Originally Posted by Whymee

I read this thread with great interest. I have not read the "other" thread, so I go on the assumption that the other thread was about brown outs too.

The answer is fairly simple. Size the electronics in your plane for the maximum amp draw that the plane is capable of. The main word here is "capable".

You can use the KISS method. Usually this means no redundancy, and not enough amps.

I am all for redundancy in a plane larger than 33%. I use a Power Expander (PE), A123's and pin switches.

The movable switch is usually the most likely failure point in any system, new or old. The pin switch is always open except when your prop isn't turning.

One thing I have not seen talked about, but is extremely important. The servo lead connector. This connector is only good for 2 amps or so. This is the biggest bottle neck in our "electronics package" that we fliers are using to date. Add more connectors between the RX and the servo, (extensions, y's etc) the resistance goes up & the amps (voltage) go down. Always make sure that you only have 1 connector in the line to the servo, and that is at the RX/PE/powersource. Learn to solder.

For the life of me I cannot understand why someone would use a 3 pin connector to power a RX with many amp drawing servos hanging off of it. It is beyond me. I also see some setups where they have used as many as 4 of these connectors to power the RX from the battery. Good grief dudes, talk about potential brown outs! Other posters have seen spikes in the 30 amp range. Do you think 2-4 of these 2 amp connectors are going to pass 30 amps to the RX for a couple seconds?

I have been building battery packs for many moons now. I have built nicad, nickel metal, Li, LiPo & A123 packs. As of this writing I have had one Nickel metal pack fail on me (many years ago). I solder on all with a very big iron. Some of my A123's have been in service for 7 years. Still going strong. For the average / above average flier I see no need to fly with any other chemistry. You can damn near weld with the amp output of these packs. Even the cheaper knock offs (of A123) put out more than our models will ever need.

I have also been using A123's with all my Hitec servos. From the 56XX series to the 79XX series. All have lived up to A123's unregulated. I don't need anything better(?) than a 7955. My fingers can't tell the difference!

In conclusion, get rid of that slide switch, one 3 pin connector per servo and run a PE with A123's through Deans connectors. Your system will NEVER have a problem with not enough amps/voltage at the servo* or at the RX.


Regards,

Stan


* The one condition I can see overloading the connector to the servo is if it stalls, that servo is going to draw more amps than the connector can pass. At this time, with the 3 pin connectors being used, this cannot be helped.