Ok, we all know the most popular mini RC out on the market is the Traxxas mini E-Revo and its chassis sharing cousins: The Rally, Slash and mini Summit. So what is the best way to power these mini machines? Do we use a NiMh battery, LiPo, and what about parallel and series systems? We will break this question down for our readers and give some answers!
So the mini E-Revo from Traxxas is an interesting chassis in that it can accept two batteries and run them either in parallel or series. Parallel connected batteries add MAH (capacity) for more run time while series connected battery packs add voltage for more power and speed. Whatever the choice, we must make sure that the two batteries are the same brand, type, and capacity. Another choice is to simply run one battery pack…..though due to the design of the chassis, many people feel that their RC car will run lop sided due to uneven weight distribution.
Traxxas warns that two 7.4V 2S Lipos should not be series connected as the voltage with be too high, and cause the Traxxas ESC to possibly overload. Traxxas does not warn against using two 6 cell NiMh packs in series….so that is a common configuration that speed hungry people run in their mini E-Revos. The brushless versions can run upwards of 50 mph in this configuration. Speed does not come without compromise; the ESC and the motor will get very hot……so may the battery packs if they are not the better high discharge type Nimh. Be careful running this type configuration, and give some time for everything to cool down. I recommend a 5 minute break for every 10 minute run.
To take advantage of the Lipo’s lower weight, many people find 3S 11.4V packs that fit the mini E-Revo and run them in parallel. Make sure that they will fit before buying…..there are so many different choices on the market. Get at least a 20C rated type to prevent overloading the battery packs. Like the Nimh battery packs….give a 5 minute break for every 10 minute run. Over heating the motor will cause the magnets to loose power and render the motor unrepairable and less able to put out its original output.
Parallel running two battery packs gives two advantages: longer run time and shared load. With two batteries in parallel the power draw is distributed between the two packs so that they don’t get over stressed. So a pair of 20C 1800 mah 7.4V Lipos connected in parallel would act and perform like a 40C 3600mah 7.4V Lipo.
Series running two battery packs gives the advantage of higher top speed, and acceleration because the voltage is doubled. Running in series, two 7.2V 1500 mah battery packs would act like one 14.4V 1500 mah battery. The disadvantage is higher amp draw from the motor which also will create heat for the ESC, battery, and motor. So choose this option carefully and understand that higher speeds come with higher wear and chance for damage to all the components involved with running higher voltage power.
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Michael Mizzi is a 30 year veteran of the electric RC car hobby and owner of Hi Power RC-an importer of the finest RC Car battery packs. Specializing in 1/18 to 1/10th scale, his NiMh and Lipo battery packs have been well received. You can buy direct from his website at http://www.HiPowerRC.com
Steve Jobs announced the release of the new iPhone 4 recently, and we’re still not sure whether to regard this as a mobile device as a Tablet PC because its Apple A4 CPU is so powerful that it would rival any Tablet PC out there.
iPhone case
From the outset if you look at the form factor of the device, it’s pretty clear that it’s taken lessons from its bigger brother, the iPad tablet PC, because the iPhone has swayed away from it’s previon smooth and rounded incarnations, and opted for crisp sharp corners. This makes it a bit difficult to hold in your hands, however because the chassis is made out of stainless steel rather than plastic, it feels more expensive. It is also slightly thinner than the iPhone 3Gs which make the trade of worth it, (the rounded edge on the iPhone 3GS adds up to the thickness of the device as it’s difficult to place components on the edge of the device)
Features
The iPhone 4 takes a microSIM which is one of the first mobile devices to feature it, this would in practice make the iPhone slightly harder to acquire on networks which do not have contracts with Apple.
Even space of the iPhone aka tablet PC has a purpose for being there, the iPhone 4’s steel chassis works are part of the antenna on the device, so you should theoretically get greater wifi, 3G, cellular and bluetooth signals and connections from using it.
We found the high res camera (960×640) a delight to use and can finally take pictures worthy of sharing on Facebook and generally uploading on the net. This is in stark contrast to the appalling camera of the iPhone 3GS.
It’s also a sigh of relief that apple has taken into consideration the feedback from its users and introduced a high capacity battery with 40% more talk time compared to the iPhone 3GS. This is impressive given the fact that the iPhone 4 is draws more power than the iPhone 3GS.
Apple has introduced an gyroscope into its device which expands further from it’s existing sensory awareness features such as the accelerometer, compass, proximity and ambient light by adding motion sensor, tilt and rotate features in its gyroscope, this adds another dimension and almost limitless possibilities for new app designers.
However
The iPhone 4 will definitely be a hit with existing iPhone users and Apple fans in general, however for much more educated and informed mobile phone users, the iPhone’s extremely slow rate of improvement leaves a lot to be desired, it took the iPhone 4 incarnations to produce a phone which the HTC can easily rival and quite possibly outdo in terms of hardware capabilities in its first introduction. Many would say that despite the iPhone 4’s improved battery, it’s still not sufficient to relieve the critics concerns about running out of battery life within a single day.
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-Abdul Karim
An avid writer for Quaduro Tablet PC, and a huge iPhone and macbook enthusiast, although an open critic of the iphone battery pack. Joe Enjoys blogging, salsa dancing and travelling in his spare time.
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