RCU Forums - View Single Post - Using two batteries at the same time - Update - Its bad!
Old 11-04-2007 | 10:55 AM
  #26  
Shadow99
Senior Member
 
Joined: Aug 2007
Posts: 511
Likes: 0
Received 0 Likes on 0 Posts
From: Southwick, MA
Default RE: Using two batteries at the same time

So Kenny, are you gonna go with separates now?

Watch out for ESC's with an AUTO-CUTOFF for Lipo's at 9 volts, like the Great Planes ElectriFly series of brushed ESC's (C-25), cause if you don't keep tract of your flight time, it will drop from the sky like a rock. I have a GP C-12 on my tail motor & I hate it! You have to really know your machine, and how it behaves near a low battery situation. When the voltage approachs low-level (your at 3/4 throttle, been airborne for 10-12 minutes), LAND NOW, or take the risk of losing tail control in mid-flight (not pretty). I couldn't even imagine having losing main motor during flight, that would REALLY SUCK!
I'd rather an ESC with an adjustable cutoff, although if your not careful you can ruin a Lipo battery by running it down too low. The Castle Creations Pegasus 35P I'm using now has it's cutoff set for 8.4v (max setting) & a "soft-cutoff," meaning I keep main motor control, just at a reduced throttle and risk of losing RX control. I use a flight timer attached to the stock TX so I can keep tract of how long I've been airborne, and land before I lose the tail motor at 9v. I saw somewhere a Lipo or Lion pack that can handle voltages as low as 2v per cell, so if that's true, you wouldn't have to worry about over-discharging during flight. I have to look to see who makes them, their in one of those RC magazines, somewhere?!

Rick