strulag

My Feedback: (-1)

I have a Futaba PCM 9ch receiver with a 9CAP Tx. I hooked up 2 batteries to two switches to 2 channels in the receiver. My problem is that when I turn on one switch the other switch detects the voltage (I have leds on them). Another problem is that I can't charge through the switches both batteries at once. I have to open a hatch disconect one of them and charge directly to the battery. Am I supposed to use that DSC slot for one of them?

Arthur K

As far as I know you are not supposed to put two batteries in one receaver you need to seperate your power source from the receaver and feed the servos only most guys set up two batery pacs to the servos and one small pack for the receaver to do this you need to make a board ar simpler yet make up a cluster of conectors female ends and run the negative and pos wires to your switch plug the signal wire to the receaver one only one black lead from the receaver to the cluster and plug your servos directly to the cluterin their cresponding position I had my yak set up this way and it wrked well to bad I do not have pics to show you

Icebird

There is nothing wrong with connecting 2 batteries to a receiver, so please don't say there is.

You will see both sets of leds light up when you turn on one switch, it's a fact of the way the leds are connected in the switch. There is nothing wrong with this, but make sure both switches are actually working when you power up. What I do is turn on switch A and make sure the surfaces move. Then I turn on B and turn off A, and again make sure the surfaces all move. Then I turn A back on. This only powers up the receiver once and that is when a receiver is most likely to fail. You will find some problems charging both packs at the same time since the switches only disconnect the positive battery leads. The common ground can cause problems with some chargers, but there are some that will charge both at the same time. The simplest solution is to charge one after the other.

HTH
Jim

bpryor

My Feedback: (45)

Jim, you are correct, and it was right to correct Arthur, but how about using some tact next time. Arthur was trying to help, and he even qualified his statement with "As far as I know". No one is 100% right all the time and the last thing that needs to happen is to shut someone down for trying to help. Lot's of people never even try to help. It's up to the person that asked the question to sort through the data and decide what advice to follow.

Arthur, thanks for contributing.

...you guys are even both Canadians, so you can't use that as an excuse.

I & C Tech

Hooked up the way that is described, would there ever be a chance that a fault or some other large difference in voltage between the batteries would cause an excessive current flow though the receiver bus from battery to battery, possibly damaging the rx?

bpryor

My Feedback: (45)

Hi I & C Tech,

While I am not the one to give you a difinitive answer(qualifier), I have used this method for many years with no issues. There are many more ways to hook up two batteries that are either more complex, expensive, or both. I hate to send people off searching, but there are a ton of existing threads on this subject that beat this issue to death. So if you want to read enough opinions to make your head spin do a little searching. If you want to insure that you get an informed answer go to the battery forum, then search on "dual batteries". You're sure to find a lot of good, knowledgable input in the existing threads.

J. Campbell

My Feedback: (31)

I have been using 2 batteries and 2 switches for some time, 1 hooked up to the battery port and the other to a seperate port on the reciever.. Yes mine always gets the ground fault also, My question for the "experts" is:

HOW would you hook up 1 battery to 2 switches??? Just modify a y-harness?? You may ask why i would do this and im not sure i would BUT if you cycle and maintain a battery it most likley will not go bad without notice but i dont trust a switch at all... Russ

MR G

I also have two batteries; one plugged into the battery port on the reciever and the other pluggged into an available port on the reciever.

I also use two switches, one for each battery. I charge both reciever batteries at the same time with my charge+ battery charger. I have not had any problems yet. I do however notice that I have the same response from my system as IceBird, turning on either switch will make both switches light up. I am VERY careful to make sure both switches are turned on.

strulag

My Feedback: (-1)

My question is how do you make it so you don't get both switches be active when you turn only one. I want to be able to charge both batteries at the same time through the switches.

Rockyaged

I also have the redundant rwo battery system. Both sets of switch lights should come on
when turning on just one switch as both batteries are plugged into the same power buss
of the reciever. That's normal. I charge both reciever batteries and my ignition battery
all at the same time. They are Fromeco 2400 Mah batteries charged by Fromeco three
port charger. I just make sure my switches are in the off position.
One of the downfalls of redundant systems is that one battery supplies most of the power
while the other battery does little more than being a backup if the other fails. Smart-Fly
has solved this problem with their Bat-Share device. It senses the capacity of both batteries
and switches current draw back and forth so that both batteries are used equally. On my 28%
Extra, I use one ten of a volt, per battery, per flight. About 20 flights now, with no problems.
I offer this as true fact and not just opinion.

Gerald

Panzlflyer

My Feedback: (15)

The answer is to get good switches ALA the JR ones that disconnect both Neg and Pos when switched off. The ity bitty ones most times only break one wire.

Icebird

I guess they must have changed them then, because earlier this year I had occasion to take a couple apart, and they only disconnected the positive wire. They did use a double contact, so it would have been possible, but both sets of contacts were wired to the positive side, and the negative wire just passed through.

Jim

strulag

My Feedback: (-1)

I don't think that's the case. Mine are plugged in exactly the way you described and after each flight, the voltage on both batteries are similar. I think they equalize each other just like the different cells in the pack do.

bpryor

My Feedback: (45)

You are correct strulag.

Panzlflyer

My Feedback: (15)

Was that the DSC type or regular. I havent checked all mine but some of them do disconnect both sides. I use a double battery system on all 4 of mine currently and never had a charging problem

Panzlflyer

My Feedback: (15)

Also check out Reds battery clinic on the subject of dual systems and Hangtime Hobbies has a bit on it.

Arthur K

OK I have a question here what is the advantage of using 2 batteries into one receaver
I use 2 receaver and 2 batteries now we all know this topic has been beaten to death this is the choice I have made
But just for my curiosity why have 2 batteries on two switches into one receaver is this in case one system fails one switch fails or one battery fails or is it to distrubute the load
and feeding one receaver with all that amps is that not dangereous
now nobody jump down my throght I AM JUST ASKING

bpryor

My Feedback: (45)

That is a better setup than two batteries into one reciever, but most people don't have two receivers.

Yes, those are the primary reasons, plus you have double the capacity.

strulag

My Feedback: (-1)

Some other advantages...Those Rx leads can only take about 3A load and if you have a lot of digital servos the load will be much greater when doing 3D. With loads distributed to two different batteries they actually last longer. When charging you get to charge 2 batteries at once, switch failure.

I haven't been part of the "beaten to death" subject but why have 2 receivers? Do they fail once in a while? I mean if you loose signal you lose it with 1 or 2 receivers. Is the extra weight and money worth it?

Icebird

I didn't think I jumped down your throat before, all I did was ask you to please not spread misinformation. In any case, this will be my last post as I've decided it's not worth it to bother posting here.

The reason for 2 batteries and 2 switches in most cases is for redundancy. One of the most common things that will cause a crash is a switch failure. I have seen literally hundreds of them over the years. With 2 switches, you can almost totally eliminate that cause. We had a fellow lose a switch here a couple of weeks ago, and since he was using 2 switches, it just meant he had to replace a switch rather than the whole plane. Dual battery packs, while not as necessary, are the easy way to use 2 switches, and if you use an appropriate capacity for the pair, you don't add a whole lot of weight. In most cases, you can get sufficient capacity these days with one battery pack, but with 2 smaller ones, you get the benefit of having a seperate power source as well, so that also gives you another chance to save your plane. Some people have even gone so far as using 2 receivers and 4 battery packs to give themselves more protection, but at some point, you either put the plane at risk, or you hang it up somewhere.

Jim

bpryor

My Feedback: (45)

40%er's almost all use 2 receivers. Yes, receivers can fail like any other component. I typically put two receivers in 35% up planes, though that is a personal decision. You set them up so different controls are routed to the different receivers, so if one fails you still have enough control to theoretically increase the likelyhood of getting your plane down in one piece. This HAS saved more than one plane. Though I've fortunately never had to use the redundancy, it's very good insurance when you have $5K+ in your plane.

mglavin

My Feedback: (31)

The JR DSC switches and others only switch the positive lead, multiple contact or not.

mglavin

My Feedback: (31)

Rockyaged response is specific to systems with regulators, but is only true in low current static scenarios. When the electrical load increases both batteries/regulators pass current simultaneously.

Spurlag the batteries don't cross charge or equalize as many believe. The electrical demand simply loads each battery, cells do not equalize one another as suggested either. Power or voltage is a semi balanced output contiguous of the source..

Arthur K

Ok now that the experts have spoken and I have listened let say why IN MY OPINION AND THE TESTS that HAVE BEEN DONE is not a good idea to pump all that current into your receaver
it is tru that your receaver will only draw what the servos demand I read an article couple of years back they took a receaver and tested how much current it could handle before the circit board started to peel
in bursts of pulses they fed 6 amps 8 amps and then 10amps no more then 5 seconds at a time with a 30 second break in between this was done on a 8 chanel pcm futaba board it peeled by burst # 7 and melted at 8 amps
now I do not know about smaller planes but on a 40% plane set up with high torque servos like 8611s or 5945s or 5955s what sort of load do you think they will draw on a snap roll with all your serfaces loaded up you are drawing anywhare for 8 to 12 amps depending on your servos 3 rudder servos set up with 3 8611s in a knife edge loop will
draw minumum of 2.5 amps each for at least 30 seconds now if you guys think your receaver will handle this load then all the power to you
the main reason why I use two receavers is to distribute the load as far as switchs go I have been useing the same two MPI switches for 3 years in two diferent planes now
I dump the connectors that they come with and put a dean plug from the battery to the switch plug into the receaver and go I use two sanyo nickel M AA 5 cells 2300ma and I get 4 20 minute flights We are now testing li po in bobs carden with 10 amp regulators so far no problem same set up as mine two mpi switches
like I said you want to use 2 batteries with one receaver Isolate the servos You can by one from a supplier or email me and I will send you a diagram and this way you can have two batteries supply current to your servos and have a smaller pack supply your receaver if you are going 40% with one receaver this is a safe set up that has worked for years with the fellows at our club The GTA Giant scale flyers and we all fly 40% + Some of us at least 7 years + It's your choice and it is my opinion If this helps good if not
good luck fly safe and have fun

strulag

My Feedback: (-1)

Hey Arthur...I don't get what you're trying to say. I have it setup like that anyway.