bikerbc

I have a brand new DX8 radio system that I am going to install in a 1/3 scale Cub..I have been told that it is better to have extra satalite recievers and extra fail safe battery packs..I dont know how to add these or if it is even possible..I see there is a JR reciever with 3 satalites and wonder if this is compatible with the Spektrum system...Can any body tell me where to look or what to do? Thank you

grizzly59

Of courset all the Spekrtum receivers will work with the DX8. The 9000 series receivers have two satallites. You can also use the Jr receivers. They have a 9 channel and a 12 channel receiver that have two satellites. The Spektrum 8000 only takes one satellite and will work well in your plane.

I believe the fail safe battery set up you talk about are two batteries with a switch on each battery plugged into a receiver.

Zor

Hello Hoosier06,

So the two batteries would be on board the aircraft.

If a fail safe occur the switches are useless with the aircraft in flight.

I am trying to understand what you wrote.

Zor

BuschBarber

My Feedback: (2)

The Spektrum AR9100 Powersafe Rx is designed for 3 Satellite Rx's and two Rx battery packs. There are others by both Spektrum and JR.

http://www.spektrumrc.com/Products/D...odID=SPMAR9100

You can hook up Rx batteries to the Batt/Bind port, the Data port, or any Servo port on any receiver. Many pilots with expensive aircraft use Redundant battery packs whether it is 72Mhz or 2.4Ghz Rx's. When I need to, I plug one Rx battery into the Batt/Bind port and if all the Servo ports are used, I unplug a servo, plug in a Y Harness to the Servo port, connect the Servo to one side and the battery to the other. I have never used the Powersafe Rx, but many do.

You need to set up each Rx battery on a separate Switch Harness and charge each separately. This is very common.

Zor

All readers,

From reading Rich (BushBarber) the two batteries are connected to the receiver at the same time and the switches are used on the ground to charge the batteries individually without taking them out of the aircraft.

It makes me wonder why they are referred to as "fail safe batteries".

In flight they are simply in parallel and if a fail safe do occur there would be no difference from a single battery having twice the capacity assuming they are both rated the same mAh.

Somehow some clarification will come out of this discussion.

Zor

BuschBarber

My Feedback: (2)

Failsafe occurs when the Rx loses the signal from the Tx, either by Interference, or by loss of Tx power. The Rx has to be powered in order to switch to Failsafe mode.

These are no Failsafe batteries, but rather Redundant batteries. If one battery quits, the other battery still powers the Rx. If both batteries quit, you crash. If you have a Brownout, you do not go into Failsafe, but you have not control until the Rx reboots. Also with Redundant batteries, you have two Switch Harnesses, so if the batteries are OK, but one of the Switch Harnesses shorts out or breaks, you still have power from the Redundant battery.

bikerbc

Thanks BuschBarber, I believe you have me on the rite track. I think the AR9100 is what I was looking for , Also thanks for taking the time to explain how this all works...Ken

BuschBarber

My Feedback: (2)

Thanks!! It is one of the things that makes this hobby enjoyable.

Zor

[quote]ORIGINAL: BuschBarber


[quote]ORIGINAL: Zor

All readers,

From reading Rich (BushBarber) the two batteries are connected to the receiver at the same time and the switches are used on the ground to charge the batteries individually without taking them out of the aircraft.

It makes me wonder why they are referred to as ''fail safe batteries''.

In flight they are simply in parallel and if a fail safe do occur there would be no difference from a single battery having twice the capacity assuming they are both rated the same mAh.

Somehow some clarification will come out of this discussion.

Zor

Best regards to you Busch______

Zor

flyallday

BuschBarber, what about using a BEC, like a CC 20 amp Pro and a back up battery? Is that possible?

Harry

BuschBarber

My Feedback: (2)

Most Switch Harnesses will Fail Open. Only more expensive ones are designed to keep the circuit closed when the Switch fails. Most people do not have these more expensive Switch Harnesses, which is one common cause of crashes that are commonly blamed on Rx failure.

BuschBarber

My Feedback: (2)

I may not have mentioned it but in my larger electric aircraft, I choose to use a separate battery for my Rx. Since I use LiPo Rx packs, I use a Castle Creations BEC Pro. I can adjust the voltage manually, using Castlelink software or the Castle Card. I let the motor battery just power the motor. You can also wire the CC BEC or BEC Pro directly to the motor battery leads and connect it to the battery port on your Rx. The CC BEC from 4.8v to 9v/10a and the BEC Pro is adjustable from 4.8v to 12.5v/20a.

flyallday

I am using the CC Pro on 3 of my large electrics as well but power them with the flight pack. My largest is 80" so I am ok with the current set up but was thinking about going larger and would most likely want some back up power. I like the way you do it with a separate lipo, but could you also include another battery for redundancy?

Harry

BuschBarber

My Feedback: (2)

Here is an article by an Electrical Engineer who writes a column, every month, called Amp'd. He lives in my town and I see him at local meets and at our flying field. He is a well respected expert on RC electrics. This article is on his latest project.

http://www.rcuniverse.com/magazine/a...rticle_id=1330

You can connect more than one battery to your Rx. You certainly use a voltage regulator of the same type (or BEC) with each battery.

flyallday

Thanks Rich, I started reading the article and realized that I had already seen it! Great article, some of the vids from the motor testing are almost funny. Just waiting for that rig to take off.. Again, thanks for the reply.

Harry

BuschBarber

My Feedback: (2)

Thanks!! His motor is the big brother to the one I am using on a H9 89" Carden Yak 54.

grizzly59

I guess I meant redundant not thinking (remembering) there were failsafe products for the planes electrical set up.

Zeeb

My Feedback: (41)

Just a couple of notes about using the Spektrum or JR "PowerSafe" rx's of which the AR9100 is one; It's great concept with dual 16g wire power inputs to the rx so you can have lots of power available. It has a built in "Fail On" softswitch so if the switch (basically the weakest part of the electrical system) happens to fail the system will default to "On", it also has built in battery isolation so if one battery should catastrophically fail it will not affec the other battery. It comes with three satellite rx's because there is no RF section inside the main unit like an AR9000/R921 would have and it can use a total of 4 satellite rx's.

Now here's a bit of information that's caught more than one of us on setup; the manual says you can use only two satellites but that is incorrect. It MUST have at least three satellites connected to work and no I won't mention how I and others found that out.... lol

BarracudaHockey

My Feedback: (11)

Experience is what you get right AFTER you need it

Pecanpatch

Your flying Nitro or Gas not electric.... right?

We have one of these units in our 56CC UAV and the way I understand it.... if one battery fails it switches to the other battery..... so one bad battery wont drag down the good battery...


http://www.smart-fly.com/Products/Expander/expander.htm

BuschBarber

My Feedback: (2)

Smartly makes excellent products.

indubitably

My Feedback: (14)

I would be careful with the DX8. Even though it is stated as DSM2, it apparently is DSMX, and the reciever has DSMX satellites even though they are DSM2 labeled. It would be wrong to mix satellites DSM2 and DSMX with each other. Presently there is some confusion as to what is really DSMX with the recievers, and satellites, with their labeling. Even though they are labelled DSM2 if there is a X in small print on the back of the satellite then its DSMX. Dont get them mixed, apparently that would not be good. Apparently, the telemetry modules have been DSMX, all along, even though labelled DSM2. Not so critical here however.

Zor

indubitably,

I understood from previous postings by others that DSMX transmitters work correctly with DSM2 receivers and DSM2 transmitters work correctly with DSMX receivers.

Zor

BarracudaHockey

My Feedback: (11)

Thats correct they do, but you cant add DSM2 satalites to a DSMX receiver and vice versa

Zor

Thanks BarracudaHockey ___gotcha (got you ok).

Zor