Bob Pastorello

My Feedback: (198)

I've used a Sirius for years on dual packs..... no mods to anything, no batt shares, no regulators, no b.s. stuff in the circuits. Just two MPI HD charging switches, and I leave them connected to the RX all the time. The solution to the "shared ground" issue is very simple. Charge one pack at a time. Never will be a problem.

Have to admit - there is no way in the world I would get a bunch of added on complexity (read "additional failure modes/points") to something so easy to make work perfectly.

Sirius chargers are just ideal for this..... a few minutes between flights on each pack..... I can't fly enough in one day to wear down my dual Hangtimes 1900 low-impedance NiMh's on my 30%'ers.

niteman

Hey Bob,

Thanks for chiming in. Got alot of good advice from your site in the past, thanks. I agree with your take on keeping it short and simple.

The only advantage was added protection of having one battery short (rare I admit) and not take down the other, provided the back'r doesn't fail in the loop as you suggested.

I also did not realize or have tried, (because I'm still waiting for the my quad charger to come ) that charging one at a time would solve the ground loop, at least for one at a time.

So the other battery not being charged, but still sharing the common ground, does not inhibit the the ability of the quad charger to detect the real mah's left in the battery your charging ?? No false peaks etc..??

Really appreciate your reply, Dan [8D]

Josey Wales

My Feedback: (61)

Yep..if you only charge 1 pack at a time there is no common ground issue...

Bob..don't bring any common sense in this..we frown upon that!

Bob Pastorello

My Feedback: (198)

No issues at all. The non-charging battery is not in the circuit. THe MPI switches open the + side of the battery. So the charger is only sensing the one connected. It doesn't "see" the other battery at all. You can check all this with an ohmmeter; measure in the charging jack of your switches red to red. With both switches "off", in the "Charging" position, there is no connection.

With them "on", then yes, both + battery connections are tied together effectively through the + side of the receiver. They share both the + power buss and the negative terminal in the RX circuit.

Actually, you can safely charge BOTH using MPI switches.

Now - if there are switches out there that switch the NEGATIVE wire of the batteries, then George is absolutely correct, as the Sirius would be "seeing" both + terminals through the shared ground on the Rx.

I seem to remember there are switches out there that switch the negative lead (make/break the black wire from the switching action). That would be a problem, for sure.

niteman

[quote]ORIGINAL: aerobob

Actually, you can safely charge BOTH using MPI switches.








Does that mean you have charged both batteries at the same time through the MPI switches-charge ports with no trouble ??

Bob Pastorello

My Feedback: (198)

Yes. But it is working because the MPI switches break the positive (+) red lead internally, with the black tied across. The DPDT terminals have the red connected to both, to produce mechanical internal redundancy in the switch.

Josey Wales

My Feedback: (61)

Bob what MPI switch are you using.

niteman

Happy 4th !!

Hi Bob,

Can you confirm for Joe and I which MPI switch you use ?? Is it the MPI Standard Heavy Duty Charge switch like the: SOFT MOUNT ONE-PIECE CHARGE SWITCH (http://www.maxxprod.com/mpi/mpi-4.html)

OR are you using the MPI 6 volt regulated miracle switch: http://www.maxxprod.com/mpi/mpi-21.h...racle%20Switch ??

Thanks a million Bob

GalenB

My Feedback: (18)

Is it working? That's the question? All of the heavy duty charge/switches that I have looked at: EletroDynamics, Cermark, and now MPI only break the + lead which leaves the common ground intact. The common ground between the batts is a known problem for Sirius Quad and Limited Edition chargers. I too have been charging my simple dual switch and battery setups through these switches without problems for years using my Limited Edition charger. This raises the question: "Just how bad is this problem?" I don't know, but once I learned it existed I started breaking the common ground by pulling one plug from the Rx. Not the best solution, but it is simple and nearly foolproof. It's only foolproof if you isolate each battery as part of your pre-flight check -- if one is not working then I forgot to plug the battery lead back into the Rx...

I've been looking for HD charge/swtiches that break both + and - so that I can stop pulling a plug, but so far have not found any... The common ground issue is one reason I am looking at the Dual-Battery Regulators from Smart-Fly...

Josey Wales

My Feedback: (61)

Wouldn't it be easier to design a charger to handle the common ground ? The only chargers Ive used that can handle this is the Alpha 4 and the Fromeco Reliacharger....The Spectra can handle it but I never used or seen one in person...