E-Power Entry Notes- This will help you understand electircs

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Neons
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E-Power Entry Notes- This will help you understand electircs

Postby Neons » Fri Nov 16, 2012 5:11 pm

This is a great explanation from Nov AMA magazine article. It helps someone that has no idea what it is about and what the basics are. Click the pictures 2 times for a full page view. It is New Wave.
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AMA- Nov(0) - Battery Clinic.jpg
AMA- Nov (1) - Battery Clinic.jpg
Bob Pacheco

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Re: E-Power Entry Notes- This will help you understand elect

Postby admin » Fri Nov 16, 2012 8:51 pm

Nice Bob!... Red's an awesome fella... met him at an electric meet in NY several years back... we converse via email often too... smart guy!

Not to scare anyone away from Lipo's.... but thought I'd share some personal experiences (and saftey notes) to those considering electrics and use of LiPos :shock:

http://www.diyrc.com/RC-fire.html
Tom Laureanno

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Now you can up your E-Powered Plane Power Redundancy

Postby Neons » Tue Apr 16, 2013 9:41 pm

This is a good article on having your ESC Bec activated and have an additional UBEC in line also. No need to remove the signal wire either. This gives you a dual powered system. When you are running a larger plane it is wise to have a higher amperage UBEC onboard. Most Esc controllers only give you 3 amps of safety in the built in Bec. Most are for 2 servos. 3 if on a 4s lipo.You would have to install a good UBEC with 5-8 amps if you have a ton of servos and other options just in case of a brown out glitch of power to the receiver. This system gives you a backup circuit to funnel power direct to the receiver when the Bec fails to provide steady current. Simple and very cheap to make this unit.

Info, diagrams, and video here.
http://www.rcgroups.com/forums/showthread.php?t=1854050
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Shottkey Bec circuit.txt
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Bob Pacheco

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Re: E-Power Entry Notes- Battery Voltages

Postby Neons » Sat Aug 24, 2013 8:27 am

Originally Posted by Budge View Post
..<snip>... I have the alarm set for 99 (9.9v). And it goes from slow beep to constant in about 10 seconds. When I check the safe screen after "landing", it usually says it has 9.1 - 9.3v. Does this sound about right to you? ..<snip>...
Not in the least. You need to end the flight when the battery gets to about 3.7-3.8V and the voltage needs to be measured under load (that is the condition under which I assume the KK board is measuring it).

Here are some excerpts from some posts on the batteries forum, it is a few years old, some of the newest and best batteries do a little better, but it still applies to the majority of the LiPO packs that the majority of us use:

LIPO Capacity @ Voltage per cell (cell voltages, multiply by cell count for pack voltage, i.e. for 3S pack multiply x 3)

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

Capacity below 3.7V "resting" is not usable for flying, it's where the battery voltage dumps and damage begins.

Avg Resting V % Remaining Capacity (for 3S pack, divide by 3 for cell voltages)

11.0V-- 17% (3.67V per cell)
11.1 --- 26 (3.70V per cell)
11.2 --- 30 (3.73V per cell)
11.3 --- 37 (3.77V per cell)
11.4 --- 46 (3.80v per cell)
11.5 --- 50 (3.83V per cell)
11.6 --- 57 (3.87V per cell)
11.7 --- 63 (3.90V per cell)
11.8 --- 69 (3.93V per cell)
11.9 --- 77 (3.97V per cell)
12.0 --- 83 (4.00V per cell)

These values are the average of many discharges of different size/age/brand packs. As you can see, the values are not absolute. A new pack gives different results from a well used pack but the chart is still useful for the broad picture.

Within a few minutes after landing a pack that was down to 3.7V per cell will be back up to 3.9V per cell or so, in 15 minutes it might see 4.0V per cell. And when you recharge it you'll find that you are putting back 75-80% of the rated capacity. That is the real tell, the amount of capacity recharged.

Batteries should never be more than warm when you wrap your hand around them after a flight, like 105F or so. If they are hot they are suffering unrecoverable and irreversible damage and losing capacity. The next step is puffed cell packs, then very very hot packs and even rupturing and fires.

If you are only taking batteries down to 3.7-3.78V or so and they are getting hot you are discharging at too high a rate or for too long at a higher rate. The only real cure for that is batteries with more capacity to lessen the voltage drop buffer the discharge rate. Usually a higher demand motor like ducted fans or motors using higher Kv rpms like 2000 to 4000 Kv's are very hard on a battery. They eat a lot of amps in very short times. Low Kv motors like 1000Kv are slower and use large slow turning props. They are easier on the battery and flight times. If you go into helicopters or the Ducted fans boost the C ratings up to at least 40C for instance. General slow flying park flyers use 20-25C batteries.

Any one of the checkers below will monitor your battery before and after a flight. Do not ever try to make a high amount of minutes record flight with a new unfamiliar aircraft. Take it up for a 3 minute timed flight as a test. Land it and see the individual cell voltage. Look at the graph above to get a percentage of life left in the battery. Always leave some reserve. You never know when you have to abort a landing and you go around again for a new landing approach and do not make the field and spiral in destroying the plane. Common sense and practice. Always have a checker on your person while flying. They are cheap on eBay or Amazon. Buy a few.
http://www.ebay.com/sch/i.html?_nkw=lip ... ry+checker
Attachments
Lipo battery low voltage.jpg
It can be set for a low voltage alarm. Also an on board alarm with a spare channel to beep when you go in the corn field or grass. Indoor flight or low voltages on a multicopter too.
Lipo battery low volt check.jpg
Lipo battery checker.jpg
Last edited by Neons on Tue May 26, 2015 7:23 pm, edited 3 times in total.
Bob Pacheco

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Re: E-Power Entry Notes- Have a low unbalanced cell?

Postby Neons » Tue May 26, 2015 6:40 pm

Here is a fast way to bring up a low cell. A good way to make a jumper is to use a servo straight wire extension. On the male pin end cut the plastic housing off around the pin housing and remove the white or yellow wire pin flush. Snip it off. Bruce talks fast with a New Zealand accent. You may have to run it through a couple times.
https://www.youtube.com/watch?v=wIbHLacozFo
Bob Pacheco

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Re: E-Power Entry Notes- A Note on Battery fires

Postby Neons » Tue Nov 24, 2015 8:13 am

Tom's link above does not show the lipo fire. I do not have to tell you to double check the battery charger settings to match the Lipo battery size and amps. Fortunately the new chargers are smarter and will not start if the settings do not match the battery.There still are some older chargers out there that do not check the settings though. One way to tell is if you own a lipo charger that does not have balanc plugs built into it. But even that is not always the case. I use Imax B6 chargers. They are smart and work well.
Sample fire video here
https://www.youtube.com/watch?v=ZEkewCjiDs0
Bob Pacheco

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Lipoly Basic Safety and Charging-How To Article

Postby Neons » Tue Nov 01, 2016 12:38 pm

Thanks to and article by T Jin Tech this will also give you almost all you want to know about using and handling Lipoly batteries the correct and safe way in your hobbies. All broken down here.Please spend some time here.

http://www.tjinguytech.com/charging-how-tos
Bob Pacheco

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Re: E-Power Entry Notes- Thanks to repost from Libre-Pilot

Postby Neons » Thu Apr 06, 2017 6:14 pm

Thanks to the Libre-Pilot website. Makers of the CC3D boards for multi copters.
https://librepilot.atlassian.net/wiki/d ... tery+info#
I have some more info on trimming and watching your Lipos to keep them healthy and get the best use from them

LIPO battery info
Created by Cliff, last modified on Feb 10, 2017

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Lipos do not like to be too cold or hot when being used. Ideally they should be 20C/68F to 35C/95F before the flight. They work best when hot (52C/125F), but they don't last as long (use cycles). When flying on a winter day it is best to keep the battery for the next flight in a warm place. A pocket in your inside clothes can be used, but be warned that this could cause severe burns if the battery is shorted out by something metal in the pocket, or if the battery is damaged such as by falling and landing on it. Research lipo safety and decide for yourself if you are willing to assume this risk.

3.8 volts per cell is "storage voltage". Store at that voltage every time and they will last longer. If they sit at full voltage for a year, they are basically bad at that point. If they sit at full voltage in a hot car for a month they are basically bad at that point. Charge just before usage. If you fly every week and charge them fully as soon as you get home, after a year, you have still made them sit at full voltage for a year.

Unused packs should be charged/discharged to storage level and stored in a sealed baggie in your refrigerator if you aren't going to use them (like at end of flying season or extra batteries not currently in use). After removing from the refrigerator, leave them in the baggie until they have reached room temperature to avoid condensation on the battery.

Batteries show a lower voltage under a flight load then they do when checking them after landing.

If you set your battery alarm voltage a little above the minimum, you get a minute or so to fly back and land.

Well used packs have more voltage drop so you can set the alarm voltage lower. Newer packs hold the voltage more constant, higher, longer and then drop quickly, so you should set the alarm a little higher.

Some people just time their flights instead of using a voltage alarm, but that doesn't handle the differences of temperature or stunt vs. gentle flight. With an alarm, you can tell if you are "over amping" (which causes a lower voltage condition) your pack. If the alarm goes off too soon, under a heavy load, don't hit it so hard, and your battery will last longer. A pack that is too cold will also alarm when loaded, so warm it up more next time.

The better alarms watch individual cells. It's better to do that than to watch total voltage. You can fly a pack with one weak cell in it as long as you don't damage the weak cell further. 3.1+3.7+3.7 looks the same as 3.5+3.5+3.5. At those voltages you are hurting the 3.1 cell, but not the 3.5 cells.

On typical quadcopters a 3.6v per cell alarm works well. Land quickly when the alarm goes off. The resting voltage will be 3.7 to 3.8 volts per cell. If you fly just a little longer the resting voltage will be more like 3.6.

For old batteries (or very high current applications), using a 3.5v or 3.4v per cell alarm is very comparable in final resting voltage to good batteries with alarm at 3.6v, because of the increased voltage drop under load.

For lower current applications such as fixed wing, you can set the alarm to 3.7v per cell. The low current means less voltage drop, so when it says 3.7 in flight it is probably 3.8 resting. A high current application should be set at 3.6 and then the alarm will sound at about the same charge level.

Examine your resting voltage after every flight and adjust these guidelines and your alarm loitering time, so that your lowest resting voltage is never less than 3.6 per cell after a flight. There isn't much power left after that and 3.7 is much safer. You probably haven't hurt it, even down to 3.5 resting after a flight, but immediately charge to storage level.

Remember that a multicopter must still be hovered for a little while while you are landing, and that does take some charge. Fixed wing power can be cut off and glide in with basically no further drain.

At the last flight of the day, land immediately when the alarm goes off and you should have something between 3.7 and 3.8 volts, perfect for storage, otherwise you can get an additional 30 seconds or so and resting voltage will be down to 3.6 or so. It really isn't worth it to try to get more out of it. At 3.7v resting you have used about 90% of the pack capacity. It isn't worth it to try to use more.

Some manufacturers claim 3.3v per cell is as low as you should go. Some claim 3.0v per cell. Don't ever let them go below 3.0v per cell under load or 3.3v resting.

If you drain the pack down low for some reason, IMMEDIATELY (within minutes) charge it up to storage voltage. It can survive a minor deviation once or maybe twice for one minute each time. You might have hurt one or more cells so expect weak cells to loose power more quickly than before. If you leave it dead overnight, it has probably been damaged beyond repair.

Only charge at the recommended charge current or less. If you don't know, assume it is 1C. 1C means 1 times capacity. If the capacity is 2200mah (milli amp hours) (= 2.2 amp hours) then for 1C you charge at 2200ma = 2.2a and it will take about an hour (actually a little more). If the capacity is 2200mah and the recommended charge rate is 2C, then you can charge at twice that current, 4400ma or 4.4a and it will take about 1/2 hour to charge. All 1C (charge rate) batteries take about an hour to charge.

Batteries are also marked for maximum discharge rate. That is also measured in C's. Typical generic batteries are 20C discharge. The maximum current you should draw from a 2200mah 20C battery is 2.2 amps (2200ma) times 20 = 44 amps. A good rule of thumb for long battery lifetime, is to only use half of the stated discharge rate.

Search eBay for:
8s lipo alarm
and you will find these. Once in a while you will find a setup where you get an early beep that goes away because of noise on the power lines.

Here are good 2s-8s lipo alarms that watch individual cells $1.13 shipped, but you can buy multiples.
http://www.ebay.com/itm/1-8S-Lipo-Li-io ... 2483892762

Here is an eBay search for the 2s-8s lipo alarms that watch individual cells
http://www.ebay.com/sch/i.html?_from=R4 ... c&LH_BIN=1


Balance Connector Cables

The name of the standard lipo "balance" connector is JST-XH (beware, some lipos come with different connectors, get your lipos with JST-XH balance connectors for compatibility)

These cables are good for balance connector extensions. $3.66 for 10 (shipped)
http://www.ebay.com/itm/10pcs-JST-XH-3S ... 2753839406

$4.50 for 10 (shipped) if the cheap once sell out (or just search eBay)
http://www.ebay.com/itm/10pcs-JST-XH-Li ... 2037799359


Further General Information on RCGroupshttps://www.rcgroups.com/forums ... ost3066606
Bob Pacheco

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Neons
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More Lipo Battery Basics - AMA Article

Postby Neons » Tue Jun 13, 2017 6:28 pm

Copy of the AMA link
http://modelaviation.com/lipo-battery-basics

There are some updates that have been worth noting.
Bob Pacheco

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Neons
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Lipo Battery Internal Resistance Testing

Postby Neons » Wed Nov 15, 2017 7:18 pm

Here is a video explanation that simplifies testing the lipo batteries into a simple way using a Whatmeter, bulbs for a drain, and a calculator. You will find out just how good or bad a battery is fairly quickly.
https://www.youtube.com/watch?v=usRE3gLFnOc&t=570s
After watching this instructional video read the comments and pick up a few more tips. For my own use I may save a battery by rebuilding a pack which has some good low resistance cells. It is not a thing I would recommend unless you are mechanically inclined. We would not like to arc a battery or have a fire.
Bob Pacheco


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