Beginners New to e-power flying? Get the low down in here from experienced e-power RC pilots!

safe lipo charge

Old 04-07-2019, 07:02 PM
  #1  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default safe lipo charge

Hi. Was on the field to day and several pilots charged their lipos with higher amps then was on the lipo. Say 2800mah 45C was charged with 6 amps. I know is faster but is it safe for the battery?
Oh, and any idea what switch i can use between my receiver and the battery? Pretty sure it's a three cord wire I'm tired of connect and disconnect the lipo when i shut both off And what wires do i put the switch in?
I'm on Spektrum dx6 with as3x receiver.

Last edited by jangodog; 04-07-2019 at 07:23 PM.
jangodog is offline  
Old 04-07-2019, 11:28 PM
  #2  
Abuelo
Member
 
Abuelo's Avatar
 
Join Date: Sep 2013
Location: Arizona desert
Posts: 291
Default

Forget the switch.

Remove the LIPO and charge it in a fireproof location and store it where it cannot short out or otherwise fail and start a fire. You don 't want to charge or store it in the plane. The history of electric RC is rife with stories of burned up cars and garages due to improper handling of LIPO batteries.
Abuelo is offline  
Old 04-07-2019, 11:39 PM
  #3  
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Nederland
Posts: 1,046
Default

A few points
  • A switch is an extra point of failure.
  • Even when ESC is not driving the motor it still draws a little bit of current. Leave them connected long enough and the ESC will drain your LiPo, thus ruining it.
  • Always disconnect LiPo after a day flying.
  • Don't charge LiPo in plane.
  • Don't charge LiPo unattended or overnight.

Last edited by ron_van_sommeren; 04-08-2019 at 12:26 AM.
ron_van_sommeren is offline  
Old 04-08-2019, 10:22 AM
  #4  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

Think you misunderstand my issue. It's between shift with the battery. I won't charge my lipos in the plane just make it easier with the " transmitter turned on first then lipo/ESC second" Call it a safety switch if you will And the battery question? Is it safe to charge with the double amps where i can charge with 12V instead of 220V? My SkyRc d100 can charge with 2X100 watt on 12V connection and 100watt on 220V.
jangodog is offline  
Old 04-08-2019, 12:37 PM
  #5  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,125
Default

Of course you can use a standard RC Rx switch as the fuel boys use for switching off power to Rx.

BUT ... you cannot put a switch for main power to motor / ESC .. so please - forget it and resign yourself as we all do ... unplug LiPo if not flying.

OK - Charge rates .... most LiPo's today can take 2C charge rate ... many 3C rates .... There is a lot of debate about life of LiPo's when fast charged ... but keeping to maximum 2C is safe. 1C of course is the best and kindest to battery - but means longer charge time.

Just to recap :

1C rate is basically battery capacity number in Amps ... so a 2000mAh battery is a 2AH pack ...
1C = 2A
2C = 4A
3C = 6A
on that same pack ..
solentlife is offline  
Old 04-08-2019, 05:56 PM
  #6  
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Nederland
Posts: 1,046
Default

Originally Posted by jangodog View Post
... It's between shift with the battery. I won't charge my lipos in the plane just make it easier with the " transmitter turned on first then lipo/ESC second" ...
Aha
You would need a very beefy and heavy switch to handle motorcurrent. Otherwise the contacts in the switch would weld themselves together. A switch would also introduce extra losses, more losses than connectors.

Connector tests, plus pictures
translate...www.elektromodellflug.de/hochstrom-st.-bu..html
Older version of that page, contains some other connectors
translate...www.elektromodellflug.de/oldpage/hochstromst/hochstromstecker.htm
Excellent site, do have a look at the controller, motor, charger, power supply, battery etc. tests.
ron_van_sommeren is offline  
Old 04-09-2019, 04:01 PM
  #7  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

I'm so "green"/Rookie" with this electric planes so forgive me for asking lot of questions
I have a flight buddy who is having the same switch on his Timber. Maybe i just leave it as it is

Thank you all for you input.
jangodog is offline  
Old 04-09-2019, 04:34 PM
  #8  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

What's your experience with this lipo: https://hobbyking.com/en_us/turnigy-...b28004s30.html

And last question. Are there some kind of device that can show how much power that is left on the lipo from outside the plane? Mean without taking the wing off, Some kind of connection?
jangodog is offline  
Old 04-09-2019, 05:35 PM
  #9  
Wildflyer
Past President of PSSF
 
Wildflyer's Avatar
 
Join Date: Sep 2009
Location: Lacey WA, 1 mile E of Mushroom Corner
Posts: 1,981
Default

I have had good luck with all the batteries I have bought from Hobbyking. In most of my planes I don't push the batteries anywhere close to max draw, so that helps a lot.
In a couple of EDF's that do push the battery, I don't expect as long a life.

The only outside device that can handle the current and still shut off everything is really just a pair of good battery connectors. One munted in the fuselage in series with the battery, and the other with a piece of heavy wire across it as a connection plug you insert from outside the fuse.
But it still adds a failure point and resistance.

To have an IDEA of your battery remaining capacity requires measuring the battery voltage with an accurate digital voltmeter, or buying a special purpose meter. It still just gives you an idea of what's left as there are many other factors to consider to understand how much flying time you have left.
Wildflyer is offline  
Old 04-09-2019, 06:38 PM
  #10  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

Well that's good enough for me. That could be the solution with battery connector in the fuselage and the other as mentioned. Any chance of you giving me a diagram/sketch showing the connetion order?
jangodog is offline  
Old 04-09-2019, 06:48 PM
  #11  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,125
Default

Originally Posted by jangodog View Post
What's your experience with this lipo: https://hobbyking.com/en_us/turnigy-...b28004s30.html

And last question. Are there some kind of device that can show how much power that is left on the lipo from outside the plane? Mean without taking the wing off, Some kind of connection?
Hobby KIng batterys are commonly used and about middle road .. I use nearly all Hobby King lipo's.

As to measuring the power left ... again honest answer is fly ... remove battery ... put in a fresh battery for next flight ..

It is not a good policy to follow flying part used batterys. For example - you set a timer on your Tx so a BEEP warning tells you time to land. Lets say you land well before that beep. You fire up again and take off ... your Tx warning BEEP as far as its concerned is you are flying with a full battery and will not save you from running out of battery.

You can use Telemetry senders to tell you state of battery or as I have a warning receiver that is triggered by a small Tx card ... but it does not show voltage - it only gives alarm when a cell drops to user set voltage
solentlife is offline  
Old 04-09-2019, 08:23 PM
  #12  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

I'll go with the HK lipos. And will follow the beeps in my tx for changing battery.
Thank's for all the help here in this great forum
jangodog is offline  
Old 04-10-2019, 09:08 AM
  #13  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,125
Default

Originally Posted by jangodog View Post
I'll go with the HK lipos. And will follow the beeps in my tx for changing battery.
Thank's for all the help here in this great forum
That warning BEEP in Tx .... is usually based on User setting the timer ...

To set ideally - you need to know what power draw is being exacted on your LiPo ... then you set your timer to use 80% of the available capacity. Once you have a few flights - you will find that adjustment to an average can be made.
The Tx will not automatically set warning for you.

What radio do you have ?
solentlife is offline  
Old 04-10-2019, 09:52 AM
  #14  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

I have Spektrum DX6. I know i have to manuelly set the timer for the lipos
Use both 2200 2600 2800mah 3 and 4 cell
jangodog is offline  
Old 04-10-2019, 11:06 AM
  #15  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,125
Default

Now you have a Wattmeter .... you can measure the power draw of your motor at full throttle ... using the readings - this will give you Time to Zero flight time. But we should never run a LiPo past the 20% level ... so that flight time should be 80% ...

I have an Excel sheet I use to list out combos for various models - then I can have good idea of what to use etc. (attached)

Calculation ? Battery capacity in A/Hrs... Amps at full throttle

Battery Capacity / AMPS x 60 gives 100% run time to zero at full throttle.

But we need to leave at least 20% or more in the pack to prevent going too low.

Therefore :

Battery Capacity / AMPS x 60 x 0.8 = max throttle run time.

Lets say you test your combo and you have :

LiPo 2800mAh = 2.8 A/hr
Watmeter shows 20A at full throttle.

Therefore : 2.8 / 20 x 60 x 0.8 = 6.72 mins

I would then set my Tx timer to 6m 30s ... giving me a margin of error. After a number of flights and checking average battery levels after - I may be able to increase that timer to 7 mins or so because of part of the flight is not at full throttle.

That Wattmeter is the gold standard in this ...
Attached Files
File Type: zip
Run time calculator.zip (10.8 KB, 8 views)
solentlife is offline  
Old 04-10-2019, 01:44 PM
  #16  
jangodog
Member
Thread Starter
 
jangodog's Avatar
 
Join Date: Feb 2019
Location: Odense Denmark
Posts: 47
Default

Very, very good info there I will test my setup as soon as my wattmeter arrives from Hobbyking
Hope the Turnigy 2800 4s lipos will give a boost on my Turbo Timber

And thank's for the calculator sheet
jangodog is offline  
Old 04-10-2019, 03:59 PM
  #17  
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Nederland
Posts: 1,046
Default

Batteryvoltage is a poor inidicator for battery charge state. The discharge curve is too flat for that. Measuring voltage (batterychecker) will tell you if battery is full or almost empty. Anything between is a wild guess.


E-flight 101 by RCG member Ken Myers, will at least save you a ruined LiPo (or worse!), a burnt motor and a fried ESC:
The Ampeer

→ Articles: Electric Power Basics (Ken Myers)
Table of Contents, a.o.
  • Recommended First Purchase - Power Meter & How to Use it
  • About Chargers & LiPo Batteries
  • Power Lead Connectors and Wire
  • Brushless Electronic Speed Controls (ESC) Basics, LVC and BEC
  • Motors for Electric Flight, Kv, Timing, Efficiency, Props



The Ampeer

→ Articles: Everything youw wanted to know about e-flight (Ed Anderson)
Table of Contents, a.o.
  • What You Need To Know About Receivers
  • Battery Basics, Battery Chargers
  • Amps Versus Volts Versus C
  • Understanding the Electronic Speed Control (ESC)
  • Sizing Power Systems for Electric Airplanes, Prop Versus Amps
  • What Do the Kv Numbers On Motors Mean?
  • Who Needs a Wattmeter/Powermeter?
    (Everyone! But don't buy one if you plan on sponsoring motor and ESC manufacturers RvS)


About charge, current, voltage, resistance, power, energy
www.rc-cars-planes.com/docs/wu100v2_user_manual.pdf
ron_van_sommeren is offline  
Old 04-10-2019, 04:42 PM
  #18  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,125
Default

Batteryvoltage is a poor inidicator for battery charge state. The discharge curve is too flat for that. Measuring voltage (batterychecker) will tell you if battery is full or almost empty. Anything between is a wild guess.
Its not usual to have different opinion to you Ron ... but sorry I do not agree with that statement. For very good reason :

1. There is no other practical easy way to measure battery state without doing discharge / charge cycle to measure the mA in / out etc.
2. Millions of RC LiPo users around the world use voltage as a reasonable indicator of battery state.
3. Battery manufacturers and such as Battery University - so often quoted by many use voltage as a quick indicator.
4. Battery charge table accepted and used :



If using voltage was so bad - then why do they bother to program it into .... Wattmeter ... Cell Checker .... all Programmable LiPo Chargers ..... LVC on ESC's ..... Low Voltage Telemetry alarms .... the list just goes on ...

There is no other practical way to check charge state of LiPo quickly and with sufficiently reasonable result. Even to setting Storage levels - which chargers use ...
solentlife is offline  
Old 04-10-2019, 09:49 PM
  #19  
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Nederland
Posts: 1,046
Default

You are right Nigel, what I wrote, goes for NiMH, LiPo's have a bigger voltage swing.
ron_van_sommeren is offline  
Old 04-11-2019, 02:56 PM
  #20  
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 12,125
Default

Originally Posted by ron_van_sommeren View Post
You are right Nigel, what I wrote, goes for NiMH, LiPo's have a bigger voltage swing.
Cheers Ron .... honest - I wasn't trying to be smart ..


solentlife is offline  
Old 04-12-2019, 09:45 AM
  #21  
ron_van_sommeren
homo ludens modelisticus
 
ron_van_sommeren's Avatar
 
Join Date: Jul 2005
Location: near Nijmegen, Nederland
Posts: 1,046
Default

That's not how you come accross, good info is never about being smart.
ron_van_sommeren is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
SimonXi
Power Systems
0
08-17-2011 11:02 AM
SimonXi
Batteries & Chargers
0
08-12-2011 05:08 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Quick Reply: safe lipo charge


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.08787 seconds with 17 queries