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Li-Ion vs. NiMh the verdict is out...

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Li-Ion vs. NiMh the verdict is out...

Old 02-03-2006, 02:23 PM
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Default Li-Ion vs. NiMh the verdict is out...

Many of you have read on my posts my love for Li-Ion power and heard me touting the benefits... some agree with me, some don't. I decided to post some data here that hopefully will reinforce my point, or at the very least - give you some hard, factual data you can use to make a decision as to whether Li-Ion is for you.

We have all seen the numbers on the websites and the factoids circulating here on RCU... well, I got the scale and the calculator out and ran the numbers....

I have a plane on the bench where the customer wants Ni-Mh power, so he has supplied all the parts to me. I also have an identical Li-Ion setup going so I decided to take all the stuff and weigh it and cost it out..... here are my results:

Both planes are 33%, have Hitec 5955TG servos throughout, 3W engines (so no ignition regulator is required). The setup included 2 RX batteries and 1 IGN battery through separate switches into the RX. Provisions for an electronic cut-off are also included.


NiMh Setup:

3 1950 mAh 5-cell (6V) batts Cost $40 each , weight 7.9 oz on high accuracy scale
3 JR HD charge / switches Cost - $22 each weight, 1 oz ea

This is a 6V system for a 33% Aircraft. Total weight = 27 oz Total cost = $186

Batteries were purchased from hangtimes hobbies (NO BS batteries)


Li-Ion Setup:

3 2400 mAh Li-Ion Relion Batteries Cost $27.00 each, weight 3.3 oz each
1 Duralite (powerbox) two channel regulated E-Switch Cost $118 weight 1.5 oz

Total weight 11.5 oz Total Cost $199


# of 15 minute sequence flights with NiMh - 4-5
# of 15 minute sequence flights with Li-Ion - 8-9


So in conclusion

COST = about the same, NiMh a bit less overall
Weight = The Li-Ion setup is a full pound less than NiMh
Capacity = Li-Ion is nearly double do to there being no "drop off" current (i.e. the Li-Ion pack will produce the full current right down to its no-fly voltage)
Time = no forming charge required, simply charge the Li-Ion pack and use it.

There is of course the issue of changing chargers which does add expense - but Fromeco makes a great no-brainer of a 3 channel charger for $110 bucks.

As for the so called "dangers" of Li-Ion.. .they are no more dangerous to charge (assuming you have the right chargers) than any other technology. In fact, since the chargers are microprocessor controlled and include overcurrent sensors and constant current monitors I would debate that they are actually SAFER than older technologies.


There also is one other very nagging annoyance with NiMh... they discharge themselves over time. It is very necessary to "top off" charge a NiMh after it sat for a while... with Li-Ion, I have had packs sit for 6 months without use and still have nearly a full charge... HUGE benefit. What that means is that you can make multiple trips to the field and if you monitor your battery level like you would a fuel tank, you eliminate many charge cycles... saving time and extending the battery life tremendously.

Before Li-Ion technology I thought batteries were a complete PITA. I spent a lot of time checking, charging, discharging, etc, etc... now.. I just fly.
IMO Li-Ion is the only way to go!
DP




Old 02-03-2006, 04:52 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Concise and complete with real live facts. If I hadn't already made the conversion
this would have sure made me think hard about it. Nice job.
Old 02-03-2006, 06:38 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Does the Duralite box also provide a switch for the ignition in the LiIon setup?
Old 02-03-2006, 07:26 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Another bit of info about the Fromeco charger is that it doesnt have an issue with a common ground so you can charge both packs while plugged into the rx.
Old 02-03-2006, 07:26 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

The only thing that wasn't mentioned is pack life. From what I've read Li-Ion has a shorter useful life of about 2 years as compared to 3 for NiMh. Please correct me if I'm wrong. Only other minor point is that you've listed a dual regulator switch for the Li-Ion but none for the ignition system.

One other point is that the regulator limits the peak current output of the Li-Ion batteries. There is no regulator on the NiMh packs, its current is limited by the packs internal resistance. Does it matter? I don't know. Peak current available should matter to power hunger digital servos. The only way to really find out is with an airborne data logger. I'd run one side of the plane with NiMh and the other with Li-Ion that way the torque experienced by the servos would be as equal as possible the only differences being the batteries themselves.

Good solid information, good job.
John
Old 02-03-2006, 09:09 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Great post DP...........You can get the same 1950 mAh FAUP cell packs from Radical RC for $30 including connector of choice.
Old 02-03-2006, 09:51 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

NiMh Setup: MODIFIED

3 1950 mAh 5-cell (6V) batts Cost $30 each , weight 7.9 oz on high accuracy scale
3 JR HD charge / switches Cost - $13 each weight, 1 oz ea

This is a 6V system for a 33% Aircraft. Total weight = 27 oz Total cost = $129

Batteries and switches were priced from Radical RC

Li-Ion Setup:

3 2400 mAh Li-Ion Relion Batteries Cost $27.00 each, weight 3.3 oz each
1 Duralite (powerbox) two channel regulated E-Switch Cost $118 weight 1.5 oz
1 JR Heavy Duty Switch - $13 each
Total weight 11.5 oz Total Cost $212
So using better pricing $129 verses $212 about 60% difference. Is it enough of a difference? Only you can answer the question.

John

EDIT-> I swear I'm getting senile. The RRC heavy duty switch harness is $9.50 not $13.00 and no I'm not going to re calculate it.
Old 02-04-2006, 12:04 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...


ORIGINAL: JNorton
Only other minor point is that you've listed a dual regulator switch for the Li-Ion but none for the ignition system.


the new 3W ignitions do not require or recommend that you use a regulator
Old 02-04-2006, 07:59 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

ORIGINAL: exeter_acres

ORIGINAL: JNorton
Only other minor point is that you've listed a dual regulator switch for the Li-Ion but none for the ignition system.
the new 3W ignitions do not require or recommend that you use a regulator
I'm sorry I just meant a switch to turn off the ignition battery the same as you had shown for the NiMh setup. Surely you need to turn off the ignition?

I'm not against Li-Ion packs. I believe you and I had this conversation before and what I took from the conversation was that it was very much up to the individual. I don't have problems maintaining NiMh packs that you seem to. I just use Red's method of having them on a trickle charge for one hour out of 24.

For 3D ships I can see where the weight savings is important. For scale models with a short nose moment perhaps the heavier NiCads make more sense used as nose weight.

The price of Li-Ion packs keeps coming down to where as you have shown it's very competitive with NiMh packs. It's up to the individual where they want to spend additional money to have lighter weight.

John
Old 02-04-2006, 08:27 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

And now I'm confusing DesertPig and ExerterAcres - Sorry guys.
Old 02-04-2006, 10:10 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

sorry...missed that....correct it appears the third switch is not listed.........



and I do agree with you 100%... while I use LiIon (on a 3D and IMAC machine) Ni setup would also work just fine..... it is a personal preference.....
Old 02-04-2006, 06:55 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Dp, I do have a question for you....
Have you talked to Duralite about the E switch as I see its listed as 5amps...is that each channel or combined?
Old 02-06-2006, 05:58 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

ORIGINAL: SitNFly

Does the Duralite box also provide a switch for the ignition in the LiIon setup?
No - I hard wire the ignition cut-off relay into the ignition battery, therefore, unless there is RX power, the ignition pack will not be in the ign circuit. I use a RC-100 cutoff (NOT the opto-isolated one) and plug it into the gear channel on the RX. I do this on all my models as I hate having 3 switches.

DP
Old 02-06-2006, 06:08 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

ORIGINAL: andyt

Dp, I do have a question for you....
Have you talked to Duralite about the E switch as I see its listed as 5amps...is that each channel or combined?
If you look on www.aircraftinternational.com in the powerbox section, they have several styles. The best one is the powerbox 12 sensor it handles 6A per side and is completely redundant. . more than enough for any app at a very good price.

Mfrs are finally getting smart. NOW if servo and RX makers would just design their stuff to run on the 7.4 unregulated voltage and eliminate the need for regs altogether we would really be getting somewhere...

DP
Old 02-06-2006, 06:17 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

ORIGINAL: JNorton

So using better pricing $129 verses $212 about 60% difference. Is it enough of a difference? Only you can answer the question.

Even with the difference in cost, you are greatly simplifying operations (i.e. one switch instead of 3) and shedding a full pound of excess weight. I don't know too many other ways of spending only $80 to lose a pound. Many of us routinely spend $100 on a CF spinner to shed 3 oz!!

I figured there were cheaper batteries out there, but I tend to stick to the good brands like NoBS, Duralite, JR, etc...

DP



Old 02-06-2006, 07:06 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...


ORIGINAL: desertpig



Even with the difference in cost, you are greatly simplifying operations

DP

Not ot mention that you dont need to bring a field charger and charge between flights..one less thing to lug around
Old 02-06-2006, 07:34 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

ORIGINAL: desertpig
ORIGINAL: JNorton
So using better pricing $129 verses $212 about 60% difference. Is it enough of a difference? Only you can answer the question.
Even with the difference in cost, you are greatly simplifying operations (i.e. one switch instead of 3) and shedding a full pound of excess weight. I don't know too many other ways of spending only $80 to lose a pound. Many of us routinely spend $100 on a CF spinner to shed 3 oz!!

I figured there were cheaper batteries out there, but I tend to stick to the good brands like NoBS, Duralite, JR, etc...

DP
DP

Your original post showed parity. The modified post showed there was a 60% difference in price. You said the verdict is in. My reply is that it is still a matter of personal preference and or application.

I'm really interested in building a war bird. On a warbird that needs weight in the nose I'll take the weight, NiCd batteries and less cost. It all depends upon your application. I do not know anyone building tail heavy scale models that would shell out $100 on a carbon fiber spinner. Do you? How about the guy who is just a sport flyer. He wants a plane that flys good but isn't concerned about competition or 3D. Is he going to spend the extra money? I don't know I'm not him.

In reference to one switch being simpler than three. Granted so take the one switch and use parallel switching FET's and you can have the same thing regardless of the battery technology. Something like this http://www.flyheli.de/english/eel_switch.htm

As far as brands of batteries I've never heard anyone bad mouth Radical RC. They are a supplier that Red has recommended. they sell quality battery packs.

John

PS If I was flying 3D (which I don't show much interest in since my reflexes have been compared to someone wearing boxing gloves) I'd have Lithium packs in a heat beat. As I said before you've done an excellent job comparing the two chemistries
Old 02-06-2006, 07:39 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...


ORIGINAL: JNorton

my reflexes have been compared to someone wearing boxing gloves
LOL!! Thas a good one[8D]
Old 02-06-2006, 07:58 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Hey Josey, someone said know your limitations.
Old 02-07-2006, 10:21 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

I consider Duralites some of the best money I've spent on helis. No field charging, a switch safe regulator eliminates switch failures from vibration etc and with all digitals and a governor I can get 8 flights + per day. Also if I charge them when I get home from the field, whenever I get a chance to fly next I know the batteries are ready to go.
Old 02-07-2006, 10:52 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

I will clarify my statement above. I agree it all depends on the application - no sense putting in light batteries if you have to add nose weight anyway. I am mainly recommending this system to those who fly high performance aerobatic planes. In that application we are always challenged to keep the weight down and maximize our flight time.

I forget that that others call warbirds Giant Scale as well.. (there are some very big warbirds out there of course)..

My definition of a giant scale plane for this discussion is a 85" or larger lightweight Aerobatic airplane with 6-10 digital servos and an engine with a electronic ignition.. it is flown for sequences or 3D.

In that application, Li-Ion chemistry makes perfect sense. Others - well you will have to judge for yourself if its worth the $$.

DP



Old 02-09-2006, 09:38 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

What about Li-ion compared to li-poly??
Old 02-09-2006, 01:31 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Li-Poly (Li-Po) is expensive, fragile, and has issues with cell balance that either make for a low battery life, or a complex charging regimen. They also are not tolerant of any mistakes and will go incendiary if overcharged, or even damaged (as in a crash)... they don't like vibration either (i.e. like in gas powered planes).

I won't use them except on small park flyers or foamies (where I can take cover when I see them swell up!). The E-flight guys who have 10 grand to blow on batteries use bricks of them in a single plane.. and they don't last long! Duralite, Powebox, and Emcotech make some nice balanced Li-Po packs for general use, but they are ungodly expensive and other than looking really cool.. they don't save much weight over Li-Ion....

Like everything else though... as technology improves, cost will go down, and safety will go up.... form factor will shrink. I would stick to Li-Ion for now though on anything gas powered... no real advantage using Li-Po.

DP
Old 02-27-2006, 02:34 PM
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Default RE: Li-Ion vs. NiMh the verdict is out...

I am finding out it seems that Li-Ions don't like to sit unused. Although the literature says cycling is not necessary, sitting unused can weaken the batteries. So I have to think that if the batteries are cycled it will function as would using them for flight.

Anyone have any recommendations for cycling Li-Ions?

Another consideration in your equation is longevity/shelf life

How do Li-Ion, NiMh and NiCd compare?

I think Li-Ion is about 2 yrs, no idea on NiMh and NiCds seem to last a long time

Thanks
Old 02-28-2006, 03:56 AM
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Default RE: Li-Ion vs. NiMh the verdict is out...

Good Post .. congratulation

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