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 20th June 2005, 08:47 AM   #1
diyAudio Member
 
Diy_Ambitious's Avatar
 
Join Date: Sep 2004
Location: NZ
Default Charging Lithium ion batteries

I got bored today and decide to open up a Compaq laptop battery pack, then I took out the 8 batteries in it. 4 of them measured 0.00 Volts and the other 4 still had about 3.5 Volts in them.

Some searches were done and from what I've read these batteries aren't like others that you can just put dc voltage in and charge away. Very little tolerance . I'll probably not use the batteries with 0.0 Volts cause I have a strange feeling about them shorting when charging.

So I would like to know a cheap and safe way to recharge these things so I can build something portable with them.

small pic, sorry it's not so clear. but I can write down what it says if needed.
Attached Images
File Type: jpg picture 001.jpg (6.2 KB, 274 views)
  Reply With Quote
Old 20th June 2005, 09:51 AM   #2
Bakmeel is offline Bakmeel  Netherlands
diyAudio Member
 
Bakmeel's Avatar
 
Join Date: Jan 2002
Location: The Netherlands
The only catch is a charge current limitation. do not charge the batteries with >0.5C, or currents more than half the rated capacity. Try to find some manufacturer data about the cells, because they look kindof standard. With the manufacturers data you know for example end-of-charge voltage, which is the max votage to apply, in order to avoid overcharging.

Do not discharge below 3.someting volts, or you will deep-discharge the cells. The 0V cells are useless.

Bouke
__________________
More Power Igor! More Power!
  Reply With Quote
Old 20th June 2005, 10:18 AM   #3
joensd is offline joensd  Germany
diyAudio Member
 
Join Date: Dec 2001
Location: Germany
Hi,
have a look at the LTC4054 lithium charger-IC.
You just need a handful of additional parts and are done with it.

greets
__________________
jens
  Reply With Quote
Old 20th June 2005, 10:34 AM   #4
diyAudio Member
 
Diy_Ambitious's Avatar
 
Join Date: Sep 2004
Location: NZ
Thanks, I didn't know batteries have datasheets

I tried various thing written on the cells, and with ICR-18650E
came up with this

http://24.237.160.4/files/Omnibook/L...DSA50147ba.pdf

I measured my cells dimensions (size) and it's arond 1 mm off, weighed around 50 grams, and also have to word "MOLI" on the cells themselves. So it's probably safe to say they are the same one as in the datasheet.

Now, how can I get a 4.2V supply with such a low tolerance . Does current have to be regulated as well ?

I just did a search and cannot find even 1 "LTC4054" IC in NZ. Ordering from overseas is the last thing I want to do. A "play around" on a weekend turns into a misson
  Reply With Quote
Old 20th June 2005, 01:40 PM   #5
Bakmeel is offline Bakmeel  Netherlands
diyAudio Member
 
Bakmeel's Avatar
 
Join Date: Jan 2002
Location: The Netherlands
These are probably equivalent to the Sony CGR 18650 Cells, and they are very standard indeed

Any 4.2 Voltage regulation principle would be sufficient in this case, so try something easy like LM317 or an other voltage regulator. The Only tricky thing is that you will have to limit the charge current to the 0.5*Capacity value. If I recall correctly, this is somewhere around 0.75A

An LTC4054 is the easyest to go, an alternative is the ISL6294 from Intersil. I myself did it with solid state, but that may become a bit complex.

Good Luck
__________________
More Power Igor! More Power!
  Reply With Quote
Old 27th June 2005, 02:36 PM   #6
diyAudio Member
 
Join Date: Jun 2005
Location: Pennsylvania
Send a message via ICQ to sndscietist Send a message via AIM to sndscietist Send a message via MSN to sndscietist Send a message via Yahoo to sndscietist
this is a very confusing post indeed, i myself have torn apart mercilessly many many camcorder battery packs and collected a staggering number of LI-ion batteries, i can honestly say i have never had a problem charging them. my latest creation with one was as a battery backup on a alarm system i was designing for automotive use it utilizes a panasonic CGR18650HG. this goes against everything i have read but it charges up to 4.25v in a little over 6 hours and retains it for like 3 days or so with load. all i personally used was a 5 volt regulator and a 5 watt 10 ohm resistor. keep in mind it's torment for the regulator because not only does it charge the battery but it drives the entire circuit.
  Reply With Quote
Old 27th June 2005, 03:03 PM   #7
jc2 is offline jc2
diyAudio Member
 
Join Date: Dec 2001
Location: Atlanta, Georgia
18650 cells are an industry standard and made by most every manufacturer that makes lithium Ion batteries. There can be a wide variation in performance between 2 manufacturers, even in the charging voltage. Your cells are made by Moli, while not being one of the companies I consider to be leading the pack, they are well made.

The cells that have 0 volts should be disposed of, when a lithium Ion cell is deepely discharged it will plate lithium metal onto the anode. Lithium is highly reactive and can make the cells unstable and dangerous. For charging the others, you should use a 4.2V constant current-constant voltage charge circuit. The reason that cell manufacturers call for such a tight tolerance is that any charge voltage increase over the 4.2V will decrease the cycle life and might bring the cycle life out of spec. if you can't meet such a tight tolerance on the charge voltage, decrease the volatge to 4.1 or 4.0V, you'll lose about 5% in overall capacity, but that really isn't too noticeable. Figure out what tolearnce you can keep and adjust the set voltage down until you can keep the maximum voltage below 4.25. Charging them with volatges above 4.3 can start to create safety issues, different manufacturers will behave differently in this regard, but there is a reason why lithium Ion cells are designed to be used with saftey electronics that have over voltage protection that kicks in around 4.3V.
  Reply With Quote
Old 10th November 2009, 08:54 AM   #8
diyAudio Member
 
Join Date: Nov 2009
Hello
18650 lithium ion battery 14.8 charger circuits
please
  Reply With Quote
Old 10th November 2009, 01:30 PM   #9
star882 is offline star882  United States
diyAudio Member
 
star882's Avatar
 
Join Date: Mar 2007
Charge them to 4.1v with a current limit such that they charge in over 2 hours. They'll last longer that way. There are many charger chips that can be set for 4.1v.
__________________
"Fully on MOSFET = closed switch, Fully off MOSFET = open switch, Half on MOSFET = poor imitation of Tiffany Yep." - also applies to IGBTs!
  Reply With Quote
Old 23rd January 2013, 11:44 AM   #10
blmn is offline blmn  Brazil
diyAudio Member
 
blmn's Avatar
 
Join Date: Feb 2001
Location: .
Hi,

I just bought an 18650 battery (3800mAh capacity) and tried to charge it using a 4,2v current limited (400mA) circuit, but actually the battery charges at a very low current (<30mA) and achieves 4.2v, but is not capable to deliver significative current to the load.

When I measure the voltage at the terminals is ok, more or less 4,2v, but when I connect the load (8 ohms resistive) it goes down to 0,5v.

Any clues about the problem in the charge process? I didnīt find additional info searching the net.

regards,
  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
Charging batteries with a variable power supply jacquesl Power Supplies 4 13th March 2013 07:52 PM
Charging batteries with a variable power supply jacquesl Power Supplies 4 14th April 2007 06:25 PM
smart way to charging batteries. hacknet Solid State 26 28th November 2003 05:43 AM
charging 3x 12V batteries in series. RichJones Solid State 7 24th September 2003 10:10 AM


New To Site? Need Help?

All times are GMT. The time now is 01:39 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2