charger that was ONLY good for lithium, that would at least eliminate that possible mistake at the field.  Third, the 109 is reasonably priced and has the ability to charge up packs as large as  8000ma.  That’s 8 amps!  While I currently have no plans to use packs much over 2100ma, who knows what the future will bring, so that 8 amp margin is great.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

As you can see, the unit is rather handsome looking.  It has a 2 line backlit LCD display, a control knob, input cable and output cable.  The output cable comes with an AstroFlight Zero Loss connector that I replaced with a Dean’s Ultra connector to match my packs.  I also made up an adapter to go from the Ultra to the Deans polarized 2 pin connector that I use on all my smaller packs.

If the charger sort of looks familiar, it should be …  the AstroFlight 110 (Nicad/NiMH charger) looks just like it, except for the graphics.  As a matter of fact, the entire charger internally is the same as the 110 except for the EPROM chip that controls everything.  It is the EPROM chip that makes this a 109, LITHIUM ONLY, charger.  This is a nice feature because if there are ever any updates to the programming, it is a simple matter to switch out the chip.  My Orbit is setup this way and I’ve updated that firmware twice now.

When you apply voltage to the input leads, the display first shows the AstroFlight name and the version number of the software.  Then, the display says, “waiting for battery” and gives you the voltage of the input source.

 

 

 

 

 

 

 

 

To begin charging, you first turn the AMPS ADJUST knob all the way counterclockwise and then plug in the battery.

Once connected you adjust the charging current to match the capacity of the pack.  At this point, the fan will be running and the display will show.

 

(Continued on page 4)

A number of years ago I did a write up on the electric event I attended up in Chilliwack, Canada.  Much of what I saw in terms of power and duration satisfied the glow powered flyer within me.  However, while I thought electric flight was at the edge of becoming much more mainstream, it just hadn’t reached that level yet.

Within the last several years a battery technology, that had been with us in various electronic gear, took a big step forward and produced a power source that has given electric flight that first step over the line into mainstream modeling.  The LITHIUM POLYMER battery pack.

The rush to adapt this new power source to modeling has brought various problems associated with a new learning curve.  One of these problems is the proper charging of these new power packs.  Unlike nickel based battery packs, lithium cells/packs are much less tolerant of sloppiness when it comes to charging.  They require a special charging algorithm that is different from the one used for a Nicad or NiMH cell.  Trying to use a Nicad charger with a lithium pack is just asking for trouble.

So what sort of charging does a lithium cell require?  The maximum voltage for a lithium polymer cell is 4.235v per cell, which we can round down to 4.2v.  So a pack made of 2 cell in series (2s) has a maximum voltage at rest of 8.4 volts.  A 3 cell in series pack (3s) would be 12.6 volts and so forth.

Lithium packs should always be charged at 1C.  That is to say, the same rating as the pack.  If you have a 1200ma pack, then it should be charged at 1.2 amps (1200ma). It can be charged at a lower rate, but that just increases the charge time and there is no advantage.

Let’s assume you have a 2 cell, 1200ma pack that is fully discharged.  The standard charging procedure is first to set a charger at a Constant Current (CC) rate of 1.2 amps until the voltage of the pack reaches 8.4 volts.  At this time the charger needs to switch over to a Constant Voltage (CV) mode.  Here the current is lowered to maintain a constant 8.4 volts.  Eventually, the current falls so low that the charger will stop the charging program.

Which brings us to the subject of this review, the Astro-flight 109 charger.  I currently own 2 rapid chargers.  The first is the FMA SuperNova 250 that will charge all my nickel-based packs, be they receiver, transmitter or flight packs.  The other charger is an Orbit V6 that will charge, nickel-based cells, lead/gel cells and Lithium cells.  I always have the SuperNova with me, but I leave the Orbit at the house as my home based charger. 

My normal practice is to have several lithium packs charged and just take them to the field with me.  After use, I recharge them at home.  However, I’ve wanted a lithium field charger also.  There are a number of “do it all” chargers, the Great Planes Triton comes to mind. But I settled on the AstroFlight 109 for several reasons.  First, my SuperNova already did all the nickel based stuff, so I really didn’t need to duplicate that.  Second, while do it all chargers are nice (love my Orbit), there is always the possibility that somehow you might goof and accidentally start a charge using the Nicad setting.  So if I had a