RunRyder RC
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1863 views POST REPLY
HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › pros and cons of lipos over Nicad?
01-18-2010 05:52 PM  8 years agoPost 1
777ER

rrApprentice

Westchester county, NY, USA

My Posts: All  Forum  Topic

Hi,

I currently have nicads in my RC fleet (all glow powered) but have noticed many are using lipos to power the Rx and on board electronics. While I do know the dangers of lipos which can start a fire when damaged or punctured, or by overcharging them.

However what's the benefit of using them compared to nicads?

Back then, I kept using nicads when nimh was coming out but was a issue with the mah rating and the voltage dropping off bigtime instead of slowly dropping like nicads does.

-Chris

PM  EMAIL  GALLERY  Attn:RR  Quote
01-18-2010 06:10 PM  8 years agoPost 2
cbflys

rrVeteran

Nesconset, NY - USA

My Posts: All  Forum  Topic

However what's the benefit of using them compared to nicads?
Better energy density (lighter, lasts longer).

PM  EMAIL  GALLERY  Attn:RR  Quote
01-18-2010 06:26 PM  8 years agoPost 3
2LTime

rrKey Veteran

Walworth,NY

My Posts: All  Forum  Topic

Here's what I got:

LIPO:
Pros:need to charge less, cells have no memory, constant voltage
Cons:Possibility of fire, needs a regulator

Nicd/mh:
Pros:Safer, no regulator
Cons:charge more often, heavier for same capacity, output voltage varies as pack is dicharged

I have gone to almost all LIPO simply so I don't need to charge as often. If I burn my house down, I'll probably switch back. It is real nice to charge the helis once every 10 flights and no you still have plenty of reserve. I have a plane running standard servos and a switching regulator that with a relatively moderate size Lipo will last at least 40 flights, and then still not need charging ( but I do just because I can't believe it's still going).

Jeff

If you can't learn to do it well, learn to enjoy doing it badly.

PM  EMAIL  GALLERY  Attn:RR  Quote
01-18-2010 06:33 PM  8 years agoPost 4
cbflys

rrVeteran

Nesconset, NY - USA

My Posts: All  Forum  Topic

Pros:need to charge less
With all due respect, this statement is relative ...

For example a 2S LiPo pack (7.4v) and a 6S NiMH pack (7.2v) with identical capacity (mAh) ratings will have essentially identical performance (discharge current rating not withstanding). However, due to the energy density - the LiPo pack will be lighter.

Maybe my original statement is misleading (light, lasts longer). Given equal ratings the LiPo will be lighter. But given equal weight, the LiPo will have a higher capacity (last longer).

PM  EMAIL  GALLERY  Attn:RR  Quote
01-18-2010 07:23 PM  8 years agoPost 5
xxcysxx

rrKey Veteran

Baltimore, MD - USA

My Posts: All  Forum  Topic

On a conservative lipo setup, a regulator is required. A regulator adds to another point of failure, rf noise issues that can be dificult to diagnose and cause misserable amount of crash cost. A lipo battery also looses it voltage in the cold when i fly in the winter. Thunder power as rx here!!

i have used arizona, align and reactor, and although i've never experience any problem with them, i have swich back all of my models to round cells NiMh for piece of mind sake. I even eliminate a power switch and use a heavy duty ultra deans in its place to power my electronics. Very reliable!!
Although round cells are known to be slightly heavier than the lipo cells, it actually weight out to be the same as the lipo cells with the regulator and its wires harness and swtching system.
My models balance out very well with five 'a' round cells. i get about four to five flights to a charge and at about three dollars a cells i built about two to three packs for spares.

I have since sold all my regulators and used the rx lipo on my slow stick for fun.

Tam

PM  EMAIL  Attn:RR  Quote
01-19-2010 01:31 AM  8 years agoPost 6
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

Nicads are reliable, have a relatively flat discharge curve, can supply some serious amperage when needed, are pretty tame and forgiving when it comes to charging, discharging, and overcharging. They can be fast charged without damage. The memory effect is way over rated, and if you cycle your batteries perhaps once a season, is not a concern. They stand up well to vibration and survive crashes well. They are relatively inexpensive. Nicads, if cared for properly last for hundreds of cycles and can deliver good power for years.

On the down side, they do have a propensity for self-discharge. If you leave a pack on the shelf for awhile, it will eventually discharge on its own. Considering the amount of energy you can get into a cell, they end up being somewhat heavy for their size.

NiMh cells share about the same pro/con list with Nicads. Unless you get hold of cells based on the Sanyo Eneloop technology, they have a pretty fast self-discharge characteristic. Cells using the Eneloop technology, however, can remain on the shelf for up to a year and lose only about 15% of their original charge. These cells are great. Early technology NiMh cells had a relatively high internal impedance and could not deliver high amps without a severe droop in the terminal voltage. As the technology has improved, the internal impedance has gone down and the cells approach the discharge characteristics of Nicads.

Nicads and NiMh cells have a wider temperature operating range than LiPos. As with most battery chemistries, they don't like cold, but can be operated (and charged) in lower temperatures where you wouldn't operate or charge a LiPo.

LiPo cells have a higher cell voltage than Nicads or Nimh -- 3.7 volts nominal as opposed to 1.2 volts for Nicad/NiMh. You need a minimum of two in series to do you any good with the current crop of radio gear, and this requires that you use an external regulator to use with most common systems available today. That's an added expense, and an added point of potential failure.

LiPos have tremendous energy density. The amount of energy you can stuff into a cell compared to its weight and size is phenomenal. They can also deliver massive amounts of current with little or no self-heating. They are not, however, very forgiving. If you discharge too deeply (below about 3.0 volts per cell) you run the definite risk of destroying the battery pack. They don't hold up well in crashes. They have a tendency to burst into flames if overcharged, if over discharged, and some if simply discharged at too high a rate. Until recently, LiPo cells have been priced very high, making the decision to use them a difficult one. The price of LiPos has eroded to the point where there are reasonably priced packs for just about any heli configuration you can think of. A 6S battery pack for a Trex 500 is no longer $250, they can be had for $35 - $55 easily these days.

LiPos need a special charger to extend their life -- a balancing charger. Balancing was something no one thought about having to do with Nicad or NiMh packs. It never seemed to be an issue. If you don't balance charge, and if you overdischarge, it's easy to destroy a pack if the cells that make it up aren't particularly well matched for discharge characteristics.

LiPos begin to deteriorate from the date of their manufacture. They have a lifespan of about three years, and the clock starts ticking when the cell is made.

-----

If you are currently using Nicads and having good luck with them, there really is no need to switch over to LiPos.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 01:41 AM  8 years agoPost 7
cbflys

rrVeteran

Nesconset, NY - USA

My Posts: All  Forum  Topic

If you are currently using Nicads and having good luck with them, there really is no need to switch over to LiPos.
That says it right there ...

In fact, I personally wouldn't use a LiPo in a transmitter at all. I believe the risks far outweigh the benefits. In fact, the only benefit I can think of is faster charging.

As Dave pointed out, eneloop NiMH cells are great for this application and can be found in capacities almost if not as high as the LiPos some are using in their transmitters.

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 01:55 AM  8 years agoPost 8
Ironhide

rrVeteran

dexter mi us

My Posts: All  Forum  Topic

You guys probably don't like cell phones either

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 01:57 AM  8 years agoPost 9
cbflys

rrVeteran

Nesconset, NY - USA

My Posts: All  Forum  Topic

What's a cell phone?

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 03:57 AM  8 years agoPost 10
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

Cell phones are fine, but really, there is no need for a LiPo in a transmitter, NiMh cells using the Eneloop process work exceptionally well and you get all of the advantages of a LiPo and none of the risk.

As for the Original Post, I suspect the question was about flight packs, not TX packs.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 04:25 AM  8 years agoPost 11
koppter

rrApprentice

Virginia

My Posts: All  Forum  Topic

a few points - and keep in mind this just relates to a receiver pack..

1. don't forget LiFe...3.3v per cell, no need for a regulator, and truly flat discharge, no balancer. Don't explode into flames. Must have LiFe charging capability on charger. check out sin city jets or airwild pilot's shop. giving serious thought to LiFe for a 50cc gasser on both receiver and ignition.

2. fast charging does prematurely wear on nicads. the delta detection used in 99% of the chargers brings back the voltage only after the battery reaches peak, and that's hard on the battery. if done often, need to cycle once in a while to see what's left.

3. Each cell is unique, but in general, Nicads do not have flat discharge. they come off the charger hot, lose voltage immediately under load, and then begin a steady decline to about 1.2v, whereby they go down fast.

3. Pretty much all of the initial concerns regarding Nimh has proven to be baseless - they have been used successfully in a wide range of applications.

4. Would not put lipo in transmitter. Get 2700Mah Nimh cells. Cermark.com

5. according to the Sanyo Engineering Handbook...memory is caused by a repeated constant discharge to within 3% of the same point (remaining capacity) on a nicad. since our discharge varies with use, it really is a non issue for modelers.

6. Regulator/switch/glow ignitor systems like the Align 2n1 work well, and serve a purpose beyond just a regulator.

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 08:08 AM  8 years agoPost 12
naked painter

rrVeteran

Mid glamorgan uk

My Posts: All  Forum  Topic

I understand the benefits of a rx lipo, but I've seen a number of crashes due to lipo failure that I stick to nimh rx batteries.

The lipo either fails suddenly or the reg fails.

PM  EMAIL  Attn:RR  Quote
01-19-2010 12:09 PM  8 years agoPost 13
Ironhide

rrVeteran

dexter mi us

My Posts: All  Forum  Topic

I have had a lipo in my tx for over a year now . I don't see how you guys don't like it . I have a 2100 mah 3s in there . The stock crap is 900 mah . Over double the battery in the same spot .

As a rx lipo you can get away from the regs now with the right servo combination .

You guys still use those AA packs so you can keep a couple of spares in your pocket !

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 02:14 PM  8 years agoPost 14
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

I don't see how you guys don't like it . I have a 2100 mah 3s in there . The stock crap is 900 mah . Over double the battery in the same spot.
I get all the same advantages using 2100 mah NiMh cells using cells based on Eneloop technology. I get none of the disadvantages.

BTW, the "stock crap" is 1500 mah, not 900 mah for a DX7/X9303.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 03:55 PM  8 years agoPost 15
jake21

rrApprentice

ontario canada

My Posts: All  Forum  Topic

dkshema.
What NIMH size receiver battery pack would you recommend for a 90 size bird using all 9252s and a 9254? AA SubC? What brand and how much MAH? Sport to mild 3D flying.

The only way to not crash is up

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 04:08 PM  8 years agoPost 16
Darren Lee

rrElite Veteran

Woodstock, GA

My Posts: All  Forum  Topic

don't forget LiFe...3.3v per cell, no need for a regulator, and truly flat discharge, no balancer. Don't explode into flames.
+1

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 07:59 PM  8 years agoPost 17
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

I had been using some JR 4 cell packs, I think they were sub-c 2400 mah guys like these:

http://www.horizonhobby.com/Product...ProdID=JRPB4460

Used them both in a Freya (with JR 8231 servos/GY401-9254 and AR7000) and EVO 50 with AR7000/DS811/401-9254 stuff installed. Never a problem with these packs.

There are other similar packs you can buy on-line, just shop around.

The JR packs used Sanyo cells as I recall.

I thnk the Horizon site also has either a 3000 or 3300 mah pack similar to those, too, if you want more mah capacity.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 08:49 PM  8 years agoPost 18
Ironhide

rrVeteran

dexter mi us

My Posts: All  Forum  Topic

How much does that brick weigh ?

PM  EMAIL  GALLERY  Attn:RR  Quote
01-19-2010 10:51 PM  8 years agoPost 19
xxcysxx

rrKey Veteran

Baltimore, MD - USA

My Posts: All  Forum  Topic

Dave,
does the eneloop nimh cells capable of handling high current drain like the regular nimh, say about 15 amps burst.

by the way, this is what i used as my rx pack before on one of my ninety. You would consider this a monster pack. But on my trex 700 it balances out perfectly with the canopy mounted and horizontal fin removed. My setup is as simple as it get as you can see and i get 'a lot' of flights on a charge.

Tam

PM  EMAIL  Attn:RR  Quote
01-20-2010 03:46 AM  8 years agoPost 20
777ER

rrApprentice

Westchester county, NY, USA

My Posts: All  Forum  Topic

Sounds promising with the lipos.

Thanks for the the additional info, I have a new 90 planned and will be building it soon (when MA releases the 90).

This lipo stuff is new to me in RC applications...I do know my cell phone has a lipo in it.

So when I go to lipo's, I would have to get a new charger then.

What I do before heading out to the flying club (about 30-40 mins drive), I hook up the first aircraft and tx to fly to the Quick field charger to top it off and keep it trickle mode. About halfway to 3/4ths of the way there, it's in trickle mode and ready to fly.

Can this be done safetly with a lipo?

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1863 views POST REPLY
HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › pros and cons of lipos over Nicad?
 Print TOPIC  Make Suggestion 

 8  Topic Subscribe

Saturday, September 22 - 12:30 am - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online