Lipo auto power off

Billthetug · Post by **Billthetug** » Sat Apr 12, 2014 6:00 am

Hi All lipo,s are a new thing to me so a bit confused
The situation was this
T9x running er9x withe turnigy 2650 mamp battery
Ive been running for about two hours and sudenly the tx switches off, the voltage was 10.6 when I started and I had the low volage set at 8v but as I was busy watching the yacht and walking up and down the side of the pond in races I did not see what voltage the tx switched off at. Checked the voltage when I got home and was reading 8.9v recharged put back in and all working fine so the question is
Do lipo,s cut off at a certain volt level or does the tx cut off? Or do I need to set something in the tx
Many thanks for any help
Bill

Post by **Rob Thomson** » Sat Apr 12, 2014 6:20 am

You should not allow a lilo to go below 3.3v per cell.

Assuming by in where running a 3 cell, you should not be running lower then 9.9v.

After that, the pack will be damaged. It may charge again, but it is unlikely to ever retain power for any length of time.

Rob

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Post by **jhsa** » Sat Apr 12, 2014 6:29 am

Good that you weren't flying a plane or helicopter.

It seems that you have to do some learning about lipos

I suggest doing some research. Google is your friend. But here are a couple of points.

1- at 10.6V in a transmitter the lipo is already completely discharged. When using it on a tx, you should have the alarm set at around 11.1V. Between 10.8 and 11.1 should be ok.

2- Always try to do a balance charge. That brings all the cells to an equal level of charge. If one cell is too low compared to the others, chances are that it will get damaged or in your case the battery will shut down. Not good. I do not recommend to charge lipos inside the transmitter. A decent charger is also recommended. YOU CAN'T CHARGE LIPOS WITH A NORMAL NIMH CHARGER.

Please do some research. It is very important to handle these batteries properly. The risk of fire is very high if you don't know what you're doing.

Joao

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Post by **jhsa** » Sat Apr 12, 2014 6:42 am

Rob. 9.9V on a tx pack is way too low. Don't forget that as the tx doesn't take so much current and the voltage doesn't drop so low. And when it does the lipo is already discharged. A lipo at rest should show a voltage of around 11.1V when about 80% discharged. In a tx the voltage under load will be very close to the voltage at rest as the drop is very low. If the alarm is set very low, lets say 10V, you will see that when it reaches about 10.5v the voltage will just start dropping very fast and when the alarm sounds at 10V you don't have time to land your plane anymore. Batt will probably get damaged as well..

Just my 2c

Joao

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Daedalus66 · Post by **Daedalus66** » Sat Apr 12, 2014 11:36 am

Just to echo Joao. The magic number to remember for minimum resting voltage is 3.7volts per cell (11.1 for 3s).

A 3s LiPo battery comes off the charger at 12.6v with 100% charge. By the time it gets to 11.1v only 20% remains. That's when you should stop and recharge, as the battery will drop increasingly rapidly from there. By the time you get to 10.8v it's virtually all over and the battery is about to plunge off a voltage cliff into the zone where damage occurs.

The transmitter will work perfectly well at much lower voltages, but that's not the point. It's all about how much capacity remains and when it's going to run out. Also whether you are risking damage to the battery by over-discharge.

One thing that confuses people is that an ESC is commonly set to cut off at 3.0 to 3.2v per cell. This assumes that the battery will be delivering many amps of current to the motor and therefore will show major voltage depression as a result of Ohms Law (V=IR). But it should still bounce back to a resting voltage above 11.1 when the ESC shuts down.

A modern transmitter pulls under 200 mA, even with lights and sound going. That's 0.1C for a 2000 mAh battery, which explains why the application is totally different from driving a propeller and why LiPos for transmitter use have low C ratings.

pmullen503 · Post by **pmullen503** » Sat Apr 12, 2014 1:14 pm

The voltages the OP cites are appropriate for a LiFePO4 battery but not a Lipo. I have a 1800mAh LiFe battery in my 9x. It's good for at least 10 hrs.

I don't think you can set a TX voltage warning on the 9x with ER9x, IIRC there was a battery calibration setting. It's been a long time since I went to the LiFe battery.

Post by **MikeB** » Sat Apr 12, 2014 1:21 pm

Er9x does include a battery warning voltage setting in the RADIO SETUP menu.

Mike.

Post by **jhsa** » Sat Apr 12, 2014 1:26 pm

Yes it does

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Billthetug · Post by **Billthetug** » Sat Apr 12, 2014 3:39 pm

Hi all first of all thank you all for the advise
Yes I do have a turnigy accucell 6 charger and fire bag and have ballance charged it but will keep a close eye on it tomorrow, I have bought a life 04 9.9v to use as it is a bit smaller in size so not as tight a fit
And yes I did a lot of google and found so many conflicting ideas I got confused with them so will now look up the safe cut off for the life and see how long it lasts then get another as stanby the lipo can get religated to powering the fire hydrants on the big tug.
One thing I have learned these modern batteries are not like the old nicads where you could run them down to empty (we all have to learn sometime) and at my age its getting harder lol
Once again thank you all and your avice has been taken on board
Bill
Just found a descent manual for the charger the imax b6 this gives me the min cut off for
Lipo 3v so will set the alarm as suggested at 11.1 if it ever get used in the tx again
And 2v for life 9.9v so will set the alarm for 7.5 to be on the safe side and I think I will have to look into fitting the haptic to get the alarm feel as my hearing isn't that good (the wife always said I had selective hearing)

Billthetug · Post by **Billthetug** » Sat Apr 12, 2014 4:00 pm

Next stop PayPal to do the honers

Daedalus66 · Post by **Daedalus66** » Sat Apr 12, 2014 4:23 pm

Billthetug wrote:Hi all first of all thank you all for the advise

And 2v for life 9.9v so will set the alarm for 7.5 to be on the safe side and I think I will have to look into fitting the haptic to get the alarm feel as my hearing isn't that good (the wife always said I had selective hearing)

No, no, no!

Again these minimum numbers are the point where damage to the battery starts to happen. They are NOT a guide to using the battery in a transmitter. Once a 3s LiFe battery gets to 3.0v it's essential game over as far as delivering power is concerned. After that, the battery will very rapidly drop to the point where the transmitter shuts off.

For a 3s LiFe, the appropriate warning voltage is about 9.3. (Some people suggest 9.0v but I see absolutely no reason to push to the limit. I charge when the battery gets to 9.5 or 9.6, or sooner.)

By the way, my experience is that the 1500 LiFe battery can survive ONE complete discharge (leaving on overnight) with only moderate swelling? To recover, you have to charge for a few minutes on NiMH cycle to get up into the voltage range where the LiFe cycle will work. Be very careful. Do it outdoors and stay there!

A second complete discharge will cause the battery to swell excessively when recharged. Don't ask how I know.

Billthetug · Post by **Billthetug** » Sat Apr 12, 2014 4:38 pm

Ok so a life 9.9v cant go below 9.5 so will set the alarm for 9.6 as yet I have not used this one only the lipo
This is what I mean by getting confused reading one thing from the manual then getting advise from people that actually use it and knowing what they are talking about.
I have set the alarm at 9.6 and the battery calibration at 9.9 hope this is correct now

Flaps 30 · Post by **Flaps 30** » Sat Apr 12, 2014 6:58 pm

Billthetug wrote:I have set the alarm at 9.6 and the battery calibration at 9.9 hope this is correct now

You should really measure the battery voltage with a multimeter and then adjust the calibration, so that the voltage indicated on the transmitter matches what you had/have on the multimeter.

Post by **jhsa** » Sat Apr 12, 2014 7:38 pm

I have a 1500 LiFe in my TX. Alarm set at 9.3V
Today I decided to rise the alarm to 9.4V as I watched the voltage drop really quickly after the alarm sounded at 9.3V
I asked a friend to let me use his battery checker and the reading was 9.3V and 0% charge. So obviously 9.3V is still too low. Again the radios today take very little current and the voltage being higher can be a little misleading, because there is very little voltage drop. So, then when the battery is already discharged, the voltage just drops so fast that it could be too late to land the plane before the radio shut down and plane will crash, the battery gets damaged, or both..

João

Daedalus66 · Post by **Daedalus66** » Sat Apr 12, 2014 7:41 pm

Billthetug wrote:Ok so a life 9.9v cant go below 9.5 so will set the alarm for 9.6 as yet I have not used this one only the lipo
This is what I mean by getting confused reading one thing from the manual then getting advise from people that actually use it and knowing what they are talking about.
I have set the alarm at 9.6 and the battery calibration at 9.9 hope this is correct now

Please read what I said. I specifically recommended 9.3v for the alarm. I said I charge by the time it gets to about 9.5 or 9.6v or earlier. The point is that you should never hear the alarm if you are paying attention and charge when appropriate. Setting the alarm at 9.6v is unnecessarily high.

With respect to calibration, there is no guesswork involved. Measure the pack voltage and set the calibration accordingly. If you don't have a meter handy, a good approximation can be achieved by assuming that a recently charged battery will be at 9.9v after half an hour to an hour or so of transmitter operation. This will give a pretty good calibration.

You can expect it to decline only very slowly over several hours of further operation. Once it gets down to about 9.7v it gradually starts to decline more rapidly.

EDIT: regarding Joao's suggestion of 9.4v for the alarm, I think he's being a bit more conservative than he needs to, but a little more caution doesn't hurt. Anyway, you should be charging before it gets that low. But certainly 9.6 is needlessly high. The alarm should be a last ditch warning telling you to stop flying while there's still time, not a casual reminder to charge some time soon.

Post by **jhsa** » Sat Apr 12, 2014 8:00 pm

I decided to rise it to 9.4V after I saw the voltage really dropping very fast. maybe it is more conservative, but I feel it is the right thing to do as I don't like to be looking for trouble if I have the choice to avoid it

I do agree with you when you say that we shouldn't wait for the alarm to recharge the battery..
João

Post by **MikeB** » Sat Apr 12, 2014 8:20 pm

Batt is an input available to the custom switches as in:
v<ofs Batt 9.8
This means you can add a warning level alarm in addition to the hard coded alarm.

Mike.

Daedalus66 · Post by **Daedalus66** » Sat Apr 12, 2014 10:25 pm

So maybe a "Time to charge" reminder could be programmed for 9.6v. And a "Land now! Land now! Land now!" announcement in a panicky voice for say 9.1v.

Billthetug · Post by **Billthetug** » Sun Apr 13, 2014 6:57 am

Sounds like a good idea when I can work out how to do it

Post by **jhsa** » Sun Apr 13, 2014 7:06 am

The correct panic voice for 9.1V with a LiFe battery would be "you're crashing in 10, 9, 8, 7..........3, 2, 1, whoop whoop terrain, terrain.."

Joao

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Billthetug · Post by **Billthetug** » Sun Apr 13, 2014 7:08 am

jhsa wrote:The correct panic voice for 9.1V with a LiFe battery would be "you're crashing in 10, 9, 8, 7..........3, 2, 1, whoop whoop terrain, terrain.."

Joao

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In my case Sinking lol

Post by **Rob Thomson** » Sun Apr 13, 2014 7:16 am

Daedalus66 wrote:
Billthetug wrote:Hi all first of all thank you all for the advise

And 2v for life 9.9v so will set the alarm for 7.5 to be on the safe side and I think I will have to look into fitting the haptic to get the alarm feel as my hearing isn't that good (the wife always said I had selective hearing)
No, no, no!

Again these minimum numbers are the point where damage to the battery starts to happen. They are NOT a guide to using the battery in a transmitter. Once a 3s LiFe battery gets to 3.0v it's essential game over as far as delivering power is concerned. After that, the battery will very rapidly drop to the point where the transmitter shuts off.

For a 3s LiFe, the appropriate warning voltage is about 9.3. (Some people suggest 9.0v but I see absolutely no reason to push to the limit. I charge when the battery gets to 9.5 or 9.6, or sooner.)

By the way, my experience is that the 1500 LiFe battery can survive ONE complete discharge (leaving on overnight) with only moderate swelling? To recover, you have to charge for a few minutes on NiMH cycle to get up into the voltage range where the LiFe cycle will work. Be very careful. Do it outdoors and stay there!

A second complete discharge will cause the battery to swell excessively when recharged. Don't ask how I know.

jhsa wrote:Rob. 9.9V on a tx pack is way too low. Don't forget that as the tx doesn't take so much current and the voltage doesn't drop so low. And when it does the lipo is already discharged. A lipo at rest should show a voltage of around 11.1V when about 80% discharged. In a tx the voltage under load will be very close to the voltage at rest as the drop is very low. If the alarm is set very low, lets say 10V, you will see that when it reaches about 10.5v the voltage will just start dropping very fast and when the alarm sounds at 10V you don't have time to land your plane anymore. Batt will probably get damaged as well..

Just my 2c

Joao

Sent from my GT-I9195 using Tapatalk

Agreed. I was referring to the absolute minimum you should go. Certainly then time margins would be very small!

Sent from my GT-I9300 using Tapatalk

Post by **MikeB** » Sun Apr 13, 2014 8:53 am

Are you running the 9X standard, or have you done any telemetry or voice mods? The alarms you can have vary depending on these.

Mike.

Billthetug · Post by **Billthetug** » Sun Apr 13, 2014 7:28 pm

Hi Mike yes done the telemetry mod and is running fine with er9x telemetry nhtemplates
Bill

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Post by **MikeB** » Sun Apr 13, 2014 7:44 pm

One of the audio mods possible is to use a piezo speaker instead of the standard buzzer. Interestingly, the buzzer doesn't do too badly when used in piezo speaker mode.
Try setting the sound mode (RADIO SETUP menu) to PiSpkr. Then go to the Safety Switches, pick a channel not being used for the safety function, and change its type to 'A' (for Audio). Select a switch (say GEA for now). When the switch is ON, the audio specified by the last parameter (Warn1 by default) sounds every few seconds. Change the selected sound until you find one you like!

Now set up a CUSTOM SWITCH as:
CS1: v<ofs Batt 9.5
Change the switch entry in the safety switch to SW1.
Now, when your battery voltage drops below 9.5 volts, you will get the audio sound selected playing.

Mike

Billthetug · Post by **Billthetug** » Mon Apr 14, 2014 12:43 pm

Thanks for that Mike
Set it up but I think it will be a while before it triggers as I started yesterday at 10.1 ran for two hrs and today is still at 10.1 so we will see how it goes
Cheers
Bill

Billthetug · Post by **Billthetug** » Tue Apr 15, 2014 12:37 pm

Hi Mike managed to test it by moving the batt alarm level up and it works fine
Got my new toy delivered today (battery tester) and it has now convinced me about power in batteries
My 9.9 life was still reading 10v after two hrs use so decided to try the meter and was amazed that there was only 35% left so it is on charge.
Cheers
Bill

Post by **jhsa** » Tue Apr 15, 2014 1:09 pm

That's what we have been saying here..

It would be interesting to know how much the charger put back in..

João

Billthetug · Post by **Billthetug** » Tue Apr 15, 2014 3:48 pm

It put about 700 Back in then tested on the meter =95% When it cut off but after four hrs rest it is reading 90% c1 3.399 c2 3.395 c3 3.396
Bill
This is the life04 battery I am using
9.9v 1300 mAh

Daedalus66 · Post by **Daedalus66** » Tue Apr 15, 2014 10:59 pm

Billthetug wrote:Hi Mike managed to test it by moving the batt alarm level up and it works fine
Got my new toy delivered today (battery tester) and it has now convinced me about power in batteries
My 9.9 life was still reading 10v after two hrs use so decided to try the meter and was amazed that there was only 35% left so it is on charge.
Cheers
Bill

What kind of battery tester are you using?

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