Who using A123 batteries?

[robertp17]

Thats what I thought. I dont understand why it matters what kind of battery you use because dc voltage is dc voltage right? My fully charged 5 cells are close to the same voltage as my a123's are. If i remember right my charger kicks off with my a123 at 3.6v per cell so thats a total of 7.2 which is close to the same voltage as a 5 cell that is fully charged right?

[dick hanson]

yes A123 has a effective operating range which is more constant in voltage than the 5 cell packs- in mid 6 volt 6.5-6.4 etc..

[Jim Woodward]

So far I am running two 40% planes, and 1 pattern plane on Dewalt and VPX A123 cells. They are working quite well for me so far. I have not done the experimentation that Dick (or others have done), rather just monitored the mah used during flights, and ensured that I charge way before a low-critical level is reached.
thanks,
Jim

[dick hanson]

In looking at your picture of your girrl/wife (whomever )
It is apparant she is holding two puppies -but I can't make out the breed Pointers?

[Pale Rider]

	Quote: Originally Posted by dick hanson
	In looking at your picture of your girrl/wife (whomever ) It is apparant she is holding two puppies -but I can't make out the breed Pointers?

LOL!!

[robertp17]

I agree, nice cans

[canavanbob]

	Quote: Originally Posted by dick hanson
	In looking at your picture of your girrl/wife (whomever ) It is apparant she is holding two puppies -but I can't make out the breed Pointers?

They used to be setters but the doggy bra makes pointers out of setters.

[sideways312]

i am using 2 A123 on my radio and 1 on the ignition on my 101 yak 54. the radio i get a bout 5 flights a charge but i usely charge them every two flight just because it doesn't take that long to charge them. on the ignition i have gotenn 10 flights. (i only know that because i forgot to charge it.) i have not put a meter on them to see the draw from my servos but after 3 flights my cell pros put back in 230-290mah on a 2380mah 2 cell pack

[gareth.ky]

Some numbers from a new setup:

I have 2 x 2300mah packs on my 50cc. They are run into a Spektrum AR9100 Rx and one pack has a Y so it also runs the ignition.

I flew some test flights and 3 rounds of an IMAC contest and charged the packs. Pack #1 took 711mah and pack #2 took 712mah. They are staying perfectly balanced.

I think use about 450mah per full tank of fuel. So that's 8 full tanks I could burn and still have a 20% safety margin. I think that DA-50 burns about 1 oz a minute (the way I fly it) so that's roughly 2 1/2 hours of flight time per charge.

[hubb]

AR9100 Rx, Duralite A123 2300 x2, 8 Hitec 7955's in my 40% Carden 260 unbeleivable power from the servos. 3 IMAC practice flights I put back in 640-650mah each pack, still flying Nimh on Ignition. IMAC this weekend we'll see how they perform!

[STLAV8R]

With a 2300 mah A123 pack, how many mah can it be pulled down to to fly safely.
(Two 2300 packs on RX, one 2300 on ignition - Fromeco Iron Corps Extreme).

Note: Fromeco Weasels are installed in the plane to monitor the mah used.

[wildhare]

	Quote: Originally Posted by STLAV8R
	With a 3600 mah A123 pack, how many mah can it be pulled down to to fly safely. (Two 3600 packs on RX, one 3600 on ignition). Note: Fromeco Weasels are installed in the plane to monitor the mah used.

As far as I know there is no such thing as a 3600mah A123 cell or pack. Cells are available in 1100 and 2300, and K2 makes them in 1200 and 2500.

But to answer your question, using a 2300mah pack they are good up to the 2000mah point of discharge, at that point they begin to drop off pretty quickly.

I make it a rule never to take off with 75% of actual capacity (the 2000 figure) or more used from a pack. I calculate amount used based on airplane size, it's usually in the 250-400mah per flight. So on a single 2300 pack I would not make more than 5 flights without recharging to be safe. You might get away with more but why chance it?

TF

[wildhare]

	Quote: Originally Posted by dick hanson
	One last observation- it ain't the wires - it is the connectors and the resistance which builds at the junction of the wire and the connection.

Partially true, connectors are the bigger problem.

But, I did a test recently, I had a 24 inch extension which I made from 20 ga. silicon insulated wires (good ones) with Deans plugs on each end.

I ran my usual A123 load test where I see how much current I can pull from a pack without going below 5 volts. Usually this will give me 20 amps, +/- a fraction depending on the state of the pack.

With the 24 inch extension in the circuit voltage was way down. My recollection is that I was able to get only about 4.4-4.5 volts when pulling my normal 20 amps. I removed the extension and the results came back to where I expected them to be.

So I shortened the extension to 6 inches and performance came back up but not to where it was without the extension.

Clearly smaller wires and especially long runs of small wires will affect performance. The voltage difference is enough to have an effect on servo performance in a hard snap on some planes where servo torque is marginal to begin with.

TF

[STLAV8R]

	Quote: Originally Posted by wildhare
	As far as I know there is no such thing as a 3600mah A123 cell or pack. Cells are available in 1100 and 2300, and K2 makes them in 1200 and 2500. But to answer your question, using a 2300mah pack they are good up to the 2000mah point of discharge, at that point they begin to drop off pretty quickly. I make it a rule never to take off with 75% of actual capacity (the 2000 figure) or more used from a pack. I calculate amount used based on airplane size, it's usually in the 250-400mah per flight. So on a single 2300 pack I would not make more than 5 flights without recharging to be safe. You might get away with more but why chance it? TF

How long is the average flight?
I edited my info. They are 2300 mah packs. How long is it OK to leave these packs fully charged for without flying them?
At about only 15 min. per pack to recharge, it would definitely be smart recharging them.

[wildhare]

	Quote: Originally Posted by STLAV8R
	How long is the average flight? I edited my info. They are 2300 mah packs. How long is it OK to leave these packs fully charged for without flying them? At about only 15 min. per pack to recharge, it would definitely be smart recharging them.

Maybe it's better to state it this way. I find that a 50cc plane uses about 20-25 mah per minute, 100cc 25-30, 150cc probably 30-40. This depends on how hard you fly, the weight of the plane, and several other factors.

I recommend to my customers that they use this procedure when getting started.

Charge the batteries and make one flight. Recharge, noting how much you put back into the pack and how long you flew. Fly again, this time 2 flights. Repeat the recharge again noting amount used and flight time. Then go to 3 flights, assuming the numbers say that you have plenty of power available.

You will quickly get a feel for how much power your plane uses per minute and per flight. Once you have done this use 70% of available capacity as the no-fly point. Never take off if you calculate that you have used 70% of the available capacity, this will give you some cushion in case you forget or your calculations are off slightly.

When in doubt, recharge. If you don't remember if you have recharged, recharge. Putting a charger on a full battery won't hurt anything and it will tell you within a few seconds if it's already charged.

I normally equip my planes with enough power to make at least 5 flights with some margin, and I rarely make 4 in a day, so all I have to remember is did I charge before I started. I don't really have to think about it unless I do something stupid like leave the switch on all night.

TF