Sep 12, 2015, 10:43 PM Registered User Joined Sep 2015 2 Posts Discussion How to test 1S lipos? I would like to test my 4 different kinds of 1S lipos to see how they perform. The idea is to measure the power output by discharging. If it is 150 mAh and 25C, then I guess: 150 mAh *25C = 3.75 A So, the max power draw should be 3.75 A. Can I test the battery by using my charger to discharge at 3.75 A? What happens if the battery cannot supply 3.75A? Can I measure the power output of each battery by finding the maximum discharge amperage, as long as it does not exceed the C rating?
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 Sep 13, 2015, 02:51 AM Registered User Letchworth, Great Britain (UK) Joined Jul 2004 13,034 Posts Welcome to the forum Your numbers are correct, and you can "test" your batteries the way you suggest, but I would say that it's perhaps a bit pointless, and risks damaging the batteries. Your main concern should be, "does the battery hold up in my application, which is hopefully demanding much less than 3.75A?" If you discharge at 3.75A for a test, how long are you going to hold that amps rate? At 3.75A the battery will be completely dead -- perhaps incapable of being recovered -- in 2.4 minutes. For sensible flight durations you really need to be drawing only about 10C (6-minute flight), and the battery should only be slightly warm at the end of it. That would be my only "test"
Sep 13, 2015, 11:40 AM
Registered User
Joined Sep 2015
2 Posts
Quote:
 Originally Posted by abenn Welcome to the forum Your numbers are correct, and you can "test" your batteries the way you suggest, but I would say that it's perhaps a bit pointless, and risks damaging the batteries. Your main concern should be, "does the battery hold up in my application, which is hopefully demanding much less than 3.75A?" If you discharge at 3.75A for a test, how long are you going to hold that amps rate? At 3.75A the battery will be completely dead -- perhaps incapable of being recovered -- in 2.4 minutes. For sensible flight durations you really need to be drawing only about 10C (6-minute flight), and the battery should only be slightly warm at the end of it. That would be my only "test"
I would drain 120 mA,h or 80%. So, if it can provide 3.75 A, that is 62.5 mA/min. 120 mAh would be drained in less than 2 min.

Would not go below 3.8 resting v.

I'm not really sure what the max application amperage is, because I am not measuring amperage in situ. The idea was to compare the batteries and see if they provide different levels of power.

Also, I don't know if the motor will consume more power if the battery provides more power. It is a brushed motor.

Regarding the application, the battery is drained to 3.8v after 3 min.
Sep 13, 2015, 01:30 PM
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Letchworth, Great Britain (UK)
Joined Jul 2004
13,034 Posts
Quote:
 Originally Posted by itshelitime ...Also, I don't know if the motor will consume more power if the battery provides more power. It is a brushed motor. ...
NO, the motor won't consume more power if the battery "provides more power" -- i.e. if it's bigger capacity or higher C rating.

All else being equal, it's the prop size and the battery volts that determines what's the maximum power output of a motor. The motor tries to develop enough power to move the prop or load, and will draw as many amps as necessary to do so. If the prop or load is too big, the motor amps will go beyond its maximum spec, and perhaps beyond the maximum spec of the ESC and battery too, with predictable consequences (smoke)

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