jhall2242

My Feedback: (8)

I have searched around for some common sense answers to LIFE batteries and can't find much to answer my questions. First how do you know when they are about dead? I had been used to Nimh or Nicad packs under load showing a voltage drop. For example I wouldn't fly a 4.8v pack when I would put my voltmeter load of .5amp on and it would drop to 4.9 or below. That was easy. Here is what I have learned so far:

1) When charging up the pack it peaks out at 7.2v. Now interestingly within 10 minutes it drops down to 6.6v and stays there. It will stay there for a month without use so far.

2) I have been using a 6.6v 1800mah Hobbico LIFE battery in a 60 size Profile plane. I also have a Hitec Aurara 9 with live battery telemetry. I watch it constantly while flying. During the first 2 flights the battery will stay at 6.6v when the plane is sitting there and plane is switched on. If you move the sticks around it might drop to 6.4v on a fresh charge.

3) After about a month and 7 flights the same battery without charging is at 6.5v and will drop to about 6.2v under load while flying with servos at full deflection. When I land it with the plane on it says 6.5v still.

4) I discharged the pack to the recommended 5.0v and got another 1100mah. (I had to sit there and watch it because the default in my charger will take it to 4.0v) That means that my 3D flying 60 size plane with 4 Hitec 645MG servos and a 82MG only pulled about 600-700mah in 7 flights. That is actually unbelievable. Flights were average of about 8-12 minutes each too.

5) I guess since I still had 1100mah in the pack that I can get around 12 flights out of this battery and be safe running it as long as the voltage doesn't drop too low on the screen. Telemetry is another variable that is a bit hard to judge, but it is actually more accurate of a battery check than using a voltmeter with the plane off.

I would like to know if this seems normal to anyone else or if this helps anyone esle. I'll keep flying and try to update this later. Right now I think this might be the longest lasting 1800mah pack ever created. It just scares me to use something that doesn't seem to show a voltage drop even after 7 flights. I have seen some voltage curves posted somewhere that didn't really jive with the above, but I feel that mine is more of a real-world result.

madman75

Check this out. This may or may not answer your inquiry but it's full of info.
http://www.hangtimes.com/a123_batter...iants_faq.html

Maybe we'll get to fly at the field this weekend. I assume there's a meeting Sunday.

jhall2242

My Feedback: (8)

I forgot about their website. I read through that back about 2 years ago when I bought two of their batteries. I put them in a plane that I ended up selling before I could test out the LIFE cells in it. I forgot about their discharge curve graph. I guess if you look at their graph it makes sense to start worrying about charging when it gets to 6.4v while flying. But I would be worried if I didn't have telemetry. The big plus on these batteries is the fact that they hold their charge so well. I have heard that most people just charge the battery no matter what after 2-3 flights. That would work too I guess.

I'll be there Sunday at the field. Later man and I still have that other battery for you if you want it.

BarracudaHockey

My Feedback: (11)

Really the only accurate way is to fly a few flights and recharge the battery noting what gets put back in and figure out how many flights you can get with a safety fudge factor.

I run about 220 to 250 mah per flight 10 minute flight on a 55cc gasser with all 5 7955 servos and the ignition running on 1 A123 pack.

mbosaz

Hi guys, this is an old thread but wanted to give it a try since I am having a concern about LIFE batteries at the moment.

I am flying a gasser 35cc with HV Rx and Servos (Hitecs)...I am using Life 2100mah (6.6v) from Hobbico and I bought it new less than a month ago. The other day I told the plane to the field and the battery fully charged. When I measured the charge %, it was indicating 96%.

We did one turn and the muffler went lose so we landed. This was literally after 2 mins flight. While we fix the muffler back, I decided to check the battery and it was indicating 65% (!). 100% sure we measured correctly and we used two different testers. I was shocked and went back to Lipo.

However, I bought 3 LIFE and understood that they were good alternatives to LIPOS.

Anyhow, here my questions:

1. Is it safe to fly 35cc or 50cc using LIFE batteries?
2. How many flights (or time) should I be getting with a full battery?
3. Is the % irrelevant and I should stick to the voltage coming out of the Jr plug they have?

I appreciate any help. Safe and joyful flying.

Mariano

SeaJay

My Feedback: (6)

The way I determine the health of my LiFe battery packs is to cycle them on a good charger/cycler that has an mAh reading.



1. Fully charge the pack, then let it rest for an hour or so.

2. do a Full discharge, taking note of how many mAh is drawn out of the pack.

3. Recharge the pack, again, taking note of how many mAh was put back into the pack.



the pack should be at least 80+ percent of the rated capacity. If the pack shows less than 80% rated capacity, it's time to retire that pack from aircraft use!


If that checks out, then fully charge the pack, then do a Flight. after you land, recharge the pack, taking note of the mAh that the charger puts back into the pack. if the flight takes out less than 10% of the packs capacity, then I usually do 3 flights on a fully charged pack, re-charge the pack, taking note of the mAh put back into the pack, then divide by 3, this gives you an average discharge amount per flight.



for example, I have found that my 77" WS Edge 540 with 7 High torque servos with a 2500mAh LiFe pack takes about 200 mAh per average flight, so I feel safe flying my plane 5 times removing about 1000 mAh out of my 2500 mAh pack, keeping me above my 50% threshold of 1250 mAh maximum discharge prior to recharging. I never fly with less than 50% battery capacity.



From what I understand, Due to their discharge curves, LiFe packs are difficult to check, and not very accurate with a voltage or capacity checker. That's why I use a computerized cycler/charger to check the health of my packs!



Hope some of this helps..




P.S. I love My LiFe battery packs. I have been slowly replacing all of my NiMh packs with LiFe packs.. As My Older Packs reach my limit of 80% rated pack capacity, those packs are retired from Flight service, and replaced with a LiFe pack!

Craig!

mbosaz

Thank you Craig. This helps. I will start by getting a proper charger then with display and then take the time to crack the safe range for flying. Maybe the HV servos are taking more voltage and this can also be another factor of faster discharge. Just guessing. I will share my discoveries. Good flying! M

SeaJay

My Feedback: (6)

Glad I could help..

Keep us updated as to what you find!

Craig!

SeaJay

My Feedback: (6)

BTW, I have a HiTec X2 charger and I love it..

If you wanted to get REAL serious about the health of your Battery packs, you could get a Computerized Battery Analyzer by West Mountain Radio.. They are amazing, gives you curve print outs, averages, etc. I got one in a Buyout of a flier getting out of the hobby, and it gives me more info about my packs then I would ever need!!

Take a Look, just for Kicks and Grins!! http://www.westmountainradio.com/pro...oducts_id=cba4

Craig.