Elev8 first flight-pack voltage
I finally had my first test flight for about 5 minutes late last night.. and that brings up a few questions about the parallax 3300mAh battery pack. And the start of many more to come as I put in more flight time.
What are the charging rates/settings I should use for the TB6B charger?
Whats a safe fast or slow charge?
How long of flight time should I get from said pack? Once fully charged.
What is the lowest pack voltage I can go down to without killing the pack?
I plan on getting the telemetry module for my dx8 to read voltage and maybe temp.
As you can see(or read) I'm new to the taking care of/feeding of LiPo's.
-dan
What are the charging rates/settings I should use for the TB6B charger?
Whats a safe fast or slow charge?
How long of flight time should I get from said pack? Once fully charged.
What is the lowest pack voltage I can go down to without killing the pack?
I plan on getting the telemetry module for my dx8 to read voltage and maybe temp.
As you can see(or read) I'm new to the taking care of/feeding of LiPo's.
-dan
Comments
Not sure on flight time. The lipo alarm will tell you what your flight time is, then you can setup a timer on your transmitter to back it up. http://www.parallax.com/product/752-00014
I do not go lower than 3.6v on the lowest cell while flying, the packs will survive more cycles if you don't go too low. Make sure you're using a lipo monitor while flying. The voltage will be a lot lower in flight than on the ground. Testing the pack while it is "resting" doesn't do much good and will usually be at least .5v higher than when you're in the air. Put the pack at storage voltage if you don't plan on using it for a few days.
Telemetry is awesome, it will pay for itself in making sure you don't damage your pack. If the telemetry doesn't measure the individual cells it isn't as good as the lipo alarm which does. You have to be really careful with per cell voltage some cells drop faster than others. If you have just pack voltage, dividing by three to get cell voltage leaves a gap that could potentially cause a cell to run too low. This is why it's good to have a backup timer.
After you have some more flying experience you will develop a feel for the battery stuff. Those 3300mah packs for $30 are a good deal! You'd be best off with a few of them so you don't try to stretch one pack too far.
I started at less than the 1C max rate of 3.3A. I now typically use 3.0 A.
I get about 7 minutes of flight time and on recharge I'm putting 2600 to 2700 mAhr back into the battery. One thing I ran into was that I was using CHARGE mode for a while, when I should have been using BALANCE mode. CHARGE would recharge in less than an hour, whereas BALANCE takes 2 hours. The advantage is additional capacity and, of course, a balanced charge between cells.
My radio has telemetry and I set the alarm at 9.7V for the pack. The alarm sounds 30 secs or so before the ESC's start limiting motor power. I also use a timer just to make sure I'm "close to home" when it's time to land.
Good luck,
-Russ
I'll have to remember to order one the next time.
-dan
xanadu is spot on with the charging rate. Also take a look at the safe usage guidelines at http://www.parallax.com/downloads/lithium-ion-polymer-safety-instructions this will help you get the most out of your battery possible.
For a stock ELEV-8 v2 at a density altitude of 2100 feet and non-aggressive flying with an 80% discharge (max recommended), my average flight time was just under 8 minutes.
No harm done using CHARGE a few times rather than BALANCE, but try to avoid it, as the former will shorten battery life.
And I highly recommend a low voltage alarm. If you are not using one, I'd set a timer for 6-7 minutes to be safe.