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2 smart fly regs on a JR R921 rx?

Old 12-29-2008, 10:53 PM
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Default 2 smart fly regs on a JR R921 rx?

Hey guys. I just got my new JR X9303 w/R921 Rx. I will be installing this into my GP Ultimate for testing, but I have a quick question about setting up my batteries on this Rx. I was going to use my typical smartfly setup which was one SF Regulator, SF Batshare, 2 HD switches, and 2 Fromeco batteries. Now, I see that this new Rx has two battery inputs on it so I was wondering if I could get away without using the batshare and using two regulators in it's place. Each battery input would have 1 fromeco battery, 1 HD Switch, and 1 SF regulator. Sooooo.........I guess my question is this. Will the Rx still share the voltage of the two batteries the same as if I was using the Batshare?

Sorry, I'm new to this Radio and Rx so I'm sorry if this is a dumb question.

Old 12-30-2008, 09:43 AM
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Default RE: 2 smart fly regs on a JR R921 rx?

Hi Chris,
When you connect the output of two regulators together they will not want to share current equally. This is because they both actively try to set the output voltage and one regulator will be set to regulate a slightly different output voltage than the other (it may be as little as 0.005V) so the regulator that wants to regulate to the higher voltage (say 6.005V) will supply most of the current and the other regulator (which wants to regulate to 6.000V) will sit by until it is sees a voltage of less than 6.000V on its output before it starts supplying current. Because of wiring and connector resistance, this will happen when the load on the first regulator increases. The mismatch between batteries can be small or large depending on how close the regulators are matched. Let me know if you have any other questions.

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