HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 01, 2006, 05:41 PM
on a windswept field
E. Windsor, CT
Joined Oct 2006
67 Posts
Question
Are LIPOs Cost Effective vs. NIMH?

Just a beginner here. Wondering if Lipos are cost effective vs. NIMH. Comparing a 2100mah (2s) lipo to a 1500mah nimh (7 celll), I see 1.9 cents for lipos vs. 1.6 for nimh (assuming cycles are the same). Please educate me so I know what to buy. Use is in EZ* for AP. Thanks in advance.
n1st is offline Find More Posts by n1st
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 01, 2006, 05:50 PM
Back in black............
dodd city tx
Joined Sep 2005
2,059 Posts
If your series about the ap thing with your easy* then i would highly recommend lipos. you will be adding weight with the camerae so you need to shed as much a possible. I have just started switching over to lipo's wish had done it a long time ago. the easy is a great plane and when you want to go brush less and run 3s for more power you will already be set up for the lipos and want have to by new stuff like me.
cars4fun2001 is offline Find More Posts by cars4fun2001
Reply With Quote
Old Dec 01, 2006, 05:51 PM
Back in black............
dodd city tx
Joined Sep 2005
2,059 Posts
by the way check out http://www.rcgroups.com/forums/forumdisplay.php?f=128
cars4fun2001 is offline Find More Posts by cars4fun2001
Reply With Quote
Old Dec 02, 2006, 08:36 AM
on a windswept field
E. Windsor, CT
Joined Oct 2006
67 Posts
Quote:
Originally Posted by cars4fun2001
If your series about the ap thing with your easy* then i would highly recommend lipos. you will be adding weight with the camerae so you need to shed as much a possible. I have just started switching over to lipo's wish had done it a long time ago. the easy is a great plane and when you want to go brush less and run 3s for more power you will already be set up for the lipos and want have to by new stuff like me.
Thanks for the opinions. Any information available on how many cycles you typically get out of lipo vs. nimh?
n1st is offline Find More Posts by n1st
Reply With Quote
Old Dec 02, 2006, 09:25 AM
Back in black............
dodd city tx
Joined Sep 2005
2,059 Posts
If you take care of them they last for a very long time from what i understand. When buying your lipos get some that are rated for higher amp draw then you intend to draw. on the easy star the stock motor will draw 16amps if proped for it. so I would get some that are rated for at least 30 amps. That Way if you go to a brush less motor you still want be pushing the lipos to hard. The easier you are on them the longer they will last. the stock 480 that comes in the easy can run 3s and 10 amps pretty easy and give good power. It will last a long time this way and your flight times will be good with the lower amp draw.
cars4fun2001 is offline Find More Posts by cars4fun2001
Reply With Quote
Old Dec 02, 2006, 09:40 AM
Registered User
Madrid (Spain)
Joined Oct 2004
483 Posts
n1st,

For a 10A plane such as the EZ, there are many options, but to me the cheapest seems a 8-cell pakc of 1400 NiMh (2/3A size) like VTEC or IB1400 or GP1300. Those retail for around $1'50 to $2'50 each, can be charged in a hurry in less than 30 minutes so you are done with a couple of packs. Total cost around $35, and non stop flying.
They will last hundreds of charges, lipos are more fragile and rarely you got more than 50 charges of them, specially on the cheap side. My oldest VTEC1400 pack has been used now for more than 60 cycles, some of them really bad (charging in 12 minutes at 7A and to 70 Celsius a coulpe of times...), and still going strong and showing +1300mAh on controlled discharging. Hard to beat, really.
Josep
armengol is offline Find More Posts by armengol
Reply With Quote
Old Dec 02, 2006, 09:42 AM
Registered User
Florida
Joined Aug 2004
4,048 Posts
You will typically get 10 times as many cycles out of NiMh versus LiPo before replacement is required and 20 times as many cycles out of NiCad.
Rodney is offline Find More Posts by Rodney
Reply With Quote
Old Dec 02, 2006, 09:54 AM
Motors beat engines!
Milwaukee Wisconsin, United States
Joined Feb 2001
4,564 Posts
Quote:
Originally Posted by n1st
Just a beginner here. Wondering if Lipos are cost effective vs. NIMH. Comparing a 2100mah (2s) lipo to a 1500mah nimh (7 celll), I see 1.9 cents for lipos vs. 1.6 for nimh (assuming cycles are the same). Please educate me so I know what to buy. Use is in EZ* for AP. Thanks in advance.
Are you just multiplying 2100 x 1.9 and 1500 x 1.6?

That would seem to indicate a $40 lipo and a $24 nimh.

That number seems right for the nims, but for the lipo why would'nt you use a $20 common sense 2s2000 lipo? 16 amps continous, and your easy star on 2s is probally using only 12 amps.
That would drop your multipling number to only 0.95 for the lipo, so based on cost alone the lipo wins, but then theres the other factors, run time, voltage under load, ( especially at the end of charge), and the convenience of not needing to top off the batts at the field before every flight.

The nimh might be slightly more powerful, ( depends on the which one you choose), but has a bigger total voltage drop during discharge then the lipo's so it seems much weaker at the end then the lipo's do.

2s lipo volts under load start: 7.4 end 6.6 total loss 0.8v or about 11%
7s nimh volts under load start 8.4 end 6.0 total loss 2.4v or about 29%

So, nimh starts out a bit stronger, but ends up noticably weaker, plus they're heavier, plus the don't hold as much juice, plus they need to be topped up before each flight, plus they now cost more.

Hard to imagine anybody using nimhs anymore unless they maybe already owned the parts.

Dean in Milwaukee
DeaninMilwaukee is offline Find More Posts by DeaninMilwaukee
Reply With Quote
Old Dec 02, 2006, 10:01 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,512 Posts
To many variables however I have used NiCads for over 40 years,NiMH for 20 years and LiPolys for 2-1/2 years and my experience seems much different from others.

NiCads such as the old Sanyo SCR 1000s lasted what seems like forever if not always charged at 6C and discharged at 30C plus.
Higher capacity NiCads such as 2400s are no where near as long lived.

My top quality(?) GP3300 NiMH packs ,charged at 1-1.5C and discharged at 4-6C started going downhill fast at just over 50 cycles.

http://www.rcgroups.com/forums/showp...67&postcount=1


I have LiPolys which have been used mostly in the 5-7 C range that have lasted well over 100 cycles and a few that have lasted between 200 and 400 cycles.

I am hoping that the new A123 / M1 cells are everything they are claimed to be. If they are then NiCad , NiMH and even LiPoly useage will be greatly reduced in many RC applications.


Charles
everydayflyer is offline Find More Posts by everydayflyer
Reply With Quote
Old Dec 02, 2006, 10:04 AM
on a windswept field
E. Windsor, CT
Joined Oct 2006
67 Posts
Quote:
Originally Posted by armengol
n1st,

For a 10A plane such as the EZ, there are many options, but to me the cheapest seems a 8-cell pakc of 1400 NiMh (2/3A size) like VTEC or IB1400 or GP1300. Those retail for around $1'50 to $2'50 each, can be charged in a hurry in less than 30 minutes so you are done with a couple of packs. Total cost around $35, and non stop flying.
They will last hundreds of charges, lipos are more fragile and rarely you got more than 50 charges of them, specially on the cheap side. My oldest VTEC1400 pack has been used now for more than 60 cycles, some of them really bad (charging in 12 minutes at 7A and to 70 Celsius a coulpe of times...), and still going strong and showing +1300mAh on controlled discharging. Hard to beat, really.
Josep
Quote:
Originally Posted by Rodney
You will typically get 10 times as many cycles out of NiMh versus LiPo before replacement is required and 20 times as many cycles out of NiCad.
You've helped me decide to go with nimh for my EZ*. I use 380ma lipos for a 6oz plane of mine, but that's a specialized application. Thanks guys.
n1st is offline Find More Posts by n1st
Reply With Quote
Old Dec 02, 2006, 10:25 AM
Registered User
Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Most decent NiMH cells last far beyond 50 cycles in normal use.

No question, though, that the future is Li, with Saphions, A123s and M1s being among the first to combine safety, performance and weight advantages over NiCd, NiMH and early Li-ions and LiPos.
Dave Hederich is offline Find More Posts by Dave Hederich
Reply With Quote
Old Dec 02, 2006, 10:27 AM
Ego varius quis.
Cheesehead's Avatar
Wisconsin
Joined Nov 2003
1,923 Posts
CommonsenseRC has 2,000mah lipo packs for $20, or 2/$35.
Cheesehead is offline Find More Posts by Cheesehead
Reply With Quote
Old Dec 02, 2006, 10:29 AM
UN Earth peoples true enemy
treehog's Avatar
Euroland
Joined Jan 2004
1,797 Posts
I would rarely consider to NIMH for most small planes unless bujet was realy tight

I would rarely consider to NIMH for most small planes unless bujet was realy tight
I use both and the small lipos for small planes even at 200 cycles wouild be cents per flight and would often be 30% lighter and i find small planes which are lighter dont break so often and so I get saving from that

On bigger planes i cant afford the LIPO and often my bigger planes are 20C plus so Lipo isnt a real option anyway

but the small packs of NIMH can sometimes be for nearly nothing probably fire seling them to get rid of them so for 20c plus use in pylon are still interesting and flight costs can sometimes be real low cents per flight

Ralf
treehog is offline Find More Posts by treehog
Reply With Quote
Old Dec 02, 2006, 10:45 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,512 Posts
Quote:
Originally Posted by Dave Hederich
Most decent NiMH cells last far beyond 50 cycles in normal use.

No question, though, that the future is Li, with Saphions, A123s and M1s being among the first to combine safety, performance and weight advantages over NiCd, NiMH and early Li-ions and LiPos.

Dave that is exactly why I provided a link to real usage, hard data not use here say on the GP3300s.

CBA Graphs show original capacity and Data Logger Graphs shows typical usage for these packs.

Also why I opened with

Quote:
To many variables however
and made a point of comparing like digharge C rate comparisions.


I have NiMH AAs over 11 years old with well over 1000 cycles on them and I have Sanyo SCR 1000 NiCads that are over 25 years old with hundreds of cycles on them .


NiMH cells will last 1000 cycles ,LiPolys will last 500 cycles and A123 will last 1000 and each manufacture has graphs data to prove it.

Myself and son have 3 cordless Drill / power tool sets ( 3 Drills,Saw and flash light)with a total of 6 battery packs. The oldest are just over two years old and the newest are approx. 1 year old. None have been used over 100 cycles and even though I have tried to take reasonable care of them non will hold a charge.

Charles
everydayflyer is offline Find More Posts by everydayflyer
Last edited by everydayflyer; Dec 02, 2006 at 10:51 AM.
Reply With Quote
Old Dec 02, 2006, 10:46 AM
on a windswept field
E. Windsor, CT
Joined Oct 2006
67 Posts
Quote:
Originally Posted by DeaninMilwaukee
Are you just multiplying 2100 x 1.9 and 1500 x 1.6?
That would seem to indicate a $40 lipo and a $24 nimh.
Dean in Milwaukee
Dean,

Exactly. I didn't know about the $20 price and was using a $40 Apex 2100mah price. But still, if there really is a factor of 10 X more cycles for nimh, nimh is far cheaper.

Would someone post the link for the $20 2/35$ common sense 2000mah lipos - I'm not finding them on their website.

Any other # of cycles opinion/expericence folks can offer?
n1st is offline Find More Posts by n1st
Last edited by n1st; Dec 02, 2006 at 12:07 PM.
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion What are the dis/advantages of 2s vs. 3s lipos? DaveInLA Batteries and Chargers 13 Nov 05, 2006 09:25 PM
10 Cell Nicad Vs Nimh F5b High Amp RV4PILOT Batteries and Chargers 4 Dec 07, 2002 04:05 PM
Kokams vs Nimh- What do you all think? austinelse Batteries and Chargers 10 Dec 01, 2002 10:16 PM
What are the best >=3000 ma Nimh Sub Cs jmelzer Electric Plane Talk 2 Sep 29, 2002 12:28 PM
500AR's - VS - NIMH RonJ Electric Plane Talk 3 Dec 09, 2001 06:44 AM