Does Impres refresh for Li-Ion make sense?

[mab]

I've noticed that once a month or so, my Impres chargers (mostly 4111's running 3.40) will decide to do a "recondition" cycle (yellow light). The recondition cycle is similar (to the user at least) to the initialization process, and takes time proportional to the capacity of the battery (up to overnight). I'm using XTS2500s and XTS5000s with a variety of battery types (NiCD, NiMH and Li Ion).

I understand why reconditioning is helpful for NiCd and NiMH batteries (which benefit from a periodic deep discharge), but it also does it (monthly or so) for my Li Ion batteries. My understanding of Li Ion chemistry is that they definitely do NOT benefit from deep discharge, and in fact should be topped up frequently for longest life. So what's the recondition cycle doing for these batteries? Is it a deep discharge or something else? And is it actually good for Li Ion batteries? If it's doing a deep discharge, I would think this would actually be shorten their life and reduce their capacity over time.

Anyone know?

Thanks

[escomm]

Yes but it does benefit from calibration so that the capacity readings shown by your radio are a little more accurate. As more cycles are put on the battery the calibration can get further off, to the point that it says your battery is dead but still has 20% capacity left, or that it says you have 20% capacity left but the battery is actually dead.

[mab]

Yes, I understand how doing a deep discharge periodically might help with more accurate *calibration*, but I'm asking about maximizing battery life and capacity, not about maximizing the accuracy of the battery meter.

Does anyone know what the Impres calibration cycle actually does (for LiIon batteries)? Is it actually a deep discharge? Because if so, doing it as often as the Impres chargers want do it seems like a terrible idea from the point of view of maximizing battery life.

[Tom in D.C.]

I have read Motorola advice about Impres equipment that says "over reconditioning" should not be done to the Impres battery. When my XTS or TRBO Impres batteries get run down to 50% or 60% I charge them with the red light running, which is a normal fast charge from where they are back up to as far as they'll go.

[escomm]

Yes, I understand how doing a deep discharge periodically might help with more accurate *calibration*, but I'm asking about maximizing battery life and capacity, not about maximizing the accuracy of the battery meter.

Does anyone know what the Impres calibration cycle actually does (for LiIon batteries)? Is it actually a deep discharge? Because if so, doing it as often as the Impres chargers want do it seems like a terrible idea from the point of view of maximizing battery life.

Since you don't want to believe me, why don't you take it from Isidor Buchmann? www.batteryuniversity.com

Although lithium-ion is memory-free in terms of performance deterioration, batteries with fuel gauges exhibit what engineers refer to as "digital memory". Here is the reason: Short discharges with subsequent recharges do not provide the periodic calibration needed to synchronize the fuel gauge with the battery's state-of-charge. A deliberate full discharge and recharge every 30 charges corrects this problem. Letting the battery run down to the cut-off point in the equipment will do this. If ignored, the fuel gauge will become increasingly less accurate. (Read more in 'Choosing the right battery for portable computing', Part Two.)

Again, the conditioning cycle in Impres is not for conditioning Li-Ion, which cannot be done. It is to ensure the calibration is more accurate and therefore more useful. Rest assured that the discharge is not a deep one and will not bring the battery below its cutoff for low voltage. If it did then the battery would be a brick and require replacement

[mab]

Escomm,

You misunderstand my question. It's not that I don't believe you, or that I don't think you're a smart person of goodwill. I'm asking whether anyone knows what the Impres calibration cycle *actually does in the real product*, not what might it potentially be doing if it were designed the way we hope it might have been.

I'm hoping someone here has actually measured its behavior or has access to a more detailed spec than I've seen.

Thanks

[tvsjr]

Escomm,

You misunderstand my question. It's not that I don't believe you, or that I don't think you're a smart person of goodwill. I'm asking whether anyone knows what the Impres calibration cycle *actually does in the real product*, not what might it potentially be doing if it were designed the way we hope it might have been.

I'm hoping someone here has actually measured its behavior or has access to a more detailed spec than I've seen.

Thanks

Dude, he's answered your question and provided references to answer your question.

Impres reconditioning of a LiIon battery does *absolutely farking nothing to the battery chemistry* other than putting one full cycle on it. LiIon doesn't develop the "memory effect" of NiCd and NiMH so there's nothing for the refresh cycle to do.

The refresh cycle simply recalibrates the battery's charge/discharge state, so that the capacity numbers given by the various impres-enabled devices (radios, chargers, etc.) are more accurate. Unless you're going to add an ammeter and the necessary logic to every portable radio (which won't happen - too expensive and too much space consumed), you have to make some inferences to determine the amount of battery capacity being consumed over time. Fully discharging/recharging the battery gets you back to a better-defined state, so the inferences being made are better.

This technique is used in all sorts of industries. In the broadcast television world, the Anton Bauer packs go through reconditioning cycles to refresh the digital battery gauge (in the case of Dionics which are LiIon - the older Hytron and Pro Pac batteries are NiMH/NiCd and their chemistry benefits from the recycle). In the PC world, laptops often recommend a "recalibration" cycle every so often to recalibrate the battery gauge.

In all of these cases, as escomm has already told you, the battery is discharged to it's standard end-of-life cutoff (LiIons should always have safety circuitry to prevent a true deep discharge, as this tends to make the batteries turn into small explosive devices) and is then recharged using the standard impres charging algorithm to a full charge state, again determined by the battery and charger algorithm.