Battery Testing Results

Battery Testing Results


Video links and resuts at the bottom of the page.


 I’ve been testing and selling RC race packs for 30 or so years now.  My goal since the first day was to provide my fellow RC racer with the best possible race packs and is still my goal today.  Now that RC has moved on to LiPo packs it seems that marketing has created a lot of confusion and many racers and customers who use LiPos get taken advantage of by marketing gimmicks such as C rate, Graphene and LiHv.  I am frequently asked when SMC will have so called Graphene packs or LiHv packs and this made me realize that the marketing behind these packs works well as customers want to believe that there is something better available.   I decided to purchase various packs from various companies and test them in a way that shows the pack’s data and performance for everyone to see.  I will also show the data and performance of equivalent SMC models.

 
 My thoughts on Graphene and LiHv are as follows.  Graphene is supposed to increase the cell’s energy density and performance.  All the so-called Graphene packs I tested to date have cells that are the same size and mAh as cells from a few years ago.  If Graphene truly was used in these packs we would see an increase in mAh or the same mAh and a smaller size cell/pack, which isn’t the case.  If you read up on LiPo studies and what is going on with LiPo technology there are only a few LiPo cells on the market that have Graphene, they just recently came out and based on the size I tend to believe that they might have Graphene in them but these aren’t RC cells/packs.   Samsung, a world leader in smartphones, has millions of dollars invested in battery technology to try and improve the cells they put in their phones.  They recently announced that they finally found a way to use Graphene that made for a better cell.  If a company like Samsung just figured out how to use Graphene to make better cells what are the chances that RC LiPo factories figured this out close to 2 years ago?  In my testing of the Turnigy Graphene RC car hardcase packs I noticed they gave the same data and performance as the Turnigy Ultimate hardcase car packs.   Once again this confirms my theory that there is no Graphene used in RC car cells/packs.  As far as LiHv goes this is real and the cells can safely be charged at 4.35V as the materials used in these packs are a bit different than normal LiPos.  The major issue with LiHv is I have yet seen a cell/pack have data as good as 3.7V Lipo made with quality materials.   Another thing to note is in racing you aren’t allowed to charge higher than 4.22v and some of the RTR ESCs will not turn on or work if a pack is charged higher than 4.20v per cell.  This is why SMC has yet to release LiHv packs.   I believe companies who jumped on this bandwagon did so as LiHv sounds good as HV means high voltage so racers/customers think these packs are stronger/faster but this isn’t the case.  Another good thing about LiHv is companies put the mAh that the pack provides at 4.35v so 8400mAh sounds allot better then 7200mAh but when charged at 4.20v the 8400 LiHv will give out 7200mAh.


 The other big marketing trick when it comes to LiPos is C rates.  At one time C rates use to be accurate and could be used to judge the performance of the pack.   Unfortunately this went out of control 6-7 years ago as factories, resellers and the final company selling the packs all decided to boost C rates to try and sell more packs.  The factories who make RC cells tend to not want to deal direct with the end companies who will sell packs as the volume isn’t big enough. So most factories sell to resellers in China who then pretend to be factories.   SMC is not different as we went through resellers at first.  The factories who make the cells tend to inflate the C rates, the resellers inflate the C rates some more and then the company selling the packs also inflates it.  SMC is big enough to work with factories direct as our volume is high enough and when you ask for true C rate testing the factories will show you the real data.  Based on what I’ve learnt by testing and getting info from the engineers at the new factory we deal with the very best possible C rate is 50C with the latest materials available.


 As you can see this is a good bit different then what most claim for C rates.  In most part, C rate is directly related to the cell’s IR (internal resistance) and the mAh.  Due to this practice, I created the True Spec Amp rating so all SMC True Spec packs have an Amp rating that is based off the cells IR and mAh.  This way the customer can see which ones of our packs offer the best performance.  We still use C rates as ROAR demands C rates to be listed on packs sent for approval but we try and put the C rate we feel reflects how the pack will perform.  So our 150C packs have more performance then our 90C packs.  Another thing to note is C rate and mAh work against each other just like torque and RPM you can’t improve one without dropping the other.   This is why our Extreme packs have lower mAh but have a higher true amp rating and we claim a higher C rate. 
 
I will share testing that shows the IR of the cells within a pack using the ESR IR meter, which is in my opinion the best device to accurately measure IR of the cells.  The packs will then by cycled using a 12 amp balance charge an iCharger Duo and 35 amp constant discharge using the Competition Electronics GFX.   The GFX will show the IR of the pack, average voltage and mAh.  I will also show the voltage at 300 seconds which is 2916mAh into the discharge.  I believe this is a bit more mAh then would be used in stock style races but is a good way to show the voltage of the pack near the end of a race.  I will do a 100 amp test for 35 or so seconds and I will then show the voltage at 30 seconds.  This will show which packs have the best voltage under heavier loads which you can encounter under acceleration.  Think of this as the punch test.   I will also calculate the watt hour per kilogram of the packs using the data from the 100 amp test as this will figure in the weight of the pack as this plays a role in the performance of the pack. 

 

Testing methods and equipment used:

 IR testing is done using the Lipo ESR Meter which in my opinion is the best meter to accurately test Lipos.  All tests are done with the packs at storage voltage and at 22 degrees Celsius.  In my testing I’ve found that static IR readings at storage voltage under a controlled temperature is more accurate then testing IR on a charger while the pack is charging. 
 
Charging of the packs is done on an iCharger 4010 Duo in balance mode at 12 amps.   As soon as the pack is done charging it’s discharged on the Competition Electronics Turbo 35 GFX.   This charger/discharger can do up to 35 amp for discharge and measures the packs voltage and gives average voltage, mAh and IR under discharge which is an accurate way to measure IR as it measures it at 121 seconds on each pack.   The discharge rate selected is 35 amps.   I will show the mAh, average voltage, IR and voltage at 300 seconds, which is 2916mAh, to show the voltage of the pack at the end of a stock run.  I believe 300 seconds at 35 amps is more then what racers typically use in a 5 minute run but all pack voltages at 300 seconds will be shown.
 
In my testing I’ve noticed that some packs may give similar results at 35 amps but when tested at 100 amps the results are different.  I believe different materials react differently to the higher loads so the 100 amp test represents a punch test to show which packs drop less under heavier loads and will give more acceleration.  The test is done for around 35-40 seconds then it’s stopped and the voltage at 30 seconds is looked at.  I use external loads controlled by FETS that I set to get a total of 100 amps in combination with the Turbo 35 GFX.   The GFX triggers the external loads once the discharge is started and the GFX registers the voltage of the pack.



 All packs were pruchased in January 2018.  If any company who is featured in this testing believes the packs purchased is from a bad batch or results should be better please contact us and let us know when a new batch is available so we can purchase a revised pack.  The goal of this testing is to show how C rates are useless and used as marketing and that exotic materials like Graphene really don't seem to improve performance over a regular Lipo built with quality materials.  We can also offer our testing services to other companies to give a proper evaluation of the packs they sell or intend to sell. A detailed report of the tests will be sent.   If any company is interested in purchasing cells/packs from the factory we deal with please contact us.  


Static IR Testing Video

35 Amp Test Results

100 Amp Test






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