icharger calibration.. don't ignore it!

[nyc863]

I was privately tut-tut ing about how my new hyperion 5s packs were taking quite a while to get one of the 5 cells up to 4.20v .. thinking they had been built with cells that didn't match well at the factory.

Turns out .. my icharger 208b, actually both of them, had drifted out of calibration. One for one cell (under-read), the second one over-read one.

To fix this, I had to
a) upgrade the firmware (not so hard, just install the USB driver, then download and run the updater, download the 3.13 firmware and transfer it)
b) get a 6s pack and very carefully measure the voltage on each pair of balance taps starting at black and working along. I used a scope, but you definitely need something accurate to 0.01v, not a rubbish multimeter.
c) hold down the four buttons (turn on beep sounds if you haven't!) power up the icharger and release them after it beeps madly at you.
d) hold down stop to go to the monitor screen, plug in your 6s pack (or 8s, or whatever)
e) get to the voltage display screen, each voltage will be 4 digits no decimals
f) hold down the left 3 buttons and then adjust each delta in turn to match what you know is the voltage. In my case, one of the ports was over-reading by 0.05v, so it was pushing one cell to 4.24v ! no wonder it was taking a while at the end.
g) for accuracy you might want to do it again with a fully charged pack, re-measure, re-calibrate. Just to check the calibration is on the money at ~4.2v

all this info is posted in the rcgroups thread but there is a lot more to read through there. This is the guide for non-dummies

that's it.

Definitely worth checking now and again because if there is a drift, and you don't notice it, and it widens, you really could punish one cell.

I'm not sure if my ichargers (both of them) were out when new. I think not. I think they drifted as i only had this cell balance delay with the latest packs. For some reason the hyperions showed this problem up more than the turnigy 6s packs I was using.

[pqr]

Thanks for that. I Balance charged a 3S battery on my TP 1010C with 210C balancer, and then did the same on the 208B. The 208B showed one cell at 4.1v where the TP had shown 4.2v. I like the 208B so much I was blaming the TP,but you are right the 208B is wrong - I used a Fluke meter and a cheap Hobby King indicator which were both in agreement, nearly, with each other.

Will do the calibration as a matter of urgency.

Any ideas how often it needs doing?

[TJinGuy]

I would like to point out that a "non-rubbish" multimeter has a price tag of about $1000. So if you have anything less, then I would not attempt calibration.

I happen to have access to a lot of quality equipment and so I choose to see how close my 208B was. I used Fluke 45, a bench top high precision meter. I also compared it with a $200ish "True RMS" Amprobe meter but it was not even close to the Fluke, off by upwards of .05V from the readings of the Fluke.

Anyhow I found my charger to be very close to the Fluke's readings. At most it was off .004V on the cells, .05V on the Vout and .01V on the Vin. However the voltages did constantly fluctuate on the iCharger, so I had to sorta take an average.

[Mentalic]

I've had to calibrate all 3 of my ichargers at least once. Out the box they were spot on, after as little as 12 charges both my new 206b chargers had cell #6 drift out of calibration.

Also have a 1010b+ with about 700 10amp charges on it. Never noticed the calibration error when I used to run A123 cells because A123's can tolerate over charging just fine. But when I switched to lipos this winter I ruined a Lipo with it before I noticed the calibration issue. Finally noticed one lipo cell was always reading low and taking forever to ballance.. Only thing is it was not actually low on voltage...

Seems to me these units could benefit from some breakin at the factory. Still I like them for the high wattage but I'm not happy with the calibration drifting.

[nyc863]

one way of doing it, I think, is to run two known good 6s packs down to 3.8v, with half a flight, then connect the main taps and balance taps in parallel. this evens out any remaining difference in cell volts.
at that point every cell should be the same in voltage, so use it to calibrate the icharger.
the other way is to stick a label on the icharger and note what cell seems to always be last or first to get to 4.2 over all the packs you charge on it.
chances are that one needs the nudge.

[airnoob]

Dang it, it happened to my 208B just now. Plugged in a 6S to charge and noticed cell #6 was .08V lower than the others, IT SEEMED. Thought the battery had a failing cell. It took forever to charge that "bad" cell. Later, I discovered that this "weak cell" was charged to 4.26V. Then hooked up 2 6S in parallel. Same thing: cell #6 seemed low.

Sadly, the only voltmeter I have costs $14, though I have a GT Power charger. Don't know how accurate that charger is.

nyc863, how do I connect the leads in parallel? Connect the black balance wire with the black discharge wire? Then connect all 6 non-black balance wires with the red discharge wire? Thanks.

[nyc863]

to do it safely you need a parallel cable, which for every wire is like a Y with N connections into 1. (2 into 1 in the case of a "Y" diagram). So a Y balance cable and a Y main cable.

you said you already hooked up two 6s in parallel .. so you did it already?

[airnoob]

Yes, I've been parallel charging for a few months. I have parallel discharge and balance wire harnesses.

So, how do I "connect the main taps and balance taps in parallel"?

Thanks for the reply.

[nyc863]

yeah so if you are parallel charging you already are.

I'm not an expert, so this is just what I reckon. Take it as that advice.

so take two packs that are about half full each, connect them both to the icharger with the parallel cables and review the cell voltages.

I think they should be all the same give or take 0.01v even if the pack was charged with the faulty icharger and one cell was stuffed with more MaH because after a flight, the cells will be closer, and using two packs will average them all out even more.

If one is reading low (or high), then go into the calibration menu and change the odd one out.

Then charge them up to full, verify one cell (really, two cells) are not lagging a lot by the end (a sign that calibration may be out), then disconnect and let them rest, then reconnect individually, see if the icharger sees all the cells at the same 4.18v or so.

Yeah this isn't going to calibrate to less than 0.01v but it should fix any gross error. Basically if your lipo isn't old, or stuffed, all the cells should pretty much come up at the same speed and reach 4.19v/4.20v at the same time, and the icharger shouldn't be fixated one one and flash voltage (discharge) all the rest for the last 15 minutes of the charge.

[airnoob]

Sorry, I'm not getting this.

The charger is overcharging a cell to 4.26 because it is reading it low, taking 90 minutes to do what normally takes 40.

So I should:
Discharge a pack to make all cells almost balanced.
Plug into charger, recalibrate, and charge.
Repeat process until CV cycle returns to normal speed?

Thanks.

[TJinGuy]

Assuming the pack is not TOO overcharged, just run it. The risk is having the pack overcharged, not running the pack.

Removed: Looks like that won't work, sorry.

You can try to recalibrate the charger but only adjust the high/low cell. Leave the others as constants unless you have a very accurate meter.

---
As a note I recently compared my 2 iChargers. My 208B is over a year old and has charged about 800 packs, and my 206B is brand new. Both are running the current non-beta firmware. The cell voltages were both within .01V of each other at worst and mostly the same on all 3 packs I looked at. The IR values were almost exactly the same except for one pack that shows 1mohm difference on 1 cell. Seems both my chargers are in great working order, as expected.

[airnoob]

The pack is not grossly overcharged. 5 cells are around 4.19V. Cell #6 is 4.26V on 2 cheap meters; this same cell APPEARED .08V lower when I first plugged it in to charge. Again, cell #6 on 2 other packs APPEARED to be .08V lower upon plugging in as well.

I am discharging this pack and recharging with my other charger. This will be my baseline for recalibration. Not the best tools or methods.

Is it possible to rig up a harness to allow the pack to balance all 6 cells on their own without a balancer or charger?

[TJinGuy]

Originally Posted by airnoob

Is it possible to rig up a harness to allow the pack to balance all 6 cells on their own without a balancer or charger?

Not really unless you have a blinky. Of course yo can not use balance charge if you want. Just use "Charge" mode and it will not balance the packs.

Assuming you only have one cell that is out of balance, here is a way to check things out with a pair of 3s packs.
[ame]http://www.youtube.com/watch?v=SmwaJ2uTDxE[/ame]

[BorgeBorge]

Originally Posted by nyc863

f) hold down the left 3 buttons and then adjust each delta in turn to match what you know is the voltage. In my case, one of the ports was over-reading by 0.05v, so it was pushing one cell to 4.24v ! no wonder it was taking a while at the end.

On mine, I have to hold down the right 3 buttons.

[airnoob]

Thanks for the video, Chris.

Using your technique, the readings on my 208B were:
3.93 3.94 3.93 4.19 4.19 4.12
4.19 4.19 4.20 3.93 3.93 3.85

The reading on cell #6 is .08V too low, exactly as I suspected when I first discovered this problem. I won't worry about the other cells that are off by .01V.

Gonna recalibrate it now.

[TJinGuy]

Go ahead and recalibrate cell 6. Then repeat the process in the video see where you end up. Once you are happy with the results, carry on charging like normal. If you ever need to check it later, now you have a way of taking the battery out of the mix

[airnoob]

Originally Posted by Konrad78

On mine, I have to hold down the right 3 buttons.

You are correct, sir. The Right 3 buttons.

Thanks to you, Chris, and the OP, I got it now.

Why are these procedures not documented in the manual?

[JookSing]

Reviving thread for clarification.
So in the video, after the "test", does the icharger used in this video need to be calibrated or not?

[Gregor99]

Originally Posted by JookSing

Reviving thread for clarification.
So in the video, after the "test", does the icharger used in this video need to be calibrated or not?

No. The differences described in the test were attributed to a rounding error. Please be aware the process in the video is only a quick check and requires two packs and a serial board. If you need to calibrate the charger, you'd need to use good quality volt meter, not a cell checker.

[JookSing]

Thanks for confirming what I thought. Just wanted to be sure. Is there a video in English that details the calibration procedure in detail? There are a couple on YouTube but they are in foreign languages.