RC India

RC Equipments => Electric Power => Topic started by: foolsworldus on December 03, 2014, 02:04:12 PM

Title: How long will the battery last..
Post by: foolsworldus on December 03, 2014, 02:04:12 PM
I am using 2 nos. of Brushed motors with the following specification for my boat setup..

Rated Voltage Current : DC 12V
No Load Current: 0.2Amps (Max ~1.2 Amps)
No load Power Consumption: 2.4 Watts (Max ~15 Watts)
No Load Speed: 6000RPM
Motor Shaft Diameter: 3.17mm
Mounting Screw Hole Diameter : 3mm
Distance between Screw Holes: 25mm
Diameter of the Motor: 36mm
Length of the Motor (Body): 50mm
Length of Shaft: 16mm
Main Color : Silver Tone
Material : Metal
Net Weight : 150gm
Cylindrical shape and with 3mm diameter shaft and 2 pin connectors.

I am using turnigy 30amp brushed ESC..the watt meter shows its consuming MAX 3.7 amps..
HOW LONG SHOULD a 5000Mah 3s battery last on full 4 amp load..??
Title: Re: How long will the battery last..
Post by: sooraj.palakkad on December 03, 2014, 02:10:37 PM
What is the discharge rating of your battery (C rating) ?
Title: Re: How long will the battery last..
Post by: rcrcnitesh on December 03, 2014, 02:34:54 PM
more than an hour I guess.
Title: Re: How long will the battery last..
Post by: IndianHobbyShop on December 03, 2014, 02:38:15 PM
Since this motor is consuming max 3.7 Amps, at full throttle (3.7 Amps), it would last 5.0/3.7 = 1.35 hours = about 1 Hour 21 mins on this 5Amp Battery.
Of course you should never discharge a LiPo completly. So until the Low Voltage alarm Kicks in, the realistic figure should be just a bit above 1 hour.

@sooraj.palakkad, Discharge rating is not required for this calculation since the power requirement of the motor in this setup is even less than 1C !
Title: Re: How long will the battery last..
Post by: foolsworldus on December 03, 2014, 03:02:48 PM
Thanks guys.. verry helpful..
Title: Re: How long will the battery last..
Post by: sooraj.palakkad on December 03, 2014, 04:14:08 PM
But it depends on Ampere hour and also Discharge rating of battery ???
Title: Re: How long will the battery last..
Post by: SK1701 on December 03, 2014, 04:21:36 PM
Hey, the discharge rating does not affect the battery life. It only tells you how much the battery CAN supply constantly. The 5Ah battery in your example CAN supply 100 Amps but at that draw it would run out in (60/20)= 3 minutes since you are running at 20x 5A you will get 1 hour/ 20 flight time.
Title: Re: How long will the battery last..
Post by: IndianHobbyShop on December 03, 2014, 04:26:25 PM
Discharge rating only depicts "How fast the LiPo can discharge itself."
The capacity of a battery is limited and does not changes with the Discharge rating. In this case it's 5000mah.

So a 1Ah (1000mAh) 1C battery means it can yield 1A of current constantly for 1Hour, In that way, a 5Ah, 20C pack can provide 5*20=100A
True, but not for 1 hour. The time will decrease as per SK1701's explanation.
Title: Re: How long will the battery last..
Post by: sooraj.palakkad on December 03, 2014, 04:27:21 PM
yeah I got it, was little confused on that matter !
Title: Re: How long will the battery last..
Post by: foolsworldus on December 03, 2014, 06:34:11 PM
Its irrelevant now...but still the battery is rated as 30c..
Title: Re: How long will the battery last..
Post by: sooraj.palakkad on December 03, 2014, 06:46:22 PM
5000mAh pack will give you at least 1Hr playtime, even if the total current consumption is 5Amps constantly !!
Title: Re: How long will the battery last..
Post by: IndianHobbyShop on December 04, 2014, 12:07:46 AM
Quote from: sooraj.palakkad on December 03, 2014, 06:46:22 PM
...even if the total current consumption is 5Amps constantly !!

Sooraj, You never discharge a LiPo Completly ;)