LiFe Battery Pack

[erazz]

Thems fighting words!!!

Didn't you read the war that went on over on RCG?!?!? Do you really want to drag it here? With all the crazies around? Do ya?!??!

[Crucial]

I used up all my troll food over there.

[GyroGearloose]

(or were "unexpectedly thwarted by gravity with an impact modality")

That's a great expression!

I use an HK 6 way parallel lead to charge my MSR X batts - 1S 160 Mah and it works OK, but the Accucell is too coarse to set 160mah so I generally set it at 100, and let it get on with it as I waste my life browsing

Thanks... I've hung out with too many lawyers and politicians, and can make a total splatter-crash sound like a successful technical endeavor.

As for your 6-way, it's really not a good way to charge those tiny batteries (I have a bucket of them to fuel my mSR). The 4-cell charger that comes with many of the ParkZone models is FAR better at trickle-charging, and it is idiot proof and allows overlapping charge cycles (each batt is it's own cycle). The AC6 really IS too coarse to do those little cells well IMHO. The only advantage to your parallel charging is that you're producing a 6Px1S pack that could be charged at .84 amps (6x.160), but I'm still not sure the cells end up balanced (each charged right instead of over/under based on their individual resistances and charge levels). I'd always be careful charging cells in parallel if they weren't discharged in parallel.

-G

[GyroGearloose]

You guys are all nuts with your lipo and life's You should only use NiMh batteries. You only need a wall wart then.
ONE WALL WART TO RULE THEM ALL!

Why stop there? I recommend flying your 450 using a car battery. With 840 amps available, you should be able to fly for days once you get it off the ground with a catapult.

-G

[jhsa]

Now I'm rolling on the ground laughing again.. what a good way to start the day

[Redbrickman]

Just charged the LIFe battery again after the crude test I did.

It took 1353 ma to charge and finished at 10.8V

Does that sound about right?

As MikeB suggests I will have to hook up a lead to measure current draw, and see what the radio is actually drawing in normal use.

[GrootWitbaas]

sounds plus minus almost exactly correct

[Redbrickman]

Guess I should forget about the battery specs and concentrate on learning how to program this "Eierlegendevollmilchsau"

[GyroGearloose]

IRofl.. love that phrase, although I don't think 9X will qualify until it contains a can opener, a laser designator, and a floor mop.

Now that I might have some time, just wait until I start molesting the codebase...

Gyro 'coredump' Bitsloose

[Redbrickman]

I had planned to charge this battery via the balance lead as discussed earlier in the thread.

Now I am looking at using the small connector (red+black) for charging, as charging via the balance lead will not result in a balanced battery. I am thinking why not mod the charging socket so that a purpose made lead can connect the small plug and the balance plug to the charger?

Any thoughts on this?

[Kilrah]

He did something neat:
http://www.rc-cam.com/forum/index.php?/ ... __p__26476

[Redbrickman]

That is a nice solution, I'll bring out the Smartieparts USB socket too, so that there is no need to open the battery hatch.

[Westy]

I like that too...... mine is a little different from that...... have to pop the back just to connect the Balance Leads. I use the Stock fitting and have a plug that plugs direct into my bat charger.

http://www.youtube.com/watch?v=Bc3HBCiPX9k

and

http://www.youtube.com/watch?v=XoEwp5xIoAE

[rdrnnr1971]

Hi, new to the forum and new to the Turnigy X9. I was wondering if this battery I found in the discussions at HK would work for the TX9? Seems to have the same connectors as the Life recommended at the start of this thread. And the dimensions seem to be nearly the same, except the length is 2 mm's shorter (more room for the usb?). Sorry if this battery question has been asked already, but I couldn't find it if it was! Thanks for any recommendations!

http://www.hobbyking.com/hobbyking/stor ... oduct=6955#

[Westy]

The battery you have found is a LIpo ..... not a LIFE battery..... it will work ... but not as safe as LIFE Batteries.

[rdrnnr1971]

Thanks for the quick reply Westy! I realized that after posting and saw the voltage would be a problem. Couldn't figure out how to delete the post. Appreciate the quick reply tho!

[Westy]

Voltage will be fine...... and it will certainly fit..... however if you leave your TX on ... and run it down ..... you will have to biff the battery out ...... however if you do that with a Life BAttery ... you can simply recharge it ad it will hold normal charge as per usual.

[rdrnnr1971]

Ok, thats good to know! But since it is a 3-cell lipo, I thought at full charge it would be over 12 volts. And I thought I read somewhere that over 12 volts is not good for this TX. I think you are right though, its not worth taking the chance of leaving the TX on and ruining the battery. But at $14.99US, and the extra mah, it might be worth trying! Wonder how much more time you would get out of this battery?

[Westy]

Well as above in my Tuts on LIFE $8.00 bat mod.... I get about 10-12 hours on mine ..... but am running ER9x, so I am able to reset my batt min voltages and not have that annoying beep sound warning. you can however do the resistor mod if you are running STD Turnigy Firmware and that way you can fool the system into thinking you have 12 volts and not the 8.4 volts of 2 series 3.7V surefire batteries.

[Kilrah]

I have the 2500mAh Li-Po, but removed one of the cells to make it a 2s and save some weight and make it easier to connect the plug... and as (depending on RF module) the 3rd cell serves no purpose but heating the voltage regulators, I don't even lose run time. I have about 15 hours from my current draw measurements.

[GyroGearloose]

Couldn't figure out how to delete the post. Appreciate the quick reply tho!

Before someone replies to your posting, there's a little "X" to let you delete. After a reply, it seems locked in -- you can edit but not delete. Wonder what editing to blank would do?

Voltage will be fine...... and it will certainly fit..... however if you leave your TX on ... and run it down ..... you will have to biff the battery out ...... however if you do that with a Life BAttery ... you can simply recharge it ad it will hold normal charge as per usual.

Voltage is not "perfectly" fine, just acceptable. As later noted, anything over about 8V is just going to heat. Technically 6V, but you need some lifetime to your battery...

As for LiFE being fine to discharge, again not "quite" right. They are safer to discharge to dead compared to LiPO (which should be discarded after a "severe" discharge, since LiPO won't take a recharge properly there after), but LiFE is still damaged by going below 2V/cell. Yes, that's better than what LiPO tolerates before damage, but still damagable.

But at $14.99US, and the extra mah, it might be worth trying! Wonder how much more time you would get out of this battery?

I would expect you to get almost no extra life, at twice the cost. As noted, the extra volts are just dumping to VR heat, so it's as if you removed one of the cells. Sadly, you can't use that heat to warm up your hands winter flying, or I might go for it. Now, as for actually removing the 3rd cell...

I have the 2500mAh Li-Po, but removed one of the cells to make it a 2s and save some weight and make it easier to connect the plug... and as (depending on RF module) the 3rd cell serves no purpose but heating the voltage regulators, I don't even lose run time. I have about 15 hours from my current draw measurements.

So, you spent $15 to make a 2S-2500mah, and get 15 hours on a battery with worse safety and abuse tolerance (as above). We spent $8 for a LiFE that works without any modification, and gives almost exactly the same runtime. I'm not seeing the "win" there... If it's what you bought before you knew better, then bravo for making it work... but I wouldn't recommend it.

Why don't you get better life? Look at the wattages, and we'll assume "lossless" V/A transfers just to make this easier math:

1500mah at 10.8V = 16200mahV charged
1500mah at 8.4V = 12600mahV discharged
= 3600mahV usable safely
1500mah at 6.9V = 10350mahV max-discharged
= 5850mahV usable aggressively

2500mah at 8.4V = 21000mahV charged
2500mah at 6.8V = 17000mahV discharged
= 4000mahV usable safely

So, using LiFE instead of LiPO only loses 10% usable time (which LiFE 13hrs against your LiPO 15hrs confirms real world). If you want to life dangerously, you CAN push the LiFE to actually give you a longer runtime than the LiPO (not recommended, as I've found the radio less reliable towards the extreme low voltages).

So, there you have it... I can't justify spending twice as much for 10% more life and less stability.

-Gyro

[GyroGearloose]

PS: For those wondering about leaving a 2500mah/3S alone, the math gets too wonky to process easily outside of real-world measurements...

2500mah going 12.6 to 10.2 would appear to give you 6000 mahV to use, BUT by then you've changed the voltage "enough" that the voltage regulators are kicking in hard. So, where my radio draws 120mah at 9V, it may be drawing 200-250mah at 12V (I haven't tested... someone want to confirm?). Ultimately, I'd be curious what the ultimate runtime for this LiPO ends up being... my solution was two LiFE for the same price and knowing I have 26-28 continuous hours of usage available before I recharge them -- it's not THAT hard to change the battery if I HAVE to, and 13 hours between being at a charger is rare for me.

This all reminds me of an extended discussion on plane batteries I once had -- why can't you double MAH to double flight times? Obviously there the issue is weight, or we'd all fly our EDF on car batteries... I even had a cool spreadsheet that would tell you estimated flight times and cost/minute between batteries.... I'll dig it up if anyone is interested...

G

[Kilrah]

So, you spent $15 to make a 2S-2500mah, and get 15 hours on a battery with worse safety and abuse tolerance (as above).

I already had it before buying the 9x, and then you'll see another reason at the end of the post
As of safety... well, I've been using Li-Pos in anything and everything for about 6 years now, I think I know how to handle them pretty well... Also, the 9X beeps at you if you forget it, so even if I happened to forget it once it would warn me.
And by the way I have reused many overdischarged Li-Pos in the past, some with zero loss in capacity/performance even after a discharge to 0V...

Why don't you get better life? Look at the wattages, and we'll assume "lossless" V/A transfers just to make this easier math:

1500mah at 10.8V = 16200mahV charged
1500mah at 8.4V = 12600mahV discharged
= 3600mahV usable safely
1500mah at 6.9V = 10350mahV max-discharged
= 5850mahV usable aggressively

2500mah at 8.4V = 21000mahV charged
2500mah at 6.8V = 17000mahV discharged
= 4000mahV usable safely

Sorry, but I don't see anything worth keeping in this math

Firstly, batteries have anything but flat discharge curves when we consider the entire safe range, so calculating VAs makes no sense. My Li-Po will give me about 2000 mAh between 7.8V and 7.3V, but maybe 100mAh between 7.3V and 6V.
Secondly, as voltage is internally reduced to 5V with a linear regulator (anything above 5V just creates heat, unlike with a switching-mode regulator where energy conservation can be assumed indeed), battery voltage is irrelevant, and the 9X's current consumption is constant.
The only relevant variable is the pack's capacity, which is of course specified to be what you can draw within safe limits for the pack.
So, as my 9X with HP DSM2 module draws 93mA, with the 1500mAh LiFe I'd have 1500/93 = 16h runtime. With the 2500mAh LiPo I have 2500/93 = ~27h. With my FrSky module, the total draw is 140mA, so I get about 18h (this one could actually make a little use of a higher voltage battery, as the module uses a switching regulator for its internal supply).

Of course I don't need that much runtime, BUT I fly FPV and use the 9x's battery to power a set of video goggles with integrated video receiver and headtracker through the trainer port. Those draw 380mA, so when I fly FPV (with FrSky and goggles) I draw 380+140=520mA. So about 3h operation on the LiFe, and 5h on my LiPo, where the difference is much more meaningful

[GyroGearloose]

Yes I was using very quick and dirty math, assuming flat drains and lossless conversions which don't exiswt. It was a ballpark demonstration.

I myself have never fully recovered a battery from full drain, seen or heard it done, or heard the chemistry could allow it done. But as you note ER9X warnings should prevent it happening in this case. Most of all, at some point the radio shuts down and probably saves a lot of current drain.

So, as I concluded with, math is bunk after a point, and you have to go with experiences. For me, LiFE lasts much longer and safer at similar size packs. As noted, you have a super high drain application - for me, 13 hours is alreaady more than needed.

G

[rdrnnr1971]

WOW! Didn't mean to open up a can of worms here guys!!

But, I appreciate all the posts and info. Learned a lot, especially being a noob. I think after reading all the info, I will stick with the LiFe batteries. And I will be purchasing the SmartieParts add on board and going with Er9x, so I will be able to change the battery minimum voltage!

Thanks again for the replies. I'm sure I will have more questions in time!

[ShowMaster]

I just ordered another 5 1500Ma HK life batteries for friends and a few smart chargers.
Like me, they have many favorite older TX's that have bad nicad packs. We like the idea of the the life holding a charge up to a year and $10 each to my door. Any other pack with 9.9v would be $20+ and $50 if we use OEM JR packs. 
So 5 packs for $50 or $50 ea, hard decision?

Using the normal tx charge jack question/idea?
More for field charging but....
How about a constant voltage, constant current charger circuit?
Set constant voltage to 10.8 and the current to let's say 800ma to not damage the internal diode or wiring from too much current.
The 10.8v constant voltage would actuall be set to 11.2v to compensate for the internal diode but the battery would see 10.8v max.
This setup, except for balancing, would make sure the battery would stop charging when it gets to 10.8v and the lower current would keep heating down. If I'm correct, one hour charge would put back 800ma, 30 Min 400. Enough for several hours of flying if my batteries are low and the weather is great.
I do charge using the balance port regularly but it's a pain at the field opening up the battery compartment.
I have a 14a hell cell battery in a home made small box with a handle, volt meter, and every connector used for my planes, ham radio, and soldering iron. I added a super small/thin 100 watt inverter so I can use 12VDC or 110@100w AC for larger soldering irons or other AC devices.
I use this idea for years to charge planes and TX's Nicads on the way to the field if I forgot to at home.
I want that same option with the life batteries now.
I also don't want to add more external charging connectors but I'm open to the best, smallest 6pin solution that's working well for everyone I guess.
At $10 a pack, and such a long charge retention, maybe a spare life pack in the accessory kit is even simpler being that life batteries are way less prone to self igniting it would seem over lipo's? KISS?
Comments and ideas welcome 
SM   

[Kilrah]

FWIW I rewired the original charge jack directly onto the battery connector, so no diode to screw up voltage measurement, and no diode / backplane PCB track / wire / mainboard PCB track / wire / switch PCB track / switch / switch PCB track / wire / mainboard PCB track / wire / backplane PCB track to go through and heat (and that looong path was screwing up voltage measurement nearly as much as the diode itself actually).

[ShowMaster]

Actually early on I bypassed the diode with a 3 A Pico fuse and charged that way in another 9x build that has Nimh batteries.
The life battery brought on a new charging requirement.
 After seeing a great diagram/ flow chart by a member on RCG of the charge and voltage path through all the 9x diode, connectors and switch, I limited my current to under 1  A.
He, as you pointed out that a direct path to the battery would be a much better option for higher current and less circuit damage, as well as not confusing the smart charger.
My latest 9x build still has the diode in circuit and no Pico fuse because I wasn't sure about the life charging options.   
I think I'll take another look at his and your post and consider a rewriting without the diode. Because the diode will be gone I'm still going to use the 3A or Pico fuse for short circuit protection to the charge jack. I'm so used to having the charge stop if I turn on tx power switch as well as not powering while charging, I think I'll still leave the switch in the circuit. It should be good for the 1500 ma charge and a quick 3A if the jack it shorted before the fuse goes. 
All this should allow me to charge the life if at the field and don't want to bother to ballance for a few more flights before the sun goes down. 
Thanks for the feedback as it is a more direct and easy solution than building up a super circuit charger.
More time for flying.
SM

[SamoaFlyer]

ShowMaster,

Here's a simple CCCV xmtr charger/maintainer that i built to keep up the packs. The fixed resistor sets the current and the pot sets the float voltage. Other voltages and currents are easily set up. I used a small meter to monitor output current but certainly isn't necessary. When current drops to zero, it's done. This particular one was set up for Eneloop packs in other xmtrs. No reason not to leave it plugged in all the time so xmtr is always ready to go. FET type is non-critical. Small heat sinks needed on both FET and LM317.

By the way, I'm using two A123 M1 2300mAh LiFe cells with a LDO regulator in my 9x.

Bill

[ReSt]

Why do you want to use a special charger? Why not simply using the normal charger.
Many of them work with 12 volt car battery (like e.g. imax B6)

Reinhard