Ultrafire charger overcharging cells?

I noticed my cells read up to 4.3 V after charging them with the ultrafire li-ion charger. Has someone else noticed that?

As far as i know, this is not healthy for the cells. I dont want to destroy $100 worth of cells with a $16 charger...

For 3.6v RCR123 cells that voltage is exactly correct with my chargers too.

4.3v charged is the norm using my soshine chargers.

Only thing to worry about, can your bulb, incandescent or LED take that voltage, which will reduce a bit under load.

I have notice the same thing with my Ultrafire charger. At the time the LED switch to green the cells read 4.2 - 4.25V.
If I leave the cells in the charger over night the cells read up to 4.35V!
This is really high for Li-ion and will significant reduce the cycle life!

What standards have you folks used to establish the accuracy of your meters?

c_c

Curious_character said:

What standards have you folks used to establish the accuracy of your meters?

c_c

Click to expand...

Perhaps we all bought our meters from the same shop, so they must all be inaccurate !! :lolsign:

I have several meters, battery testers, DMM's, and they all read similar voltages, off load, off charge.

Hello BBL,

Li-Ion chargers are supposed to shut off at the end of the charge. It appears that these chargers continue to trickle charge after the green light comes on.

Trickle charging after the full charge is not healthy for Li-Ion cells.

4.200 volts was chosen as a full charge in an effort to balance capacity and cycle life. When you charge to 4.200 volts you can expect 300 - 500 cycles from your cells.

If you charge above 4.4 volts, you are very close to the voltage that triggers rapid venting with flame.

If you charge to 4.3 volts, you will get roughly 18% increased capacity, but your cycle life drops down to roughly 10 - 20 cycles, or less. I don't think this is a worthwhile trade off.

Continuing to trickle charge at the end of a charge cycle, and charging to a higher voltage bring you closer to a rapid venting with flame incident. I prefer to use a charger with a "proper" charging algorithm. It may initially cost more, but my cells will last longer and in the end, it may actually save me some money. On top of this are the safety issues.

Tom

Life is too short to have to babysit one's charger. SilverFox, is there any chambered charger--you know, that doesnt' require alligator clips--that lets you set it and forget it? Perhaps the newest Pila charger?

Hello Paul,

I use the new Pila ICB charger and it seems to follow the Li-Ion charging algorithm very well. Keep in mind that if your cells are lower than 600 mAh, it will be charging at over the 1C recommend charging rate.

Tom

If your meters actually are correct, then I think you're risking the lifetime of your Li-ion cells by charging them to 4.3 volts, and maybe even risking fire or explosion if it can get any higher. Here's some general information:

http://www.batteryuniversity.com/partone-12.htm
http://www.powerstream.com/li.htm
http://www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_LiIon_Charging.pdf

4.2 volts is the recommended charge end voltage, and 4.3 is the recommended backup safety limit to disconnect the charger in case of an internal failure.

c_c

I think we need a larger sample than 3 peoples experience.

In the olden days we had to modify Li-ion chargers to go up to 4.2v with ye olde resistor trick. By decreasing resistance instead (adding a trimpot in parallel would probably be easiest) perhaps initial voltage could be reduced to 4.1-4.15v (and thus hopefully terminal voltage to 4.25v tops). You'll obviously have to check to see if it doesn't work and still eventually gets to 4.35v, but it's probably worth trying to salvage the charger considering the low cost of a trimpot.

My Ultrafire WF-139 will charge my unprotected 14500s way past 4.2 volts if I leave them in there too long (4.37v is the highest I've seen). Tenergy protected 18650s get to 4.2v exactly, and AW protected RCR123 (the new black ones) get up to 4.15v.

I have the Ultrafire charger and mine would terminate at 4.1/4.2 but I removed the cell when the light turned green.
I later purchased the Pila charger after reading some posts from Tom and I can tell you that I love the Pila charger. Guess you get what you pay for sometimes.

just read this thread getting worried im going to test my batts and let you know results. john i have the wf-139 gharger AW 18650 AND AW RCR123 CELLS. I also have a good meter ISO TECH -IEK 67

abvidledUK said:

I think we need a larger sample than 3 peoples experience.

Click to expand...

OK, how about four?

I checked a couple cells after charging with the Ultrafire and it was OVER 4.4!!!
Looks like we may need to sit with the batteries and babysit the cheap charger.

Anyone know of a "good" charger that will not cost a week's wages?

4.35 volts seems perilously close to putting the "FIRE" in "UltraFire"

If they are protected cells, I would have thought the overcharge protection should
have kicked in before it got so high. Is that faulty too?

way back not too long ago... before all this li-ion madness started and R123 was still a twinkle in JSB's eyes. Li14430 with it's dougS custom made charger was news.

had a few conversations with dougS concerning most cheap li-ion chargers. his take was most inexpensive li-ion chargers would not truly terminate charge at 4.2v, but would continue to trickle charge long at you left cell in charger. left long enough voltage would raise to dangerous levels. unless cell is protected like pilas. li-ion cells have no peak and will accept current for long as you deliver it to cell.

this is the reason I've always tried using a quality charger like Triton and soon to be Schulze for li-ion cells. don't want to catch my house on fire.

No wonder few women are mad enough to join our hobby. They have too much sense.

SilverFox said:

Hello Paul,

I use the new Pila ICB charger and it seems to follow the Li-Ion charging algorithm very well. Keep in mind that if your cells are lower than 600 mAh, it will be charging at over the 1C recommend charging rate.

Tom

Click to expand...

Thanks, Tom. Based on your post, I've just ordered one of these Pila chargers.

Hi Tom,

I just got this from Pila's website.

Pila IBC™ 4-stage Charger

Charging process

Stage 1 – Automatic analyzing battery status
Stage 2 – Quick charge
Stage 3 – Slow charge
Stage 4 – Standby mode, trickle charge

Since it trickle charges at the end, does it mean we can't leave it unattended?