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Old Oct 29, 2014, 08:00 PM
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Originally Posted by RedOctobyr View Post
OK, I just did some quick testing with Detect Balance and End Current settings.

...

There are other settings which may be able to help speed this process. Such as "Balance Over Charge", but I have not experimented with that setting.
Hey Red,

I've found that Balance Over Charge can dramatically reduce "balance charge" time, especially when used with a lower-than-4.2V terminus voltage.

It would be interesting to see what your results for the above test were if you set it to the max of 50mV. For my larger-than-most 3S42P setup, in the final config, it (and some other settings) reduced a 24hr charge to an 8hr charge

-=dave
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Old Oct 29, 2014, 08:08 PM
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Originally Posted by mrforsyth View Post
When using different chargers to charge the same packs, the balancers within the chargers will effectively be fighting one another if they're not in 'agreement'.
Agreed, this is the main reason I was going to consider calibrating, if they measured as being close.

When I charge a pack on channel 1, then charge it on channel 2, I had the same thought you did, that one is now trying to re-balance/"undo" what the other one had done.

And I suppose that, for consistency in my charge logs, I could at least try and get the main voltages a little closer to each other. Heh, you may have helped talk me into tweaking the calibration after all...
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Old Oct 29, 2014, 08:16 PM
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For inexpensive hobby grade equipment, that's simply outstanding.
I agree. This is one area where I really have noticed a manufacture focus on: voltage accuracy

Of the 6 (not a huge sampling, yes) Junsi devices (1x 106b+, 2x 206b, 2x 308Duo, 1x Powerlog 6S), and the one 206b clone (Turnigy Reaktor 20A) I've had the pleasure of playing with, the voltage accuracy has been a surprising standout feature. Only on the 106/206 line did I even feel the need to calibrate, and even then it was to quell my own OCD tendencies

My flying buddy's TP820CD is a yardstick compared to my iCharger's micrometer, by comparison. I've seen the default final charge imbalance on the TP820CD be around 0.03v (indicated) in general. That said, while absolute accuracy isn't not so important (contrary to what so many on this forum tend to believe) it is still a testament to quality design where it counts.

-=dave
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Old Yesterday, 12:10 AM
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I agree. This is one area where I really have noticed a manufacture focus on: voltage accuracy
Could not agree more Dave, and precisely why I exclusively recommend iCharger and FMA PowerLab chargers to modelers who desire highest possible safety, accuracy, and charge performance.

The PowerLabs cannot be recalibrated by the end-user but are calibrated at the factory to extremely accurate tolerances, at least in my experience.

IMO, most would save $$ by investing in good quality gear right from the start rather than incrementally improving their equipment over time as needs and desire for 'more time flying, less time charging' grow.

Mark
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Old Yesterday, 12:12 AM
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Originally Posted by RedOctobyr View Post
And I suppose that, for consistency in my charge logs, I could at least try and get the main voltages a little closer to each other. Heh, you may have helped talk me into tweaking the calibration after all...
Not a bad idea Red, and not something that I've considered. I typically charge multiple packs in parallel so keeping charge logs is not something that is part of my normal process. If it were, I'd likely follow suit.

Honestly, I'm now quite certain that I'll do the same at some point now that you've firmly planted the idea in my head!

Cheers,
Mark
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Old Yesterday, 08:19 AM
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how can you recommend the dual port iChargers over PowerLab when the PowerLab 8x2 is made better for longevity and has better computer control of the settings?

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Originally Posted by mrforsyth View Post
Could not agree more Dave, and precisely why I exclusively recommend iCharger and FMA PowerLab chargers to modelers who desire highest possible safety, accuracy, and charge performance.

The PowerLabs cannot be recalibrated by the end-user but are calibrated at the factory to extremely accurate tolerances, at least in my experience.

IMO, most would save $$ by investing in good quality gear right from the start rather than incrementally improving their equipment over time as needs and desire for 'more time flying, less time charging' grow.

Mark
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Old Yesterday, 09:31 AM
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how can you recommend the dual port iChargers over PowerLab when the PowerLab 8x2 is made better for longevity and has better computer control of the settings?
I was unaware that I recommended one over the other...

They both have merits and I recommend iCharger and PowerLabs over other chargers. Some prefer iCharger features. Other folks prefer PowerLab features. I happen to embrace both.
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Old Yesterday, 09:51 AM
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I'm not sure if it showed 4.2 on the screen or not. It kinda caught me off guard by finishing so early and I wasn't looking at the charger. I will have to try it again and see if it shows 4.2. I would have to guess that it didn't show 4.2 because I literally got to it seconds after it stopped (notification was still going off) and it was at 4.15 already.
The other thing I forgot to ask is what size pack is this? Cell count, for curiosity, but the more important is mAh. And one pack, or multiple in parallel?

A 300mAh battery will likely show a larger voltage fall-back than a 5000mAh, even if charging at the same C rate, as the 300mAh has a higher internal resistance.
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Old Yesterday, 10:14 AM
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Originally Posted by snowwhite View Post
how can you recommend the dual port iChargers over PowerLab when the PowerLab 8x2 is made better for longevity and has better computer control of the settings?
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Originally Posted by mrforsyth View Post
I was unaware that I recommended one over the other...

They both have merits and I recommend iCharger and PowerLabs over other chargers. Some prefer iCharger features. Other folks prefer PowerLab features. I happen to embrace both.
Yeah, I didn't draw that conclusion from what you said either. I opted for an iCharger 308DUO mainly due to my desire to make as small and light of a high power charging setup as possible. I also like seeing all the cell voltages on both packs during a charge. PowerLabs are great, but they are a bit bulky.
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Old Yesterday, 10:16 AM
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Originally Posted by RedOctobyr View Post
The other thing I forgot to ask is what size pack is this? Cell count, for curiosity, but the more important is mAh. And one pack, or multiple in parallel?

A 300mAh battery will likely show a larger voltage fall-back than a 5000mAh, even if charging at the same C rate, as the 300mAh has a higher internal resistance.
It was a 4s 3700mah Revo pack. I still don't understand the fall back to 4.15... When I charge this exact pack on any of my other chargers they will charge to 4.2 per cell and when I check the voltage all cells are at least 4.19 for the most part. Some may occasionally fall to 4.18 but that is the lowest. This is all verified by external battery testers so I'm not just relying on the charger itself. I'm still wondering if it isn't just a setting I need to change or a calibration I need to do (if I knew how)? Thanks for following up.
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Old Yesterday, 10:30 AM
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The reason why your other chargers have higher resting voltage upon completion of charge is that they're effectively overcharging your packs. In order to yield a resting voltage of 4.20 volts/cell at completion of charge, the voltage at the main output of the charger must exceed 4.20 volts in order for any current to flow. As such, your iCharger is more accurately calibrated than your other chargers.

If you would like to recover the extra few seconds of flight time, you can remedy this by changing the termination voltage to higher voltage (e.g. 4.25 volts/cell) or change the 'Charge End Current' to ~5%. Both of these features are covered on page 16 and 17 of the 308B manual and will precipitate higher terminal resting voltage.

As others have noted, charging to 4.20 volts/cell causes higher voltage stress to a lipoly cell and will reduce the number of useful cycles. It's for this reason that many of us deliberately lower the termination voltage of our chargers to gain the benefit of greater useful life at the modest expense of slightly reduced flight times. My personal preferred termination voltage is no greater than 4.15 volts/cell.
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Old Yesterday, 11:54 AM
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I'm still wondering if it isn't just a setting I need to change or a calibration I need to do (if I knew how)? Thanks for following up.
As far as changing settings, yes, there are definitely things you can do that will get you closer to your target voltage.

Posts 4519 and 4529 weren't made *just* for fun on my part

Adjust the "Chg End Current" settings to "End Current AND Detect Balance", and if you want, lower the 10% to a lower % (say 5%), if you want to get even closer to your target.

And as Mark and Dave mentioned, Balance Over Charge may also help with this. I'm going to try and do a bit more testing with that when I get a chance, to better understand it.

Personally, I'd think there is no need for re-calibration. If the charger said you were at 4.20V/cell, and every other device you have showed 4.10V/cell, then you might need to calibrate. If everything agrees that your cells are at 4.15V (or whatever), then you do not have a calibration issue.

Calibration does not impact how close the charger gets to its own setpoints. It affects how the charger's readings compare with those of another device (preferably of "known" accuracy, otherwise you may not be sure which to trust).
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Old Yesterday, 12:23 PM
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Thanks Red, I'll give all that a try. Appreciate the help.
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Old Yesterday, 05:53 PM
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Originally Posted by mrforsyth View Post
As others have noted, charging to 4.20 volts/cell causes higher voltage stress to a lipoly cell and will reduce the number of useful cycles. It's for this reason that many of us deliberately lower the termination voltage of our chargers to gain the benefit of greater useful life at the modest expense of slightly reduced flight times. My personal preferred termination voltage is no greater than 4.15 volts/cell.
On my Bafang 750W mid-drive e-bike motor, instead of paying the $650+ for a 11Ahr 13S5P Panasonic 18650 25R cell professional pack, I bought 6x HK 4S1P 5A hardpacks for $25ea for a total of $170 shipped that I currently run 3 of in a 12S1P fashion, and deliberately charge them to only 4.1v in order to extend their life from 150+ to (hopefully) 800+ charge cycles, since lifetime is more important than capacity in an e-bike application.

I personally find the OCD everyone has around getting to 4.2V on the dot at the severe detriment of cell life and hardly any real usable capacity is somwhat humorous

You can see even on this old tired pack of reclaimed 18650 laptop cells I built, the usable capacity between a full 4.2v and 4.1v is just 400Wh of the total 8600Wh capacity, or just 4.7% (at the cost of orders of magnitude fewer charge cycles):
Word from ex-enlisted personnel is that US military charges Li-Ion to only 3.95v in order to extend battery life as long as possible since aquisition budget is so sporadic *shrug*

-=dave
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Old Yesterday, 07:21 PM
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That's really good information tungsten2k. I've been charging to 4.2v/cell for years as that's what the charger brought them to. With all the new batteries packs coming to market that claim 4.27 and soon to be 4.35v/cell, it's going to get even more confusing as to what level is appropriate. I usually only discharge to 3.6v/cell when I have telemetry enabled so going from 4.20 to 4.15 probably won't even be noticable. My Icharger stops at 4.2v/cell and the cells settle at 4.15v/cell which has been perfect for my needs. I might even change the Powerlabs charger to do the same.
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