Air Thunder 3S 2200 25C / Revolution 3S 2100 18C / Kokam 3S 2000 15C Lipo comparison

 

Overview

The following is a three-way comparison of the Airthunder 2200, Kokam 2000 and Revolution 2100 lithium polymer batteries. The comparison has been conducted based on my experiences flying these packs back-to-back as well as taking flight logs using a Micropower E-logger. I have attempted to compare the flight logs to show how the performance of the packs differs for the same type of flight manoeuvres.

It is important to understand that this is an in-flight comparison not a technological review. So items such as ability to withstand deep discharge are mentioned but not a factor in comparing flight performance of the individual packs. Where as voltage hold under load and weight are very strong factors in comparing the packs once airborne.

As with any packs there are many different factors that lead to good performance and below are some tables which allow a quick comparison of the key factors such as weight, size and current delivery capabilities.

All testing was completed using a T-Rex SE V2 fitted with the Align speed controller and 430XL motor. The packs were flown back to back with a suitable cooling off period for the motor between flights.

All three packs were provided FOC by the respective pack manufacturers for this test. Therefore no bias is applied to any pack as a result. The Kokam pack is in this test as a benchmark to assist in understanding how the two newer packs have moved lipo performance forward. None of the manufacturers here sponsor the site in anyway. Furthermore if TrexTuning wants more of any manufacturers packs it pays retail price like everyone else, only one item is accepted by TrexTuning FOC for testing and further items are only ever sent FOC should the original item either fail or a new item is sent to participate in further tests against other products. This is done as it is unfair to test an old used pack against new ones and TrexTuning will not compromise it's independence by accepting continued free products from any manufacturer for personal use.

Lastly this is a comparison of these three packs ONLY against one another and is not a reflection on other packs in the market. The winner in this test is the winner ONLY against the two packs it is being tested against. Had other manufacturers chosen to submit packs for testing they would have been included.

All of the raw data is provided from the tests and presented exactly as it came off the datalogger.

Pack Specifications

 

 

In-flight performance

All in-flight testing was performed with the new T-Rex SE V2 in stock configuration.

Airthunder

The pack fits nicely between the frames and butts up against the battery stop on the tray. The battery stop just stops the pack from resting against the motor. These packs are quite long and do stretch down into the nose of the canopy. However, the canopy still fits nicely without putting too much strain on the canopy mounting posts.

I've fitted the pack with a deans connector which should handle the power of a micro helicopter without a problem. Spooling up the head speed climbed to the usual 3000 RPM of the T-Rex SE V2.

Taking off the pack provides adequate power for some quite spirited 3-D flying. Certainly continuous tic tocs or continuous flips are not a problem. After four minutes of 3-D I landed to check the packs temperature. The pack was quite warm but certainly not hot enough to warrant any concern.

My thoughts on flight performance were that the pack offered a good performance. Of course it's not clear what the cycle life is on these packs and it will take some time to ascertain this. The recent lab test of this pack offers some guidance in this area.

Kokam

This pack and has never been one to fit between the frames, however, it does sit nicely on the battery tray although it is quite snug once you put the canopy on.

When powering up the head speed reached the required 3000 RPM but I did notice that it didn't sound quite as spirited as the Airthunder or Revolution pack.

Taking off the pack provides adequate power for spirited 3-D flying. Again there is enough power for tic tocs or continuous flips. After four minutes of 3-D the pack is warm but again certainly nothing to be concerned about.

The kokam pack has a long known history for being a good, solid performer in the T-Rex. It also has an exceptional cycle life. The only downside being that it is rated as a 15C pack, and this can be felt in flight, when compared to newer and higher specification packs.

Revolution

The Revolution pack is by far the smallest and lightest of the three packs on test. It fits easily between the frames and doesn't reach too far down into the T-Rex canopy.

Spooling up the head speed climbed to the usual 3000 RPM and the no load head speed sounded just as spirited as that of the Airthunder pack.

Taking off the pack provides plenty of power for spirited 3-D flying. Additionally the light weight of this pack is evident in the flight performance as it feels much more sprightly than the previous two packs. After four minutes of 3-D the pack is warm but certainly nothing to be concerned about.

This pack offers maximum flight performance and was the most exhilarating to fly of the three packs.

In-flight graphs

The Airthunder was tested against the Kokam 2000 15C and the Revolution 2100 18C.
I chose these two packs as the first one is a tried and tested pack for the T-Rex that offers good performance and fantastic cycle life. I chose the Revolution pack as it is a newcomer and I thought it would be interesting to compare two very new technologies. Each packs graph is identified by the caption under the graph.

As always it is very difficult to compare in-flight graphs as it is almost impossible to fly exactly the same flight from one pack to the next in order to get a comparison. However, we can dissect the overall information for the entire flight as well as looking at subsets of the flights where I know what manoeuvres I was performing.

Initially let's take a look at the overall picture of how these packs compare.
Overall the Kokam 2000 has the lowest performance, followed by the Air Thunder and the Revolution gave the strongest performance. I have summarised this in the table below:

 

Analysing these figures are little further we can see that overall the revolution pack had the hardest flight in that the average amps and maximum amps were greater than the other two packs. Despite this it managed to average a higher voltage than the other two packs as well. However, the Revolution and Air Thunder were very close in terms of their overall performance.

Now let's take a look at the beginning of the flight where I was doing fast side on tic tocs. I will just compare the Revolution and the Air Thunder as they are the most similar in terms of overall performance. The two graphs below were taken right at the beginning of the flight where the machine was put into a fast side on tic toc for 30 seconds. As neither pack has done anything except spool up there should be no inherent advantage to either pack in terms of it's performance.

 

 

Again I have summarised the results in a table:

 

Analysing the results from this we can see that the Air Thunder is much less happy under heavy load than the Revolution. Of particular note is the minimum voltage for the Air Thunder which has dropped down to 9.65 V. Looking at the graph you can see that the Air Thunder also has the advantage that I hit it harder right at the beginning of the 30 seconds whereas the Revolution pack was hit harder at the end of the 30 seconds and therefore theoretically should have been more tired and less willing to perform.

Conclusion

It has certainly been interesting testing these three very different packs. They are different in terms of size, weight and internal chemistry.

The kokam pack continues to be a good choice for a beginner or sport flyer in that it offers a rugged pack that is resilient and has exceptional cycle life. For those not wanting maximum performance but cycle life (value for money) this pack has for some considerable time been a good choice. In recent months I have felt that newer technologies are starting to overtake the kokam pack and it is testament to just how good this pack was when it was released two years ago that it is still a contender today.

The Airthunder pack is the heaviest on test and this is evident in its in-flight performance. Although it outperforms the kokam pack on voltage hold its extra weight serves to make it only just beat the kokam pack in the air. The Airthunder was proven in the lab test to have good cycle life and also to be resilient to overdischarge which is one of the manufacturers claims.

The revolution pack is the lightest on test and also exhibits the best voltage hold characteristics of the three. This equates to the most powerful performance in the air. The revolution is also a very new pack and is very modestly rated (18C) considering how well it performs in comparison to a 25C rated pack (Airthunder). The revolution is also the cheapest pack in the test although at this stage it's cycle life (value for money) has not been ascertained.

The revolution pack for me is the clear winner as it is the lightest, smallest, cheapest and provides the best performance amongst the three packs on test.
The Airthunder gains a second-place but only just as whilst it did outperform the kokam on voltage in the air it was extremely difficult to separate the performance of these two packs.
The kokam by default gets third place but this is still a very respectable performance in that it's almost matched the Airthunder in-flight. It also carries with it a long pedigree of being a proven performer in the T-Rex.