Vincent

My Feedback: (61)

I have several jets with just one A123 2300mah batt plugged directly into a spektrum AR9000 rx thru a HD jr switch. I also have a couple of jets with twin A123 packs plugged directly into a Spektrum AR9100 rx using the provided spektrum "soft" switch. Both setups have proved to be solid in hundreds of flights.
Vin...

smitty1001

My Feedback: (29)

Istarted using the battshare when Iwas flying 2 x 2600 TBM 7.4 Lions for rx power. Landed Bobcat, opened hatch and everything orange was blinking

ONe of the Lions had dropped a cell in flight and at some point the rx did a quick reboot (glad Ihad the revision) - anyways - everyone said use a battshare to isolate in case of dropping a cell again - so Idid. When Iswitched to 123's Icarried over the battshares and dropped the regs for the new install - agree that probably fine to go without battshare but already had them and they saved me once with the Lion cell drop so.........

You can see my data logger next time Dan, when Ipower up after a full charge on the 123's, the data logger never says higher than 6.5 on the 16, 6.4 on the bobcat.
You're not going to have an overvolt problem trust me, if you do you can kick me in the nuts

furloughed ual

My Feedback: (31)

Yep...u are talking about a common negatinve ground....MOST chargers will not handle that setup...I recently switched all my switches to the Electroteck rocker switches....solved all the charging issues related to the common ground issue.

SinCityJets

If you charge one battery at a time, there will not be any issues. Or if you want to charge both batteries at the same time, just disconnect ONE of the batteries from the receiver/power expander. This eliminates the common ground issue.

Chad

furloughed ual

My Feedback: (31)

Yes it does....just a PITA to do this each time...Electroteck switches were the answer for me.

SinCityJets

I find most people charge just one battery at a time anyway, so it's not an issue for them. Especially with A123's. Their super fast charge times really negate the need to charge your batteries at the same time....plus you save a little money.

Chad

Vincent

My Feedback: (61)

My A123 batts each have a seperate charge/balance lead so i dont have to disconnect them from the rx. The leads are stubbed off so i can get at them and hook up two cellpro 4 chargers. Chad is correct though, they soak up a charge so fast i typically just do one at a time.
V..

quist

My Feedback: (198)

Even with the balance tab as a charge lead you still have a common ground.....I think.

furloughed ual

My Feedback: (31)

Tony, correct. The black wire within the switch is still unbroken if wired to charge/balance thru the charge jack type switch....even if using the balance taps on the batts, the 2 batts are still connected together via the unbroken negative (black) wire in the switches. That's what most chargers cannot deal with as they sense on the low side, using the negative wire to provide info to the charger...problem is it is reading the charge info from the other battery/charger, since it is linked together, and that's the issue. Only way around this is to unplug 1 battery like Chad said, which to me is a complete PITA, find a charger that senses on the high side (positive red wire), or to break the gorund with a proper switch...the JR, Futaba, and MPI switches will not.

Beavis

My Feedback: (19)

This is not a statement of preference for the simple, straight 2 batteries/switches to the Rx, with no battery isolating device, but there are other points to be considered that may render that simpler setup desirable. First, should one pack fail with a short, any sizeable energy transfer from the bad pack to the good one takes a long time with A123's (usually way more than a day), much more than the time we would spend flying, hence plenty of time for us to diagnose the problem when we check the batteries after the flying is over, or before the next flying session. Second, there are benefits to having 2 sets of plugs, switch contacts and connector pins at the Rx instead of just one, namely an effective 50% reduction in system impedance, which is relevant to our high drain setups. Third, the elimination of an additional item that may fail (the isolating device). So, it is understandable that there is a lot of debate on that.

Personally, I don't consider myself knowledgeable or experienced enough to make a final judgment on this. For example, it is unclear to me how important it is to regulate 2S A123's (like the PowerBox Sensor Switch does), which would be, perhaps, the only "mandatory" reason to use a battery isolation device - i.e. the concomitant regulation. Then again, many say that 6.6V is essentially no different from 6V for the servos and Rx we use. Dunno... What I do know is that I don't trust my planes to any batteries other than A123's.

JohnMac

Beavis you are assuming a lot of things here that we simply do not know and cannot accurately speculate on. The whole point of a redundant system is to deal with as many failure modes as possible. Two good, correctly speced batteries, isolated via a diode that is correctly speced for the purpose, through two switches and into two Rx ports covers pretty much every evantuallty. For example what happens if one switch should fail? Who knows? But let me give you a real life example that was fortunate to happen to a jet.
My friend used two 4 cell NiMh batteries, via two switches, into two Rx ports (one via a Y lead). He was puzzled on day when switching on that his ervos twitched once and then nothing else happened. He then switched on the second Battery. 5 seconds later he had thick black smoke issuing from his cockpit. He was fortunate that this was a jet because we had a fire extinguisher, and we quickly needed it.
Examining the disgusting mess of burnt wiring afterwards it became clear that the first switch had failed, probably a short circuit within the switch. This had flattened the first battery. The second battery had clearly seen a dead short. Why it happened in this way I can only speculate, but what is clear s that there is more than one failure mode.
In this case, had a diode been fitted to isolate the two batteries, the fire could not have occured.

Vincent

My Feedback: (61)

I guess i have to clarify my dual batt setups are with the AR9100 rx and the "soft switch" supplied by spektrum. There is no common link on the two packs as they are plugged directly into the dual rx batt leads.
V..

Beavis

My Feedback: (19)

Vincent, I may be misunderstanding your setup, but there may still be a common link, given that receivers share a common ground strip - hence the common ground problem when charging two batteries connected to the Rx at the same time.

JohnMac, I didn't know one could use a diode and two connections to two Rx ports. If I understand correctly, the BattShare, the PowerBox Sensor switch and the other similar devices all may use two switches, but have only one connection to the Rx. Am I missing another setup possibility, namely one with a diode and two Rx ports (?). As to the case you've mentioned, it is indeed quite disturbing. On the other hand, A123's handle parallel installation mishaps differently from Nixx. They take much longer to drain into each other.

Thank you both for enriching the discussion. I believe that this is one critical aspect of our installs that still needs much clarification...

furloughed ual

My Feedback: (31)

Nope... the batt share has dual batt inputs and dual rx outputs....

The above scenario is exactly why I run the batt share....to isolate a short somewhere in the system....any other type of failure is handled by having 2 batts, 2 switches, into 2 rx ports....

Vin, not sure about the JR/Spectrum stuff, but u do indeed have a common link to each batt via the rx....

FYI, the $800 Powerbox Royal and SmartFly power expanders do not break the common ground either....isolate a bad batt, yes. One batt must still be disconnected to charg 2 at a time.

Vincent

My Feedback: (61)

Not sure about the common ground issue but i have dual charged my packs connected to the rx with two cellpro 4s chargers with no problems??[:-]
Vin...

rcjetsaok

My Feedback: (7)

Thats why have asked the original question about common grounds through the charge switches... Andy at E/Dynamics says his Ultra Switch II breaks the common ground inside the switch. Has anyone used those or the Ultra Nano ???


Danno

Tom Antlfinger

My Feedback: (24)

Ryan and Vin:

Currently, all my birds , including my F-100D, F-4, Firebird, and KC all use the same setup. Dual A-123 and Andy Lo's(ElectroDynamics) Battery Backer(EDR-108T) with two leads input and 2 leads output. He rates at 6 amps continuous and 20 amps pulsed at a 20ms On/40 ms Off cycle. I use JR 1222 with EC-3 connectors and integral soft switch. Andy's unit is so small with no bulky external heat sink that you can hide anywhere with sticky tape.

I have Andy wire everything with 16 ga wire and EC-3 connectors which match up with the leads coming out of the 1222 or 9100 as well in my Eurosport. That way, everthing from the batts to the RX bus are good for 40 amps. My balance charge line on the batts is still typical 22ga with JR connector.

I still have to disconnect the batts if I am not going to fly for a few days as there is a small current draw even with everything switched off at the soft switch, but the 108 does break the + and - sides of the line so no problem charging both packs at once with my CellPro 10S. On my Hun takes about 5 minutes between flights, 10 minutes if I wait for a 100% balance.

The 108T has an intrinsic voltage drop of about 0.47-0.60v which leads to a bus voltage of 5.9-6.0 volts on the Data Logger with either A-123 or 5 cell NiCd or NiMh packs. I agree you can run A-123 direct which I do on my BARF and BCARF, but if you inadvertently stall a 3301 or 350 series mini servo with a fresh A-123 off the charger at 7.2, they will smoke faster than you can say W*F?....been there.

Almost lost my BARF a month ago. Flying with a single 2 1/2 year old Li-Ion and brain farted. Left full flaps down after making some adjustments in trim and went to full throttle. The current draw from the flap servos led to a voltage drop which browned out my 1221 momentarily, power failed the P-70 ECU, and instant deadstick. Fortunately our field at the ends is very wide so saved it. No more old Li-ions for me......all 123.

http://www.youtube.com/watch?v=r13PX1r-H5w

Tom Antlfinger

My Feedback: (24)

Don't know Danno about his newest switches......I use all soft switches on my stuff now.......Andy's HD switches a while back did not......

furloughed ual

My Feedback: (31)

Tom, I actually had the ED batt backer....chose not to use it because of the voltage drop....personal preference.

Tom Antlfinger

My Feedback: (24)

Yea, understood Ryan.....the only reason I was running them was that without it in the circuit, I could not charge both packs at once with my 10S, as there still was a common ground in the 1221, 1222, and 9100 bus. Actually, the voltage drop is not always 0.6 like in the regulators, but about 0.47 at low to intermediate current flow, but still a drop.

rcjetsaok

My Feedback: (7)

UPDATE/CORRECTION

Just talked to Andy a while ago, he says his or none of the charge switches he knows of open the ground wire... He said the problem is the Signal wire going from the switch to the RX... It will be carring 3.3v+ to the reciever and confuse the whole circuit when charging 2 battery's at the same time. Cut the signal lead and problem solved. ( No DSC capibility though ) . I'm gonna also get his "Backer" device which his is version of the BattShare. It is deigned specifically for the 123Nano Batts. The "Backer" is designed to go between your 2 switches and the Rx. 2 Inputs and 1 Output. I told him I was useing JR1221 Rx which has 2 Batt input slots. He also has the "Backer" with 2 in and 2 out leads. Another tidbit of info, He also said that the 1221 Rx has circuit built in the Rx between the 2 Batt inputs that Isolate and control input from the Batt''s. I would assume the 1222 would also have this also.

I hope this is all the info I need !!!!!

Danno

frankle951

My Feedback: (35)

[8D][8D][8D] I love A123 Race battery, I have 12 A123 race battery four in my Robert Godfrey 40% Extra 300, best battery on the market [8D][8D][8D]

JohnMac

Hi Danno,
I don't understand that. Where does this 3.3v+ on the signal wire come from? The Rx is switched off for charging I expect, and since it is the Rx that produces this signal for the servo....? Am I missing something?
Re the twin battery capability of the mentioned Rx, Multiplex did this on their IPD synth Rx's for years. However they have taken this superb feature out of their new 2.4 Rx's[&o]

rmh

The guys using A123 -are seeing what we found out a coupleof years ago
Namely; forget everything you knew about other batteries .
All the redundancy and in line regs battery balance stuf is just more stuff to potentially fail
All JR stuff runs fine with A123 going directly into one of their rx. The "soft switch being the better approach
I threw away all the other stuff an use A123 for rx and power and ENELOOPS for tx power.
Also I use A123 in my old hand drills - no surprise dead batteries after they set for days/weeks/months.
Ditto for ENELOOPS in my Canon camera - always ready to go.
Charging two packs in a model is the only point of real possible confusion.
One pack MUST always be disconnected
A good charger (the FMA10 for example )uses three wires - per pack- it is to permit charge balance of each cell.
As long as you do this correctly - the BEST bet is just the most direct path from bat to rx

Because Ialso have models -planes and cars powered by A123 - I prefer a direct plug in setup - no power switches wherever possible.
My latest generation LiPos (40-50 amp cells) are great but the simple reliability and apparantly limitless number of cycles - The A123 remain a favorite.

furloughed ual

My Feedback: (31)

"One pack MUST always be disconnected"

Dick, most of the time yes, but not always....with the proper setup, unplugging 1 batt is not a requirement. The Electrotec rocker switches will allow simultaneous charging with and type of charger.....also, there are a few chargers that handle the common ground issue of the "normal" switches like the Futaba, JR, MPI, etc. The Hughes Spectra handles this and I believe the Ion Cubes do also.

But for 99% of the setups being used by most, yes, disconnecting 1 batt is a requirement.

How's Libby doing? I stopped by your place a few years back with York Z to get his flagged tail CARF Extra.


Ryan