Turnigy Accucell-6 problems

So I recently got a Turnigy Accucell-6 hobby charger to complement my Ultrafire 139.

Here's the problem, I used the LiPo charge setting to charge a single Ultrafire 18650 2400mah cell. I checked the voltage at start and it was 4.10v. when the charger signaled it was finished I checked the voltage and it read 4.14v.

Huh. So I tried it again. Kicked off again, and was "reading" 4.20V as the finished voltage. I tried another 18650. Same thing, kicked off at 4.14V, verified by my voltmeter(s).

I then calibrated it, and during the calibrating setting it was right on in reading the cell voltage at 4.14V.

I tried charging both cells in 2S mode, kicked off at "8.4v" but each cell read 4.14V. Checked them with 2 different DVM, same thing.

I then tried to "trick" the charger by under-calibrating it and it charged to 4.15v.

So I put both cells in the Ultrafire W-139 charger and it topped them both off to 4.20V at the end of the charge read by both of my DVM.

Is it acceptable for the charger to go to 4.14V? Seems like I am not getting a full charge or is this where I would ideally like to charge to to maintain my cells in tip top shape?

I don't feel like shipping this back to Hong Kong and it seems to be working fine. Any thoughts?

Hi sailah.

What charge rate were you charging the cells at?

A hobby charger will terminate the charge when the charge current, during the CV stage, drops to somewhere between 0.03C and 0.1C (where C=the charge rate).

The faster the charge rate used, the longer the CV stage will take. The slower the charge rate used, the shorter the CV stage will be. So, when a faster charge rate, eg. 1C is used, the charge will result in a long CV stage. When a slower charge rate, eg. 0.5C is used, the CV stage will be shorter. The shorter the CV stage, the higher the ending OC voltage of the cell will be, as it will receive more of the charge during the CC stage.

Also, the higher the charge termination current, the lower the ending OC voltage will be. So if your charger terminates at 0.1C, the cell will be at a lower voltage than when using a charger that terminates at 0.03C.

sailah said:

I tried charging both cells in 2S mode, kicked off at "8.4v" but each cell read 4.14V. Checked them with 2 different DVM, same thing.

Click to expand...

I seriously hope you were using balancing leads when you did this! If not, you run the risk of running into serous problems, as in ! Without balancing leads, the charger has no way of knowing what the voltage is of an individual cell in the string. While not guaranteed, this can result in grossly overcharging a cell and result in an explosion!

Don't charge Li-Ion cells in series without using balancing leads

Hope this helps.

Dave

Dave,

I think you may be on to something...

I was charging the 2400mah cells at 2.4A or 1C correct? Should I lower that down to 0.5C or 1.2A?

I do know about the balancing leads as I have some on order. I only charged them for about 20 seconds and it kicked off saying they were full anyways.

I may discharge the 18650's and charge at a much slower rate and see if I can get the voltage higher. Thanks for the tips.

Peter

It's worth a try, Peter. I think you will find that the cells will come off with a somewhat higher OC voltage. My Dynam Supermate DC6 typically charges cells to 4.16 Volts (OC) when charged at 0.5C. I can't remember exactly, but at slower rates, the cells come off a bit higher and at higher rates a bit lower.

The reason your WF-139 charges to 4.20 Volts, is that it is a CC only charger. Bad for the cells, but I suppose it does more completely charge cells. :sick2:

One thing I forgot to mention,

sailah said:

......Is it acceptable for the charger to go to 4.14V? Seems like I am not getting a full charge or is this where I would ideally like to charge to to maintain my cells in tip top shape?

Click to expand...

If you're not going to use your cells for a while, or are going to store them, you want to charge/discharge them to about 3.80-3.85 Volts. At this voltage (about 40% SOC) the least amount of oxidation will occur within the cell. Storing Li-Ion cells at either very low SOC or very high SOC promotes internal oxidation of the cell. In addition, I keep my unused cells in the fridge. This alone can reduce degradation of the cells by up to 70%.

EDIT: I should have mentioned, that by only charging your cells to ~4.10 Volts (as in using the "LiIo" setting), you can extend the number of complete cycles from 300 to as much as 1000. The only drawback is that the cells will only be about 90% charged.

Dave

acceptable sure. nessisary for that charger to do so? i donno.
but i can run a test here, i never thought about it because 4.20 (+- .05) is close enough

what Wires are you using to connect?
it keeps dropping down in current near the end as it should, then finnaly terminates, trying to reach 4.20. Hmm why it is everyone is so obsessed with 4:20 anyways :thinking:
I dont think it PAUSES to check a battery voltage, so the wire type and length would probably make some of the difference, the voltage it is using/seeing is both the charge and the battery.
and there is no very slow final topping stuff at very low currents, But i think there is in Balancing a set.

at the first of the charge it just jams the set current in, but doesnt voltage over 4.20
when the cell reaches higher voltages the rate goes down (continually)
and its reading mostly the battery voltage, when the rate drops, but the charge still exists slightly. (so you SEE 4.20 but the battery itself isnt there yet)
(geesh how do i say that right)
Terminate is done when the current goes low, and the voltage was being KEPT at/below 4.20 via current control. when the battery goes back to resting, it should read about what your saying.

sounds like a proper CC to CV , then when C goes below i think about 50-100ma it bails. (in standard charge modes)

so in engrish, it does Constant Current (CC) (voltage hasnt reached 4.2 so current set by user is used).
When the battery is reading high voltage (actually at that current) the current keeps going down ,
Once the current drops it is Basically having CV Constant voltage, current keeps dropping.
once current goes below some set ammount , at the (psudo) CV it then terminates.

Other chargers are Lock down connected, neer 0 Ohms resistance between battery and charge curcuit stuff, and will taper down much slower, and "top" off for a bit longer. have a lower Current value before terminations.
like your Fired charger probably never has a voltage above ~5 , and it does a psudo CC CV thing too, but slower and ends slower.

geez i think i finnaly said it right.
Freak that, it just keep lowering the current to keep it under the voltage. It is a digital current controlled "Max Voltage" , at a SET "Max Current" type alogrythm. you can do basically the same thing with a bench power supply.

So I tried the lower current method. Put both batteries in my M1X for 30 minutes to draw them down.

I have one on the Turnigy charger at 0.5A and it's been on there 45 minutes, 330mah added. Funny, the battery is COLD. When they used to charge in the Ultrafire, they were def warm.

I checked the voltage and it's at 4.18V and the charger isn't done yet. So I guess that's the answer. Glad I asked and glad you guys know way more about this stuff than I.

I'm not obsessed over the 4.20 now, but about 10 years ago i sure as hell was.:ironic:

Aside from not understanding how the whole charging thing works, I am mightily impressed with this Turnigy from Hobbycity. I scrapped a power supply from an old computer and it works great. esp since I just bought every size LiPo battery known to man, I'm glad I have a universal charger. Can't wait to build my balancing leads and a custom charging cradle.

Thanks for the helplovecpf

Where are you guys getting your Accucel-6's from? I've been looking on the HobbyKing web site and it's been showing out of stock for weeks now...?

I got mine from them like a year ago. I bought it from hobbycitys US warehouse... The voltage of mine is a little off. Charging termination is typically at around 4.15-4.17 not that bad. But when I discharge batteries its off by about .05v. Is there an online manual where you can calibrate this thing???

Mr Happy said:

Where are you guys getting your Accucel-6's from? I've been looking on the HobbyKing web site and it's been showing out of stock for weeks now...?

Click to expand...

there is a new better one.
mabey they even fixed the worthless fan

if i tossed more money into one, i would want Much Faster Discharge, the machine doing balancing is Coool.

i finish test, same thing, it finished at ~4.22 Charge & Battery voltage. then of course (old) battery went down to ~4.13v after that.
I have very short copper speaker wires going to strong magnet connection going at the time. (obviously didnt help)

set to lower current, and like you said it keeps plugging away. yaawwwn
after it slowly kept topping with this lower current rate battery read about ~4.18

I just charged an AW 10440 on my Supermate. It's about 2 years old (one of the older blue wrapper 320mAh ones), but has mostly been stored in the fridge @ ~3.80 Volts and 35-40F. I charged it @ 100mA and the OC voltage was 4.18 Volts. I think the OC voltage readings of charged cells will vary a bit depending on the size of the cell, how old it is and it's general condition.

VidPro said:

......why it is everyone is so obsessed with 4:20 anyways

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One reason that I like to have the capability to charge cells to 4.20 Volts is it's a lot more accurate when determining the health of LiCo cells. If you can't charge them up to 4.20 Volts, you have to extrapolate a bit. I use other chargers for this purpose, like the YOHO-122 for example. It almost always will charge cells to 4.20 Volts, but occasionally to 4.21 Volts.

Dave

hmm, i usually use this thing for balancing actual packs, which seems to take a long time. long enough that . . . but i think i should check that better too now.

balance 5000ma 14.4v pack, inital current 1.6amp
final resting voltages ~4.17 , variation +-.01 (meter accuracy .01
correction, the variation across cells was .02 without the +-
meaning it looks like this 4.18 4.17 4.16 4.17

lowered the current to .1amp yaaawwn, let it play with it for a hour
about same variation seen, teeney bit higher voltages
looks like this now 4.19 4.17 4.17 4.18
that was a waste of time

Mr Happy said:

Where are you guys getting your Accucel-6's from? I've been looking on the HobbyKing web site and it's been showing out of stock for weeks now...?

Click to expand...

I put myself on the email list and got an email probably about 2 weeks ago and ordered one right away. Got it yesterday.

jasonck08 said:

I got mine from them like a year ago. I bought it from hobbycitys US warehouse... The voltage of mine is a little off. Charging termination is typically at around 4.15-4.17 not that bad. But when I discharge batteries its off by about .05v. Is there an online manual where you can calibrate this thing???

Click to expand...

Jason,

If you unplug it, hold down the start & negative buttons, replug it in, it will start flashing. Put a known battery voltage to the leads and adjust the voltage from there. I've heard that it only calibrates the screen voltage. Here's a link to youtube.

http://www.youtube.com/watch?v=9hvR7dGAkEo

Mr Happy said:

Where are you guys getting your Accucel-6's from? I've been looking on the HobbyKing web site and it's been showing out of stock for weeks now...?

Click to expand...

I ordered my one three weeks ago and have just received a email that it has
shipped

Sorry for going OT

VidPro said:

Hmm why it is everyone is so obsessed with 4:20 anyways :thinking:

Click to expand...

Because it's the best time of the day?

I'm satisfied with the 4.18V final voltage I get from my Accucel-6 when using a .7C charge rate. I have verified that mine always holds a steady 4.20 volts across the cell (charging voltage) during the CV stage. Sailah, that is something that you might want to measure.

VidPro said:

there is a new better one.

Click to expand...

And that would be?

So one more quick question...

I'm discharging a fully charged 18650 Ultrafire. What I want to know is the capacity vs the claimed capacity. I am discharging at 1A. How do I calculate the capacity? My charger has a timer on it, as well as voltage (started at 4.17V and will terminate at 3.00V) and a climbing number which I assume is mah. Is this correct for determining capacity or do I need to do math?

Thanks guys

Black Rose said:

And that would be?

Click to expand...

i dont know, HobbyKing was e-mailing me about it (another turnigy).
also check thunder6 AC , connects to computer has software, runs on AC ($55 amazon and hobby places)
also the supermate AC , if you want EU plug . (same interface look style) like 45/70 said

still didnt see (cheap) one that does better than 1A discharge. The 50W max charge works for enough stuff.
some of them dont bother with 40mm fans that scream and die early (passive sync)