Batteries
Lithium Polymer (LiPo) batteries have really changed the micro airplane
scene. The weight savings of LiPo batteries is amazing, for example 3 NiCd
120 mAh cells (3.6V) weigh about 18g (0.62oz) a single cell LiPo 130 mAh
cell (3.7V) weighs about 3.2g (0.11oz). That is over an 80% weight savings
for about the same voltage and capacity. Below is a list of some of the
more common LiPo cells being used in micro RC airplanes.
| Lithium Polymer Batteries | ||||||
|---|---|---|---|---|---|---|
| Brand | Model | Cap (mAh) | Voltage | Wt g (oz) | Max Current (A) | Price (US$) |
| Kokam | 40 | 3.7 | 1.8 (0.06) | 0.25 | 5.00 | |
| Kokam | 45 | 3.7 | 1.8 (0.06) | 0.14 | 4.50 | |
| E-Tec | High-C | 90 | 3.7 | 2.3 (0.08) | 0.5 | 8.50 |
| Polycell | 120 | 3.7 | 3.2 (0.11) | 0.24 | 13.00 | |
| E-Tec | High-C | 130 | 3.7 | 3.2 (0.11) | 0.6 | 8.00 |
| Kokam | 140 | 3.7 | 3.6 (0.13) | 1.0 | 6.00 | |
| Kokam | High Discharge | 145 | 3.7 | 3.5 (0.12) | 0.7 | 8.00 |
| Polycell | 200 | 3.7 | 5.2 (0.18) | 0.4 | 14.00 | |
| E-Tec | High-C | 210 | 3.7 | 4.7 (0.17) | 1.47 | 7.50 |
| E-Tec | High-C | 250 | 3.7 | 5.7 (0.20) | 1.5 | 8.00 |
| Kokam | High Discharge | 340 | 3.7 | 9.9 (0.35) | 6.8 | 14.00 |
| Kokam | 350 | 3.7 | 9.0 (0.32) | 3.5 | 12.00 | |
| Kokam | 560 | 3.7 | 11.7 (0.41) | 1.7 | 5.50 | |
| Kokam | 640 | 3.7 | 13.0 (0.46) | 4.0 | 12.00 | |
| Kokam | High Discharge | 640 | 3.7 | 16.0 (0.56) | 6.2 | 7.00 |
| Polycell | 650 | 3.7 | 14.0 (0.49) | 1.3 | 22.00 | |
| E-Tec | High-C | 700 | 3.7 | 14.9 (0.53) | 4.2 | 9.50 |
| Kokam | 880 | 3.7 | 18.0 (0.63) | 2.6 | 6.50 | |
| Polycell | 910 | 3.7 | 21.8 (0.77) | 1.8 | 23.00 | |
| E-Tec | High-C | 1200 | 3.7 | 24.1 (0.85) | 7.2 | 12.00 |
| Kokam | 1200 | 3.7 | 21.5 (0.76) | 4.0 | 17.00 | |
| Kokam | High Discharge | 1500 | 3.7 | 34.0 (1.20) | 12.0 | 19.00 |
| Polycell | 1700 | 3.7 | 50.0 (1.76) | 3.4 | 23.00 | |
Chargers
LiPo cells require different chargers then NiCd and NiMH cells. Below is a
list of chargers suitable for LiPo cells. (If you know of another one that
you think should be added to the table, please let me know.)
| Lithium Polymer Battery Chargers | ||||
|---|---|---|---|---|
| Brand | Model | # of cells | Current settings(mA) | Price (US$) |
| Homefly | Xc | 1 | 60,200,450,650 | 17 |
| BSD | BSLiPC4 | 1 | 40 | 20 |
| BSD | BSLiPC1 | 1 | 140 | 25 |
| FMA | Lipo-102 | 1 | 5-225 | 30 |
| FMA | Lipo-202 | 2 | 5-225 | 30 |
| Apache | 1215 | 1-2 | 110,250,700,1200,1500 | 40 |
| Homefly | Xi | 1-3 | 100,200,450,700,1000 | 44 |
| Plantraco | LPC-400 | 1-3 | 50,100,200,400 | 60 |
| Apache | 1500 | 1-4 | 110,250,700,1200,1500 | 80 |
| Kokam | Lipo-402 | 1-4 | 100,250,500,750,1000,1500 | 100 |
| Great Planes | Triton | 1-4 | 200-1300 | 130 |
| AstroFlight | 109 Deluxe | 1-9 | 140-8000 | 130 |
Batteries
Back when I became interested micro airplanes, Nickel Cadmium (NiCd)
batteries were pretty much the only rechargeable batteries used in RC.
When I first started building micro airplanes, I experimented with a number
of different kinds of NiCds. A few years later, Nickel Metal Hydride
(NiMH) cells started to become available and offered about twice as much
capacity as NiCds for the same weight and size. Some people started using
Lithium-Ion (Li-Ion) cells around the same time as NiMHs. Li-Ions offer
much better capacity for weight then NiCds and NiMHs, but are much more
expensive. There are few other options too, including some
non-rechargeable cells, like Alkaline and Lithium. Below are some of the
batteries I tested to use in my micro planes. From left to right (in the
image below), the first battery is a Radio Shack 9V (7.2V actually) 120 mAh
NiCd with the outer casing removed to save weight, as you see it here it
weighs 27.0g (0.95oz). Next in line is a 4-cell 4.8V Sanyo 50 mAh NiCd
pack that weighs 16.4g (0.58oz), I could shorten the wire and probably
decrease its weight by a gram or two. The blue pack I got from FMA Direct,
and is a 110 mAh 4-cell 4.8V NiCd pack that weighs 27.9g (0.98oz). The
copper top is the only battery in the picture that is not a rechargeable.
It is a Duracell DLCR2 lithium 3V 750mAh battery that weighs 10.7g
(0.38oz). Next is a single Sanyo 120mAh 1.2V NiCd cell that weighs 6g
(0.21oz). Finally there is a 7-cell 8.4V Sanyo 50 mAh NiCd pack that
weighs 25.9g (0.91oz). (And no the disk toward for front on the right is
not a button type cell, it is a quarter to illustrate size.)
Batteries and battery packs.
Pictured below are two NiMH packs and a NiCd pack. Both NiMH packs are rated at 110-120mAh, the NiCd pack is rated at 50mAh. The top pack weighs 13.5g (0.48oz), the middle 14.7g (0.52oz) and the bottom 14.6g (0.51oz).
Bob Selman's BSPC1 Peak Battery Charger
Below are a couple of images of a battery charger I use to charge my 50-120
mAh NiCd/NiMH battery packs, the BSPC1. This little gadget was created by
Bob Selman. It peak charges the pack and then sets itself on trickle. It
can be used to charge packs with 2-7 cells. On the back there is an LED
the lights up when it is charging, and then starts flashing once it hits
peak voltage and starts trickle charging. There is switch to toggle
between 2-4 cell packs and 4-7 cell packs. You need a 12V DC source to
supply power to the charger. The NiCd/NiMH chargers are no longer
available, but Bob does have chargers for Lithium Polymer cells.
 Front of the BSPC1. |
 Back of the BSPC1. |
|