Dual RC Receiver RX Life Battery Packs

Dual RC Receiver RX Life Battery Packs - Red Scholefield  a long time rc aeromodeller from Florida (and also an former electrical engineer for GE)  promoted the use of dual receiver packs. Though his dual rx battery set-up articles featured using nicad batteries, the same principles can be applied using life batteries. Red's articles are at this link and this is Red's AMA bio.

My flying buddy, Dan Fyfe started using this Life setup in 2012, Jeff and I started using this setup in 2013, Marc in 2015. So far we have had no failures in our rx power setups. though some have left their rx switches on for days and drained the battery to failure or used the wrong charge program on their chargers and fooked the life packs but no failure of this rx battery setup in flight use.

We like this setup because if is simple and redundant.

The components we use are: a pair of  2S or 2 cell Life battery packs, a pair of good charge rx switches, and a good charger that balance charges Life packs. We use a three wire charge switches because we balance charge our life packs in the model through the charge switch.  

This link to  Hangtime Hobbies has been an excellent A123 or LIFE resource on pack and charge switch wiring. 

We were using these Hobby King 2500mah 2S Life packs because they were a good price at $8.95US, I see they are no longer offered so we'll go to another 2000 - 2500mah 2S Life pack. These packs have been used in Dan's 50cc Yak ( a lot of 3D flying) and in our 50cc warbirds and have performed well. On my pack shown below, the balance lead has been re-wired to a 3 wire JR plug.

packs. We use a three wire charge switches because we balance charge our life packs in the model through the charge switch.  

Zippy Life 2s Life pack, re-wired to a 3 wire JR plug

We use good 3 wire charge switch like like the Electrodynamics, MPI or JR brand. Three input wires are needed to balance charge the Life rx pack through the charge switch port. NOTE: the signal wire on the charge switch lead to the receiver has been snipped, this is to prevent feedback during charging charging from one pack to the other pack and this further explanation is from Hangtime Hobbies "In any case, most HD switches are equipped with that 'third' wire.. it's a 'signal' lead and we need to remove it from the plug that goes into the Rx so we don't put power to the Rx on that lead. To remove it you need a razor knife and a bit of electrical tape. With this mod, we're going to turn your switches 3 wire Rx power feed into a 2 wire power feed."

signal wire snipped on power lead to the receiver

The completed dual rx battery pack set up - two life packs into two charge switches that feed into the receiver.

my dual life rx battery set up

Charging - you must have a good charge that has a life battery routine and does a balance charge.  Dan and I use the FMA Cellpro Multi 4 charger, Jeff and Marc use the Hitec X4 charger. We use the Life battery balance charge "routine" on the charger and charge through the charge plug on the switch with the life packs in the model. My charge setup is shown below. 

charging Life rx pack via the switch charge port

We normally charge each morning at the start of the flying day. When plugged in, the Multi 4 shows the current charge level and voltages and upon charging shows how much "mah" was put into the battery. We charge at one to two amps. Keep a mental record at the field of how your Life batteries are charging - watch for any abnormalities in voltage and "Mah" going in. 

I cycle my Life rx batteries at the start of the flying season, when I get new Life packs and when any abnormalities show up. These results are kept in my Life battery record book. If the characteristics of a Life RX pack, change then a battery cycle is in order. If the cycling shows the pack deficient, then that pack is replaced. Don't lose your $1000 plane  to a $20 to $40 battery pack.

Ken's record of Life battery pack cycles.

We currently fly around a dozen or so of 50cc size planes using this dual Life battery rx pack set up, some of the models are shown below, so far so good!

Dan's TF P-51D

Marc's TF P-40, Ken's Ziroli Harvard, YA Spitfire, TF P-51D

Jeff's TF Corsair

A pdf on this dual Life RX battery post is on google drive at this link.

Any questions or comments?

We use Life packs on our gas motor ignitions too, we use a separate charge switch for the ignition pack. Note what voltage your ignition can take, if the 2S life voltage at 6.6 volts is too high for your ignition system, you will have to be dropped using a UBEC or put a diode in the power lead to the ignition.

diode in ignition battery power lead

ubec to drop down 2S Life pack to ignition