RC Extreme power

My Feedback: (24)

The reason I say to run on 4.8 volts is that a 6 volt battery that is fully charged is over 6 volts and has damaged some ignitions, You gain nothing running 6 volts except dumping your battery quicker.

If you want to run a 2S A123 battery use a regulator and set to 5.2 volts or you will damage the ignition

Milton

Gatorb8

Thanks Milton,
I'll look for a suitable regulator. I like the fast charge of the A123.
Gator

FLPilot

My Feedback: (23)

A simple diode or rectifier can be used as well. No additional weight of any significance, simple to install and work great.

Use one with a .7 or .8v drop. I use these from Mouser Electronics. Silicone Rectifier (Diode) 610-1N5627 800V 3.0A (.8v drop) Use one (1) or two (2) depending upon your needs. I am using two 1n5627 on each of my two A51's.

Also, this thread is an excellent read..... http://www.rcuniverse.com/forum/m_61..._1/key_/tm.htm

And this site has excellent A123 information... http://www.rcaerobats.net/

Radio shack is also a good source. Cost is under a dollar.

A123's are excellent, re-charge at field with the FMA Cellpro 4S in 15 minutes or so.

Gatorb8

I'm embarressed! I'm an electrical engineer and I didn't think of that! I'm so overwhelmed with all the details of my first 50cc build....
Thx
Gator

Bass1

Yeah, me too!

JoeAirPort

My Feedback: (41)

What kind if current can those diodes take before melting?

craigteffe

My Feedback: (24)

I think if you look at the post above the diode listed is rated at 3A. You can purchase different amp rating diodes.

Gatorb8

I just spent a few hours reading that thread, GREAT THREAD!
thx
Gator

Super08

My Feedback: (2)

It is too late for me, I bought a 102cc in Oct. Maybe you can be saved........but I doubt it.

FLPilot

My Feedback: (23)

The 1n5627 listed is a silicone 3amp capacity. RCEXL Ignition documentation indicates an amperage draw of less than 1 amp at max 9000 rpm.

RC Extreme power

My Feedback: (24)

I know that I am going to get a lot of slack for this post but going to post it anyway.

I still can not figure out the advantage of using A123 batteries for the ignition, the only thing I see is being able to charge them in 15 min compared to about 30 min for NIMH.

Now
A set of 2300 A123 cost around $50.00 and weigh about 5.5 ozs plus the regulator which comes up to about 7 ozs total and then another charger to charge the A123
I can understand using them for the flight system with the use of more servos and some of the higher amp draw servos to keep the voltage drop up a little higher.

A set NIMH 4.8 volt 2250 cost about $30.00, Weight is about 5 ozs and needs no regulator and can be charged in about 30 min.

Now again if you go to the flying field and fly continuously till you pack up and go home the A123 would be best for you as they will charge in 15 min but for the most part people do not fly continuously and have ample time in between flight to charge there batteries.

Also you gain nothing running a RC Xel ignition on voltage higher than 4.8 volts

Maybe I have my head in the sand or still leaving in the back woods, But I still do not see the advantage.

Milton

FLPilot

My Feedback: (23)

Well,

All, make that all, my batteries are the same tecnology, use the same charger that balances. Flight dischage is very flat.

Fast re-charge is simply wonderful. Hold a charge for a very long time. Not much self discharge. Safe technology.

You can build A123 1100ma ignition packs from B&D VPX packs for cheap... Recently you could buy VPX packs for $12 at WalMart. A couple of leads and a soldering iron and your good to go. Receiver packs ( 2300ma ) can be built from DeWalt 36 volts packs. Around $ 13.00 per cell.


I use diodes to regulate to 4.8. And, NIMH in my transmitter is a PITA! Self discharges, always have to be aware to do a full charge before going to the field the day before. Don't what them for a receiver pack. Period.

Eneloops solve the transmitter problem.

DR

Bob Pastorello

My Feedback: (198)

The clear, and well-documented, advantage of using A123 over ANY other battery technology is quite simple.
They have ALL of the advantages of Lipo's, with NONE of the risks.
They do not self-discharge, which means charge 'em up, leave 'em, when you're good to fly, the equipment is READY. No "charging first".... a big advantage to those without a lot of "prep time".
Then, there is the FLAT discharge curve... this means servo speed is constant from first flight to last.... and that no regulator is needed. (If you read the RcExcell instructions closely, they state that A123's **MAY** be used without a diode as long as you're not running at full rated rpm of the ignition (9500rpm)) That also is important.

Finally, the real advantage is one charger....and the storage life....and the flat discharge...and the rapid recharge without baby-sitting, and NO explosion risks, fire, swelling, flame, etc.

I have had FAR too many NiMh packs lay down from self-discharge, and false peak on recharge to ever go back to them again.

Super08

My Feedback: (2)

I used NiMH exclusively this past year and I came to realize all the disadvantages Bob listed above. Every time I want to go flying I end up staying up half the night trying to get everything charged.

fritzdecat

Is this an engine thread or a battery argument thread?

rlmcnii

My Feedback: (3)

This is an engine thread and these engines are apparently very nice. There is a 100cc project in my mid-term future and the 102 will receive great consideration.

The 123 cells are so nice to use (Were you ever to use them for receiver/servo or ignition packs you would have to be forced back to NiMH or perhaps even NiCd. My pursuit of the R/C hobby is somewhat limited, but all of my planes have been converted to 123. This includes 1100 igniton packs on two gasoline-engined planes. As an aside, these packs were built from VPX cells for a cost of less than $15 each.) that the inability of an ignition system to use them without regulation will come to be a noticeable disadvantage.

Just an observation.

Gatorb8

Sorry Milton!
I may have derailed your engine thread!
I'll try to keep the ?'s to the A51!
Gator

RC Extreme power

My Feedback: (24)

No, That is fine, this is the best place to post your questions and get answers from me and others that have the knowledge.

The ignition is just as important as any other part of the engine.

Milton

jamesrxx951

i have some electronic training and really don't want a huge issue on this but what i understand on electronics just about any electronic device only works on 5v. any more and it generates alot of heat and tears down the board and all the transistors resistors etc. just like the computer we are on that 120v from the wall is droped to 5v to power the board. automotive electronics all are dropped to 5v max. so the ignitions on these gas motors infact i am thinking of buying this engine for a aw yak but anyways the boards should only really see 5v. the internal coil can handle it well it should be able to but unless the board has an internal resistor to regulate the voltage,a 4.8v pack should only be used for long term durability. i know alot of people say that 7.4v is ok and it works but i would really be concerned about long term heat issues.

FLPilot

My Feedback: (23)

My last words on the battery subject:

From the RCXEL manual......... verbatim ,,,,,, Check the last sentence..... We do not operate at 9000 rpm, so it would apply....

Milton wants 4.8 for warranty purposes so I comply using diodes.

I) 6.4 Volt Li-Fe(A123) Packs
2cell Li-Fe(A123) The Volts Max of 7.2
volts. Nominal 6.6 Volts, use a voltage
regulator. Or connects one IN4007 diode
to fall voltage the use.
If engines not highest rotational speed,
Also may directly use

JoeAirPort

My Feedback: (41)

I'm with Milton. I use the NiMh 1500 Intellect 4-cell on my igniton. 3.4 ounces. Fly all day, no problem. A diode and regulator can fail. I use the 1950 FAUP 5-cell on the rx. Fly all day and still have plenty left. One day I will go to LI-Fe but not yet. Maybe next year. Never have problems with false peak, I always charge before I fly so self discharge is not an issue.

Reasons I don't like Li-Fe right now:
1) Cost of new charger and I love my Accu-cyle Elite (which set me back $150).
2) Need diode or regulator for ignition. These devices can fail.
3) Can't use my awesome H9 variable battery tester since the Li-Fe loaded voltage curve is flat.
4) Purchased Li-Fe packs are pretty expensive conmpared to purchased NiMh packs.
5) I have a system that's not broken. Why fix it.

Why I would like Li-Fe in the future:
1) Fast charge.
2) High discharge.
3) Durable.

These are great engines.

Bob Pastorello

My Feedback: (198)

Perceptions pave the road to experience.

And yes, these engines are pretty good.

fritzdecat

when will the 45cc hit the line?

RC Extreme power

My Feedback: (24)

We are still doing testing on the 40cc to make sure all is up to par, Testing is slower in the winter time.

Milton

Super08

My Feedback: (2)

Everything is slower in the wintertime.