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View Full Version : High discharge li-po needed?


dmgadway
08-09-2005, 09:02 PM
I have a problem with my power system in my cub. The esc(castle creations ph35) keeps shutting down the motor after short runs. Its not over heating. I used a watt meter and its kicking out at 9 volts which is proper for a 3 cell lipo. The problem is the battery is a 2000mah 10c discharge battery from dymond r/c that should be able to supply the 20amps max that the motor draws. Do I need a better quality battery? The plane flys great at half throttle but it even kicked out a few times at lower throttle settings. (Around 8 amps currrent draw) Can anyone recommend a good 2000mah 3cell lipo that wont sag voltage at 15-20 amps?

Matt Kirsch
08-09-2005, 09:24 PM
ThunderPower 2100.
Kokam 2000 (15C High Discharge).

Red Scholefield
08-09-2005, 09:46 PM
Setting your Pheonix to a lower cut off voltage would help. Try 8.00volts. This will not be too low for a battery under a load of 8 amps or so. Of course a pack with lower internal resistance would be better.

dmgadway
08-09-2005, 10:43 PM
Thanks, I had thought of setting a lower cut off so I ordered the phoenix link today so I can try this. I will also take Matts advice and order a new kokam battery. I guess I should have known that a 35$ 2000mah 3s lipo wouldn't cut the mustard!

Milton
08-10-2005, 12:19 AM
On the other site I posted some test results for the battery that you have, They are rated 10C and will only give about 6C. At least the one's that I got would only do that.
Milton

GeraldRosebery
08-10-2005, 02:37 AM
There are plenty of 15C LiPo's coming on the market. Set the cut-off a little lower and it will solve your immediate problem. I don't understand why the first instruction in the Phoenix speed control manual is not "Invest $20 in our prgrammer". It's the best $20 I ever invested. All this blinky-blinky nonsense is for the birds. Programming the Phoenix ESC's now takes 15 seconds if I am not in a hurry.

dmgadway
08-10-2005, 05:22 PM
I just ordered the programmer cable etc. Also ordered the new HV85 controller for my ultra stick 60 conversion. Was going to order a Jetti, but since I have two other cc controllers and now the programmer, I decided it would be the best choice. I will set the cut off lower and use the cheap battery untill I get a better one. I'll just be careful with the throttle and limit my flights to 8-9 minutes instead of 10-12.

GeraldRosebery
08-10-2005, 09:43 PM
Good plan but the cheaper 80 amp Phoenix will do the job just as well. Download the Beta version of the Castle Creations software - CastleLink V2.03 It works great.

dmgadway
08-14-2005, 03:14 AM
Got the castle link today. Set the cut off to 8volts. Had an absolutly perfect flight. I am really impressed with the castle creation controllers. I also test flew my ultra stick 60 electric today. The HV controller and axi outrunner really work great together. I can't believe how well these brushless motors pull large planes around! My .60 size glow can't even come close to the performance.

GeraldRosebery
08-14-2005, 02:28 PM
That's great. I think what most people don't realize is that you CAN take LiPo's quite safely under a technical readout of 3V per cell under load. If you stress the LiPo's close to their advertised C output (say 10C) some cells can't really deliver close to this rate without dropping in voltage significantly. The result will be controller drop-out and shut down. The voltage bounces back up immediately. The REAL issue is that you have to keep net no-load voltage above 3V per cell or cell chemistry will quickly be affected. You have to learn what the capacity of each pack to deliver current (and volatge) actually is and adjust your controller accordingly. It is wise to be conservative or you could lose the pack if you get too greedy.