Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

NiMH battery discharger
NiMH battery discharger
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
Thread Tools Search this Thread
Old 7th February 2013, 04:03 AM   #11
Andrew Eckhardt is offline Andrew Eckhardt  United States
diyAudio Member
Join Date: Nov 2005
Are you sure what to expect from deep cycling NiMH batteries? Most sources say it doesn't help anything, and not doing it ensures the dreaded polarity reversal never happens. You'd likely improve cycle life without deep cycling.
  Reply With Quote
Old 7th February 2013, 04:39 AM   #12
nattawa is offline nattawa  Canada
diyAudio Member
Join Date: Apr 2010
Location: Mississauga, Ontario
Originally Posted by Bradford336 View Post
Does C9 polarity not matter?
C9 is a 0.1uF ceramic or film cap, has no polarity.

Originally Posted by Bradford336 View Post
What would the V and A specifics be for D2?
D2 can be any generic LED of any color of your choice, forward voltage drop is usually in the range of 1.7V - 2.5V. When working with 5.5V +B, the voltage across R6 is about 3.5V, the current through the LED would then be about 3.5mA.

Originally Posted by Bradford336 View Post
...how the Q1-A is actually put into the schematic...
Q1-A is a power MOSFET, its source goes to ground, drain is at R4, and its gate is driven by the U1-A output.

Since the comparator LM139 is powered by the battery, its output goes between the ground level and the battery voltage. That works just fine with a 5-6V battery. However, if you use this circuit on different voltage batteries you need to take caution about a few things. The mosfet requires a minimum 4.5V across gate-source to turn on, the circuit may not work on batteries of a voltage lower than that. The mosfet can be damaged if 20V or higher voltage is applied across gate-source, you want to put in some protection when working with higher voltage batteries to limit the gate drive under, say 12V or 15V. The feedback resistor R3, together with R1, R2, and R7, give the comparator a hysteresis behavior. The hysteresis level is affected by the battery voltage as well. I would suggest a separate power supply, 9V or 12V, for the comparator and the voltage reference D1, if you want the circuit to suit various voltage batteries.
  Reply With Quote


NiMH battery dischargerHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Schematic for 12v NimH battery charger carlmart Power Supplies 7 10th September 2012 11:52 AM
Lithium or NiMH battery? formula 22 Equipment & Tools 0 30th June 2012 06:46 AM
Smart charger for NIMH Cyberzim Everything Else 4 25th October 2009 10:48 PM
NiMH break-in Prune Parts 21 13th February 2005 08:37 PM
NiMh Battery Charger? SkinnyBoy Everything Else 6 14th January 2003 10:59 PM

New To Site? Need Help?

All times are GMT. The time now is 09:29 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio