[Guest]

Good Morning guys

I'm getting my new *Unique* plane ready for its maidin flight since its new bird to me. My question is, can I connect two battery packs to one reciever and if so how?

By connecting both packs with Y-harness into single port or by
Inserting seprate battery connectors into 2 unused ports of the reciever.

Packs are 1 Futaba 600 mah Nicd and 2100 mah Nimh that I bought from Gary Maker with my Multiplex.

Thanks in advance.
Sammy

[jake_027]

Use two switches and plug the lead from one switch into the "batt" port of your receiver and the second switch lead into an unused port. Make sure you use the second switch so you can kill the power from the second battery. I would use two batteries that are the same with the same mah.

Dave

[aceplant00]

Curious as to why you would need 2 packs for the plane. The 2100 Mah should be enough to fly for a while. I guess maybe some more info as to specs of the plane and what is being used. Eg how many servos and digital or not.

[Guest]

Originally Posted by aceplant00

Curious as to why you would need 2 packs for the plane. The 2100 Mah should be enough to fly for a while. I guess maybe some more info as to specs of the plane and what is being used. Eg how many servos and digital or not.

Well you are right on using 2100 pack on 5 std servos but the reason I asked this because I need weight in the nose so I thought why not see if I can make use of extra battery also since its going to be there for ballest reason. Thats pretty much it really.

[Guest]

Originally Posted by jake_027

Use two switches and plug the lead from one switch into the "batt" port of your receiver and the second switch lead into an unused port. Make sure you use the second switch so you can kill the power from the second battery. I would use two batteries that are the same with the same mah.

Dave

Thanks for the set up info Dave, I will now pull switch and other Nicd battery out of learjet and put in this one.

[Billpilotca]

Originally Posted by Scratchbuilder

Well you are right on using 2100 pack on 5 std servos but the reason I asked this because I need weight in the nose so I thought why not see if I can make use of extra battery also since its going to be there for ballest reason. Thats pretty much it really.

Strikes me that 2100 mah is plenty for 5 std servos. I don't like the idea of mixing packs of different mah ratings. Best to use equal packs rather than mixing and matching. If there was a way to get the 2100 mah pack or other servos located more forward I would do that, maybe even a weighted spinner.

In any case with multiple batteries you plug the switch leads into different ports on the receiver or you can use a Y connector. Just be careful to charge only one battery at a time if they are connected through a common ground lead or you will not charge the packs to their full capacity.

Bill

[Gary Maker]

This setup is clearly shown on Red's RC Battery clinic.

I asked Red about this personally a few years ago at a battery siminar at the Toledo RC Expo and he said to use two seperate switch harnesses, one pluged into the regular RX slot and the other in ANY empty slot in the receiver and plug your batteries into the switch harnesses.

HE said you can use packs of different mAH ratings but they must be the same voltage and same size of cells - ie. AA cells and both 4.8 OR 6.0 volt packs.

There are all sorts of theories of how if one pack fails or if they are different mAH rating, it will suck all the power out of the other pack - NOT TRUE. Red Sholefield is one of the foremost experts in battery tech and engineering and he says that is a falacy and just will not ever happen!

This setup is good for a couple of impt reasons - it gives your plane a backup/redundant battery source in case of a pack or switch failure and you can add the mAH of both packs to give you a larger total overall battery capacity - more flights.

[Gary Maker]

For a fuller discussion on this subject go to www.rcbatteryclinic.com

Look under the heading "Parallel Operation = Relyability and More Flight Time.

Here is a pic of the setup recommended

Although the box is blacked out, click on it and you will see the picture:

[voyager_663rd]

You need more weight? Put a bigger engine on.

More power. OOH! OOH!

[Billpilotca]

Originally Posted by Gary Maker

HE said you can use packs of different mAH ratings but they must be the same voltage and same size of cells - ie. AA cells and both 4.8 OR 6.0 volt packs.

Gary - I am not going to argue with you (or Red). But I don't think it is necessary to mix packs of different sizes in this case. Firstly, for 5 standard servos why bother, 2100 mah is more than enough for a whole day at the field, maybe 10-15 flights (with checking frequently). I appreciate that you can make a case for redundancy perhaps in case a cell shorts out, you still have a backup.

In a practical sense having different size packs means different charging rates and capacities and charging through 2 different jacks, sooner or later it is easy to confuse which is which. Although I always label mine somehow because I am getting too old trust my memory, and with gassers you are usually running different size packs for ignition and receiver, I have to label them.

Whether you add lead weights or a 600 mah battery that is not needed seems the same to me. First choice is re-align or shift things around to avoid the need for added 'dead weight' if that is the real issue.

Not arguing electrical theory my friend, only the practical side. My opinion and I will leave it at that.

Bill