Calculating The True C Rating of an RC LiPo Battery Pack

A LiPo Battery packs C rating is a very important specification on a LiPo.It represents the ability for a LiPo battery pack to provide continuous current. There is a fairly simple calculation to be performed to get the maximum discharge current from the C rating.
The question then becomes, how do you know that the C rating specified on a battery pack is accurate and not just some buy now bait from a marketing team? Or how do you know if a battery pack is weakening with age and or wear?
The most simplistic approach to quickly estimate the actual C rating of a battery pack is to calculate it!
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[@AJ-js1yw]

one of the best RC channels. please never stop.

[@RCexplained]

Thank You James, appreciate your awesome comment, it means a lot to me. I have no plans of stopping.

[@Eden_M]

The comments below prove to me that what I felt while watching this was completely authentic, you're awesome Ryan, honestly. this topic couldn't be explained better, thank you!

[@RCexplained]

Hey Eden, thanks for the kind words!

[@marksmola7299]

Excellent video as always. Thanks for sharing.

[@RCexplained]

My pleasure!

[@juancisneros725]

The most usefull thing ever! thanks a lot!!

[@elisamuelhernandez3636]

Thank you! you are awesome.

[@RCexplained]

Happy to help!

[@LawrenceTimme]

I can't measure the resistance and charge at the same time, is a completely different setting to measure the resistance.

[@evoxer87]

Me too, I can NOT take the measurement of the battery pack WHILE being charged. In SkyRc chargers (mine: Ultimate Duo 400W) this measurement is in "main menu-batt resistance"...

[@RCexplained]

Yes, there's no set standards for charger manufactures as to how battery resistance is to be measured for those that can even do it. There's a few different methods used. I like how SkyRc forces a *more* consistent method for measuring resistance. But I'm not clear as to their process and even if it is as consistent as I'm assuming. The charger must be either be charging or discharging in this battery measuring mode. Do you know how much current the charger uses to measure resistance?

[@LawrenceTimme]

@@RCexplained I'm guessing it does it through the balance connector? So maybe if I use the current clamp it will tell me?

[@RCexplained]

It's possible it is taking current from the balance tap. You may be able to tell if this is true by seeing if you can plug the balance tap in only and the units starts the resistance reading. If it requires you to plug in the main leads to the charger I would try and measure this by using a current meter of some sort.

[@evoxer87]

@@RCexplained when connect the battery only on balance tap the charger says: NO BATT DETECTED (SkyRC UD400)

[@takenpictures]

Dude, good poop, subscribed!!!

[@RCexplained]

Thanks Mike!

[@jdd1777]

Check Joshua Bardwell's channel. He has a battery tester and has done extensive testing of all the latest batteries.

[@KurNorock]

I've never seen a charger that give the internal resistance...

[@RCexplained]

I'm a bit surprised. I haven't seen a good charger that does not support that feature. I wouldn't want to buy a charger without that feature.

[@KurNorock]

@@RCexplained I didn't know that was even a feature that chargers had until I watched this video. I checked and it turns out my new charger does have this feature, it is just buried in the menu. I suppose I should start making use of it.

[@RCexplained]

awesome, that is great

[@g.b-MTB-trail-jumps3062]

Nice vid bro I use a battery 4s 6000mah. 55C Now I bought a battery 4s 6000 mah 120C. What change will I feel ... by power ...driving time.. I charge regular ? Thanks

[@RCexplained]

Your battery will hold better voltage under higher loads. You can charge the pack using the recommendations from the manufacture.

[@furiouswolf777voodoo4]

Esc to motor what's better 8 gauge copper or 8 gauge aluminum wire...Thanks love your vids , stay safe🙂

[@RCexplained]

Copper has a better conductivity then Aluminum. Copper will also take more mechanical abuse. Thanks! You too!

[@akmalphoenix7959]

hello. i have 60A ESC, and 4370KV motor. what C rating is suitable for my rc car? hope u can help me.

[@RCexplained]

Hello, this should help you! kzbin.info/www/bejne/Y3-9ZnV5ibGlqpY

[@fiskeflax4894]

Disapointed ! I thougt this video would teach me how to messure internal resistance and do the calulation. After ten minutes of watching I realize it teaches nothing but how to use a function on a web site.

[@ericklein5097]

1. Measure open circuit voltage. 2. Apply a load (with something like a resistor or whatever) and wait 1 second and record the voltage. Determine what that loads current (I) was. 3. Open circuit voltage -Under Load Voltage=Voltage Drop (V) 4. V/I=IR ie 0.071/10=0.0071 Ohms 5. There you go. 7.1milliohms 6. All testing that is done comparing packs should be done at the exact same temperature. DC IR is also very dependent on pack voltage, unlike AC Impedance which barely changes throughout the voltage range. I'm not into the Lipo world as much as NCM/LFP but I believe testing IR at 3.8-4.0V is fine so long as you use the same voltage for all packs. A more accurate number can be had by using multiple different loads. I can't remember off the top of my head how to put that equation together but its' quite simple Less voltage drop equals better f;;;;;l

[@robertjacobson1399]

What charger are you using?

[@RCexplained]

EX1400

[@JoaoPaulo-pb9zv]

I have been seeing your videos with great attention, and this one in particulary got me sad, because altought I am very concerned with my lipos always going to storage and not going too far when running I discovered that all my batteries are low grade batteries because even the newest ones Don t have the "C" rating that is on the label. I m glad my rc s are not top notch😔😔😎😎

[@RCexplained]

I have found that Turnigy Graphene packs do very well. However, in your case, if your packs are performing well in your application and not getting hot, then it doesn't matter what the "true" rating is.

[@JoaoPaulo-pb9zv]

@@RCexplained ok... Well in the summer specially those that run in the supervee 27 get in the mid 40 s centigrade, but I always run the boat in a big pond and almost all the time at full throtle to"unleash it's bad temper"😉😉

[@kasrasahami3036]

hi. how can I make sure that my Ni-Mh battery is 10C as the company said? I do not trust what they say!

[@RCexplained]

I do not have any data on 10C batteries, sorry.

[@ericklein5097]

Use a power resistor that would draw a 10C load. So lets say you have a 12V battery. That battery is 2000mah. 2Ah*10C=20A of discharge current. To get 20A from a resistor you need to find out what number you can divide 12 by to get 20. 12/1=12A so 12/0.6=20A. So a resistor that is 0.6 ohms or 0.6R. Now here's the power part of what your resistor is rated for (5W, 10W, 25W, 50W, 100W, etc) 12V at 20A creates 240W of power. You would need a 250W or 300W resistor to absorb that power. Those are a little pricey like more than $10, closer to $20 or $30 Easier way would be a discharger like an Atorch DL24 ($35 shipped for regular 150W, 20A version, they make an expandable version that goes up in 150W increments to 600W max, 40A). Buy the main unit and one expansion so you can do 12V at 20A for 240W. This is all hypothetical about your batteries size of course. Other options: EBC A20 85W, 20A max with charging abilities for CC CV. EBC A40L 185W, 40A charge/discharge max but limited to 5V cells. ZKE Tech makes also EBD chargers....the D means discharge only. The C versions have charging ability. They make them in a few sizes for pack discharging 12V to 72V. The cheapest models like the EBC A05 is $50'ish and the EBC A20 is $80'ish. A40L is $200 and the EBD's are usually a bit more.

[@ericklein5097]

your battery passes the test if it can withstand the load without the voltage crashing into the ground and provides its rated capacity or something close to it

[@TheoriginalRcRat]

😎👍

[@txkflier]

Not bad, but too many "go aheads"..

[@ChiggyMakonga]

Blah blah blah blah blah blah blah blah blah annoying going on and on and on and on just to make the video longer... Thumbs down!

[@ChiggyMakonga]

This video is incredibly annoying. If theres not an acceptable answer by the end im going to raise hell