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
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
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.
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