JR R921 Rx--->Battery Question

[cje0114]

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.


Chris

[sweetpea]

No it will not. What you will find is one battery will be the primary drain. They tend to be within .10v of each other though as they drain. Where you get a problem is if one battery shorts while in the RX it can run across the buss of the rx and drain the other battery. The battshare is supposed to elimnate this while sharing the power equally between batteries. The battshare has 2 output plugs so you can still plug it into the RX in 2 spots incase the input spot on the RX shorts out you still have a backup.

[cje0114]

	Quote: Originally Posted by sweetpea
	No it will not. What you will find is one battery will be the primary drain. They tend to be within .10v of each other though as they drain. Where you get a problem is if one battery shorts while in the RX it can run across the buss of the rx and drain the other battery. The battshare is supposed to elimnate this while sharing the power equally between batteries. The battshare has 2 output plugs so you can still plug it into the RX in 2 spots incase the input spot on the RX shorts out you still have a backup.

Thanks. I have one more question if you don't mind.

If I still use the batshare, can I plug one input into the battery plug on the Rx and the other into an unused port so I can still use the data port for my data logger?

Thanks,

Chris

[cje0114]

also, if the batteries won't drain equally, what is the point of the two battery inputs on the R921 Rx?

[sweetpea]

Of course. That would be no different than not using the battshare and plugging a battery directly into each of those ports. I've been doing this on my 35% Edge for years in both 72mhz and 2.4

Try this trick for your data port as well. You never have to take the hatch off to check the numbers and you only have to buy one data logger for your entire fleet of planes.

[2walla]

The receiver has two ports because you are limited on current with servo connections to approx 4-5 amps. If you have a bunch of high draw servos one imput can't handle the current. I would run two batteries/switches before I would run a battshare and one imput on this as I would see the likelyhood of a battery shorting and causing a loss less than a swich failing or burning the battery port in the receiver up because of too high a current. If the battshare has two power outputs I would plug both into the receiver.

[sweetpea]

battshares have 2 inputs and 2 outputs for just this reason. They are supposed to isolate each other as well, so if one side shorts the other takes over and won't be cross shorted. Its a handy device and is built into the Turbo Regulator and some of the upper end Power Expanders.

[cje0114]

Thanks for the quick reply Sweetpea!

please correct me if I'm wrong here now. I will run 2 batteries to 2 switches, which will go to my batshare and then to my single regulator. from there I will be hooking one plug from regulator to the Batt/bind port and the other to an open port(say aux 4). Now, from the data port, I will run an extension to the fuse of the plane so I can connect my data logger without opening the airplane to get to the Rx. Is this correct?

Again, I'm sorry for the dumb questions since I'm new to this Tx/Rx combo.


Chris

[sweetpea]

You would need 2 regulators or one regulator that can handle 2 batteries like the Turbo or Super Reg from Smart-Fly.

Everything else sounds good. The plug from the data port to the fuse has to be a male to male extension with a charge jack. I made mine. You then need to have a female to female extension for the data logger (again I made mine) Both of these were just extensions I cut then soldered back together. All in all I spent hardly anything on this setup.

[JohnVH]

typical setup= 2 batteries-2 switches-2 regulators- into two holes on 1rx

[Tired Old Man]

John nailed it.

[sweetpea]

John is correct, that is the typical setup. You already own the battshare so why not use it? It ensures each battery is used at the same rate and protects from cross shorting. I have several of these and used them all the time until I upgraded to Turbo Regs (which include this feature in the Reg).

[Sevans16]

I am confused! If the RX discharges the batteries at different rates doesn't that mean it some how isolates the batteries??

According to Reza on the Team Horizon "ask the staff" forum he indicates(posted on 12-08-2008) that the 9100, 1221, 922 and 1222 will draw equally off 2 batterie and isolate a bad battery. Reza indicates that they are true redundant systems.

Just passing on info! It's not documented in the RX manual! I am curious as I have several SF Batshares sitting on the bench based on Reza's post. I am converting over from the orange side so I don't personally know either.