when to stop flying??

[foxman500uk]

hi
i have seen you guys talk on these forums about only letting lipolys discharge 80% of there capacity but how do you tell while flying when to stop??
thanks

[mudbogger2]

You can't tell while flying. You start by flying short flights. After recharging you note the ammount of mah put back into the pack. Then you gradually increase your flight times till you get near the 80%. You will learn that your setup can fly for XX:XX ammount of time at your flying style and achieve 80% of the battery.
Then you just fly your flights limited by time and just look at the ammout of charge put back in the packs after flights. As you start flying harder and doing more power consuming manuvers your flight times may start to decrease. You will need to keep an eye on the packs to stay in the 80% range.

Another way is to add on a meter that displays the ammount of mah used during a flight. You still have to land and read it though. Plus it adds to the cost and weight of the heli.

[z11355]

you purchase a loaded voltmeter and stop flying when the battery gets to 7.0v

[jrohland]

I fly with 2 other guys. We all fly strictly electric. We all run onboard LiPo alarms. An onboard alarm monitors the pack voltage in realtime and sounds an alarm when the voltage hits a programmed low point. I love flying until the heli starts screaming.

One of the guys makes really good LiPo alarms. You may wish to email him about your needs.

I run a 3 cell (400 sized) heli, Jas flys a T-Rex 600 (6 cell) and Thanh (pronounced ton) makes the alarms and flys all kinds of cell combinations.

PM me if you wish to contact Thanh Tran about getting a custom made onboard LiPo alarm. Also, there are a number of companies making various sized alarms.

jrohland

[foxman500uk]

so what do i need to mesure the amout of MAh i put in/take out??
thanks

[WillJames]

There are a lot of chargers that wil tell you how much mah they put back in the packs. This is how you know.

[FearNot]

you purchase a loaded voltmeter and stop flying when the battery gets to 7.0v


Is this 7 V shile running or 7 V with the lipo unplugged and measured?

I have a LiPo alarm and it goes off after 3 minutes of flying and when I land it stops .. it only goes off with the motor running ..

My lipos had about 11.4 V .

what gives?

Matt

[darkside212]

I would suggest an ESC that will SOFT cut at 9V (for 3s)

[Efliernz]

Did someone mention low-volt alarms :)

Foxman, what sized models/packs are you looking at?

[pcar993]

There are a lot of chargers that wil tell you how much mah they put back in the packs. This is how you know.

My charger doesnt have a scree to tell me anything. Can someone send me a link to one of these volt meters? I havent flown my trex450se yet so i was wondering of this same question.

[Pinecone]

7 volts is WAY too low for a 3S pack. Under load is it fine for a 2S pack.

You really need to get a charger that tells you how much you put back in the pack. You can also find someone with one nad use it to get your flight times set.

Check out Efliernz here on the Freak for good lipo alarms.

[FearNot]

I dont like the whole "check how much you put in" idea .... I like to knwo when to stop flying not when I should or could have stopped flying ....

FMA sells a thing that cuts the motor if the lipo voltage is below 3V per cell ... I may get that

I have a lipo alarm but it is rather useless .. first you can hardly see or hear it and second it pretty much starts beeping 2 minutes into the flight ..


Matt

[Jermo]

1. never go below 3v per cell regardless of how many cells you run.
2. Invest in a lipo monitor, I prefer a loud buzzer AND a bright light. I set mine for 3.2V per cell. This gives me time to land regardless of conditions and not go below 3v per cell.
3. if your ESC has the ability to monitor battery enable it for the same general level.

Jermo

[pcar993]

1. never go below 3v per cell regardless of how many cells you run.
2. Invest in a lipo monitor, I prefer a loud buzzer AND a bright light. I set mine for 3.2V per cell. This gives me time to land regardless of conditions and not go below 3v per cell.
3. if your ESC has the ability to monitor battery enable it for the same general level.

Jermo

Jermo where can i find that lipo monitor that you are using? When you set it at 3.2v per cell, how many minutes of flight time do you get say under hovering and gentle flying.

[Jermo]

1. never go below 3v per cell regardless of how many cells you run.
2. Invest in a lipo monitor, I prefer a loud buzzer AND a bright light. I set mine for 3.2V per cell. This gives me time to land regardless of conditions and not go below 3v per cell.
3. if your ESC has the ability to monitor battery enable it for the same general level.

Jermo

Jermo where can i find that lipo monitor that you are using? When you set it at 3.2v per cell, how many minutes of flight time do you get say under hovering and gentle flying.

I'm looking for another one for my 2nd T-Rex, It's made my RC Model Products out of the UK. It's easily programmable, has an LED AND Buzzer. With my Hextronix 2200 packs I get 7 minutes easy. I set my DX7 timer for 6 minutes and the lipo monitor usually goes off a minute or so later. I found this one at a LHS covered in dust. The guy didn't even know he had one. I've asked Ray to see if he can get me another one.
Jermo

[FearNot]

1. never go below 3v per cell regardless of how many cells you run.
2. Invest in a lipo monitor, I prefer a loud buzzer AND a bright light. I set mine for 3.2V per cell. This gives me time to land regardless of conditions and not go below 3v per cell.
3. if your ESC has the ability to monitor battery enable it for the same general level.

Jermo

Jermo where can i find that lipo monitor that you are using? When you set it at 3.2v per cell, how many minutes of flight time do you get say under hovering and gentle flying.

I'm looking for another one for my 2nd T-Rex, It's made my RC Model Products out of the UK. It's easily programmable, has an LED AND Buzzer. With my Hextronix 2200 packs I get 7 minutes easy. I set my DX7 timer for 6 minutes and the lipo monitor usually goes off a minute or so later. I found this one at a LHS covered in dust. The guy didn't even know he had one. I've asked Ray to see if he can get me another one.
Jermo

Have a look at the FMA battery watcher ... It will monitor the voltage of all your cells and cut the motor when you run low ... there are no lights to miss or buzzers not to her

Matt

[Jermo]

hehe.. I dont' want anything to cut the motor..it's bad enough my ESC starts stuttering it's battery protection... crashing an $800 heli to protect a $32 battery is a bit overkill :) hehe.. I use my TX timer as a backup. When I start doing 3d (not for a while since I just started inverted hover training on the sim) I'm guessing my timer will be set for 4 minutes with fly by's to check alarm. I'll still have a look tho.. Never hurts to look ..maybe I'm mis-understanding how the FMA product works.
Jermo

[pcar993]

1. never go below 3v per cell regardless of how many cells you run.
2. Invest in a lipo monitor, I prefer a loud buzzer AND a bright light. I set mine for 3.2V per cell. This gives me time to land regardless of conditions and not go below 3v per cell.
3. if your ESC has the ability to monitor battery enable it for the same general level.

Jermo

Jermo where can i find that lipo monitor that you are using? When you set it at 3.2v per cell, how many minutes of flight time do you get say under hovering and gentle flying.

I'm looking for another one for my 2nd T-Rex, It's made my RC Model Products out of the UK. It's easily programmable, has an LED AND Buzzer. With my Hextronix 2200 packs I get 7 minutes easy. I set my DX7 timer for 6 minutes and the lipo monitor usually goes off a minute or so later. I found this one at a LHS covered in dust. The guy didn't even know he had one. I've asked Ray to see if he can get me another one.
Jermo

Have a look at the FMA battery watcher ... It will monitor the voltage of all your cells and cut the motor when you run low ... there are no lights to miss or buzzers not to her

Matt

Why would i want something that will cut the motor? Wouldnt the heli fall from the sky? It will be my first flight this weekend so i will fly for 5-6 min just to be on the safe side.

[FearNot]

not turn it off instantly .. it will reduce power first ... check it out at FMAdirect.com

[Jermo]

The monitor I use doesn't do anything to the motor. Just buzzes/lights. Time to fly is very dependant on mAh rating of your battery, headspeed, and flight style. To get the times I'm flying I'm using hextroniks 2200mAh batteries (rated at 2250 on the battery).
Jermo

[Pinecone]

Yeap, just reduces power as you need full power to recover. Low inverted hover and you don't have enough power to punch up and flip. NO WAY.

Use an alarm as backup. But figure out draw and use a timer as primary. So you land BEFORE your pack is too low, but if something goes wrong (extra amp draw, using a partially charged battery, etc), the alarm lets you know.

[PsychoPilot145]

Pardon me, but I'm new. I'm going to need the elementary school explanation. Lucy... Please 'splain the 80% rule. :oops:

OK, I am currently using the Align 22.2v 4600mah LiPo's. I am not using an alarm yet, so all I have to go on is the timer on my DX7.

Now, my packs are new, so I have not yet intentionally ventured beyond five minutes of run time.

Charging back up, I note that at the beginning of the charge, the cells are averaging 3.8v each. I seem to be putting about 2200-2500mah back into them upon charge completion. So, what would be my 80% target number to shoot for??? I feel like I can safely go beyond five minutes, but have so far been afraid to try... On a 4600 mah pack, how much amperage should I be pumping back in if I am running them down far enough to get the nominal time out of them???

Many thanks from the FNG. :D

[FearNot]

Pardon me, but I'm new. I'm going to need the elementary school explanation. Lucy... Please 'splain the 80% rule. :oops:




There seem to be a lot of explanations for that ... I decided to go by not running the cells below 3.3V and use a Lipo alarm and have the ESC set to cut power ...

Some guys look for how much they put back in the battery and then time the flights .. that seems to require the same flight conditions though and by the time you knwo how much you put back in the pack you may have already damaged it ..

Matt

[PsychoPilot145]

I decided to go by not running the cells below 3.3V and use a Lipo alarm and have the ESC set to cut power ...

Thanks Matt. I know that I need a LiPo alarm. In the mean time, I'll start looking at the cell voltage when I hook it back up to the TP1010. So far it has been averaging on the high side of 3.8v. I know I can get more time. I'll start watching that number.

[Gary JP4]

Not going below 3.3 volts is good but you are not going to know that unless you have a lipo alarm or something on the heli. When you put you pack on the 1010 it will have recovered somewhat and not be under load so the voltage you see will be quite a bit higher then when it was flying unless you get a load resistor and measure it with a voltmeter under load. Even that will probably be higher because the load will be less.

More importantly look at the 1010 when you are done to see how many amps you put back into the pack and adjust flying times to shoot for 80% capacity.