brett65

My Feedback: (18)

I posted a question about being new and ignorant when it comes to lipos. I put it in the electric flight forum, but not sure if it gets alot of views so here is the link. I need lots of help in this field. Thanks!

http://www.rcuniverse.com/forum/m_8269046/tm.htm

opjose

"C" is the discharge/charge rate of the battery

1C is approximately what the battery is rated at for 1 hour of discharge... e.g. a 2800mAh battery will discharge at 1C ( or 2.8 Ams ) in 1 hour though this is usually less.

A battery of this size capable of 20C will discharge at 20 times this rate or 46Amps, but in 1/20th of an hour, so to speak.


Re: Discharged?

Eh when you use them.

I think you are referring to recycling charge cycles, which for LiPo's the answer is no.

Re: Fast

It depends upon what rate.

If you charge the battery at 1C it will charge up in an hour w/o hurting it.

What that 1C rate is, is dependant upon the battery capacity...

So a 2100mAh battery would be charged at 2.1Amps to get a 1C charge.

A computer controlled charger is the best way to go with LiPo's to assure full and proper charges.

Re: Charge

I haven't tried that one, but I favor the TH Accucyle charger

Re: Zippies

As "Tony the Tiger" says: They are GREEEEAAAT!

I have a dozen or so of them.

All produce slightly better than the stated output and hold up well.


A note on LiPo's.

LiPo's have a FINITE lifespan.

They typically can last over 100 discharge/recharge cycles but by around 100 cycles they start dropping in capacity.

It is possible to hit 300+ cycles with them if you keep the current load on them fairly light and balance them periodically.

Any time the packs get very warm to hot, you are reducing their lifespans significantly.


View LiPo's as "fuel" that you purchase up front, in that they are still a finite resource, and they are not the renewable resource some people make them out to be.

Electrics are wonderful, but spending a few extra bucks on a good balancer, charger, etc. goes a long way to maximizing what you get out of them.

Care and feed your LiPo's properly and they will be good to you.

And don't forget that you also - NEED - a good Watt meter!

Without it you will not be able to tell if something is amiss with your EP configuration.

dignlivn

Hey Brett,


Do Not over discharge a Lipo !

1 C ?, On a 3200 MaH pac 1 C is
3.2 Amps. I like to charge at Less
than 1 C myself. As for for a Charger,
I use Thunder Power 610 C, It chargers
everything I own. Lipos, Nicads and Nmhi.

Do a search in the E forum, you'll have
alot of good info there.

IMO, if you have Lipos you need a Ammo
can for storage JMO. I use one !

Bob

ChuckW

It looks like your questions were answered so I won't repeat.

On the Turnigy charger and Zippy batteries, I have never personally owned them but a lot of the electric guys in the local club swear by both. I own an Acucycle Elite charger with an Electrifly balancer. It works great but with so many planes now (glow, gas and electric) I could really use another. I'm going to give the Turnigy a shot. I'm also going to order some Rhino 2150mAh 20C lipos from Hobby City. These say Zippy Battery in the fine print.

I normally shy away from super low cost stuff since a lot of it is crap. After great luck with a Turnigy motor and ESC though plus all the good reviews from flyers I know and trust, I have no reservations about the charger or batteries.

opjose

I have a box full of useless "e-bay" LiPo's that attest to that!

Jetdesign

My Feedback: (8)

What is the difference between a lipo and a li-ion? What are the advantages/disadvantages to each for Rx use? I tried posting in the electric forum too, but nothing.

The Ghost

Brett, I have used the charger that you are looking at and is a good starter charger. I here people ragging on Zippy batteries and have never used them, just because of the cost. I have had FILGHTPOWER batteries die after half a dozen flights and at $600 a battery (6cell 5000mah) compeared to $100 for the same in Zippys that have lasted over 12 with no problems. I do not drag the guts out of the batteries, using 20C batteries @ 5000mah which means that I can draw 100amps with out damage but the max that is drawn in any of my models is 70amps and that would only be for around 10secs. I have been using 3cell 2200mah 25C and 6cell 5000mah 20C zippy batteries for over 12 months and would recomend them to anyone.

Cheers

The Ghost

Lipo = Lithumn Polimer

Li-ion = Lithumn Iron

Lipo's are a little lighter than Li-ion for the same mah. Using for RX use you would need a regulator that will supply enough Amps to drive the servos that are being used. There would be very little difference in there use for that application as it is the voltage reg that controles the voltage and current.


Cheers

Jetdesign

My Feedback: (8)

Thanks. The site I found has them both; lipo is a tad smaller, lighter, and has a few more mah for the same price as the li-ion, but claims that the li-ion is the ideal battery to use for receivers.

I know lipos come in hard cases and li-ions come in soft cases, and they use different chemicals and a different system for keeping the (is it electrodes and anodes?) in place. Not sure how this all relates to me sticking one in my plane though.

Of course I like smaller, lighter, and more mah.

OH! I think the li-ion had a balance plug built-in, and the lipo didn't. Does one need to be balanced and not the other? (looking at 2300mah packs).

BTW, Rhino batteries are the ones of choice at my club, used by ALL the guys with electrics (small club so I know this). Made by Zippy battery and sold by Hobbycity.com. I'm going for another brand though as I don't want Deans plug and extra adapter.

The Ghost

Lipo's have the balance plug and the soft case. Either way should be good. I just replaced the RX and onboard glow batteries with lipo's and the two batteries and voltage reg were lighter than just the old NiMh RX pack.

Cheers

Jetdesign

My Feedback: (8)

Thanks. 2300mah, constant (regulated) 6.2 volts and max power from first flight to last, all for less weight than my current system.

Do people ever leave the hard one w/o the balance plug in the plane for charging?

brett65

My Feedback: (18)

I understand what to watch for when charging but not why I should care about the discharge rate. Do I have to watch the C or discharge rate so that I don't overpower my esc when buying extra batteries? I think it has a 30 amp esc in the plane. And what is the watt meter used for, is it for checking the pack before a flight? Can a nice industrial voltmeter do that?

The Ghost

The watt meter not only measures voltage, see photos, but also amp draw, total mah used. I use them to check current draw in different timing moads and to compare different props. Also to check that I have the right C rating on the batteries for the use that I want. If you need 30amps and have 2200mah batteries then the min C rating reguired would be 14C. If you used 10C you would be draging the guts out of the batteries snd they would not last to long. With that use I would be looking at at least 20C batteries to give me some reserve on the battery rating.

Cheers

CGRetired

My Feedback: (1)

One thing that was not brought out in any of the posts. LiPo batteries can be very dangerous if not cared for properly. The most grevious problem would come if they are charged indoors (in your house, garage, car..) and they develop a problem. They can and will become very hot very fast, and do explode, or very quickly burst into flames.

Charge them in a proper container (ceramic container or one of those "LiPo Sacks" ) and always do it outside, away from anything that could go up in flames, like perhaps a wooden deck, the trunk of a car, your kitchen table, or garage work-bench for example. They are wonderful power packs and do the job very nicely, but they do have their drawbacks, and this problem with their potential for burning things down is one of them.

CGr.

opjose

As The Ghost, said you - NEED - a watt meter if you go into non RTF EP planes.

Changing a prop has a huge effect on the amount of power being pulled out of the battery.

A Watt meter is the only way to know if you are causing damage to your system or not.

It also can indicate if you are running the motor inefficently, overdrawing the ESC, etc. etc. etc.

-

As CGRetired mentioned LiPo packs store a LOT of power in a small space.

Anytime you store that much power in a way that can be dumped relatively quickly, you have the potential for an explosion.
Think of LiPo's as little hand grenades!

This is why the computer controlled chargers are advisable... and I prefer the ones with temperature probes that also monitor the temperature of the battery during charging.

These will cut off the charge if the battery temperature starts building beyond a safe or pre-set level, giving you another layer of safety.

ChuckW

The C rating is an indication of whether or not the battery can provide the current demanded by the motor. For the Corsair, a 15C battery is more than sufficient. An 1800mAh (1.8ah), 15C battery should provide 27 Amps. Using the stock motor and props, the Corsair should draw well below this.

When you jump up to different motors or switch props, there could be an increased current demand. In this case, you might have to jump to a 20C or even a 30C battery. The 15C will work but it just won't provide the current that the motor wants and performance will suffer. It could also overheat the battery. You'll notice all the 3D flyers run high performance batteries while they may not be necessary for basic sport flying.

I could be wrong on this but I think one of the factors that goes into the C rating is internal resistance of the battery. More resistance equals less current flow and more heat.

Regardless for your stock Corsair some 1800-2200 maH 15C-20C lipos will work just fine. Use a good quality charger that will reduce the chances for mistakes. Avoid puncturing the batteries and store them in a fireproof container such as a lipo-sack, an ammo box or a ceramic jar. The ESC in the Corsair will start pulsing the motor when the batteries get low. You'll see and hear this so the chances of over-discharging the battery are reduced.

The Corsair is a blast, you'll love it.

opjose

To what ChuckW said I would add...

If you are buying spare packs for the Corsair, go with at least 20C packs.

You will not need the extra "C"'s for the Corsair, but if you move the batteries to another plane you will be glad that you got at least the 20 C packs.

It is a small extra investment now, that will buy you compatibility with other planes you may add to your stable later.

Also I'd recommend buying packs in matched pairs.

Why?

Because later you can run them in either a serial or parallel configuration for other planes giving you a lot of bang for your bucks.

E.G. two 2100mAh 20C's in Parallel will produce 4200mAh equivalence at 11v, or tow 2100mAh 20'C's in Serial will produce a 22v 2100mAh equivalence... the latter will power a .25 to .40 sized electric plane just fine!

ChuckW

Definitely. With the great prices on lipos from Hobby City it would be silly not to buy 20C.

Allfat

My Feedback: (1)

Just an added note. Just because the battery is able to deliver 27 Amps does not mean that it has to. The 15C rating will give you the maximum constant discharge rate of the battery, and many times they will be rated for a burst discharge rate as well that can be handled for 10 second bursts. But in electric systems, remember that the motor pulls current, the battery does not push current.

The Ghost

I have been buying the 25C 2200mah 3cell packs with a burst rating of 35C from them and had very good results with them, and they get a lot of use. As you say, you can't go past the price. See photo for some of my batteries.

Cheers

brett65

My Feedback: (18)

Is a burst rate like an instant demand rate when you go full throttle very quickly or is it holding full throttle? I like to go wide open quite a bit with my planes.

The Ghost

Instant demand rate when you go full throttle very quickly. Most are rated burst between 5 to 10 seconds some are less some are more, you would have to find out from the manifacture.

Cheers

Allfat

My Feedback: (1)

Well, whether you cross into the burst rate when going into full throttle is dependent on your setup. This is where a watt meter comes in handy. If you oversize your battery, then it is possible that you will never reach the maximum discharge rate of the battery, burst or continuous.

CGRetired

My Feedback: (1)

Most electrics are very critical of weight. Oversizing the battery may be a great idea to avoid that burst of energy, however, you may not even get some electrics off the ground with larger batteries, or they may not even fly as expected with even a couple of ounces of weight added.

So, be careful when going oversize, be reasonable and don't forget to expect chages in performance when going oversize.

CGr

opjose

Bret65:

As you've seen from the above posts, it is all a balancing act.

It takes some care to get things in balance, but when you do you end up with a great flyer.