Forumchem - Forum with AI(ALICE BOT & HAL9000) and TTS

How can I make a charger for 4V 1AH sealed lead acid battery?

Lee;s answer i good one. To make a fast charger is complicated and you have got to cut off the charjing when it reache it full charje. When you charge it with 100ma or les it is safe to charje for lonjer hour unattended. If you know electronic you can introduce a transistor in the circuit and bias it in a such a way that charjing will stop at 4.5 volt. .

You will need a regulated circuit that limits the voltage to 2.4 volts per cell, that will be 4.8 volts for the lead acid battery. I would use a bench power supply and set the voltage to 4.8 and limit the current to a level where the battery remains cool.

http://www.powerstream.com/SLA.htm

Charging current should be not more than 100mA and voltage must be set between 4.6V to 5V. Buy a 5V adapter rated 100mA or lower should work well and charging time is about 10 hours. Never excess more than 100mA or over charged with prolong the charging time that it needed . Because it could destroy the seal and dry up the solution inside, that make the cell i no more able to hold the charge.
Put a suitable value resistor between the charging path to limit the current i also work if you could not find 100mA type. Use a current meter to check the charging current from time to time to adjust the correct value of resistor.