Originally Posted by LeCig

Powder/Jelly doughnuts are a programmer's best friend

Originally Posted by Rocketman

We, the consumer, also tend to abuse and use products outside their designed (not advertised) parameters Driving 90+mph, tuning for max horse power, spinning tires, drifting corners, stereo turned up to max feeding several custom speakers, and then complain about poor product quality and service life of our abused automobile has nothing to do with as-delivered product quality. Some owners must think if the key and gas pedal in our car work then all must be well under the hood.

Originally Posted by tek

wow..
that was VERY well put.
i read every word, and mind you i am not a average consumer but...
that was great
so was the beer and 36 mg juice....

Originally Posted by Rocketman

Here's something that maybe Steam can research for us.

I've taken a few Dell and Lenovo battery packs apart to use the protection module to build 3S Li-ion packs (flashlights). I've noticed that the modules cut off the charging current when any cell reaches 4.35 volts. I know there are some newer Li-ion cells made for 4.3 to 4.35 volt charging algorithms but these were somewhat older packs. Discharge also cuts off at 2.5 volts for any cell. The packs were 3S3P with 9 18650 cells.

My guess is that with the high rate of charge used the 4.35 volt cutoff accounts for cell resistance and would detect a high resistance cell and cutoff charging as even more protection. A bad cell that had developed a higher than normal cell resistance would not show up with a very low charge current. This method stops charging when the weakest cell voltage climbs and stops discharge when the weakest cell (maybe a different one) drops. These modules don't seem to be really 'balancing', just monitoring and controlling charge and discharge.

After charging was terminated by the module, cell voltage quickly dropped to about 4.20 volts. You only see the 4.35 volts if you are watching while it charges. I'm sure there are smarter charge modules used in some laptop packs, including those with serial number lock outs, that have a more complicated alygorithm, but this seems to be different that the CC/CV method recommended everywhere. Strange that many name brand laptop manufacturers use the 'hit it hard' method.

Back in the day, it was common or a NiCad rapid charger to hit cells really hard and test for voltage droop to switch to trickle charge.


Steam,
have you seen this with the Dell packs you have around.

Originally Posted by Rocketman

Good and Bad Li-ion cells, my 0.02 about quality.
The Japanese have long been known for pioneering quality analysis methods, with the primary objective of cost/profit, not really quality as many seem to think. Even the “best” Japanese manufacturers will stop improving product quality when monetary returns seems be peaking. Shareholders will demand it. Quality control used to mean lot acceptance inspections to cull out poor product but now means monitoring the entire process from raw materials through assembly and finally to final product sampling. The old method can detect an unacceptable (dollars and cents related) failure rate but can do little to improve the process but process monitoring and control can detect and cull out defective product earlier in the process, saving manufacturing dollars wasted in later build steps. The “worst” manufacturers will monitor profits and spend more on process quality only when the “return” rate is expected to impact “future” profits. If sales profit margins are climbing, then process improvements are unlikely. Even then, old lots may be sold off wholesale at greatly reduced prices to fund the process improvement rather than be culled out at the manufacturing level. Like the automotive and consumer electronics industries, the technology exists to produce a very high quality product, but cost would be prohibitive. It’s usually left up to company management to rule of the cost benefit for process improvements.

We, the consumer, are often misled by branding, advertising HYPE and initial cost. We like bargains, but we are bad at math. A Li-ion cell that costs half as much as another, but has a lower initial performance, shorter lifespan, and higher DOA failure rates may or may not be a bargain. For example; purchase 1000 brand “A” Li-ion cells and 1000 brand “U” cells. Initial (as delivered) DOA rates might be 0.2% for the brand A cells, and 5% for the brand U cells. Useful service life for the brand A may be twice that of the brand U cells, and in-service failure rates twice as high for the brand U cells. It would be necessary to know these types of product performance criteria to evaluate the true cost of two brands, but there is a compromise point in cost that would make one a better deal.
We, the consumer, also tend to abuse and use products outside their designed (not advertised) parameters Driving 90+mph, tuning for max horse power, spinning tires, drifting corners, stereo turned up to max feeding several custom speakers, and then complain about poor product quality and service life of our abused automobile has nothing to do with as-delivered product quality. Some owners must think if the key and gas pedal in our car work then all must be well under the hood. Few perform all required maintenance to improve service life or detect performance degradation. The same is true with battery operated “toys”. Use it until it stops working, throw it out. The casual consumer is setting himself up for failures by ignoring early warnings of impending failure or being ignorant of maintenance requirements, whereas the typical “Hobbyist” puts himself at risk on purpose. The inconvenience of cell failure, an intangible cost in some cases can also be minimized be minimal testing by the end user with pre and post charge voltage checks, and periodic load testing to monitor cell degradation to reduce the inconvenience factor of cell failure. Just like your car, the true cost of abuse and lack of maintenance of Li-ion cells may be more than just the cost of a replacement. It may involve your safety.

I have an old IBM laptop with a Li-ion battery pack that I use in the shop to record various test data. This old computer has the capability to display its own battery voltage and charge/discharge current and tells me when the battery pack isn’t performing up to snuff. The 8 hour life of an old pack had degraded to about 4 hours. Replaced it with a cheap clone pack that seems to perform OK for now but I will monitor pack performance. Anyone think I can salvage some “high quality” Japanese 2200mah cells from the weak pack? (5 year old, heavily used, degraded high quality cells?). Not me, but I hear about others doing it. How about drawing excessive current, over the true design limit, from batteries, or leaving batteries on the charger for days on end, or storing Li-ion cells fully charged in a flashlight for months so they will be ready when you need them (or NOT periodically recharging Ni-cad, and Ni-mh cells for months, letting them discharge completely for that matter). Combining cells into strange series and parallel configurations without periodic testing for weak cells or imbalance is unsafe. My old laptop (with a 3P3S Li-ion pack) does a better job than most human battery users as far as battery safety. How many battery powered devices around you have that type of safety monitoring? Maybe a better question would be, how many potentially dangerous battery powered devices do you have that you properly use and maintain, and test? How would you rate product quality now that you’ve had your filthy hands on it?

Just what are the periodic maintenance requirements for Li-ion cells and packs. Properly designed consumer products using Li-ion batteries have “built-in” performance monitoring, and the device and battery pack have been designed to work together. Most of the systems won’t even start with a detected issue related to the Li-ion battery. Cells phones, laptops, battery powered hand tools have charge, load and temperature monitoring circuits that have probably been submitted for type acceptance and approved “safe for use by the average dumb consumer”. Hobby devices, like upper end RC toys, high powered flashlights, and big-battery e-cig mods, probably haven’t received the same design scrutiny and don’t have the same level of user protection. It’s now up to the end user to monitor performance and protect himself. It would be prudent to measure the cell voltage of every cell every time it comes off the charger, and of course not leave any cell on the charger for extended periods just waiting for it to fail would be a good idea. Conducting a physical inspection every time you use or charge a cell seems a no-brainer. Less frequently, a load test should be performed to cull out degraded cells. This could be a mid-current test (50% rated current) for a small portion (5 to 10% of rated capacity) of the total charge. A 2 ohm load test for 5 minutes on an 18650 would tell a lot about the health of a cell and help identify weak cells. Severe applications drawing currents near the design limits, or battery packs containing multiple cells should be tested more frequently as cell voltage and capacity may be critical to safe operation.

The as-delivered quality of a Li-ion cell went out with the bath water the first time you used it. Knowing the quality of a Li-ion cell once it has been used is the responsibility of the end user, and it’s not hard to learn to do this, or expensive. Being able to detect aging, deteriorated, or damaged cells may save you money and body parts in the long run. Trusting the quality of a new Li-ion cell, doesn’t keep you safe when the cell gets old. That’s your job.

Originally Posted by Rocketman

tek,
here's something from 2010 to read while you wait.
go make some more popcorn.

Originally Posted by Rocketman

Well sort of.
It's hard to believe that back in 2008/2009 I was happy with 2.2 ohm joye attys on a 10440 battery.
In 2010, it was 2.8 ohm cartos on an 18650 mod.

Now I'm vaping mostly 1.5 ohm (dual 3 ohm heaters) at 3.7 volts on even bigger batteries.

High volts? not yet.
The "h" in mah keeps me going

Originally Posted by Rocketman

I don't do the twice pipes that often.

The 1.5 ohm dual coils with a pair of 3 ohm coils in parallel vape at a round 3.7 volts. That's about 2.5 amps. The cheap BigRed cells work with these, but that's close to max capability of the cell. The 26650 LiMnNi cells, or the dual 18650 boxes give a larger "Margin of Safety" for my High Powered 9 watt vape

The lower capable cells would be better for my 2010 vape at 5 to 8 watts.

Originally Posted by Rocketman

Dual 1.5 ohm (4 coils) is just way too much, for me

Originally Posted by tek

Not quite where i was going, but hmm.. I do have a vv 26650 box that takes four cartos, got it up to one vape at 96 watts <was going for 100> before my fuse blew, <15 amp> but next time i will be prepaird..

Originally Posted by Rocketman

Here's something that maybe Steam can research for us.

I've taken a few Dell and Lenovo battery packs apart to use the protection module to build 3S Li-ion packs (flashlights). I've noticed that the modules cut off the charging current when any cell reaches 4.35 volts. I know there are some newer Li-ion cells made for 4.3 to 4.35 volt charging algorithms but these were somewhat older packs. Discharge also cuts off at 2.5 volts for any cell. The packs were 3S3P with 9 18650 cells.

My guess is that with the high rate of charge used the 4.35 volt cutoff accounts for cell resistance and would detect a high resistance cell and cutoff charging as even more protection. A bad cell that had developed a higher than normal cell resistance would not show up with a very low charge current. This method stops charging when the weakest cell voltage climbs and stops discharge when the weakest cell (maybe a different one) drops. These modules don't seem to be really 'balancing', just monitoring and controlling charge and discharge.

After charging was terminated by the module, cell voltage quickly dropped to about 4.20 volts. You only see the 4.35 volts if you are watching while it charges. I'm sure there are smarter charge modules used in some laptop packs, including those with serial number lock outs, that have a more complicated alygorithm, but this seems to be different that the CC/CV method recommended everywhere. Strange that many name brand laptop manufacturers use the 'hit it hard' method.

Back in the day, it was common or a NiCad rapid charger to hit cells really hard and test for voltage droop to switch to trickle charge.


Steam,
have you seen this with the Dell packs you have around.

Originally Posted by RY4

Originally Posted by tek