sillyness

My Feedback: (25)

As for price: First: I wouldn't pay $20 for a 2500 NiMh pack... I've had bad luck with cheap battery packs.

Second,

NiMh: A DECENT pack costs $35. Add a DECENT switch, the cheapest I will use is $25. Total: $60... double that for dual batteries.

LiIon: A GREAT pack costs $27. A GREAT reg with a BUILT IN failsafe switch, 14 gauge wire from the battery and 3 outputs from the reg to the RX is $47. Total: $74... double that for dual batteries.

Result: With dual regs and batts, LiIons ACTUALLY only cost $28 more for the superior performance and no melted RX plugs.

Hammbone

My Feedback: (309)

For you guys that are not charging your Lithium's very often:
I was told that it is much better to top them off after each flying session. It is supposed to be better for the longevity of the batteries.


Jim

ptgarcia

My Feedback: (36)

I may have said this already, but I like to use a single rx pack in my giants also. At this point I only have a couple 28% planes, a Laser and an Ultimate. On the Laser (with 5 HS-5945's and a standard digital on throttle) I use a single 2200mAh pack, on the Ultimate (with 2 HS-5945's, 1 JR 8611, 4 Futaba 3050, and high speed Futaba digital on throttle) I use a single 4400mAh pack. With these I can fly all day without charging. I'm digging my Li-Ions right now. They're just what the doctor ordered (for me )!

TT2

My Feedback: (13)

I wholeheartedly agree! The smaller (50-80cc) aircraft is where it amounts to a coin toss...especially when using redundant Rx packs.

I figured $20 for a DIY pack and about $15 for a Cermark HD switch...BUT...I'm starting to get the feeling that I'm going to be buying Li Ions for my current project (prototype 50cc 87" Edge) just to check them out.

-Tom

JohnVH

My Feedback: (38)

Tom, once you buy some, you wont go back... I am converting all my planes to them. and my heli! I have 9 packs now.

sillyness

My Feedback: (25)

Just out of curiosity for the computer stupid... DIY = Do-It-Yourself???

Mike Bogh

My Feedback: (14)

Yea, John was a late commer, he watched me for a couple of months praising Lions before he stepped up.
Believe me when I tell you that I whined, grumbled, pissed and moaned about the 350 I spent for my first lion system, checker, charger, regs, and batterys.
Snivveled like a school girl.
But after I realized the preformance, customer support, et.al. I never looked back.
Also, I bought a few of the
www.I4Cproducts.com
Voltage displays....everytime I turn on my system it displays the exact loaded voltage, that's how I get 28 flights, and no fly is 6.5V.

Panzlflyer

My Feedback: (15)

After reading this thread and the claim that there isnt that much weight saving I went out and got the old scales out.
New Radical RC 5 cell 2700 mah pack (my Scales ) 8oz.
Fromeco 2200 Lion plus regulator 4oz.
Where does that come close in weigh??
I double checked it and my 2 pack, 2 regulator Lion 4400 system weighs the same as 1 5 cell pack.
Even if my scales are off the Nimh still weighs double.
For those of you that are using 4.8v systems go get a onboard monitor system and check out the voltage drop in flight with high torque servos...bet it goes down to 4v or lower, Even 2 packs didnt make it better.
No servos binding either.
That was enough for me to change even tho that particular plane went on to have dozens of flight with those packs and is still going 2 years later.

TT2

My Feedback: (13)

Thanks for the warning! Everyone I've talked to that uses them says the same thing. The whole point of this was to gather emperical data on why people liked them more. I can't help it...I'm a geek.

Yes. I don't mind soldering my own packs up. It kinda provides me with a little added assurance...I've had spot-welds pop loose (OK it was a pack on a combat plane) from cells before.

Takes a big man to admit that. I know what you're saying...I went through the same routine when I bought my last receiver ($200+ JR 945 dual conversion PCM on 50.800Mhz)...but now that I have it I wouldn't give it up for nuttin'.

The Radical RC 2700mah packs are size 'AU' cells. The new Sanyo NiMH cells I was using as a comparison are size 'AA' cells so they're slightly smaller and lighter.

IMPORTANT NOTE REGARDING HIGH CAPACITY NIMH CELLS!!!
Looking at the Radical RC site I saw this:

'Unlike their other NiMH cells, these ultra high capacity cells should never be charged above C/2 or or about 1.1 amps on NiMH rated fast chargers. The resistance is higher than normal NiMH cells so we're not ready to recommend them in Heli's or 30% and larger airplanes for twin RX packs.'

This was in reference to their 2100mah Sanyo AA cells. It is probable that the 2500mah cells are no different.

That did it...
It's Li Ions for me!

-Tom

famousdave

My Feedback: (61)

This is a misnomer.. the older technology packs maybe, but the new panasonic and LG cells - no way !
How often do you charge your cell phone? Mine went "dead" (*) probably 40-50 times over the course of the year... battery still has most of its capacity.
and it is 2 years old. A cell phone battery gives up the ghost usually every 2 years and it sees a whole lot more charge cycles than our R/C batteries
I have 3 Li-Ion packs that are 2 years old. Last check they all rated at 96% of stated capacity!

While Li-Po and Li-Poly have different form factors their basic chemistry is the same..

DP


* - I use the term dead loosely. Li-Ion and Li-PO cells need cut off circuitry to protect them from discharging below a certain level. Without this protection the cells would discharge too far and would be unrecoverable.

TT2

My Feedback: (13)

That's very nice. Could you give a rough estimation of the number of charge / discharge cycles they've seen? Just curious...

-Tom

3D Joy

"EVERYBODY" uses these kind of packs in their large scale airplanes. That is, those that do not use the Li-ion and Li-Poly.

Are Hydrimax packs the same as Sanyo packs ?

I just purchased 2 new Sanyo 2300 mah 6V packs that are "AA" size and wonder if I can use them in my future plane with 7 coreless digitals and 2 coreless analogs.

I had 2100 mah 6V Sanyo packs and for sure, they did not like to be charged at 1C, or 2A. Actually, one of them cooked while charging.

sillyness

My Feedback: (25)

Guess what that higher internal resistance means for flight???

Higher voltage drops and warmer cells since the resistance value of the cell is going to absorb some of the batteries own energy at high current draw. Your servos will lose power when there is a high demand on them.

rmh

try the Gold Peak 3200 cells -(NIMH)
If you fly anything up to 33%-- a 5 pack of these is just fine.

famousdave

My Feedback: (61)

I would guess I have 40 cycles on them each. All three packs went 6 months on the shelf without a top-off charge, and they still had most of their capacity when I placed them back in service so a top-off was all that was needed (just did not fly that plane for whatever reason.. summers are pretty hot here!) That was 80 flights ago!

DP

mglavin

My Feedback: (31)

I not sure why your suggesting it’s a misnomer, DP. The cell manufacturers stand by their assertion with regard to the above frequent charging concept. The depth of discharge has a marked result on the cells life expectancy IMO. My use of this stuff from GS models to foamies has proven this to no end, that and very knowledgeable Aerospace Industrial user after extensive empirical testing suggests this to be an accurate depiction of lithium cells plausible life cycle. The OEM's under typical use and abuse suggest 500 cycles and with careful attention and regular charge regimens suggest 1000 cycles is the expected life cycle. Another thing that will affect the cells life is the load and or current their subjected to. It's been documented by others; that the momentary atypical current draw while performing aerobatic maneuvers is upwards of 24 amps with fourteen digital servos on board. Averaged current draw is around 3-4 amps.

I don't think comparing Li-Ions to your average everyday cell phone batteries draws a viable comparison. These batteries are typically comprised of CHEAP poly chemistry and consume minimal current (There maybe exceptions to the rule.). While they maybe regularly charged, they still consist of low quality form fitting materials.

Volfy

My Feedback: (23)

This LiPo vs. NiMH thing has been argued with near religious fervor. People seems to take offense to being told there is a less expensive alternative to their spending $150 on LiPo systems. Then again, such is the case with so many other popular RC issues, so I am not surprised. People far too often regard performance and inexpensiveness as mutually exclusive.

LiPo is definitely not required for a high performance battery power system, not only for 50cc and below, but also 33% and above. LiPo may be the latest battery technology to enter RC, but NiMH has not exactly been sitting idle either. For example, I routinely use twin 1100mAh 2/3A 5-cell NiMH packs on two switches. These cells are rated at 20C dischage rate, which means I have effectively 2200mAh capacity and 44A peak output current (which is only limited by the switch/RX wiring). Total weight: 6 Oz. I can find no LiPo system that can match this level of current output. Most regulators are rated at 10A tops, an they become less efficient at high discharge current levels. That 2200mAh LiPo pack may only yield effectively 1870mAh if the regulator carries an efficiency of 85%. The rest gets dumped out the heat sink.

Everybody's style is different. I love using a field charger. It guarantees that my battery system is operating at the maximum level EVERY single flight. I frankly don't see why I would want to carry 3 weeks worth of capacity onboard when each flight only lasts 10-15mins. It's like driving a Porsche Boxter with a 200gal gas tank.

Coupled with 2 Tritons chargers at home for cycling my battery packs, I don't bother with ESV any more. IF something is wrong with my batteries, either the Tritons or the field chargers will let me know. With this system, I have simplicity, reliability, lightweight, redundancy, and fault detection before every flight. All at a fraction of the cost of LiPo.

Then again, your mileage (or flight time) may vary.

JohnVH

My Feedback: (38)

Im the opposite, if my Porche could hold 200 gallons, and not have the weight of the 200 gallons, Id do it in a heartbeat.. Why not? Im more guarentee'd that my packs will have required juice in them. win win

Volfy

My Feedback: (23)

...Except the Porsche is used for nothing but 5-mile commutes. ...And the lightweight 200gal conversion cost US$25K. ...And it offer little performance advantage other than duration before gas-ups.

JohnVH

My Feedback: (38)

obviously differing opinions, I wouldnt buy a Porsche to go 5 miles, Id buy it to drive it. And I like my planes to be able to go 5-10 flights per day without chargers and garb. And Ive only gotten that from Fromeco's.... $25K I wouldnt spend, but on these models, $100-300 extra to me is no biggie to have that freedom of no more charging at the field, no more carrying heavy flight boxes with batteries that always seem to die when I need to charge up my planes.. FREEDOM

rmh

The LiPos I buy for my foamies are fantastic -they run at least 15 C on discharge.
these really make sense to me -- (I use TP almost exclusively )
The 3200 gold peak I mentioned can be used to weld -
and if --just if--- I wish to field charge - just nuke it--
The LiIon setups do produce a regulated output - and one of the reasons they fly longer is that you can't slurp up as much current
but that's just an other opinion .
To each his own poison.

mglavin

My Feedback: (31)

Dick

You hit the nail squarely on the head with this comment. There's nothing like having the all mighty powerful servos and then putting a choke hold on them with inadequate power and distribution sources... Remember when "just add another a servo" was the answer to blow back, more and bigger is better attitude. I always thought it made more sense to simply provide the required power to feed the flight system to achieve the same goals, while saving weight, cost and complexity. Wait a minute I still do...

Volfy

My Feedback: (23)

All the supposed advantages of LiPo eventually boils down to nothing but CAPACITY. Even that is getting easier to match with the ever increasing NiMH cell capacities.

But being able to fly for 5yrs without recharging is pointless if the regulator does not funnel enough current to meet demand.

I love LiPos for small electric airplanes with brushless motors. No regulators necessary there. Until someone develops a linear or switching regulator that can pass some serious current with some reasonable efficiency %, OR make all the servos and RXs 7.4V-rated, I'll stick with NiMH for RX and ign.

ptgarcia

My Feedback: (36)

You can bet we will see this soon.

I have a questions for the experts out there. I hear talk about receiver batteries of whatever chemistry (I'm not talking about LiPo's powering electric powered planes) being able to supply 15C to 20C (20 amps +) on discharge. I also hear talk about the connectors to our receivers only being good for 3 amps. So does this mean unless you have 7 connections to the receiver or a special power distribution system of some sort you can't take advantage of that 15C current supply?

3D Joy

What is an adequate power source ?

I always thought that Nimh internal resistance was higher than Ni-cad but lower than li-xx so with enough capacity, Nimh should (I think) provide enough current in a twin-pack, twin-switch setup.

Just went to the Sanyo website :

2300 mah "AA" size cells have an internal resistance of something like 25 uohm. Slightly larger and less capacity cells (2100 mah) have an internal resistance of only 5 uohm. All Nimh cells. The graphs presented the discharge curves at various amperages. The 2300 had highest current listed at 4A and the 2100 had the highest current set at 30A without too much capacity loss.

From what I understand, my 2 brand new 6V 2300 mah packs are useless...