A123 Question
 

Could this product be of use with the A123 battery system?

http://www.dreamworksrc.com/catalog/...oducts_id=1293

I know it says NICAD/NIMH but it also states LI-ION.... Just wondering if the capacity feature would work as well with A123.

Luis

RE: A123 Question
 

I dont believe that this will work with A123 due to the fact that a123 batteries maintain a constant voltage until the are at the very end of their capacity. Other battery types gradually decrease in voltage as you consume their energy. a123 will dump their voltage right at the end. Could be wrong but i think that is correct.

Rich

RE: A123 Question
 

I was looking at this earlier today and it says that it will go up to 20 volts so I don't see why this device wouldn't work. Voltage is voltage despite the battery medium. If above is true the device will function, but it just may not be useful.

RE: A123 Question
 

This device will certainly read the voltage of the a123 cells. The problem with the a123 cells are the voltage is not a good representation of its capacity because they maintain voltage right until they are about to die.

Rich

RE: A123 Question
 

Rich, You are correct. The way I understand it is these packs increase output to stay in volt/amp tolerances. If you put a load on it, somehow the battery pack detects that and increases output? Only way to check capacity is flying time, fly a couple flights, recharge and note how many mah you put back into the pack. Do it again until you find a very conservitive point. The plus is, it, they, are fast charge capable, 10amp rate capable, many charge cycles, 1000! and they stay charged over time. Down side, full power then nothing. So you need to fly, record charge mah in , fly, record charge mah in. Do it a couple three times to get in the ball park. Loaded with our popular ESV's will not say anything useful. BTW I am new on this chemistry and this is how I THINK you should approach it. Wayne McCosker............ STL

RE: A123 Question
 

You would be better off with a unit designed for A123 use. Fromeco has a new unit that actually measures the usage , and displays the energy used out of the pack, Jack.

RE: A123 Question
 

Jack, Is that measured under a LOAD or what. Wayne

RE: A123 Question
 

Whats the name of the new Fromeco switch?

RE: A123 Question
 

Here it is Tom
http://www.fromeco.org/Products/04FR...0/Default.aspx

RE: A123 Question
 

Yes , Thats the switch I was talking about, I just wish it had dual inputs and dual outputs so that you could use two batteries, and have two inputs to the Reciever, like when you are using a Jr 921 /9000 spectrum reciever. You could have two reciever inputs for power and spread the amp load between two JR connectors at the reciever. I sucks to have to buy two of these if you wanted to use two A123 battery packs, no regulators. I really like the idea of an amp counter to monitor the battery charge level, of these new cells. Maybe they will come out with another version. Jack.

RE: A123 Question
 

This unit will do it all, using either 1 or 2 batteries, with real time display.

http://www.rc-electronic.com/html/pd...ung_V10_EN.pdf

RE: A123 Question
 

Mach1-RCU , It doesn't list A123 cells as an option in the instructions, and is rated only at 3 amps continuous for 15 minutes, Jack

RE: A123 Question
 

Sorry Jack, That is not the correct link. That is for smaller batteries.
Look here http://www.rc-electronic.com/html/pd...ung_v10_en.pdf

RE: A123 Question
 

Sir, Could not tell from text. I assume there are no voltage regulators involved. If that is the case it would work with 123"s. WHMC

RE: A123 Question
 

There are no regulators in the unit. It is meant to be placed inline with the batteries which inturn get connected to the (a) power expander system. Power is then regulated to rx and servos. The BMS unit simply measures and monitors battery status on a real time basis and keeps track of voltage, mah's used per flight, etc, etc. It can monitor nicads 5-12 cells and would see the a123's as 5 cell nicads.
This would show 6.6v's at both batteries. As you make flights you can see immediately how many mah you have used both per flight
and in total. Plus it shows both batteries simultaniously. This is the same as flying a few flights (as suggested) and then charging and noting mah used to determine how many flights you can fly between charges. Seems to me almost a must considering the characteristics of the A123's voltage curve.

I have one coming and will use with twin A123's. Results pending.

RE: A123 Question
 

Very interesting.
Where did you get your DPSI BMS, and how much is it?

It sounds like it is not supposed to be used as your switch, but just as a monitoring device. It talks about it turning on automatically when you switch on your rx.

Jim

RE: A123 Question
 

Jim,

You're right, it's not a switch. (The switch is separate and connects to the power distribution unit, DPSI RV).
The BMS is just used to monitor and record battery use.

I had to order the BMS from [link=http://www.rc-electronic.com/html/englisch/englisch.html]Emcotec[/link] in Germany.
Desert Aircraft USA carries Emcotec products but they were out of this piece. They also make a single version of this unit if using one battery.

RE: A123 Question
 

I'm using a 2cell A123 in my Harpoon with the PowerBox Sensor switch. After 3 flights it still holds 1600Mah before dropping under 6.3V measured with 1 amp load. Another 300Mah and its empty at 5,4V. Not a very scientific result but this i measured with my Schulze charger and is "about" correct.

Eivind