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RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

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Old 08-26-2012, 08:27 PM   #26
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Nidly ... I do agree ... but the 9x in stock form shows a lower voltage than true.

My 9x is showing 10.3V ... and its been flying today for 3 flights of 10mins each ... plus switched on time etc .. lets say 35mins total.
Multimeter check shows : 11.07V

What I will do is leave it on tomorrow till alarm goes of ... and see what it says and meter again...

To be honest I've only ever heard the low alarm on it a couple of times in the 2+ years I've had it ... and that's been when I've forgotten to switch of after bench tests of models !

What I usually say to anyone who asks about the 9x and volts display .. find out what figure the alarm goes of at .. the displayed figure not the manuals figure ... by leaving it switched on ... then you have a benchmark to refer to. Also if you time it ... you know what real use you have instead of calculated time. To be honest - even if volts display was correct - it's still the way to go ...

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Old 08-27-2012, 01:09 AM   #27
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Originally Posted by solentlife View Post
This subject always amazes me how people worry ...

30 yrs ago - we flew 500mAh packs in our Tx's and models ... we flew all day. If we were at a weekend fly-in with 2 days flying - we beg stole or borrowed a field charger. I actually had one I bought !! Or we fitted 1200mAh pack to model.
You could charge actually of the Glow-Plug engerizer circuit on you power panel as that pulsed 12V to ignite the glow plug.

Today ? I have 2300mAh NiMH in Tx .. and lipo's in model. If I need to charge .. my B6 charger with 12v car lead will charge 8 AA Tx, 4.8v packs in my gasser, all my LiPo's ... whatever .. even my glow starter ...

I actually feel more comfortable knowing my batterys have just been charged than relying on some long-term set - that one day may just catch me out that one or more cells are not playing game anymore ...

I have to admit that my main concern over charge capability and run-time is more for model flight time than not having to charge a Tx ... (even though my 2300 NiMH will keep flying for hours without need for charge, will hold charge as well ... no need to pay Eneloop prices !).

My thoughts anyway ..

Nigel
One of my club members flys giant scale models with twin cylinder engines up front. Receiver power is a dual 2000 something LiFe battery that runs both the receiver and ignition system.

Eric reports that he is consistantly using about 200 Milliampere Hours out of the LiFe batteries per flight. So, with the 4000 Mah capability of the dual LiFe battery he can safely fly all day.

Another club member is flying a model with a DLE 30 gasser where the LiFe battery is powering both the receiver and ignition system. He reports that he is using about 95 Mah out of the battery per flight. (Of course your results can vary! Check out your own system for Mah requirements per flight.)

Caught another club member last year with a $$$$ wet turbine model whose receiver was powered by a five cell "AA" type 2700 Mah Nih battery. The model was full of digital servos. He was very lucky to have not lost the turbine model. He's now flying with dual LiFe battery packs.

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Old 08-27-2012, 02:34 AM   #28
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Originally Posted by solentlife View Post
Nidly ... I do agree ... but the 9x in stock form shows a lower voltage than true.

My 9x is showing 10.3V ... and its been flying today for 3 flights of 10mins each ... plus switched on time etc .. lets say 35mins total.
Multimeter check shows : 11.07V

What I will do is leave it on tomorrow till alarm goes of ... and see what it says and meter again...

To be honest I've only ever heard the low alarm on it a couple of times in the 2+ years I've had it ... and that's been when I've forgotten to switch of after bench tests of models !

What I usually say to anyone who asks about the 9x and volts display .. find out what figure the alarm goes of at .. the displayed figure not the manuals figure ... by leaving it switched on ... then you have a benchmark to refer to. Also if you time it ... you know what real use you have instead of calculated time. To be honest - even if volts display was correct - it's still the way to go ...

Nigel
Reading lower than actual voltage is a good thing, right? It gives a little more safety margin. My three 9x are all off by about 1 volt at 12 and then at 9 volts they're off about a half volt (all reading too low of course) The stock alarm works for me , but not with the lipo. I'll just have to watch the voltage on that one. I think I charged all three of my TX 1-2 times last season and 1 time this season so far. It's time to charge them again soon. Last season I used LSD cells and the first charge this season was LSD in 2 of them and alks in 1 of them.
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Old 08-27-2012, 03:38 AM   #29
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Originally Posted by nidly View Post
Reading lower than actual voltage is a good thing, right? It gives a little more safety margin. My three 9x are all off by about 1 volt at 12 and then at 9 volts they're off about a half volt (all reading too low of course) The stock alarm works for me , but not with the lipo. I'll just have to watch the voltage on that one. I think I charged all three of my TX 1-2 times last season and 1 time this season so far. It's time to charge them again soon. Last season I used LSD cells and the first charge this season was LSD in 2 of them and alks in 1 of them.
Off by a volt??? That's 1/12 or 8%. Even my three cheap Harbor Freight $4.00 digital multimeter meters check out at 1% on DC volts, as compared with my two $$$$ Fluke 87V meters.

Strange.

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Old 08-27-2012, 03:49 AM   #30
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Yep, they're all that way. Much worse at 12 volts than at 9 volts. Heck, maybe at 7 they are right on the money? The alarm and voltage reading can be calibrated with ER9X , but I don't have it yet. I'm still on stock firmware.
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Old 08-27-2012, 12:38 PM   #31
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Originally Posted by kyleservicetech View Post
Off by a volt??? That's 1/12 or 8%. Even my three cheap Harbor Freight $4.00 digital multimeter meters check out at 1% on DC volts, as compared with my two $$$$ Fluke 87V meters.

Strange.
Kyle ... the 9x out of factory has never had a correct reading of volts .. for some reason they didn't get it right. But all else is fine. Any 9x owner on stock firmware lives with it and the low volt alarm works fine. To be honest I think the LVA is not interested what the display says !!

Flashing the 9x with er9x gives possibility to calibrate the volts display ... amongst many other things it can do.

But as I posted earlier - best is to KNOW what full charged and alarm readings displayed are. Regardless of whether they are low or not.

Personally ... I flew for years with RF meters in front panels of Tx's instead of volts .. as you and I know - volts reading on rechargeables is not that good and RF output as JR, Futabe etc. did for years was much more useful.
Take the 35Mhz JR propo I have near me now ... have antena down and RF output is 60% of full ... (meter reading) ... and I know if I get good command of surfaces at distance with that - it's a good range check.

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Old 08-27-2012, 12:47 PM   #32
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Originally Posted by kyleservicetech View Post
One of my club members flys giant scale models with twin cylinder engines up front. Receiver power is a dual 2000 something LiFe battery that runs both the receiver and ignition system.

Eric reports that he is consistantly using about 200 Milliampere Hours out of the LiFe batteries per flight. So, with the 4000 Mah capability of the dual LiFe battery he can safely fly all day.

Another club member is flying a model with a DLE 30 gasser where the LiFe battery is powering both the receiver and ignition system. He reports that he is using about 95 Mah out of the battery per flight. (Of course your results can vary! Check out your own system for Mah requirements per flight.)

Caught another club member last year with a $$$$ wet turbine model whose receiver was powered by a five cell "AA" type 2700 Mah Nih battery. The model was full of digital servos. He was very lucky to have not lost the turbine model. He's now flying with dual LiFe battery packs.
But really bears no relation to what OP is on about .. safe limit on his 9x Tx battery.

Lets be honest if we want to go the big model route ... in days gone by - we had back-up packs via electronic switching, we split of servos into power groups so had more than one NiCD pack in the model ... we had failsafes ... there was far more to it than just putting a battery pack into the model. In fact LMA in UK (I was a SMAE rep before it changed name to BMFA) ... we put together serious rules and limits on Large Models.
I am not trying to upset you - far from it and I have greatest respect for your knowledge and great help to me and others on here ... but that Turbine model would be fine whether it was NiMH or Life or LiPo multiple power packs ... splitting up the load into groups as we would have done years ago.



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Old 08-27-2012, 04:39 PM   #33
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Originally Posted by solentlife View Post
But really bears no relation to what OP is on about .. safe limit on his 9x Tx battery.

Lets be honest if we want to go the big model route ... in days gone by - we had back-up packs via electronic switching, we split of servos into power groups so had more than one NiCD pack in the model ... we had failsafes ... there was far more to it than just putting a battery pack into the model. In fact LMA in UK (I was a SMAE rep before it changed name to BMFA) ... we put together serious rules and limits on Large Models.
I am not trying to upset you - far from it and I have greatest respect for your knowledge and great help to me and others on here ... but that Turbine model would be fine whether it was NiMH or Life or LiPo multiple power packs ... splitting up the load into groups as we would have done years ago.



Nigel
Yup, I agree, the original subject was transmitter batteries.

However, IMHO, a single 2700 Mah Nih battery is a real risk as to the safety of that turbine model. Even putting two or three in parallel is still risking the model.

I conducted tests on that turbine models 5 cell pack using an electronic load similar to what the turbine models multiple digital servos pulled. The 5 cell pack quickly dropped down to about 3.6 volts DC.

Again, just IMHO, Nih batteries are perfectly OK as used in transmitters. These transmitters have a constant load current, and that constant load current is well within the limits of even a cheap Nih pack.

And, years ago, we were flying models with simple four servos that pulled fairly reasonable peak currents. That is most certainly not true today. As an example, my giant Big Stick model with its 7 Hitec 645MG servos showed a peak current of 14 Amperes as measured by peak reading function of my $$$$ Fluke 87V meter. That was measured by just moving the transmitter sticks round and round while the model was on the ground.

Even with two parallel connected Nih "AA" sized receiver batteries, that's 7 amps each. (Note, do not directly parallel connect Nih or Nicad batteries. That is a big NO NO.) It's been my experience that two Nih receiver batteries cells may not share loads equally. One of my club members has been flying his giant scale models with 5 cell "Sub C" type receiver batteries. Those type batteries can easily handle the peak current loads of a giant scale model. And those sub C batteries have been around for many decades.

Adding to that, I've got no proof, but suspect the old 500 Mah receiver batteries we used back then were better equipped to put out short duration high currents than those 2700 Mah batteries made you know where nowdays.

Nice thing about those LiFe and A123 batteries as used as receiver power. The LiFe batteries I've tested showed little voltage drop at 15 Amps. And the 2300 Mah A123 cells are even better. (Yeah I Know, these are also made you know where!)

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Old 08-27-2012, 05:17 PM   #34
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In those days - the 500 packs were NiCD's ... not NiMH.

I've actually got a burn mark on my left leg from having a single 500 NiCD AA in my pocket !! The b******d shorted momentarily in my pocket ! Boy did that hurt. I never did that again.
NiMH do not despite many claims .. have the same ability to discharge at such high rates as NiCD's ...

But even so - NiMH are good enough when installed properly. But in a modsel that has high amp loads as you suggest - then I would go LiPo anyway ...

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Old 08-27-2012, 07:29 PM   #35
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Originally Posted by solentlife View Post
.............What I will do is leave it on tomorrow till alarm goes of ... and see what it says and meter again... .....Nigel
Well I'm doing as I promised ....

At 1430hrs today I switched on the 9x. Display showed 10.4V. The radio had been charged early this morning, via the Prolux auto-charger and rested for at least 3 hrs before start.

It's now just gone 2100 hrs ... that's just over 6.5 hrs and display is showing 9.0V ... still no alarm. Meter shows 9.31V

At 2130hrs - that's 7 hrs since switch on ... display dropped to 8.8V and alarm sounded as a single beep with reasonable silent gap.... meter showed 9.15V. Given that its 8 x AA ... 9.15/ 8 = 1.14V each ... still an operating voltage for a rechargeable, but getting close to the point that a rechargeable suddenly plummets to zero ! Still - the alarm is giving definite time to sort out and land.

I'm leaving it on for a little longer to see what happens .. maybe the beeps get closer together ? maybe a long beep signifies last bit ... ??

At 2140hrs ... display was showing 7.8V ... now falling quickly .. time to switch off !!

Summary :

Grundig 2300mAh AA cells in the stock battery holder. Age ? Been in use for well over 1 year .. near 2 years.

Charged by Prolux Auto RC Radio charger at rate 0.85A with auto delta peak detect and revert to trickle charge ... This time I did not use my 50mA trickle charger after to make sure cells fully charged.

Start time : 14:30hrs, display volts 10.4V
Finish time (radio still operating) : 21:40hrs, display volts 7.8V

Total working useable time : 7hrs 10mins.

For AA's that have been in for nearly 2 years - that's not bad I reckon ...
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Old 08-27-2012, 07:37 PM   #36
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Originally Posted by solentlife View Post
In those days - the 500 packs were NiCD's ... not NiMH.

I've actually got a burn mark on my left leg from having a single 500 NiCD AA in my pocket !! The b******d shorted momentarily in my pocket ! Boy did that hurt. I never did that again.
NiMH do not despite many claims .. have the same ability to discharge at such high rates as NiCD's ...

But even so - NiMH are good enough when installed properly. But in a modsel that has high amp loads as you suggest - then I would go LiPo anyway ...

Nigel
Yup
Good point. Those old Nicads were far superior to the Nih cells for short time high current outputs. Back when we were flying electric motors with these cells, the cells used were Nicads.

Nice thing about the 2000 mah or so A123's or LiFe's. If your receiver and servos work OK on a 5 cell Nih pack, the two cell A123/Life packs are a direct drop in, no voltage regulator required.

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Old 08-27-2012, 07:40 PM   #37
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Originally Posted by solentlife View Post
Well I'm doing as I promised ....

At 1430hrs today I switched on the 9x. Display showed 10.4V. The radio had been charged early this morning, via the Prolux auto-charger and rested for at least 3 hrs before start.

It's now just gone 2100 hrs ... that's just over 6.5 hrs and display is showing 9.0V ... still no alarm. Meter shows 9.31V

At 2130hrs - that's 7 hrs since switch on ... display dropped to 8.8V and alarm sounded as a single beep with reasonable silent gap.... meter showed 9.15V. Given that its 8 x AA ... 9.15/ 8 = 1.14V each ... still an operating voltage for a rechargeable, but getting close to the point that a rechargeable suddenly plummets to zero ! Still - the alarm is giving definite time to sort out and land.

I'm leaving it on for a little longer to see what happens .. maybe the beeps get closer together ? maybe a long beep signifies last bit ... ??

At 2140hrs ... display was showing 7.8V ... now falling quickly .. time to switch off !!

Summary :

Grundig 2300mAh AA cells in the stock battery holder. Age ? Been in use for well over 1 year .. near 2 years.

Charged by Prolux Auto RC Radio charger at rate 0.85A with auto delta peak detect and revert to trickle charge ... This time I did not use my 50mA trickle charger after to make sure cells fully charged.

Start time : 14:30hrs, display volts 10.4V
Finish time (radio still operating) : 21:40hrs, display volts 7.8V

Total working useable time : 7hrs 10mins.

For AA's that have been in for nearly 2 years - that's not bad I reckon ...
Nigel
Exactly!
IMHO, there is nothing wrong what ever using those Nih cells in the transmitters. They work, and work well. And there is no worry about over or undervoltage application to the transmitters electronics.

That said, my new Spektrum DX8 can be programmed for either LiPo or Nih battery packs. I might just do a flight duration cycle test with my DX8 just to see how long it will transmit in the real world. This transmitter does require moving the sticks every so often, or it will shut itself off after some 10 minutes of no action.

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Old 08-28-2012, 09:00 AM   #38
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I use a 2cell Li-ion pack in my 9x,modded with ER9x and Frsky.I have the low voltage alarm set at 7.6v.I recharge about once a month,using a 4 button charger,even though it doesn't really need it.I have never seen less than 7,8v on the readout.
In theory,since the tx's electronics run at 5v,you shouldn't need much more than 5.5v.The rest is just wasted in heat.
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Old 08-31-2012, 03:27 PM   #39
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Originally Posted by DHC Beaver View Post
I use a 2cell Li-ion pack in my 9x,modded with ER9x and Frsky.I have the low voltage alarm set at 7.6v.I recharge about once a month,using a 4 button charger,even though it doesn't really need it.I have never seen less than 7,8v on the readout.
In theory,since the tx's electronics run at 5v,you shouldn't need much more than 5.5v.The rest is just wasted in heat.
For further info see here:
http://www.rcmodelreviews.com/tendollarbattery.shtml
The 5V of the 9x is a well known and thrashed out subject ...

As to length of time you get per charge ... my NiMH being 2300mAh - I get more than enough flight time without having to consider charging. No need to alter anything ... except one little trick :

The spring contacts at -ve of cells in many appliances are not exactly the best and in a Transistor Radio or similar has no real consequence if contact breaks. But in a Rc TX - that's a different story and is not just 9x .. but any Tx that can take AA's ...
I always insert a small piece of folded card into the spring to harden it up and FORCE contact whatever happens. I've not had the 9x fail on me on the springs, but I like to be safe.

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Old 08-31-2012, 05:55 PM   #40
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Originally Posted by solentlife View Post
The 5V of the 9x is a well known and thrashed out subject ...

As to length of time you get per charge ... my NiMH being 2300mAh - I get more than enough flight time without having to consider charging. No need to alter anything ... except one little trick :

The spring contacts at -ve of cells in many appliances are not exactly the best and in a Transistor Radio or similar has no real consequence if contact breaks. But in a Rc TX - that's a different story and is not just 9x .. but any Tx that can take AA's ...
I always insert a small piece of folded card into the spring to harden it up and FORCE contact whatever happens. I've not had the 9x fail on me on the springs, but I like to be safe.

Nigel
As for me, if I hade a transmitter with loose cells, I'd take a battery pack with welded cell interconnects, and solder its wires directly into the transmitter. (Warranty be danged.) Just think of that flashlight where you need to bang it against something for it to turn on.

Only problem is, some of those cell contacts don't take solder very well.

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Old 08-31-2012, 10:31 PM   #41
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Seeing people rely on spring contact for their tx batteries makes me cringe.I have seen too many crashes caused by intermittent contact.Here is my solution:

The male plug is soldered directly to the contacts on the circuit board.
Sorry about the out of focus pic,it's the only one I have.
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Old 09-01-2012, 07:44 AM   #42
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I have one crash in my RC time due to a FACTORY soldered pack ... the hard soldered tab gave way on the NiCD cell ... and my fabulous Royal P51D smashed in on concrete.

I've taken too many packs apart to salvage cells for non-important use and found corrosion, poor soldering, half tabs etc. And I only used reputable sellers along with brand leader named packs in those days.

I KNOW what's going on with my cells - but hidden under heat shrink and padding ... well having seen some of the results - I'll stick with my system.

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Old 09-01-2012, 07:52 AM   #43
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When all is said and done,the batteries are the weakest link in an rc system.There is only so much you can do to make it as safe as possible.We need to be ever vigilant.
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Old 09-01-2012, 12:25 PM   #44
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Originally Posted by DHC Beaver View Post
When all is said and done,the batteries are the weakest link in an rc system.There is only so much you can do to make it as safe as possible.We need to be ever vigilant.
How true that is ...

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Old 09-01-2012, 04:47 PM   #45
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Originally Posted by solentlife View Post
I have one crash in my RC time due to a FACTORY soldered pack ... the hard soldered tab gave way on the NiCD cell ... and my fabulous Royal P51D smashed in on concrete.

I've taken too many packs apart to salvage cells for non-important use and found corrosion, poor soldering, half tabs etc. And I only used reputable sellers along with brand leader named packs in those days.

I KNOW what's going on with my cells - but hidden under heat shrink and padding ... well having seen some of the results - I'll stick with my system.

Nigel
Yeah
Sopme 30 years ago we had a big issue with those welded tabs on the 20 cell Nicad packs we used at work. The battery mfg had a bad production run, and a few battery packs had poor spot welds between the cells and the cell tabs.

I ran across a few dozen battery failures due to this cause. We were buying some 800 24 volt battery packs per month, both for new production and for field replacements.

Which is why nowdays many of these battery packs have multiple spot welds on those tabs.

More than a few of my club members are going to those 2300 two cell A123 batteries for their reciever power on their larger models. You can buy these cells from www.voltmanbatteries.com in the USA, and make your own battery packs. Or they are available ready to go for a lot more $$$$.

Take a look:
http://www.voltmanbatteries.com/serv...1-dsh-A/Detail

Between club members and myself, we've purchased well over 100 A123 cells from this place. No one has had any sort of problem or issue with this place. (Just wish I worked there )

If anyone would like a thread on how to build a receiver pack with these cells, let me know.

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Old 09-02-2012, 04:12 PM   #46
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Originally Posted by nidly View Post
1500/200 = 7.5 hrs and for me that is a MAX of 30 flights. Heck , I'm probably already there , but in viewing your graph I should be ok even at 9 volts. I have no way to tell how much capacity is used as I use it up (other than maybe count my time)
I wound up having to take the TX apart looking for radio trouble and the LiFe pack was at 9.2 volts on the display. Actual voltage was 9.72 and it took 1100 to recharge it to 10.8 resting. I guess that's considered full. These not only have a steep knee at the bottom , but they also have a very steep knee at the top too.

On another 9x I had finally run the alks down to the alarm and installed a 3sx2620 lipo in that one , and the voltage reads about 11.6 when turned on. I'll recharge the lipos around 10 volts.
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Old 09-03-2012, 05:51 AM   #47
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Originally Posted by nidly View Post
I wound up having to take the TX apart looking for radio trouble and the LiFe pack was at 9.2 volts on the display. Actual voltage was 9.72 and it took 1100 to recharge it to 10.8 resting. I guess that's considered full. These not only have a steep knee at the bottom , but they also have a very steep knee at the top too.
.
Yup
These LiFe and A123 cells are "Topped off" at exactly 3.6 Volts per cell, or 10.8 volts for three cells.

As you indicate, these cells pull a lot of current when charging, but the charging current really drops off fast as you hit full charge.

As for me, I just charge them after flying for the day. These cells hold near 100% charge for months.

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Old 09-03-2012, 06:50 AM   #48
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Originally Posted by kyleservicetech View Post
...If anyone would like a thread on how to build a receiver pack with these cells, let me know.
Yes, Please do.
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Old 09-04-2012, 05:48 AM   #49
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Originally Posted by Turner View Post
Yes, Please do.
Yup
It's done, take a look!

http://www.wattflyer.com/forums/show...370#post881370

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Old 12-15-2012, 11:19 PM   #50
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My Flysky TX that has the Rhino 3sx2620 has finally been recharged. I have flown more flights than I can count down to 9.9 volts on the TX display. It was exactly 10.5 actual and it took exactly 2428 mah to bring it up to 12.5 volts.

That was flying about 4 planes (two are newer) and 2-3 are older ones for about 75 days. The last recharge was about 2000 mah and 50 days.

I expect to not have to recharge till after winter months on this TX.

I'll be darned now if I can find the info on the anylink's voltage minimum. I was thinking it 5-6 volts?
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