage of a battery pack via a resistor divider network, compares it to a reference voltage (5v regulator) and then displays the battery voltage on 2 LEDs (indicating battery voltage strength).
Simple-Volt: LiPo Monitor System – [Link]
Lithium Polymer Batteries are a very common source of power today. Many electronics gadgets have one inside, and they have some reasonable features. I’ve bought great batteries, with different sizes and capacities for my electronics projects. So long I’m using this batteries, coming the problem: charge them.
USB Single Cell LiPoly Charger - [Link]
Instructables user AaronX621 writes:
This will show you how to replace the internal battery on your Sonicare Elite 7300. After having my 2nd one die on me within 3 yrs I figured out how to rip it apart and fix it.
How-To: Replace your electric toothbrush battery – [Link]
In this youtube video watch what happens when you overcharge a LiPo battery. As you understand a LiPo battery is extremely hazardous if mishandled. Please pay attention to the warnings for this type of battery!
LiPo Battery explosion - [Link]
This project shows how to wire a circuit able to power a device using a photovoltaic and recharge the backup battery from excess power of solar panel. Find out how the panel and battery is connected on the link below.
Solar Power Circuit with Rechargeable Battery – [Link]