rcfun2005

Cons installing redundant receiver batteries ? …

I was going to just run (2) Life batteries , (2) manual switches , connecting both to the receiver on (2) separate ports on the receiver.

This is going on hitec aurora 9 channel receiver in Modellbau Tornado .

Seems like a low cost solution to some redundancy .

What would be the down side to this type connections for redundancy ?

Thanks, Joe

BarracudaHockey

My Feedback: (11)

Weight and cost are the only downsides

trioval00

My Feedback: (17)

No cons from me. I have been running dual batteries for 9 years now. and I will always use dual batteries.

some of the jets I have an "Electro Dynamics Battery Backer" and some have dual output for batteries built into the receiver....



Mark

rcfun2005

good deal,

so just running batteries in parrallel is ok .

not sure any details , i just see "powerbox" comes up alot when discussing redundant batteries.

i guess it provides more features.

thanks, for the input.

Joe

John Redman

My Feedback: (8)

Running two batteries into a receiver is fine. Understand that if one starts to go bad it can drain the other in no time as tehy will talk to each other. That is why the voltage regulator is a great thing. Not as much to regulate voltage but to work more like a one way check valve in the electronics world.

Only down side to two batteries is:
1) remembering to charge both batteries.
2) remembering to turn both batteries on before a flight.

Ask me how I know this.

rcfun2005

"That is why the voltage regulator is a great thing. Not as much to regulate voltage but to work more like a one way check valve in the electronics world. "

oh, i see now ... one way ck valve ... yes that would be a big benifit ..


so i presume "powerbox" is one of the solutions to providing voltage regulator.

thanks for that insight..

joe

speed is life

not true:http://www.hangtimes.com/parallel_packs.html

There is no down side to independent parallel packs/switch/harness going into different receiver ports for redundancy (except a very small weight penalty). One does not even need a regulator if using A123's.

Dr Honda

My Feedback: (4)

As others have said... there is no "Negatives" with redundant batteries, other than weight. But... in the case of my falcon (Similar to the Tornado) I needed some weight up front to balance my heavy AMT engine. So... I have 2 NiMh 5 cell packs in it.

I'm flying JR/Spektrum and the 921 Rx has 2 battery ports. So it's easy to implement.

wfield0455

My Feedback: (7)

While there is nothing wrong with simply running the outputs of 2 switches directly to your receiver it is a good idea to use a battery share circuit. The battery share circuit provides isolation between the 2 packs and will prevent one pack from draining the other should it become discarded, etc. Voltage regulators, unless they are dual regulators, generally don't provide this functionality and if one regulator or battery fails they can still quickly drain the other battery as well. A couple of battery chare that I have used in the past are the Smart-Fly Battshare and the Fromeco Woverine switch. The Wolverine is a dual switch with a built in battery share circuit. It's also similarly priced to a pair of JR Heavy Duty switches so it's not particularly expensive.

speed is life

see link in post #7 This is an old wives tale - It can't happen.

David Gladwin

Sorry, John thats simply not true, another urban myth !

Verification, my own exhaustive tests AND see NOBS batteries web site for the expert technical explanation.

Two batteries into a single receiver is absolutely fine, in fact anything less is potentially and unneccesarily dangerous. A single battery failure and its all over ! Best to connect them at opposite ends of the receiver bus (Kirchoff's law).

In the long run its cheaper too, as batteries can be kept in service (on condition) until showing some degradation, rather than changing every couple of years or so, its a million to one chance the second battery will fail at the same time.

Dual batteries should be mandatory for any gas turbine powered model.

Regards,

David Gladwin.

BarracudaHockey

My Feedback: (11)

Thats true, if you need the weight somewhere it could be just another benifit!

Yea, you can leave batteries for hours and they wont effect each other.

erbroens

No Cons, and I would daresay that this is one of the best things you can do to your model and our hobby.




Enrique

Chris Smith

My Feedback: (2)

Even the smallest model jet has room for two lightweight 1100 A123s and two switches. Other gadgets are swoopy, but I find in my old age less is more. All the receivers I use are designed to handle the sustained voltages of both batteries directly to the receiver.

Dr Honda

My Feedback: (4)

I agree.

5skyhawk172

Not trying to hijack the thread, but I have a question.  I'm new to the turbine world and I just bought my first quart of turbine oil (aeroshell 500).  Is it correct to mix one quart to five gallons of kerosine?  Thanks,  Keith

rctech2k7

My Feedback: (1)

I've seen some points here when paralleling batteries. This is what happened when paralleling batteries with different charge level even for identical batteries. If one battery has higher voltage than the other the current will flow and energy is transfer to the lower battery until charge is completed or internal voltage becomes the same then batteries distribute the same power (only for identical batteries and feeder lines). This circulating current depends on the type of battery, condition and resistances, however at most level condition it's negligible due to LiFe battery properties but not all similar for NiCd...

For the OP,
There are different way for battery redundancy and yours is far good so this is only I can say based on your query:

1. You want to make sure both batteries are online but you still get the same reading when one switch or connection failed so you may turn off the first one to make sure the second one has power and turn it back on again.
2. You have a chance to leave one switch in off position since either one can power up the system, the solution is to tag both of them or any equivalent.
3. Both batteries are sharing power distribution and have the same voltage, when one run out of power the second one will have exactly the same. The condition is to fly within the safe limit of one battery and to determine the cause of failure if any.
4. Your system has far better to have chance of lost power than using single battery but it doesn't have protection if one battery becomes faulty, I believe this is the lowest chance of battery failure and almost eliminated on our latest high quality batteries.
5. Batteries can be used as balancer as well but in some cases if you're using large identical batteries that either one can powered more flying time then weight is a cons but it can be reduced by installing smaller backup battery instead of redundancy and although it has power indicator it will only work when main battery fail and enough to land the plane in one cycle unless it is recharge and with main battery power restored.

Dr Honda

My Feedback: (4)

What does this have to do with batteries?? Yes... you should start your own thread or search for 2 seconds.

But... to answer your Q... Yes. That will give you 5%.

Xairflyer

My Feedback: (1)

What about two battery's of different capacitys connected to a reciever

Dr Honda

My Feedback: (4)

The "Quick" answer is... that's fine, as long as they are the same voltage.



OK... here's the deal.........


If you think of a fluid... The voltage is the "pressure" of the system. So... regardless of the size of the tank (capacity of the battery) the voltage will try to balance. As the smaller "Tank" gets consumed... the pressure will start to drop, and the larger "Tank" will feed more, until the 2 pressures are balanced. (this is a pure answer)


With that said... (in the real world) if you try to mix battery types, or sizes (differences in internal resistance) then they can get out of balance. Basically... you should run 2 of the same packs with redundant batteries, especially if you aren't using any kind if isolater/regulator system.


So... yes it will work... but it's not advised.

gooseF22

me too..LOL.. I forgot to turn the second switch on too.. it was on a wolverine...woohoo..

gooseF22

deleted..

gooseF22

Keith, PM'd you.. Im local Ft Wayne

gooseF22

I prefer wolverine for a switch if not using switched regulators or a Powersafe rx..
I did some of the Flight testing and bench testing of the Wolverine design.. with 4 10 am mofsets, I can tell you that thing is robust.. I ran an electric motor thru it at 40 amps twin deans in and out.

VF84sluggo

My Feedback: (55)

Joe, this exact setup has worked very well for me in my Boomer Intro. No problems at all.