[Lithium Polymer] [NiCds/NiMH]


Lithium Polymer

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


NiCd/NiMH

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.


[Lithium Polymer] [NiCds/NiMH]

© 2001-2004, Matthew J Litke
Contact: uplanes@litke.info