MaJ. Woody

My Feedback: (28)

Hi Guys.

After loosing my jet to a bad battery pack, I have decided to go with two battery packs and two switches in my airplanes. Now my plan was to hook up one battery and switch as usual and plug it into the receiver in the battery port. I was planning to hook up the other battery and switch the same way but plug that into an empty channel on the receiver or use a Y Harness to plug it into another channel.

I was told that this would not work because if the voltage is not exactly equal between the two packs then one pack would attempt to charge the other through the receiver and that this could heat up the wires and receiver damaging one or both in the process.

Is this true?

If so, then how do I add two batteries and two switches to my next jet?

Thanks for the help!!!
Dom

Silent-AV8R

Everything you need to know about this is right here:

http://www.rcbatteryclinic.com/parallel.html

MaJ. Woody

My Feedback: (28)

Thank you Sir!!!
Dom

rlmcnii

My Feedback: (3)

Maj. Woody,

http://www.hangtimes.com/rcbattery_faq.html

Not to advertise, but there is some information here about parallel packs. I've been doing it this way in a 28% Edge. No troubles, so far.

DrV

My Feedback: (2)

Most jet guys at my field fly with redundant battery packs and they are connected the same way you described without problems. I have two 2700mAh 5 cell NiMhs in parallel through dual Duralite fail safe switch/regulators (5.1V). One output from the regulator connects to the battery port on the receiver and the other to the other end of the receiver bus (to fill the entire bus) and Y-ed just like you mentioned to whatever channel it is connected to. In my case, I fly Futaba so one end is in the battery port and the other on ch 1 with a y-harness to the servo. The voltages are slightly different but batteries will not charge each other or cause any fires. You just have to make sure that they have the same cell count and the capacity of the batteries will just add up. This setup saved my jet on my 5th flight since one of the packs was disconnected in the air. I did not even know this until I landed and noticed that one of my C-volts(voltage indicators) was showing one complete volt lower than the other. Upon inspection I noticed the disconnected lead. This combo is great since the switch is such that if it fails it stays permanently on without cutting off power to the receiver.

Good Luck

Mike

Silent-AV8R

Just a quick comment here. The 2700 NiMHs are about the worst possible cells to use due to their extremely high internal impedance. Consider this, under a 1 amp load those cells will show a voltage drop of 0.8 to 1.0 volts. A lower impedance cell, like the 1950 4/5FAUP cell will show only a .2 volt drop. What this means is that you will get less usable capacity out of these cells since the battery will drop to an unacceptable voltage sooner under load. When you cycle the pack you still have lots of capacity. But that is not the issue. The issue is what voltage is being delivered under load.

Geistware

My Feedback: (16)

Dom,
Who ever told you this lied to you.
No ifs, ands or buts.
Two packs with the same cell count cannot charge each other.
You will have a combined capacity and twice the current capability. (identical cell count and pack capacity.)

DrV

My Feedback: (2)

This may be true and makes sense. However, 40 flight on my plane, 60 and 180 flights on my two other friends’ planes. These are all baby boomerangs with same batteries and do not have digital servos. But I will reconsider using them on anything that had digitals. In addition, I get about 5-6 flights before I have to recharge and by that time I usually call it a day.

Thanks

Mike