Schematic for 12v NimH battery charger - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th September 2012, 05:28 PM   #1
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
Default Schematic for 12v NimH battery charger

I have a 12v 4500mA nimH battery that I need a charger for.

I am not sure if it's easy or not to design a charger that might allow me charging them for now.

There two things I am not sure of: charger voltage and if I should use a series resistor, to allow 10% or 20% current only.

Any suggestions?
  Reply With Quote
Old 8th September 2012, 07:46 PM   #2
DUG is online now DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
Take a look at this. or search Digi-Key for others.

http://ww1.microchip.com/downloads/e...Doc/51648a.pdf
__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 8th September 2012, 07:53 PM   #3
diyAudio Member
 
Join Date: Mar 2001
Location: Brazil
I was thinking of something much simpler. Something like the Microchip project does need

a specifiic pcb board, which I don't know where to get, and several parts.

Not too easy, and probably not too cheap.

Something like this is probably closer to my idea:

http://talkingelectronics.com/projec...rgingNiMH.html
  Reply With Quote
Old 9th September 2012, 12:47 AM   #4
diyAudio Member
 
Join Date: Nov 2009
Location: Los Angeles
Quote:
Originally Posted by carlmart View Post
Something like this is probably closer to my idea:

Charging NiMH Cells
That will work but you have to monitor the charge status or you'll ruin the cells. I used to do that with Ni-Cads running 500 mA AA cells from dead to full in 20 minutes. The time I forgot to turn them off wasn't pretty.

G
  Reply With Quote
Old 9th September 2012, 02:35 AM   #5
diyAudio Member
 
Join Date: Jun 2011
Take a look at the LM317 datasheet, it shows a current limited voltage regulator suitable for constant current/constant voltage charging with a Max. 1.5A output.
  Reply With Quote
Old 9th September 2012, 04:26 AM   #6
DUG is online now DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
As counter culture says: "a current limited voltage regulator"

Or a voltage limited current source is what is needed for these types of batteries.

The simple resistor limited battery chargers were OK for lead-acid types.

My dad used to say: "A job worth doing is worth doing right."

Your choice.

Take care.
__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 10th September 2012, 08:40 AM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Ni-mH need more than just CCS limited and Vreg charger.
This works for lead acid and Nicad.

The new battery technologies need much more sophisticated charging.
Just read the extract from the post2 link
Quote:
2.2 FEATURES
The MCP1630 Low-Cost NiMH Battery Charger has the following features:
• Programmed parameters - modified in firmware
• Factory Settings:
- Preconditioning Charge Current =170 mA
- Preconditioning Threshold = 3V
- Constant Current Fast Charge = 1.35A
- Charge Termination based on delta - VBATT / delta time
- Charge Termination based on delta + TBATT / delta time, with external
thermistor installed
• Top Off Charge Current = 130 mA for 1 Hour
• Overvoltage protection (battery removed)
• Overcharge protection to prevent damaging the battery
• Overcurrent protection in the event of a shorted battery
• Battery reversal protection
• Input short circuit protection
• Overtemperature protection to prevent the battery from reaching too high a temperature
during charge
• Soft-start capability by holding the reference voltage low during power-up
• The MCP1630 Low-Cost NiMH Battery Charger has the flexibility to optimize the
charging algorithm for new battery technology, different battery chemistries or
different battery pack configurations
• Proprietary features can be added by modifying the firmware contained in the
PIC12F683
• The factory-programmed source code is available
• Ability to adapt to environmental effects, such as ambient temperature
__________________
regards Andrew T.
  Reply With Quote
Old 10th September 2012, 10:52 AM   #8
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
To charge NiMH safely you need manual intervention or overvoltage foldback or temperature rise foldback. They need more care than NiCd cells.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
NiMH linear charger? ribolovec2 Everything Else 6 21st March 2012 03:19 PM
Smart charger for NIMH Cyberzim Everything Else 4 25th October 2009 09:48 PM
12V Battery Charger for Car Wynand Everything Else 10 15th November 2006 11:25 PM
Looking for 9v battery charger schematic Nordic Power Supplies 2 31st August 2006 07:29 AM
NiMh Battery Charger? SkinnyBoy Everything Else 6 14th January 2003 09:59 PM


New To Site? Need Help?

All times are GMT. The time now is 12:37 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2