Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Battery Charging

Status
Not open for further replies.

rednwhite

New Member
I am trying to charge 2 12V batteries (car batteries) but having read a lot of articles I am getting confused with terminal and charging voltage, what voltage would I need to charge them and what kind of currents?

Cheers
 

MikeMl

Well-Known Member
Most Helpful Member
In a nutshell:

A proper charger for lead-acid batteries does three steps:

(1) limit the initial charging current to a safe level specified by the battery maker, (and possibly to protect the charger itself)

(2) allow the battery voltage to rise to ~14.5V (2.42V/cell), hold it there until the charging current naturally decreases to ~10% of the initial charging current used in step 1, (could take hours to days, depending on state-of charge, the current used in step 1, and the A-H rating of the battery).

(3) then switch to the float voltage of ~13.2V (2.20V/cell, must be very accurately set, should be temperature compensated).


is the straight dope:

I do take issue with the following statement in that article:

"During the topping charge in Stage 2 that follows, the charge current is gradually reduced as the cell is being saturated."

Actually, all the charger needs to do is keep the voltage fixed at ~14.5V, while monitoring the current acceptance of the battery. The time to step from 14.5V to ~13.2V is after the current during step 2 drops below a few tens to hundreds of mA, depending on battery size.
 
Last edited:
Status
Not open for further replies.

Latest threads

Top