RE: A123 as receiver pack - no fly voltage? (Full Version)

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BaldEagel -> RE: A123 as receiver pack - no fly voltage? (3/18/2008 2:55:33 PM)

Guys

Have a look at the Fromeco Kodiak switch designed for the A123's, it has a Mah read out on the switch to tell you cumalitve power use during your flights, you reset the read out when you re-charge, the switch remembers each use until reset. A very good safety feature, got mine already.

Mike



Richard D Bahmann aka/Wrongway -> RE: A123 as receiver pack - no fly voltage? (6/5/2008 1:40:44 AM)

Here is an update to my exploration in post #16 of this thread. I am cutting and pasting from the F*Giant's thread so as to not have to duplicate all that typing. The tests were conducted today.

On power usage here is a little test I did this morning.

I have three home made 2S1P A123 2300's on deans connectors in my electric goodie bag. I also dug out a power-expander and the Smart fly super switch so I could run the servos off of the A123. Servos are 3x925 2x645 and one HS 81 mini. Receiver is Futaba R319. I set the servo test mode in my Futaba 9Cap so that it would continuously cycle all servos.

The three batteries (1,2,&3) were sitting in the bag and had not been charged for about two months so I topped them off with the TP-1010C at 1.0 amp A123 charge. They took (in the same order) 59, 22 & 24 mah to fill up. When the charger shuts off they are all very close to 7.26v coming down to (all) 7.22 after about 5 minutes. From there I started the test. Again all reading are in order battery #1 then 2 then 3.

Cycle time 10 minutes

voltage/mah to top off.

6.70/88... 6.70/83... 6.70/84

Cycle time 20 minutes continous.

6.66/174... 6.66/167... 6.66/165

I seem to recall about 110-120 mah usage for 10 minutes some time ago in my EF-88 with all digital servos so one might take an educated guess that flight loads add to the power draw. (not to mention different servo's)

Also the analog servo's were noticably cooler to the touch than the coreless servos I shot them for temp at at about two hours into the experiment and the air temp in the shade of the trailer is 91... the 645's 96 and the 925's 102 degrees. The module on the 9c at 119 degrees.

Next I will run the same test, twenty minutes at a time on one battery and record the voltage on the way down and at some point where I am nearing the bottom of that well, I will recharge to see what I have drawn out for a total.



Richard D Bahmann aka/Wrongway -> RE: A123 as receiver pack - no fly voltage? (6/5/2008 1:43:44 AM)

Today's test part 2.

My idea was to try to share some common ground (running the same load with Futaba servo mode cycling the servos as before) and see if there was/is a pattern in voltage and mAh used. This test is for educational purposes, please don't take my word for it, explore for yourselves.

I cycled on the same setup as I used in post above running twenty minutes at a clip and then checking the voltage at the end I recharged with interesting results. In all but one voltage reading the volts hot off the 20 minute cycle would come up .02 if you let the battery sit for about one minute. I am posting the raised voltage as that is what one might likely see after returning the plane to the barn and going for a recharge. Once or twice I waited 5 minutes before the next cycle but the voltage did not change by letting the battery rest any more.

I used battery #1 from the above test which was at 7.22 volts starting fresh off of the TP-1010C at 1 amp.

cycle time in minutes/voltage after 1 minute

20/ 6.66
40/ 6.66
60/ 6.64
80/ 6.62
100/ 6.60
120/ 6.60
140/ 6.58
160/ 6.56
180/ 6.54
200/ 6.50
220/ 6.46
240/ 6.40
260/ 6.22

I then recharged the battery at 1 amp and put back in 2150 mAh of juice.

There were 13 of the 20 minute cycles. When you divide the total 2150 mAh by those 13 cycles you get 165.39 mAh per 20 minute cycle and that is just about what I got in my shorter tests earlier today. (might be some consistency there)

It is interesting that the charger would not come on past a trickle until it got up to 6.4 volts. The A123 people must know something there because when it got below 6.4 the voltage change was faster in a given time period.

This battery has about 10 or so cycles on it since I put it together 6 months ago so it is fairly new.

So if any of you guys are going to charge your battery and want to post the starting voltage and mAh returned it would be interesting to see if the pattern holds.

Way cool that this 6 servo setup went for 260 minutes (over 4 hours on the cycler) and although not representative of any airplane it can be used to compare with your results.

There is always a right way/

and a

WrongWay



yarom -> RE: A123 as receiver pack - no fly voltage? (6/5/2008 6:55:46 PM)


While not really scientifc, I am monitoring the recharge value of my A123s after flying.

The immediate difference I notice with LiPos, is that these packs seem to consume less - 150mah per flight for LiPos and about 100mah for the A123s.

Other than that, the consumption seems to be very predictable and stable - simply multiply the number of flights per 100mah and that's about what the charger will indicate when topping off.

I am using the TP 610 charger and the battery packs are the Fromeco ones, that are a variant of the standard A123 (IronCorps).

http://fromeco.org/Categories/Iron_Corps_LiFePO4/



dick Hanson -> RE: A123 as receiver pack - no fly voltage? (6/8/2008 1:55:09 AM)


quote:

ORIGINAL: yarom


While not really scientifc, I am monitoring the recharge value of my A123s after flying.

The immediate difference I notice with LiPos, is that these packs seem to consume less - 150mah per flight for LiPos and about 100mah for the A123s.

Other than that, the consumption seems to be very predictable and stable - simply multiply the number of flights per 100mah and that's about what the charger will indicate when topping off.

I am using the TP 610 charger and the battery packs are the Fromeco ones, that are a variant of the standard A123 (IronCorps).

http://fromeco.org/Categories/Iron_Corps_LiFePO4/

Maybe your LiPos went thru a Voltage Reg -which wastes power - anyway -servo power consumption on A123 will be as high as any setup -NOT using regs - regs especially linear regs- waste power . they have to.



PropSpinner -> RE: A123 as receiver pack - no fly voltage? (6/15/2008 11:59:45 AM)


quote:

ORIGINAL: dick Hanson


quote:

ORIGINAL: yarom


While not really scientifc, I am monitoring the recharge value of my A123s after flying.

The immediate difference I notice with LiPos, is that these packs seem to consume less - 150mah per flight for LiPos and about 100mah for the A123s.

Other than that, the consumption seems to be very predictable and stable - simply multiply the number of flights per 100mah and that's about what the charger will indicate when topping off.

I am using the TP 610 charger and the battery packs are the Fromeco ones, that are a variant of the standard A123 (IronCorps).

http://fromeco.org/Categories/Iron_Corps_LiFePO4/

Maybe your LiPos went thru a Voltage Reg -which wastes power - anyway -servo power consumption on A123 will be as high as any setup -NOT using regs - regs especially linear regs- waste power . they have to.



Low impedence is a probably factor.



jaka -> RE: A123 as receiver pack - no fly voltage? (6/16/2008 1:29:21 PM)

Hi!
Found this site and eager to have some questions answered. I'm about to use two LiFePo 6,4V, 2000mAh batteries in a 216cm span Yak-54 powered by a MVVS 45cc engine and all servos being JR 8711. The receiver is Spektrum AR9100.

Can the servos cope with such high voltage as 6,4V (or 6,6V as most A123 batteries have)???
Second is there any gadget that could tell when A123 is about to be recharged. Warning for low voltage?



BaldEagel -> RE: A123 as receiver pack - no fly voltage? (6/16/2008 2:13:07 PM)

quote:

ORIGINAL: BaldEagel

Guys

Have a look at the Fromeco Kodiak switch designed for the A123's, it has a Mah read out on the switch to tell you cumalitve power use during your flights, you reset the read out when you re-charge, the switch remembers each use until reset. A very good safety feature, got mine already.

Mike


The voltage of a fully charged 5 cell Nimh pack is over 7.0volt fresh of the charger so the A123's will be fine, but do have a look at the Kodiak switch its perfect for these Batteries.

Mike



dirtybird -> RE: A123 as receiver pack - no fly voltage? (6/16/2008 4:59:03 PM)


quote:

ORIGINAL: jaka

Hi!
Found this site and eager to have some questions answered. I'm about to use two LiFePo 6,4V, 2000mAh batteries in a 216cm span Yak-54 powered by a MVVS 45cc engine and all servos being JR 8711. The receiver is Spektrum AR9100.

Can the servos cope with such high voltage as 6,4V (or 6,6V as most A123 batteries have)???
Second is there any gadget that could tell when A123 is about to be recharged. Warning for low voltage?


Just think of A123 battery like a gas engine. You have full power until it runs out of gas.



Capt Lou -> RE: A123 as receiver pack - no fly voltage? (6/22/2008 1:52:54 PM)

Jaka:

I have asked the same question and have only receieved positive answers that the RX/servos can handle it. I have a Wild Hare 300 Extra powered by a 50cc Desert Aircraft gas engine. I use a JR flight pack consisting of a JR 921 RX, and five JR 8611A and two 821 digital servos and do not use a voltage regulator. They are all rated for 6 volts. I have been told that when a 6 volt nicad/nimh (which this flight pack is rated for) comes off the charger they produce the same voltage as the A123 battery pack and will not harm the RX or servos. I use one A123 pack for the ignition and two packs for the RX/servos. Also, I checked with Desert Aircraft and they told me that their ignition can handle an A123 battery pack without a voltage regulator. I have had my plane flying for about a month, have 45 flights on it, and have had no issues with the flight pack. I like the A123 technology because it charges fast and is easy to use. I use a CellPro 4s charger which tells me how much capacity has been consumed and replaced. However, I asked the same question of Futaba's technical people here in the U.S. and got conflicting answers. Its RCU forum moderator gave me a text book answer that with respect to the Futaba servos, they are only rated 6 volts and it recommends that you use a regulator but their RX's have a built in regulator, while their technical staff has told some flyers that it is OK not to use a regulator. The result for me was that after 25 years of using Futaba, I now swithched to JR.



nonstoprc -> RE: A123 as receiver pack - no fly voltage? (6/22/2008 3:13:37 PM)

I am using 2 VPX 1100mah A123 packs (in paralll) on my WH edge 540 to power the flight system and can fly five 9-minute flights per full charge with 50%-60% capacity left. No regulators and no problems so far.

It is always a good idea to measure the power consumption of a typical flight and plan the number of flights with that data.




stephensackro -> RE: A123 as receiver pack - no fly voltage? (6/27/2008 12:25:11 AM)

Since you are using two packs in parrallel, is the power comsumption for each two cell pack about the same? Have you ever done any experimenting to see what the voltage would be if one cell failed closed (shorted). In that situation you would basically have a two cell pack in parallel with a one cell pack.



Richard D Bahmann aka/Wrongway -> RE: A123 as receiver pack - no fly voltage? (6/30/2008 8:49:44 PM)

Here is another test I did in the last day. I post them here to share and to use as a resource in the future. I tried to be as accurate as possible and know that your results may vary.

A123-Two cell cycle test.

Using the topped off 2S1P battery in my Yak-88 I put the battery on my Ace RC, Digi Pace/3 cycler to draw out 2100 mAh. The voltage had stabilized at 5.28 volts. I then drew out another 60 mAh to bring the voltage down to 2.6 volts on the 2 cell battery pack. This demonstrates that from just over 5 volts the battery pack can go down in voltage quite a bit in a short amount of mAh used.

From there I proceeded to replenish the battery and attempted to stop Every 100 mAh and check the voltage on the way up. The thunder power TP1010C Was set at 5 amps recharge but as you can see, the battery never wanted all of it. I backed up my lawn tractor motor with a 10 amp charger so power was available. In the voltage column you will see voltage after 1 minute and hot off the charger. The total mAh returned in this fashion was 2239.

mAh V=1 min/V=Hot Amps

100 6.110/6.341 4.0
104 6.422/6.442 3.9
100 6.485/6.512 3.7
100 6.563/6.592 3.2
100 6.615/6.654 2.6
100 6.650/6.674 2.1
100 6.694/6.700 1.9
100 6.671/6.703 1.8
100 6.672/6.713 1.8
100 6.678/6.714 1.6
100 6.687/6.720 1.4
100 6.708/6.752 2.2
101 6.716/6.755 1.8
100 6.729/6.768 1.7
100 6.744/6.784 1.6
200 6.761/6.800 1.6
100 6.764/6.805 1.5
100 6.768/6.816 1.4
100 6.784/6.828 1.4
100 6.824/6.880 1.4
100 6.960/7.056 0.9
034 7.082/7.152 0.4

2239 total mAh returned to battery.

I have been making my no fly voltage 6.4 for the last year based on a test done on the first page of this thread. Now I wonder if I might up that a little as it appears to be about 200 mAh from the cliff where the voltage drops rather quickly. This battery has several hundred cycles and the great majority of them I return 900-1100 mAh and few at 1500 plus. As the battery approaches the end of its life I would love to know if the curve will stay the same.



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