buzzbomb
I know nothing!
All caps and 3 and 4 had 0 chance of happening. Yep. I'm guessing it quickly turned into a bad night.
Hobby Newbie Learning Diary; Family Included!
- Thread starter mayan
- Start date
mayan
Legendary member
Actually was a quiet night but the build of the modified TT was something that I wanted to do carefully, so I took my time. Wrapped it up at around 4:30 when my shift is till 7 so prefered not to start something new and continue planning the modification of the TT while I document the build process to share with you all later on...
buzzbomb
I know nothing!
Oooh!
Looking forward to that!
mayan
Legendary member
Alright well this is what arrived
Was hoping the servos arrived which is something I need desperately right now to be able to finish the new modified TT. However I did get the R8EF receiver I needed to go back to my preferred transmitter the radio link T8FB. And I also received the battery voltage buzzer so that I don’t have to land before it goes off any more.
Anyone’s able to explain how to use it?
Was hoping the servos arrived which is something I need desperately right now to be able to finish the new modified TT. However I did get the R8EF receiver I needed to go back to my preferred transmitter the radio link T8FB. And I also received the battery voltage buzzer so that I don’t have to land before it goes off any more.
Anyone’s able to explain how to use it?
mayan
Legendary member
It is programmable and is set by default to 3.3v you still recommend changing it? How strong is the buzzer do you really hear it?
Mortis
Member
Most buzzers are really high pitched beeps and easy to pick out in the air.
Yes, definitely 3.5v. even with that, you need to land very soon after you hear the beeping.
Hai-Lee
Old and Bold RC PILOT
I use them and have mine set to 3.4V. When the alarm sounds you have enough time to cut the throttle to minimum, and start landing. There is a small reserve at half throttle if you need to extend the approach and when you land the battery voltage should still be safely above the 3V damage point.
The sound can be heard at around 100Metres or so so after a reasonable flight time bring the height down and fly in smaller circuits and you will hear it every time. Additionally it is always good to have the alarm so that it is not buried deeply in the fuselage of course.
They save me a lot of batteiry damage!
Have fun!
buzzbomb
I know nothing!
That's at room temperature. I'll call it 70 degrees fahrenheit. What about when it's much hotter or colder than that?Here's a typical lipo discharge graph, so you can see why I recommend 3.5v. You will see that the voltage accelerates downwards after 3.5v. What you choose as your warning level is a matter of personal preference. I don't like to run mine down to anywhere near 3.0V.
Hai-Lee
Old and Bold RC PILOT
The discharge curves are nice in detail and even look impressive but I run my batteries at around 20C or more in some cases. The voltage sag under load is far greater than the curved supplied indicate even for a new battery and older batteries sag even more. If anything they are misleading unless you examine the scales properly!
There is no set voltage alarm threshold and it is a matter of personal preference and experience.
Have fun!
buzzbomb
I know nothing!
You are not helping. Telling us noobs that we need experience to figure where to set the limit, doesn't help us noobs set a limit. We're just looking for a starting point, when it's not room temperature outside. We'll figure out the details with experience.
*I just punched your helmet and then you head-butted me with it.* Ouch.
Hai-Lee
Old and Bold RC PILOT
Here is a link to a page with some LiPo characteristics for beginners; http://learningrc.com/lipo-battery/
As mentioned previously I run higher discharge currents normally between 20 and 30C so I copied out the discharge curve to illustrate the different curves under real conditions of discharge currents used in RC aircraft.
Learn and then make up your own mind!
Have fun!
As mentioned previously I run higher discharge currents normally between 20 and 30C so I copied out the discharge curve to illustrate the different curves under real conditions of discharge currents used in RC aircraft.
Learn and then make up your own mind!
Have fun!
buzzbomb
I know nothing!
If I'm understanding correctly everything drops off at 20% capacity at a given temperature. Mayan is trying to fly in Israel, myself South Carolina in the U.S. There will be no given temp. What I'd like to know is how do the curves change with temp? For myself I'm getting a programmable low battery alarm. From everything thing I've seen from you and d8veh, regardless of temp, 35% seems about right. All that's really going to change is when that 35% happens.
If that's true, and given an alarm. That's OK.
I'm worried about flying through a battery!
But I am. I want to hope to and expect to. So. Just planning forward.
Hai-Lee
Old and Bold RC PILOT
Temperatures here in mid summer are not that different to Mayan's environment. I use a series of battery management techniques to prolong my battery life.
1. NEVER discharge beyond the battery's "C" rating
2. Never discharge a LiPo below 3Volts/cell
3. Never charge a battery that has an internal temperature above room temperature!
4. Never expose a battery to external heat sources, or direct sunlight for any length of time.
5. Never charge a LiPo battery pack at high current.
6. Never place discharged and warm batteries with fully charged batteries ready to be used.
7. Never fly to the limit of a batteries capacity on purpose. A flight timer is a good idea.
8. Try to keep batteries and ESCs apart, Both require cooling ideally.
9, If you need to add nose weight for balance better to fit a larger battery as the battery will last a much longer time, (Number and duration of flights).
How do I manage them! Firstly I cool my batteries in a refrigerator before i charge them and afterwards as storage.
If you need to charge a large number of batteries in a short time buy additional chargers. an extra charger cost about twice the price of a decent battery but doubling the charge current of all of your batteries can shorten their life significantly.
I charge my batteries at 1C or less!! NEVER more! NO FAST CHARGING EVER!!!
I fly until I start to get bored or I feel the time is right to land. The battery alarm is only a secondary level of protection. My batteries are COLD on arrival at the field and will remain below ambient for well over an hour kept out of the air and direct sunlight. I do not use a cooler or other insulated device.
So far I have attained battery life in excess of 18 months and in some cases safe storage of charged batteries of 12 months, (I broke the plane and it took a long time to repair). The batteries still do tend to self discharge but the loss is very slight.
Just what works for me! I recommend that each RC pilot develop his own battery management methodology!
Have fun!
1. NEVER discharge beyond the battery's "C" rating
2. Never discharge a LiPo below 3Volts/cell
3. Never charge a battery that has an internal temperature above room temperature!
4. Never expose a battery to external heat sources, or direct sunlight for any length of time.
5. Never charge a LiPo battery pack at high current.
6. Never place discharged and warm batteries with fully charged batteries ready to be used.
7. Never fly to the limit of a batteries capacity on purpose. A flight timer is a good idea.
8. Try to keep batteries and ESCs apart, Both require cooling ideally.
9, If you need to add nose weight for balance better to fit a larger battery as the battery will last a much longer time, (Number and duration of flights).
How do I manage them! Firstly I cool my batteries in a refrigerator before i charge them and afterwards as storage.
If you need to charge a large number of batteries in a short time buy additional chargers. an extra charger cost about twice the price of a decent battery but doubling the charge current of all of your batteries can shorten their life significantly.
I charge my batteries at 1C or less!! NEVER more! NO FAST CHARGING EVER!!!
I fly until I start to get bored or I feel the time is right to land. The battery alarm is only a secondary level of protection. My batteries are COLD on arrival at the field and will remain below ambient for well over an hour kept out of the air and direct sunlight. I do not use a cooler or other insulated device.
So far I have attained battery life in excess of 18 months and in some cases safe storage of charged batteries of 12 months, (I broke the plane and it took a long time to repair). The batteries still do tend to self discharge but the loss is very slight.
Just what works for me! I recommend that each RC pilot develop his own battery management methodology!
Have fun!
buzzbomb
I know nothing!
That is good information, and I am going to bookmark it. You missed the point of my question, however. How does the voltage curve change with ambient temperature? At extremes. Temps where the glue melts or everything freezes. Perhaps more pertininant is do I even have to worry about it?
Hai-Lee
Old and Bold RC PILOT
As you might expect the real thing with LiPo batteries is their internal resistance and susceptibility to irreversible heat damage. When heated the IR of the cells seems to increase quite quickly so a battery in a hot environment will still need to get rid of the internally generated heat BUT the ability to dissipate the heat is reduced due to the higher ambient temperature. Nett result is that the extra heat brings about chemical changes inside the cells including gassing which reduce the quantity of active electrolyte and even deposits on the cell plates and so reduce the maximum current ability. All of this damage actually increases the internal cell resistance and actually causes more heat to be generated.
The discharge current is a function of capacity and the cell's internal resistance.The ambient temperature does not effect the capacity significantly over our normal experience range but the higher ambient temperatures and lack of adequate cooling can really damage a battery in quick time. I have seen NEW batteries last as little as 30 minutes of total airtime life before they were too damaged to be used in a plane safely.
My aim is to keep my batteries about 5 degrees in storage, under 25 degrees during the charge cycle, and less than 50 degrees in flight.
The newb should just remember to NEVER fly until the ESC cuts the motor and to make sure that the plane gives the battery some circulation of cooling. In addition try to keep the battery and esc separate from each other to reduce battery overheating..
Once you gain flying experience you can then start thinking of increasing the battery and reducing the associated costs.
One other thought for newbies is that if your big battery cannot supply the extreme currents for the big model it might still have a number of good flights left in it in a lower current installation or plane.
Have fun!
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