Lipo C rating advice

[Leumas 1]

Guys,

 

I know this topic is done to death but I just can't seem to find any answers to my specific question.

 

I'm looking at purchasing some more Lipos for my TT-02b. 

Currently running a HPI Firebolt 15T Motor & Hobbywing 1060 ESC on Core RC Lipo - https://www.modelsport.co.uk/core-rc-4000mahr-7-4v-30-60c-2s-lipo/rc-car-products/388538

 

I'm narrowed down to two different batteries. One is 25C constant and the other is 40C-80C Burst. 

 

25C:

https://hobbyking.com/en_us/nano-tech-4200mah-2s-25c-hardcase.html

40-80C:

https://hobbyking.com/en_us/turnigy-nano-tech-4200mah-2s2p-40-80c-hardcase-stick-pack.html

 

Am I realistically going to see any difference in performance or usability? My preference is obviously the 25C because they're that much cheaper.

 

Any advise is appreciated. Thanks.

Sam

[simalarion 2195]

Ive only been reading about the C rating and its about the current discharge rate, if you drive on silver can you will not need a higher discharge rate than 25c (i was reading futrher  )

[Jonny Crumpet 112]

If it were me I would spend the extra £5 and get the higher rating. 

Then you are future proofed if you upgrade or more likely get another model.

I got 2 of these: https://www.modelsport.co.uk/index.php?product_id=444355&gclid=Cj0KCQiA7YyCBhD_ARIsALkj54powpS0dahl2i-keMGH_GeYHQhosiPsT989TPcYC2_yZX93Zflo2zAaAqeWEALw_wcB

[Juggular 4961]

25C should be plenty.  

How plenty?  Well, 4200mAh 25C should give you over 100A. That's 4200mAh drained in about 2.5 minutes. Silver can takes only about 1A burst. 15t motor will take more. But nowhere near 100A.  My guess is about 2-3A.  (13.5t Brushless can take out 5-6A burst)  Even if you get a 10C battery, you'll still get 40A. That's more than 20 times your 15t motor can take out.  

Some of us are speed demons.  In that case, you might want 40C (or higher) and install 3.5t motor or something. 40C can drain 4200mAh in 90 seconds.  For mere mortals like myself, I can't envision any situation where I'd want my battery be drained in 90 seconds.  I would keep the money and buy 25C.  

 

[Wooders28 4720]

Although I have some,  I'm always a bit wary with 2s2p lipos. That means there's 4 Lipo cells, 2 pairs in parallel, to double the Mah,  then those are wired in serise to double the voltage. So even when balance charging, you're a pair of cells with a pair of cells , not individual.....

Even the lowest discharge lipo is 4.2 X 25 = 105amps, which should be enough for a 15t firebolt, with suitable gearing.

Another thing to consider, is the plug, unless you're ok with soldering on a differnet one, I'd just get one that's plug and play. (I'm fairly confidant, and the last one I did, felt like I was defusing a bomb...😳😂😂)

[sosidge 624]

13 hours ago, Juggular said:

25C should be plenty.  

How plenty?  Well, 4200mAh 25C should give you over 100A. That's 4200mAh drained in about 2.5 minutes. Silver can takes only about 1A burst. 15t motor will take more. But nowhere near 100A.  My guess is about 2-3A.  (13.5t Brushless can take out 5-6A burst)  Even if you get a 10C battery, you'll still get 40A. That's more than 20 times your 15t motor can take out.  

Some of us are speed demons.  In that case, you might want 40C (or higher) and install 3.5t motor or something. 40C can drain 4200mAh in 90 seconds.  For mere mortals like myself, I can't envision any situation where I'd want my battery be drained in 90 seconds.  I would keep the money and buy 25C.  

 

You're miles off with your burst currents (silver can 540 probably closer to 20-30A, 13.5T brushless probably 40-50A) - if it was a 1A burst current then every car which uses a silvercan could be run "hard" for 4 hours on a 4000mAh Lipo!

Regardless of that, I agree that a 25C 4200mAh LiPo should be plenty. I have a 20C 4000mAh that i've used in Tamiya racers and bashers for years and it has never been short of performance.

[Juls1 1660]

For Tamiya cars 100A should be plenty, that being said the extra few dollars for 168A isn’t too be sniffed at. 
 

if you intend on owning anything bigger and heavier than the average Tamiya, then the extra capability is worth having. 
 

I had some 3700mah 30c lipo’s I used for 8 years on Tamiya cars and various others without a problem. Loved those battery’s. Then I bought a proboat veles 29 boat and destroyed both of my beloved battery’s on the first run, failed to consider how much current it would draw and ruined both battery’s. Later on I picked up a Traxxas UDR, and stupidly destroyed a pair of 4000mah 30c packs. Again it used more current than the battery’s where designed for. 
 

I guess what I’m saying is, that if you know you’ll only be pushing around lightweight 1/10 scale Tamiyas, then go the cheaper packs. But if anything bigger and heavier is on the horizon, the extra C purchased now can save you money and time later on. 

 

 

[Juggular 4961]

10 hours ago, sosidge said:

You're miles off with your burst currents (silver can 540 probably closer to 20-30A, 13.5T brushless probably 40-50A)

I think you are right!  13.5t was drawing 55A at burst.  Max efficiency was 3A.  

(Come to think of it, if burst stays that low, we won't need 60A or 100A ESCs!) 

 

[Wooders28 4720]

Mabuchi's official figures show a 540 to have a stalled current draw (max) of 57 or 70 amps (depending which 540 it is).

Core RC have their 15t brushed motor (I'm pretty sure it's the same motor as the 15t firebolt?) rated to a stall of 117.5 amps.

Anyone with any sense, wouldn't run a motor for long stalled (may get grass caught around axles, but you'd not try and keep going), but that's the manufactures max figures.

 

11 hours ago, Juggular said:

I think you are right!  13.5t was drawing 55A at burst.  Max efficiency was 3A.  

Great vid that, shows why sensored motors are sold as ,Turns, with the KV not set in stone, and also the gains you can make ,from having a decent sensored esc! 

With regards to C ratings, I'm not convinced they are 100% accurate , and depends on the manufacturer etc, so maybe not something you should solely focus on. A bit like speakers a £400 - 400w Rockford Fosgate amp, would be far louder than ,say a £50 - 2400w amp.