iPhone USB can be made faster too.

With the fast charge capability of the iPhone 8 and iPhone X generating hype since this is the first time Apple started supporting what is considered a fast charge, however, multiple iPhones support faster charging than the charger in the box allows

These Models support a Maximum of 5 watts from the adapter:

  • iPhone
  • iPhone 3G
  • iPhone 3GS
  • iPhone 4
  • iPhone 4S
  • iPhone 5
  • iPhone 5c
  • iPhone 5s
These models support a maximum of 12 watts with an upgraded Adapter such as used with the iPad:
  • iPhone 6 and 6 Plus
  • iPhone 6s and 6s Plus
  • iPhone 7 and 7 Plus
These models support (about) 36 watts with a USB-C to lightning cable and a USB-C adapter with Power delivery. In addition these support 12 watts with an upgraded adapter such as used with an iPad. These models support 5 watt (soon to be 7.5 after an iOS upgrade) wireless charging.
  • iPhone 8
  • iPhone X
This means that every iPhone since iPhone 6 can support faster charging than the included iPhone power adapter allows with the lightning to USB and presumably the Lightning to USB-C cables. The lighting to USB option requires an iPad (or compatible 2.1 amp third party) adapter.

The Low Self Discharge NiMh Cell or How Rechargeable batteries are now ready for Prime time

Rechargeable batteries in standard household sizes have been on the market for decades they all have their problems. NiCd had issues with chargers and the misunderstood memory effect. Rechargeable Alkaline can’t fully recharge, is limited in number of charge cycles, and usually fails by leaking. Traditional NiMh has a self discharge problem and charging is not convenient.

A new technology arrived in the past decade that changed the way rechargeable batteries are used. It has the power density of NiMh, it has low self discharge (although not as low as Rechargeable alkaline), and smart chargers prevent the charging issues of the NiCd era. What is this technology? It’s actually NiMh! Low self discharge NiMh cells were introduced by Sanyo under the Eneloop name in 2005 (now made by Panasonic) and other companies soon followed.
What does this mean in terms of usability? It means a few things, firstly these cells are sold with a partial (approx 70%) charge so they can be used out of the package without recharging first. Instant usability was a major advantage of Rechargeable Alkaline. It is still NiMh technology which means the ability to handle heavy loads is still there. The mass availability of smart chargers eliminates the overcharge problem of NiCd. Of course the memory effect never occurred in consumer applications anyway (but was the blame of other issues, namely overcharging). The only two disadvantages that remain are to make sure people don’t throw them away in error and that you don’t have the full 1.5 volts.
This new technology means a major change in how the cells are used and stored. Low self discharge cells can be stored charged in battery organizers, ready to go, and used cells can then be stored in another organizer full of cells ready to be recharged (hint, put the used ones upside down in the same organizer to easily determine which ones need recharged). The instant availability of spare cells isn’t the only game changer.
This new technology can also be used in equipment that stands by waiting for emergencies or even low drain devices such as clocks. Just make sure you check for voltage compatibility in clocks and older radios. My 1970s Panasonic transistor radio is a wonderful set, but it won’t work for long on NiMh of any type. This means you can use these cells in your pre-staged emergency flashlights, just remember to top off the charge from time to time.
Now, in order for this to work well, you need good cells and good chargers. I recommend chargers with negative Delta V termination with single cell channels. Chargers that have two cell channels (require two cells to charge) are okay for anything used in Multiples of 2.
For specifics, I recommend Panasonic’s Eneloop chargers for AA and AAA sizes and Tenergy’s T-9688 for AAA, AA, C, and D, but not 9V. In fact I don’t recommend NiMh for 9V, but I’ll get to that later.
For cells, I recommend standard Panasonic Eneloop AA or AAA, don’t bother with the Eneloop pro, the extra capacity reduces overall lifespan too much. The standard Eneloop can be recharged 2100 times where the Pro can only be recharged 500 times. If you don’t mind the Capacity loss, you can also get Eneloop Lite which can be recharged 3000 times. There are other brands including the Tenergy Centura I recommend for C and D, but be sure you don’t get cheap, low capacity types (pay attention, especially when buying the big brands).
For C and D size I recommend Tenergy Centura. This is because this is only other reputable brand I found with good capacity. In these sizes I highly discourage the big name brands, Energizer only goes up to 2500 mAH (which may not even be Low Self Discharge) and Ray-O-Vac up to 3000 mAH. These are near or slightly better than AA. Tenergy is around 4000 mAH for C cells and 8000 mAH for D-Cells.
For 9-Volt size I do not recommend NiMh as smart chargers for this size are difficult to find. In addition 9-Volt is rather complex. A Carbon Zinc or Alkaline 9-Volt has six cells. For a NiMh based battery to have the best compatibility more cells are needed. Six cells gets 7.2 volts, but the better types have seven cells for 8.4 volts or eight cells for 9.6 volts. The more cells needed in the same space, reduces the amp-hour capacity. However, there is another way to reach 7.2 to 8.4 volts with different technology. Two lithium Ion Cells in series will produce 7.4 volts nominal, but with 8.4 volts at a full charge. Lithium ion offers a few advantages, even lower self-discharge, good voltage compatibility, and even more power. In addition, lithium Ion charging requires a smart charger and in this case, probably a balancing circuit inside the pack as well.
The last question I need to answer is what you should do where you can’t use NiMh cells for reasons of voltage compatibility, safety certification, internal charger compatibility, or for safety equipment (smoke detectors). If the issue is voltage compatibility, the best answer for AA, AAA, and 9V types is to either continue using standard cells that you normally buy or switch to Lithium. The lithium type will allow you to retain the reduction of leak risk that NiMh provides. If the issue is safety certification (unlikely in household use), you must follow the requirements of certification. Some equipment may allow you to use other types and simply change back to the permitted type to restore certification. Internal chargers can either be disabled as for Alkaline or not used, if neither is an option, NiCd cells are still available in the US. Lastly, I don’t recommend rechargeable batteries for smoke detectors as most types state not to use them in the manual. For these I recommend a lithium replacement or if the detector is near end of life, replacing with a 10 year sealed battery type.


Oops, haven’t been updating the blog as much as I should have and therefore some updates are in order.

JFK Race:

Last time I posted I was talking about going to provide communications for the JFK Ultramarathon. Things did go well. The only issue I ran into was my own fault. I did not bring a spare battery with me and my battery was running low later in the race when I needed communications. This has been fixed. I was able to spend more time in my car to keep warm between races this year, so I was able to keep warmer than last year.

New (to me) HT:

I finally got a better unit than my FDC160A. Not only does this one have better quality as it is an older Yaesu, but I have more batteries for it and it is easier to maintain. I also have a high gain (Relative to a rubber duck) antenna on the HT to also improve communication and likely will be able to keep communications established on low power. The FT-490 allows me to operate using various different battery packs. I should be able to operate from the 7.2 volt packs on low power, in addition I have three packs (2 7.2 volt and 1 12 volt) and am able to purchase a AA alkaline pack to use with the HT.

RadioShack Stores Closing:

Most of the RadioShack stores near me are now closed. During this time I have purchased batteries, chargers, many parts, an Arduino Mega, a TFT shield for Arduino, and many various parts and bits. While the nearby stores are closed. There is one remaining open within 30 miles so I can still get things from RadioShack, it will just be a longer drive. Hopefully some items will become available when the online store comes back up.

Field Day 2015:

Yes it is that time of year again to start thinking of Field Day. I will likely repeat most of the same things I did last year, EXCEPT, this year I will be donating fuel for the generators and bringing my wonderful girlfriend along. Photos should be posted here to the blog sometime after Field Day.

Of VTVMs and FET VMs

Anybody that has gotten into electronics in the past 10 to 15 years is familiar with the digital multimeter and the Volt Ohm Meter. The differences are obvious, the VOM can load down the circuit but allows you to see changes in the circuit on an analog scale. The DMM is rather sensitive and won’t load down the circuit, but updates slowly and only provides a digital readout or at best a bar graph display. Can’t we have the best of both worlds?

Prior to the digital multmeter and even transistorized electronics we had what was called a vacuum tube volt meter (VTVM). These high sensitivity instruments allowed us to take measurements on electronic circuits without loading them down like a VOM would and of course digital was a few decades away. The VTVM was the best voltage measuring device out there for electronics work. The big disadvantage of the VTVM was that even portable units required a power line connection and multiple vacuum tubes even though later hybrid units only required one (solid state rectifier and solid state diodes for the AC scale).  While I own a VTVM of the hybrid variety, I need to build a probe adapter to replace the missing switching probe that should have come with the unit. As technology progressed with the field effect transistor a VTVM no longer actually required tubes. VTVMs stuck around a while in the FET era until the DMM took over

This is where the FET VM or FET Multimeter comes in. The FET Multimeter is a solid state VTVM and can be made in a battery portable package such as the Sencore FE23 Little Henry Field Effect Multimeter. In fact I just acquired one of these at the local hamfest this past weekend. The FET multimeter gives you the portability of a VOM with the versatility of a VTVM. In addition this unit has a light bulb in it to illuminate the scale. These extremely versatile instruments were made in the 1960s and 1970s, but unfortunately like VTVMs fell victim to the new digital multimeter technology.

While these older instruments are no longer being manufactured they can be found on the used market and are a useful tool to have around the lab or shop.