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Confused about lipo c rating
#1
Hello guys. Help me to choose the right lipo for my kwad please.
So i have read oscar's thread bout how to choose lipo but is still not understand yet. He said "For example, if you have a 3S 1000mah 20C LiPo pack, your safe max current draw would be 1000ma x 20C = 20A."
So i will use t-motor air 2650kv. The manufacturer says that at 100% throttle with dal 5045 it draws 27.4A. That's for 1one motor right? If yes, so it must 27.4A x 4 = 109.6A right? So if i choose 1500mAh battery, the minimum c-rating is 75 (109.6A/1.5Ah). I think 75 C is not a good choice for beginners due to price and crash rate. Please help me
And, Any recommendations for cheap but good for training lipos?
Thanks and have a nice flight.
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#2
Hey Zaqyw, the general opinion that I have found is that starting with 3s just means that you will buy 4s batteries in future and that the 3s will just gather dust after you have upgraded. You can change the settings in Betaflight or on your TX so that you don't have maximum throttle available until you feel you are ready for it.

Indestructible quads do some cheap batteries that sound like they provide a great power to price to lifespan ratio, but personally I only have experience with 1s.

Otherwise Tattu R-Line batteries are widely considered the best you can get.
Windless fields and smokeless builds
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#3
That 27.4A figure comes from a static thrust test and is way more than you'll get in real life.

I reality, you are unlikely to see the current exceed 20A. So, at full throttle (which you won't use that much), the absolute maximum current draw you'll see is 80A. Most batteries can deliver twice what their C rating implies for short bursts.

Don't be tempted to buy 1500mA/h where a 1300mA/h battery will do. If the battery is too heavy for the quad, handling is affected and you'll have something that handles like a boat instead of a nimble quadcopter. Oh, BTW, there is no such word as "kwad". Smile
[-] The following 1 user Likes unseen's post:
  • McDee
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#4
(29-Sep-2017, 10:02 AM)unseen Wrote: That 27.4A figure comes from a static thrust test and is way more than you'll get in real life.

I reality, you are unlikely to see the current exceed 20A. So, at full throttle (which you won't use that much), the absolute maximum current draw you'll see is 80A. Most batteries can deliver twice what their C rating implies for short bursts.

Don't be tempted to buy 1500mA/h where a 1300mA/h battery will do. If the battery is too heavy for the quad, handling is affected and you'll have something that handles like a boat instead of a nimble quadcopter. Oh, BTW, there is no such word as "kwad". Smile

I visibly cringed at the "word" kwad. Quad is also local slang for an all terain vehicle here in Canada.
Flying: Talon 6S 6" 2407s 381g no bat, Martian 3, 5" 2205s sooo heavy + gopro session 5 573g AUW, Aurora 5" 2205s 280g no bat, Druckbaer 3" 1404s 172g AUW 3S 550, BQE Megapixel 2.5" 1107s 139g AUW 3S 550, BabyHawk R 2.5" 164g AUW 3S 550 (stock except microeagle, CRSF, 2.5" arms) and maybe 3 more, for now...
 




[-] The following 2 users Like McDee's post:
  • RENOV8R, unseen
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#5
(02-Oct-2017, 11:09 PM)McDee Wrote: I visibly cringed at the "word" kwad. Quad is also local slang for an all terain vehicle here in Canada.

Glad to hear I'm not the only one who has a near physical aversion to language abuse! Big Grin
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#6
(29-Sep-2017, 10:02 AM)unseen Wrote: That 27.4A figure comes from a static thrust test and is way more than you'll get in real life.

I reality, you are unlikely to see the current exceed 20A. So, at full throttle (which you won't use that much), the absolute maximum current draw you'll see is 80A. Most batteries can deliver twice what their C rating implies for short bursts.

Don't be tempted to buy 1500mA/h where a 1300mA/h battery will do. If the battery is too heavy for the quad, handling is affected and you'll have something that handles like a boat instead of a nimble quadcopter. Oh, BTW, there is no such word as "kwad". Smile

Thank you, unseen! Now i have a question bout charger and power supply. Can you help me?
I will use isdt sc-608. Can i power it with 12v 30A psu?
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#7
you can use a 12V 30A PSU for the isdt.
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