Hammbone

My Feedback: (309)

How long before you come out with a Weatronic rx that is compatible with A123 batteries? That's all I'm waiting for now.

Jim

gerhardp

Hi Jim,
You can use the A123 batteries already, but you have to use the three cell version. The servo supply voltage is set at 6 V with that you have to have at least 7.2 Volts at the power supply end under load. That takes the two cell version of the A123 out of the picture. Attaching 2 A123 batteries will cause a contant switching back and forth. We are studying the application of these batteries and we will come up with a solution for it. Doing it right is our motto and so it will take a little longer.

Thanks,

Gerhard

Hammbone

My Feedback: (309)

I probably wouldn't want to use two 3-cell A123's because of weight, but maybe I could use a 3-cell A123 as my main battery and then just have a small back-up battery? I can use different battery types, right? What would you recommend I use as a back up battery?

Jim

gerhardp

Hi Jim,
I have heard that you can get 1300 mah A123 batteries. That would work or you can use adequate sized Lipos or NiMh batteries. It really depends on the draw that you have and how you flying stile influences the draw as well. You can base that on the readout that you get from your data logger. A123 combine the safety of NimH with almost the capacity and amperage and weight of Lipos, but without the dangers of the lipos. You want to have the blinking of the receiver LED visible to the outside, so that you can monitor the frequency of blinking, knowing when you had a switch of batteries occur. Then you know it is time to land.
Typically the 3D guys run the bigger digital servos with higher current draws than the Jet pilots. Jets though can have high loads as flaps causing high current loads from those servos. Again, analysis of flight data will give you your individual answer.

Thanks,

Gerhard

gbrod

My Feedback: (4)

Gerhard
I really would like to use only a 2s pack (6.6V - 2300mah) for my receiver.
1) could I set up the receiver for NIMH batteries? would that solve the switching back and forth? The A123's will stay around 6.6 which is where a 5 pack nimh usually is.
2) for testing, could I use the A123 as battery#1 and my LI-IONS as battery#2, that way if the A123 doesnt work, the receiver will go to #2 which we know works (can I have different input voltages in the 2 batteries sources and what about the setup, does it matter if I use LiIOns and setup for NIMH?)
Thanks
George

gerhardp

Hi George,
As I said before, I do not recommend to use them until we come up with new settings or you use 3 cells. Using 3 cells with LIPO setting, will cause the regulators to get a little hotter. You might have to look into using heat sinks. If you use two cell A123's, you have to set the battery choice to NIMH. Depending on the state of remaining charge you can encounter constant switching. (2/3 to 1/2 full) You will have the batteries switching back and forth all the time, depleting both batteries and at the same token it will take the feature of the backup battery away. Then you are almost actually better off to just take one 4600 A123 and no second battery. We will be coming up with a solution, but first we need to do a little R&D. I have entered a dialogue with A123, but they are not very responsive. So please be patient. We will get to a solution, one way or the other.

Thanks,

Gerhard

crhammond

My Feedback: (21)

I'm glad I came across this thread. I have read in another forum it was okay to use the A123's on LiPo mode. I was experiencing the constant switching with A123's when they were below 1/2 charge on this setting (I could tell by the servos "pausing" all the time.)

In my setup I use a Fromeco Wolverine switch in front of the Weatronic. It is a fail safe dual switch that draws from both batteries equally... which at least to me I prefer over the backup battery design of the Weatronic. It has 2 outputs that I plug in to main and backup - but it doesn't matter as they will both always be the same. Info is here: http://www.fromeco.org/awolverine.htm

Anyway - when I switched to NiMh mode it seems to work fine even onh low batteries although I have not tested it under load in flight.

I have not flown the plane and will not until spring (and not until you folks say it is okay to do so using A123.) I'm wondering if the update required will just be a software update?

What information are you trying to get from A123? If it is the nominal voltage, discharge curves etc - this is very well documented in other threads on the internet and even on A123's website.

The A123 has a very flat curve and nominal voltage around 3.3v/cell... the drop off is very sudden just like NiMh.

I love my Weatronic Rx's - any chance that some form of 2.4GHz support will come in the future?

crhammond

My Feedback: (21)

Actually - it is knid of strange - my A123's at 90% discharge and a 10A load still deliver ove 6v and yett he Weatronic switches to backup. Why is that?

gerhardp

Hi,
Sorry for the delay.
It is fairly simple. The voltage regulators cause a voltage drop of minimum 1.2 V. When you take the 6.0V that we want to maintain for the servos to always have the same performance, you add the 1.2 Volts to the 6 Volts (5.7 Volts) and there is the number that you have to sustain also under load. That means you have to be above 7.2 (6.9V)volts to begin with and be able to sustain that under load as well.
As the numbers already tell, the two cell A-123 is out of question. We are currently testing the 3S A-123 package and will get back as soon as we know more.

Thanks, Gerhard

crhammond

My Feedback: (21)

Thanks for the explanation Gerhard. I have switched back to my 4-cell Fromeco LiIo's and they work great just like they did before.
I will probably get some LiMn cells for this flying season as they are safer than LiPo and still have the power output I'd like for my 40% airplane.

Hammbone

My Feedback: (309)

Gerhard,
Please let me know your findings with the A123's. Once I know that I can use A123's with the Weatronics rx, I'll be ready to buy a Weatronics rx.

I probably will not want to use two 3 cell A123's because of weight. Can I just use one rx battery?

Thanks, Jim

crhammond

My Feedback: (21)

Jim,

Not to steal Gerhard's thunder... the Weatronic uses a Main / Backup system. It never uses the backup unless the voltage of the main drops too low (or it shorts/dies etc.) So you could use a single 3-cell A123 (once they are "okayed") and a smaller backup pack (for example a small lightweight 2 cell LiPo/LiIo/LiMn.)

Chris.

gerhardp

Hi folks,
Here an update on the last talking with Weatronic headquarters in terms of A-123 batteries.

The 3-cell variant is as I had mentioned a possibility, but it is actually a waste of energy. It is unlikely that we will recommend it. The servo's and receivers are limited to 6.0 V. Too much energy gets burned with 3 cell A-123's causing additional heat-up of the regulators.

Most likely we will be issuing a new setting in the battery choice section for the 2S A-123 batteries. It will be lower than the current setting for the NiCad or NimH batteries (5.7V). This will also mean that towards the end of the discharge, the servo's will not get the 6.0 V and with that, they will also not be as responsive as with a fully charged battery.

This will most likely follow after they have done some further testing in Germany. Then a new software / Firmware will have to follow. I can not give a timeline for this yet.

Stay tuned

Gerhard

picard1

My Feedback: (2)

Gerhard,
Any updates regarding software r firmware upgrades using the 2S1P A123 batterys?

thanks
mike

gerhardp

Hi Mike,
Sorry, but there has been no new news on the A-123's. Using a two cell is not enough voltage and a three cell is too high and you would just heat up the regulators in doing their job, by dissipating about 70 percent of one cell energy. A Lipo os still the best choice for power density.

Gerhard

gerhardp

Here is the latest on the new 2.4 and A123 batteries. The 2.4 system will be able to support the A123 batteries.

Gerhard

rceagle

My Feedback: (5)

Gerhard< I am in the process of possibly buying a 10-20r is there a software update to make this model able to use a123's in a 2s config? If not then I will withdraw my offer to buy the weatronic from the seller on RCU.