Test Results for LG INR18650-MJ1 3,500mAh 18650 Li-ion Battery

Recently, there was news of LG’s first lithium nickel cobalt aluminum oxide chemistry cells. Panasonic has long led the market for 18650 Lithium Ion batteries with their own cells based on that chemistry. Their NCR18650B at 3,350 mAh capacity has been in wide availability for the last year, and some of their 3,600mAh NCR18650G’s have also popped up.

We now have reports of the highest capacity 3,500mAh INR18650-MJ1 version of LG’s new cells in the wild. If the real-world examples match LG’s claims, Panasonic will have some serious competition.

194009wqt7itir7g7i5tmu

Lucky for all of us, cooldiy_cn managed to get his hands on two of these cells and ran them through a series of tests which he posted on the Chinese Chongdiantou forum.

The weights of his two examples were 46.60g and 46.65g.

LG INR18650-MJ1 0.5C Discharge Curve

Above, you can see the test results with a 0.2C/0.7A discharge from 4.2v to 2.5v, which delivered 3,481 & 3,496 mAh.

INR18650-MJ1 3.5A discharge

At 1C/3.5A usable capacity is only diminished by about 1% and usable capacity remains good at higher discharge rates.

LG INR18650-MJ1 5A Discharge Test

At 5A, usable capacity is 3,390 and 3,393 mAh, or ~97% that delivered at 0.2C/0.7A.

LG INR18650-MJ1 10A Discharge

10A discharge is 3,252 and 3,310 mAh, or ~95% the usable capacity at a 0.2C/0.7A discharge.

He also tested the internal resistance of his two cells, and found that they were about 28mOhm (caveat that this can vary depending on method of measurement).

All in all, this is a promising development. I look forward to being able to buy these in new-old-stock and lightly used laptop packs, in a few years.

Today’s Mail: from Hong Kong, the ZKE EBC-A05

Today’s mail brought a package from Hong Kong.

IMG_7256

Inside, was a ZKE EBC-A05.

IMG_7261
Whoops! This cell should be charged to 4.30v, not 4.35v.

 

This is a electronic load and charger for battery testing.

It can charge at up to 3A using a variety of charging voltages and profiles. For discharge testing, it can draw up to 5A @12v. There is a TTL-serial interface with a USB adapter and accompanying software for logging and controlling battery tests.

Update: I ‘ve posted a preliminary review, and I’ll be updating it as I go in the coming weeks.

Teardown Updates: EasyAcc USB Powerbank, Dell TC03, and Tomo V8-4TOMO V8-4 / SOSHINE E3 DIY USB CHARGER / POWER BANK TEARDOWN

I’ve been busy doing teardowns over the past few weeks, and neglected to post links to them, so, before I finish up a few drafts I have in the works, here are links to what I’ve already published.

New LG INR18650 MH1 (LGDBM1865) 3,200 mAh 4.2v!

I was taking advantage of Google Translate to skim through recent posts on a Chinese battery/power bank/charger blog. They have a lot of posts on new high-capacity cells from various chinese battery manufacturers, but post on a new cell from LG caught my eye.

I haven’t been keeping a on the latest developments in lithium ion batteries because I’ve been focusing on recycling cells from old laptop packs, and I have my hands full just keeping up with all the variants that were in new packs in 3-6 years ago. Still, the INR18650 MH1 (LGDBM1865) grabbed my interest because its 3,200 mAh capacity and 10A (>3c) discharge rate struck me as unusual.

The capacity itself isn’t revolutionary, Panasonic has had a 3,400 mAh cell on the market for a while, and Samsung and LG have both had 3,200 mAh cells on the market for over a year. The existing Samsung and LG cells have a maximum discharge rate of 1.5C (1.5x rated capacity), or ~4.6A, and the Panasonic seems to allow 2C/7.8A  discharges, wheras this cell is rated at 10A, or more than 3C.

It has another interesting characteristic, a 4.2v charge termination voltage, instead of the 4.35v of many existing high capacity cells. Many lithium ion chargers, and most cheap charging ICs/modules have a fixed 4.2v charge termination voltage. Charging high-capacity 4.35v cells to 4.2v doesn’t harm them, and can actually extend their lifetime, but leaves 10-15% of their capacity unused. On the other hand, when the INR18650 MH1 is charged in a 4.2v charger, all its capacity is utilized.

Of course, the 4.2v voltage also brings a tradeoff. The nominal voltage is 3.67v, vs the 3.75v of LG’s 4.35v 3,200 mAh battery. This results in a somewhat lower power capacity of 11.7Wh vs 12Wh, or 2.5%, but that’s much less than the 10-15% lost when undercharging a 4.35v cell.

I’m not sure how I missed it, but it looks like user cooldiy_cn managed to get his(?) hands on some and has posted test results for the INR18650MH1.

Some added details, and highlights of the tests:

  • In addition to this 3,200mAh cell, LG is bringing out a family of INR cells with a range of capacities, including:
    • 2,800 mAh: INR18650MG1
    • 2,900 mAh: INR18650M
    • 3,500! mAh: INR18650MJ1
  • The INR18650MH1 specifies a 1C fast-charge rate
  • Measured internal resistance of the tested samplesL 34.2 and 36.2 mOhms.
  • 0.2C/0.62A discharge tests at 3,217 and 3,214 mAh
    • Cooldiy_cn claims the discharge curve is very similar to the Panasonic NCR cells.
  • 1C discharge tests yield 3,109 mAh and 3085 mAh for the tested cells.
  • 10A discharge test of one cell yields 3,253 mAh. It maintains voltage well enough to deliver 10.39Wh.
    • The NCR18650 BD 10A can deliver 10A, though it is out of spec. When it does, it only delivers 2,831 mAh, and the voltage sags so much that the power delivered is only 8.856 Wh.

If you want to see the discharge graphs, check out cooldiy_cn’s original post.

More info:

 

 

UrJar and Re-Using Lithium Ion Batteries at the Bottom of the Pyramid

I started PowerCartel because I was interested in reusing lithium ion batteries, and I recognized that people in a variety of enthusiast communities with the same interest in li-ion reuse were missing opportunities to learn from eachother. As I thought more about the subject, I realized that there were also huge opportunities in developing markets, where labor was relatively cheap, and steady sources of electric power were hard to come by.

It wasn’t a surprise then when I came across a paper by researchers at IBM India on their pilot project to reused lithium batteries to provide economical lighting and power for poor citizens of India.

The paper, titled “UrJar: A Lighting Solution using Discarded Laptop Batteries” was authored by Vikas Chandan, Mohit Jain, Harshad Khadilkar, Zainul Charbiwala, Anupam Jain, Sunil Ghai, and Deva Seetharam of IBM Research India, and Rajesh Kunnath of Radio Studio. It makes a strong case for lithium battery reuse given the poor economics of recycling, makes an assessment of the yield of useful cells from discarded lithium battery packs, and describes the design and field testing of the UrJar.

The UrJar is a device powered with reclaimed lithium ion batteries. It provides power ports a LED light, and other devices like cell phones and/or a portable fan. There is circuitry to recharge the internal batteries, and provide the required power to the LED and external devices.

I’d challenge some of the design decisions in their prototype. They use a 3s2p (3 series, 2 parallel) topology for the cells, which requires proper cell management for safety, as well as longevity. The prototype omits this circuitry. Including it will impose an additional cost.  A 1s6p configuration would provide more safety in a simpler configuration. It would also allow a wider selection of inexpensive charging chips or even complete charging modules. The downside might be slightly lower efficiency in the circuitry to power external devices, but that could be offset by adding more cells, with the expense offset by the savings from commodified charging and power conversion modules. They might even be able to use existing commodity cases and electronics on the market for reusing 18650 batteries.

Its also worth considering that the laptop packs the source the cells from already have the circuitry to properly manage series packs by avoiding over-discharge of one bank, and balancing all of the banks during charging. There might be a viable approach to using the intact packs (when all the cells are of good quality), or reusing the circuit boards (when a working pack has to be assembled out of cells recovered from multiple packs).

I also have a quibble about their description of the Thinkpad battery packs used in their study. They describe them as 6 cell packs rated 85Wh each, and being at least three years old. This seems unlikely. The cells would have over 14Wh each, which works out to 3,800 mAh at 3.7v nominal cell voltage. 3,800 mAh 18650 cells weren’t available 3+ years ago. They aren’t even available today, so far as I know. Last I checked, the 3,400 mAh cells from Panasonic held the record.

These criticisms are all relatively minor though. The important issues aren’t the specifications of a prototype battery pack, or the  design and sourcing choices made for the hardware. What is important is that these batteries have residual economic value, and even more importantly, figuring out the right mix of cost, features and services for a product that will help poor Indian consumers better their lives, and stimulate local industry. On these fronts, the authors seem to have done good work. I also appreciate their bibliography, which will give me a head start on some literature research I planned to do. I’m in the process of drafting a letter to the authors, congratulating them on their good work, and inviting them to join the community I’m trying to start here around PackProbe, and other tools for reusing lithium ion battieries.

Their work has attracted plenty of other attention of late, I suspect the result of some savvy PR on someone’s part. IEEE Spectrum has a summary, as does the BBC News, and Technology Review.

DIY Programmable Lithium Ion Charger Shield

Update:  According to this comment on Dangerous Prototypes, the charger chip’s support for lithium ion charging is quite primitive, and so this project depends on the Arduino to properly manage the charging. Too bad.

ElectroLabs has published a nicely documented programmable single/multi cell lithium battery charger shield for Arduino. It is based on the LT1510 Constant Current/Constant Voltage Battery charger IC.

Features include:

  • Display for battery/charge status and configuring charging parameters
  • 50mA 10 1.1A charging current.
  • 2-10V charge cut-off voltage

Those voltages don’t make a whole lot of sense for Lithium Ion, but it appears the charger IC they are using also works with other chemistries.

I don’t know the BOM cost, but an assembled version is $75 on Tindie (ouch).

I don’t think I’ll be building one of these, but I am very interested in having examples of using commercial charger ICs outside their default configurations.

[via Hack-a-Day]

Dell XX326 11.1V 60Wh Battery Pack Teardown

I picked up a lot of ten Dell XX326 6-cell 60Wh battery packs from an eBay seller for about $4.50/pack. The seller described them as untested surplus, and based on the presence of unworn external labels in the photos on the listing, I thought they might be unused packs and hoped I could turn around and sell them individually for a profit.

IMG_6762 IMG_6761

No such luck. The packs had more physical wear than I expected. When I hooked them up to PackProbe, I only got data out of two of them without hassle and the data they provided seemed to have problems, for example, reporting design capacity as 0. With a little work, I got one more to spill its secrets. A couple more would ACK a query at their address, but that was it, and the rest gave nothing at all.

I decided to tear apart a few of them. When I got one of them open and measured with a multimeter, I found all the cells were flat, 0V. The next one was a little better, but not great.IMG_6764

3.18V, for 3 banks in series. Not looking good. Lets see what the individual banks registered.

IMG_6765Hmm, one bank measures 2.86V. That’s not bad. The other two banks must be junk though, with a combined voltage of less than 0.4V.

IMG_6767

Wait a second, 3.0V that’s not bad, hmmm…

IMG_6769

Yikes!!! One bank of cells has reversed polarity, in a really big way. I double checked my connections, but I still got the same result, -2.69V!

I tore into another 6 packs. One was nearly flat, with each bank just over 0v. The rest had at least one bank of cells at a reasonable voltage, with the remaining cells being low, flat, or slightly reversed.

It looks like all the packs are ~4-5 years old, and the packs I could get data out of each reported less than 40 cycles. I have to wonder what happened to these packs that they are in such crummy shape, or if the problem is with the pack design/engineering. There are also some manufacturing issues, I think two of the packs had welds break loose, without tearing the nickel conductor strips.

After pulling the individual cells out of three of the packs I’ve opened I’m even more baffled. All of them had at least one cell with failed spot welds. The first pack had all 0v cells, as expected. The second I thought would have two good cells, but it turned out only one cell in the bank was good. The other was flat. The third I thought had two good banks, but once the cells were separated, only one in each of those pairs was good. I think bad connections may have played some role in cell failures.

One theory: Cells paired with poorly connected cells failed because they were overused. I also wonder if some cells may have broken internal connections.

I’m holding off ripping apart the rest of the packs I’ve already opened, because I’m curious if I can get the battery management circuit to give up some data.

 

Notes from “Why do Li-ion Batteries Die” Lecture

Interesting video of a lecture by Dr. Jeff Dahn, professor of Physics and Chemistry at Dalhousie University in Canada on what causes lithium ion batteries to deteriorate, and how the situation can be improved. Dahn was involved in development of lithium ion battery technology, and maintains an large, active research program devoted to studying materials for batteries and fuel cells.

The video is over an hour long, and the pace is a little slow. I’ll be updating the post with my notes as I go through it.

Highlights

  • Manufacturer testing and rating of battery lifetime uses a simple cycle test that takes place under a compressed timeframe, with unfortunate results.
    • Charge/discharge cycles are done back-to-back, at charge/discharge rates that might not mirror real-world use.
    • This underrepresent the impact of the parasitic reactions during charge/discharge that lead to cell degradation.
  • During charge and discharge, lithium ions intercalate (intermingle) and de-intercalate with the the electrode material. This causes a modest, “benign” structural change of 3% in the anode and 10% in the cathode.
  • The materials used in lithium cell electrodes are stable in open air, and batteries can be assembled in open air.
    • As cells are charged, the material at both the cathode and anode become highly reactive with the electrolyte solution.
    • Fortunately, the reaction products are solid and form passivating surfaces that protect the electrodes from rapid degradation.
  • For a perfect Li-ion battery, the coulombic efficiency, the number of electrode in during charging vs the electrons out during discharge, should be exactly 1.
  • The difference between theoretical and actual coulombic efficiency, outside of the measurement area, is attributable to  undesirable parasitic reactions that lead to cell degradation.
  • With sufficient measurement precision, it is possible to predict lithium cell lifetime without intensive testing.
    • Requires at least 4 digits of precision and accuracy
  • Battery Electrolyte
    • Cyclic and linear organic carbonates
      • Ethylene Carbonate
      • Propylene Carbonate
      • Dimethyl Carbonate
      • Ethylmethyl Carbonate
    • Lithium Phosphorous Hexafluoride solute
    • Solvents are typically mixed
      • Some have low boiling points
      • Others form excellent passivating layers
  • Approximate 3-billion 18650 cells made a year
  • Parasitic reactions between electrodes and electrolytes reduce the capacity of the cell as lithium ions are consumed/trapped
    • Capacity change after first charge/discharge cycle is relatively large.
    • Loss in subsequent cycles is lower, because the reaction products form a passivating layer that protects the electrodes.
  • Extent of parasitic reactions can be quatified with a precise measure of coulombic efficiency.
    • A good cell is close to 100%.
    • 10,000 cycle life would require a cell with 99.99% efficiency
    • Need 4th digit in accuracy and precision.
  • Precision charging device
    • Developed by
      • Aaron Smith, PhD, graduated in 2012, now at Tesla in charge of Tesla’s Battery Lifetime Group
      • Chris Burns, PhD Student
    • Specs
      • 60 channels, each with precision current supplies with 5 digit precision
      • Cells under test are in temperature controlled boxes ( 0.05C)
      • Current is fed through precision resistors to measure current.
  • Longer charge cycles have higher coulombic inefficiency, and therefore more destructive parasitic reactions.
  • Coulombic Ineficiencies of common chemistries
    • Test conditions
      • Commercial 18650 cells, two per test condition
      • Charge / Discharge rates: C/24, C/50, C100
      • 30C, 40C, 50C, 60C
    • High-level
      • Coulombic inefficiency has linear relationship to charge time.
      • Strongly suggests that time under charge is the major factor in determining coulombic inefficiency for a given chemistry, at a given temperature.
    • Lithium Cobalt Oxide (LiC02)
      • Lowest parasitic reactions at 30°C
      • Moderate at 60°C, but still lower than Lithium Manganese Oxide at 30°C
      • Tesla has used chemistries with similar characteristics
    • Lithium Cobalt Manganese Oxide (Li[NiMnCo]02)
      • Moderate at 30°C
      • ~50% of Nissan Leaf and Chevy Volt packs
    • Lithium Iron Phosphate (LiFePO4)
      • Moderate parasitic reactions at 30°C, high at 60°C
      • Used by Fiskar
    • Lithium Manganese Oxide (LiMn02)
      • Highest parasitic reactions of all examples at 30°C and even worse at 60°C
      • ~50% Part of the Nissan Leaf and Chevy Volt battery pack
      • Ill-suited to use in battery packs without thermal management, like the Nissan Leaf.
  • Electrolyte additives
    • Vinylene Carbonate: reduces electrolyte oxidation on positive electrode. 2% by weight makes a huge difference
    • Trimethoxyboroxine, 1-3 propane sultone: impedence reducers.
    • Triethylphosphate and others: wetting agents to aid speed in manufacutre
    • Others for lifetime, low or high temp performance, and safety
    • Typical Li-ion cell will have 5 additives
  • Precision coulombic efficiency measurements allow impacts on cell lifetime to be assessed relatively quickly, traditional testing of discharge capacity vs cycle number requires testing to end-of-life.
    • Short term test results correlate with long term test results
  • Predicting catastrophic failures
    • Hypothesis
      • Reaction byproducts from cathode are migrating to anode, where they are reduced and gradually foul the material until the pores in the anode material are clogged. Once the pores are clogged, lithium starts plating out, and cell capacity plummets.
    • Predictions
      • The more compacted the anode material, the sooner the cells will fail.
        • This predicted behavior has been observed, and exploited to make cells that are designed to fail early in order to test other variables.
      • Coulombic Inefficiency * Cycles = A Constant
        • Coulombic Inefficiency = amount of byproducts
        • Constant is the amount of material required to clog the pores
        • A strong correlation has been observed for many additives
    • Exceptions
      • Some unknown additives from battery manufacturers have been tested and shown that make huge (20x) contributions to cycle life while falling outside the predictive model
      • Model assumes a solid reaction byproduct on negative
      • Additives may produce a reaction byproduct with different characteristics (ie liquid, gas)
    • Other observations
      • Coulombic efficiency and cycle life tend to increase with the number of additives
        • And yet most academic research on electrolyte additives only looks at one at a time.
  • New grant to put a 100 channel system on line with the capability of testing automotive scale cells
    • 10 ppm CE accuracy
  • Research Directions
    • Tests require highly uniform cells. Lab made cells can be rather inconsistent
    • Have established relationships with Chinese manufacturers of pouch cells
      • Get machine-made pouch cells without electrolyte in lots of 2,000
      • Mix and add electrolyte themselves.
      • Seal cells in vacuum sealer
    • Microcalorimeter
      • Measure the heat from parasitic reactions
      • TA Instruments TAM III
        • 12 separate calorimeters
        • 10nW sensitivity
        • Baseline stability of 500nW/month
        • Isothermal, all experiments at 40C
        • Holds AA and 200mAh cells.
      • Three sources of heat during charging (~1Wh cell capacity)
        • Entropy changes from electrodes
        • Internal resistance/polarization
        • Parasitic reactions
          • 100 uW would consume all the electrolyte in a year BAD
  • Questions from audience
    • Audience asked about the unknown additive outliers that didn’t conform to the simple model of reaction products clogging the pores on the anode.
      • Dahn replied that if those additives formed a liquid or gas reaction product, then one would expect the impedance to be lower. He then showed data showing that, indeed, the cells with outlier additives did have lower impedence.
    • Asked about using these techniques with silicon electrodes.
      • Silicon electrode cells at this point are so poor, that you can see the parasitic inefficiency with an ordinary charger.
      • Silicon electrodes need a lot of development before they need this precision.
      • Lithium Titanate
        • Incredibly durable already.
    • How can these metrics be applied to drive cycles?
      • GM wants to relate this to drive cycles.
        • Dahn’s initial approach is:
          • How does existing technology work for driving?
          • How does it look with precision charging?
          • What are the new technologies?
          • How do they perform under precision charging?
          • Based on result, he can say if the new stuff should be better or worse.
    • How do real-world discharge profiles relate to constant discharge rates seen in lab tests?
      • The biggest factor is time spent at highest voltage.
        • Longer is worse
        • Most of the parasitic reactions happen above 4v.
    • Lithium Ion Cell Overhang
      • Negative Electrode is slightly wider than the Positive
      • Prevents lithium ions from the positive electrode from plating out the edge of the negative and forming lithium metal dendrites
      • There is an overhang of graphite
      • At the beginning of charging there is some odd behavior as the ions equilibrate with the overhang
    • To extent the life of your phone or laptop battery
      • Keep it as cold as possible 🙂
      • Put it in the fridge.