Solderless Power Tubes??

[Paul]

Hello Guys,

Anybody ever tried these? The concept is cool but ya got to wonder if they worked so well why aren't they around?

Paul.

[AndyKunz]

Paul,

MEC has been pushing them for airplanes, where due to the much lower current they are far more acceptable.

Supposedly they were used to set the IMPBA speed records, or maybe he just tested them or something.

Andy

[Jeff Wohlt]

I also checked on these some time back. One thing that seems obvious is the resistance since nothing is beween them. Seems it would be ideal.

As long as they are tight and not moving, one would think they would be the hot ticket...espeically for non-racers

So why does nobody use them?

Anyone out there that has tried these? Sure would save some time,bars and solder!!

Just cut them for your 6/4/ versions and a person could maintain many combos.

I really like this idea as a sporter.

[Ben Diss]

Since they completely surround the battery, it keeps them nice and hot! Not good.

-Ben

[Patrick M]

Ran a test about two years back, comparing a power tube assembly to a Deans bar assembled pack. Using new RC2000 cells I cycled a 6 cell power tube pack on a Victor IQ and noted an internal resistance of 62 milliohms. Then disassembled the pack and reassembled the same cells with soldered bars. This time the IR of the pack was 48 milliohms.

Have heard of some racers who swear by the power tube assemblies, but I think I'll go with the lower resistance numbers. Probably OK for sport running and in the higher cell count classes the IR's have less impact on performance.

Will have to perform the same test, sometime, comparing an end to end soldered pack to a battery bar pack.

[Greg Schweers]

A guy in our club 4 or 5 years ago played with them. The thing I didn't like about them is that they were bulky and added weight. If you weren't careful, you could crush the battery by overtightening the allthread rods, especially on the old 1700s where the positive was higher than today's batteries. With today's batteries you have to cut the shrinkwrap off the top of the batteries to allow for better contact. Also, you could only use 14 guage wire the way they were set up. But it was a good idea for the guys that wanted to rematch and zap their batteries, without having to grind the solder off the batteries.

[Paul]

Hello Guys,

Lots of good points, thanks for the feedback. Did seem to good to be true.

Paul.

[jdwxly]

Another point; they have done away with the threaded rods and now use strapping tape to hold the end caps on. MEC claims this works just as well and eliminates the hassle of getting the tension correct with the rods.

For boats I would be concerned if the tape got wet! I don't know if the pack would come apart or if the tape would hold.

As a data point, I used one of these in a high-powered sailplane for a couple of flights. This power setup draws 80 amps on 10 cells. The Power Tubes worked fine but they got REALLY HOT compared to an end-to-end assembled pack (also from MEC) which only gets HOT.