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Old Aug 05, 2014, 08:58 PM
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Storage Charge current limitation

The "All brands storage charge" seems to be limited to 10A total (5A for 2 packs) regardless of what you set in the preset with CCS or try and scroll to with the panel keys. My PL8 does not seem to have this limitation.

Thanks - Greg
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Old Aug 05, 2014, 09:20 PM
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Will Library Preset #11 (High Power Storage Charge) do what you want?

Glen
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Old Aug 06, 2014, 12:50 AM
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Originally Posted by gmarsden View Post
The "All brands storage charge" seems to be limited to 10A total (5A for 2 packs) regardless of what you set in the preset with CCS or try and scroll to with the panel keys. My PL8 does not seem to have this limitation.

Thanks - Greg
The Powerlab8's storage preset is capped at 10 amps, same as the DPL. As Glen described, use High Power storage charge for charging over 10 amps. You can just copy the library preset over the existing storage charge is don't expect to be using the storage charge for low currents.
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Old Aug 31, 2014, 01:30 AM
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I posted a slightly different version of this over on the icharger 4010 thread asking a different question at the end specific to that charger. But I am having the same issue with my DPL8. Here's the post:

"Ever since I got my 4010, I suspected that the pack Voltage screen reading was about 20 Millivolts high. To test this, I played with a single, near new Panasonic 18650 unprotected Lithium cell. As charge termination was approaching, I would probe and hook my Fluke 115 Voltmeter to the output connectors as they exit the case. At termination when the screen read 4.20x V, the Voltmeter would read about 4.18. I figured maybe my Fluke was a little off. But when I bought a DMMCheck 5 Volt reference, my meter was only 3 Millivolts low from the reference. Well maybe my reference is no good. After a few hours, the cells would be down stable at about 4.167 Volts.

Well yesterday, I received my brand new Agilent/Keysight 34461A, 6.5 digit, $1,100 bench DMM with a fresh calibration certificate dated August 14, this year. Even when the highest accuracy error is factored in, it will not affect the first 3 digits to the right of the Decimal place so the Millivolts displayed on the meter are absolutely correct. Today I performed the same test with the new meter and just as before, the numbers were the same - the charger screen reads about 20 Millivolts high and therefore, the charge terminated early when the setting was for 4.2V. So I cranked up the 4010 termination Voltage to 4.22 and at termination, the Voltage on the screen was 4.22 at termination and the Agilent read 4.200367. A few hours later, the cell was at 4.197."

Now for my DPL8 specific question: When I go in to raise the termination Voltage on the 1 and 2 S, non-balanced preset to compensate for the low termination Voltage, I can choose the 4.220 Voltage but the charger will not accept the change. Why is this and if it is a safety issue, why does it allow me to select a higher termination Voltage?

I know it's only 20 Millivolts but it really bugs me.
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Old Aug 31, 2014, 03:54 AM
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Originally Posted by BVH View Post
I posted a slightly different version of this over on the icharger 4010 thread asking a different question at the end specific to that charger. But I am having the same issue with my DPL8. Here's the post:

<snip>

Now for my DPL8 specific question: When I go in to raise the termination Voltage on the 1S/2S, non-balanced preset to compensate for the low termination Voltage, I can choose the 4.220 Voltage but the charger will not accept the change. Why is this and if it is a safety issue, why does it allow me to select a higher termination Voltage?

I know it's only 20 Millivolts but it really bugs me.
FMA folks do consider this a safety issue. and even though you have a selection higher than 4.2V as you found out you get an error if you try to select a higher termination voltage.

I suspect that the same range of voltages is used for all termination voltage selections for simplicity of programming the charger. It was a bit confusing to me at first too.

You could get around this limitation by constructing a charge cable that uses both the balance and main charge/discharge connections to the charger. Use the Accurate Charge preset and you can raise the termination voltage there.

Glen
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Old Aug 31, 2014, 01:44 PM
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Glen is correct. The unbalanced presets has more safety restrictions that the other presets. The default for the LiPo presets is to add 8mv to the balance set point. So there is a very slight bump being added already. Not enough to over charge the cells.

As for the calibration, this must be done with the charge cycle stopped. You cannot use DVM during the charge cycle as the charge voltage is higher than the actual cell's resting voltage.

Finally, all cells sag a little after the charge cycle has completed. Some more than others. To achieve a resting voltage of 4.2v the cell may need to be slightly overcharged, which is bad. Or you need an extended CV period. The Accurate Charge preset include CV termination of C/20 which gets you very close. But the difference in the pack's state-of-charge between 4.197 and 4.200 is negligible. Its also beyond the accuracy specs of either charger.
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Old Sep 11, 2014, 03:40 PM
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Just having some fun and learning how to use my new 6.5 digit bench DMM. It's an Agilent 34461A with a fresh traceable calibration certificate showing that 4 digits right of the Decimal is absolutely accurate. The 5th and 6th digits will have some error. I thought I remembered reading that the DPL8 charge was pulsed. While it is pulsed, as fast as my meter can catch it, it doesn't show the Voltage falling to 0, just fluctuating about 22 mV between high and low. Looks like it pulses at about 2 per second. Anyone with knowledge of how it really works, please chime in so I can learn the difference between what my meter shows and reality. I think I could have set my meter to read faster but forgot to try doing it. This might have shown a greater difference between the high and low Voltage readings. This is a Trend plot on a 350 mAh cell at about 25 mAh before termination on the DPL8. Termination was set to 4.20 with a C/20 termination point. I rigged a 1S balance harness and used it for this charge. Second shot shows 45 seconds after termination.

How long does the current flow have to be at or below the C/20 point for termination to occur?
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Old Sep 11, 2014, 07:29 PM
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As recall, the pulse length is 15us and occurs 20 times a second.
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Old Sep 11, 2014, 09:49 PM
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So I'd probably need an oscilloscope to see it. The meters read speed is no where near fast enough.
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Old Sep 11, 2014, 10:43 PM
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So I'd probably need an oscilloscope to see it. The meters read speed is no where near fast enough.
That's what I figured. Although your Agilent produces nice looking graphs!
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Old Sep 12, 2014, 06:14 PM
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I've always understood the termination method/symbol " C/10" and "C/20" as charge current setting divided by 10 or 20 meaning that if I set a charge current at 2 Ah with a C/10 then the charge will terminate at 200 mAh. I've watched my DPL8 and my old PL8 and they never terminated when down to that current flow. Is there some amount of time that the rate has to be at or below the figure to have the charge terminated with FMA products? On my icharger 4010 Duo, the charge is terminated almost immediately when charge current reaches C/10 or C/20 depending on how it's set.
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Old Sep 12, 2014, 06:22 PM
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I've always understood the termination method/symbol " C/10" and "C/20" as charge current setting divided by 10 or 20 meaning that if I set a charge current at 2 Ah with a C/10 then the charge will terminate at 200 mAh. I've watched my DPL8 and my old PL8 and they never terminated when down to that current flow. Is there some amount of time that the rate has to be at or below the figure to have the charge terminated with FMA products? On my icharger 4010 Duo, the charge is terminated almost immediately when charge current reaches C/10 or C/20 depending on how it's set.
There's additional logic applied to the termination setting. What can happen, especially at low currents is the required current level can bounce up a down a just a bit. So the termination will occur at the percentage of the set, plus a little time to ensure its not going to bounce back up. Its not a fixed time, and it varies based on the logic applied. The complete details of the algorithm are not public.
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Old Sep 12, 2014, 11:47 PM
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OK, got it. It's fun to know the inner workings where possible.
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