Over Charging?

[ratfink]

However, I charge my ipod the same way, also being plugged into the USB port.

The difference here is that your ipod will never supply voltage over the USB connector, so there are diodes that prevent the current back flowing. On the USB charger I don't think there is anything preventing it from draining ( I don't have one of them to check). You could always solder on a diode if need be and see if things change. Granted this shouldn't happen unless the switch in the battery isn't working properly.

I also tried leaving my computer on, but my computer goes into a sleep mode after so long of inactivity, usually 20 minutes.

A computer has several stages of sleep. USB isn't typically shut off until the computer goes fully into standby mode.

[ratfink]

If there are any battery gurus in here, please let me know if my information is incorrect.

I am no genius but I am an electrical engineer.

1) These batts are not "Smart" batts...they do not communicate with the charger to say "I'm full"..."I'm over-heating"..."I'm too weak to charge."

The charge pump is on the battery itself. I haven't actually took one apart but I believe the charger measures for a current drop to signal the battery being done (which may be why people anecdotal notice that leaving the battery on past green gives you more charge as it goes beyond the last 10% but the charger cannot tell).

2) A quality charger will charge the batt to 4.6 (4.7 depending on maker), then let the batt drain 10% before trickle charging back to 4.6. THIS IS WHAT MAKES A LI+ION BATTERY ACTUALLY BE "FULL".

Close but not 100%. The battery is not charged 100% then depleated to 90%, it is charged rapidly to 90% then trickle charged the remaining bit.

3) Most cheap chargers will take the batt to 4.6 then quit. So the battery is not actually "full" but is only at approx 70% of capacity charge.

Not necisarily. It's the batteries not the charger that determine how high they are charged, really cheap or older batteries typically are charged to 90%. Newer, non-dirt cheap batteries will make it to 4.7, but, it decreases the life of the battery so in many cases were the life of the battery is more important then the length of the charge, the are only charged to 4.6 regardless of the battery type. Charge pumps that do 4.7 are no more expensive then ones that do 4.6, though there is an expectation that if you have a cheap charger you will have cheap batteries but that isn't always the case.

4) Cheap chargers do not have "leak protection" to prevent the batt from draining back through the charger. I interpret that as "live ground depletion."

For AC, at the very least the rectifier should give some semblance of prevention of backflow. For DC like USB, who knows.

[puff-puff-pass]

Close but not 100%. The battery is not charged 100% then depleated to 90%, it is charged rapidly to 90% then trickle charged the remaining bit.


Not necisarily. It's the batteries not the charger that determine how high they are charged, really cheap or older batteries typically are charged to 90%. Newer, non-dirt cheap batteries will make it to 4.7, but, it decreases the life of the battery so in many cases were the life of the battery is more important then the length of the charge, the are only charged to 4.6 regardless of the battery type. Charge pumps that do 4.7 are no more expensive then ones that do 4.6, though there is an expection that if you have a cheap charger you will have cheap batteries but that isn't always the case.

Thanks for the clarifications

There is a new announcemet from MIT that they have discovered a way to recharge lithium batteries in SECONDS...not hours! THat would be freakin awesome. Unfortunately, it's a couple of years away.

[richard-]

OK....I am looking at building my own charger. So, I did a little bit of research and here is what I found (so far).
1) These batts are not "Smart" batts...they do not communicate with the charger to say "I'm full"..."I'm over-heating"..."I'm too weak to charge."
2) A quality charger will charge the batt to 4.6 (4.7 depending on maker), then let the batt drain 10% before trickle charging back to 4.6. THIS IS WHAT MAKES A LI+ION BATTERY ACTUALLY BE "FULL".
3) Most cheap chargers will take the batt to 4.6 then quit. So the battery is not actually "full" but is only at approx 70% of capacity charge.
4) Cheap chargers do not have "leak protection" to prevent the batt from draining back through the charger. I interpret that as "live ground depletion."

From your description, I would say that #4 above is your problem. If your charger has an indicator light to show when a charge is being applied, I would try to take the batt out first thing in the morning, then put it back in the charger for 10-15 minutes...watch for the charge light to illuminate. If it does show "charging", then hopefully that will get you back to 4.6v at >70%. If no charge is applied to the batt, then just use it as normal, but try to always remove the batt and avoid overnight charges.

If there are any battery gurus in here, please let me know if my information is incorrect.

Li+Ion batteries
Although lithium-ion is memory-free in terms of performance deterioration, batteries with exhibit what is referred to as "digital memory". Here is the reason: Short discharges with subsequent recharges do not provide the periodic calibration needed to synchronize with the battery's state-of-charge which is an internal curcuit of the Lithium cell. 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 charge will become increasingly less accurate. The same is true if the cells are excessively discharged, when a cell drops below 2.5v then it appears to be totally dead and will not charge through the standard charger. To bring the battery back to life it needs quick boost charging which will reset the battery to its initial state and allow it to work again as normal. Another problem with the batteries is if they are stored with a full charge and get hot (left in car or hot enclosed area above 45 degrees c, when this happens the battery cell may become unstable and discharge, if this happens the cell may not be reusable.

I often work with Li+Ion cells in both my work (Laptops) and Hobbies (Radio control cars). I have found that the best way to keep batteries in working condition is to charge to 75% and store in a room temp or below.
I have also resurrected batteries by refrigerating over night and then allowing to return to room temperature naturally. Hopefully this may help some of us who have a battery issue. I will be testing various batteries i have to see if they exhibit the same characteristics as those i use frequently..... I will post when info has been obtained. Thanks All, great forum

[CJsKee]

Not an egg timer...geta timer that you would use for a lamp. They can be had at any home depot, canadian tire, etc. Just plug in your charger, set the timer to turn off in 3 hours, then have a good night sleep.

Excellent idea! I've just asked in another thread if a battery could be over-charged...

Kee

[ApOsTle51]

If a lithium battery is overcharged it will go BANG !!!

Lithium cells cannot absorb overcharge like a NiMh or NiCd

http://www.e-cigarette-forum.com/for...ies-truth.html

[manoverboard]

Thanks for the post richard...now i can save some of my bad batteries hopefully

[RayJ1]

I have yet to disassemble one of these e-cigs but am tempted. One of the things that I have wondered is if these e-cigs have internal discharge circuitry built into them to stop over discharging the batteries? These single cells don't like to be discharged below 2.5 volts. This really hampers future performance and reduces lifecycle.

[ApOsTle51]

I have yet to disassemble one of these e-cigs but am tempted. One of the things that I have wondered is if these e-cigs have internal discharge circuitry built into them to stop over discharging the batteries? These single cells don't like to be discharged below 2.5 volts. This really hampers future performance and reduces lifecycle.

Yes they do Ray @ around 2.7volts and stops the charge @ around 4.2volts.

that's why when the LED on your 901 or supermini flashes 10 times , the battery has reached 2.7volts and needs recharging.

for e.g. the Intellicig evo usb battery charger is just a lead with a connector , no LED , No cicuitry. It relies soley on the batteries circuity to start and stop charge.

[lewnworx]

A little bit on batteries:

I'm fortunate, in that at work, we have a guy who handles all of our product verification (PV, not the juice) who used to be the head of battery quality for Sony's professional video products division. You know, the $80,000 camera's the networks do the news with? Yeah, that stuff. This dude has forgot more about batteries than most people will ever know.

First off, why rechargeable batteries eventually die:

Poor charging techniques. End of story.

Pro Batteries (like Anton Bauer HyTrons and Digital ProPacks, the jobs that cost up to $500 a pop) have very special circuitry in them. They have a PER CELL temp sensor, a PER CELL voltage sensor, and a PER CELL amp meter that measures, temperature, voltage and current draw on each individual cell. They have separate leads besides the voltage in that communicates to the charger the status of the temp, voltage and inrush current during the charge cycle. As the temperature of the cell goes up, the incoming voltage and current are throttled to prevent the cell from heating up. When the cell gets "full" the incoming current is throttled down next to nothing to keep that cell full. Each cell in the pack are handled independently.

The purpose of this is that in most batteries the cells are put in series to bring the voltage up to the total output needed by the pack overall. This is fine, except that when charging, a given cell will fill before the rest. If you continue to dump current into it, that cell heats up, causing a positive pressure inside the cell, which escapes via a phenomena called outgassing.

It is this outgassing that is the main cause of the eventual death of a battery, as some of the cell's operating chemicals (and thus curent capacity of the cell) is irreversibly converted to a gaseous form which leaks out of the cell and is lost forever.

The very high end batteries and chargers prevent this phenomena from occurring, but it's very expensive to implement. I can personally vouch for it's efficacy in that I have a pair of Anton Bauer bricks, which are ALWAYS on the charger when not in use, and have never been allowed to completely run down before recharging. They are going on 11 years old, and have been through over 2100 charge cycles (they batteries report the cycles and capacity at each charge). After 11 years of use, they still have over 98% of their original capacity. That's a good bang for the buck.

Now, as for the batteries in the ECigs? Not so much. There's no thermocouple, no onboard volt or amp meter (although in a single cell configuration you would technically only need the thermocouple to communicate to the charger since there's only one cell, and that could be read at the charging side).

The chargers are beyond cheap. I'm guessing the don't even do a current sense on the charge side, and probably only have a voltage sense to shut off the charging circuit, and furthermore probably don't have a "keep topped off super low current trickle charge" since to do so without harming the battery requires feedback from an on cell thermocouple to do it correctly.

So...

The batteries in our eCigs, unless they take on a far different (and vastly more expensive) approach are doomed to a very short life by design.

In my case?

I built my own USB passthrough. I put in a simple voltage divider network to get the voltage down to 4.2 VDC (I figured 5VDC that comes off stock USB was probably subjecting the atomizer coil to over voltage and premature burnout, and I didn't have a single resistor of the right value to use to get it down to 3.7, so I figured 4.2 was better than 5). For portable use I power mine off a APC mobile powerpack for walkabout purposes, and off USB when deskbound. I'm getting almost 3 days off a single charge on the APC unit, which keeps my usage on the eCig batteries down to the bare minimum (like when out in public where having the corded thing draws too much attention).

As a result, I'm going to guess my eCig batteries will last for quite a good while before kicking the bucket, instead of the days to weeks the heavy users here are reporting.

I've also noticed that with the APC unit and it's far greater current capacity, that the unit performs a LOT better in terms of vapor production than when running off the stock battery. For that alone, it's worth the geek factor.

Cheers,

Mark