Discharging cells with Imax B6 - some measurements and questions

8 posts / 0 new
Last post
gorann
Offline
Last seen: 9 years 7 months ago
Joined: 06/20/2011 - 09:37
Posts: 51
Location: Croatia
Discharging cells with Imax B6 - some measurements and questions

(Its probably clone charger, bought it from Dinodirect, without adapter) 

Ok, first in Q was blue Ultrafire LC 2400.

 

I connected everything, using magnets from HD etc, laptop power supply, selected program LiPo discharging 1,0A  3,0V.

I didn't charged battery with this charger, to 4,2V, but I charged it with ordinary charger and it had voltage of 4,06-4,07V

(it took me a while to find out that I must hold start button for 3 seconds to start the process) 

In some 10-15 seconds after start of discharging at 1,0A, voltage dropped to 3,60...

It finished in I dont remember how many mins, with result of 136mA...

After that I checked the voltage and it was cca 3,6 V

So, my reasoning is that this is not good program, so now I entered NiCd discharging program, (because on LiPo you cant enter voltage less than 3,0V) , and I entered 1,0A and 2,8V. 

Because blue cell is charging now, now I connected Trustfire flame with voltage of 4,10V. Ill let you know the result... (in fifteen seconds voltage dropped to 3,80V, and than it stayed there for a while. )

SO, my question is, what bottom voltage I can enter to get most relevant results? 

 

Can you comment on Trustfire flames (protected) voltage sag? (from 4,10 to 3,8V in 15 seconds?) Is it normal? 

Thanx in advance 

 

PS: What cables I need to connect this thing with computer? And where can I buy additional cables for it? 

Edited by: gorann on 02/21/2012 - 19:56
CheapThrills
CheapThrills's picture
Offline
Last seen: 1 week 2 days ago
Joined: 07/02/2011 - 10:45
Posts: 3651
Location: Suomi

In my opinion, the voltage on load is normal.

There can be variation with batteries that have lower internal resistance.

 

You can discharge cells down to 3,0V at least.

I usually discharge them to 2,7volts. None have yet been damaged.

CheapThrills
CheapThrills's picture
Offline
Last seen: 1 week 2 days ago
Joined: 07/02/2011 - 10:45
Posts: 3651
Location: Suomi

All batteries jump up on voltage, when the load is realeased.

I have seen voltages between 3,30V -> 3,6V after a discharge to 2,70V.

The cutting at 2,7volts means, the charger cuts discharge when voltage On Load reaches this point.

brted
brted's picture
Offline
Last seen: 30 min 29 sec ago
Joined: 01/12/2010 - 19:44
Posts: 2371
Location: Atlanta

Results sound okay to me. I don't think you'll see much additional capacity by charging the battery down to 2.7V instead of 3.0V, so why stress the battery that much? You will get more cycles with less stress.

I like being able to see the voltage, charge applied, capacity, etc. with a hobby charger. They are more complicated, but I like to know more about what is going on. And you find out there are a lot of bad batteries out there. That's why everyone gets excited when one turns out to have the capacity advertised.

brted
brted's picture
Offline
Last seen: 30 min 29 sec ago
Joined: 01/12/2010 - 19:44
Posts: 2371
Location: Atlanta

Unless you have some known good batteries, then it could be you have some really bad batteries. A real Trustfire Flame should give 2200mAh, but won't give quite 2400mAh as claimed. And now there are fakes and the new ones don't seem to be as good as the old ones. The blue one that claims 3800mAh? They're lying.

Jinx
Jinx's picture
Offline
Last seen: 3 months 3 weeks ago
Joined: 10/16/2011 - 11:35
Posts: 1130
Location: Just outside the EU :)

Buy decent batteries and try them, maybe just a couple of Senybor or Xtar. My results of £&@?fire batteries have been dire!

CheapThrills
CheapThrills's picture
Offline
Last seen: 1 week 2 days ago
Joined: 07/02/2011 - 10:45
Posts: 3651
Location: Suomi
I have measured everything between 1700mah to 2400 mah from DD Trustfire flames. Bad ones were fakes. That blue one, I recommend not rechargibg it anymore, its busted. About the same with the green 1000mah one, not a good result either. From random batteries, I have also gotten just few hundreds of mah's.
Shadowww
Offline
Last seen: 11 hours 25 min ago
Joined: 01/20/2012 - 19:09
Posts: 1343
Location: Northern Europe

Don't take in account under-load voltage you see on charger's screen - there's a good deal of vdrop going on with using magnet connections, thin wires, etc etc.

Measure voltage w/ multimeter instead (with discharge process still running, obviously)