RunRyder - Logo 10 on Li-Poly

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e-Mikado Logo 400 500 600 > Logo 10 on Li-Poly

sharam
Elite Veteran
Location: Northern California

I received my Li-Poly batts from Charlie Wang today, charged them up and took my Logo 10 for a trial flight.

I mainly hovered and did some very small simple figure 8s in my backyard. I got 16 minutes of pure hover time! This probably means I will get about 20 minutes of general flying time.

The Li-Polys got warm but not "hot". They are being charged by my Triton right now and I can't wait to go flying tomorrow.

If these batts can go survive continuous charge/discharge cycles, they are ideal for the Logo 10.

These are 4S4P batts - 14.8 volts and 7800 mah. Real cool!!

05-07-2003 Over year old.

Dr Lodge
Elite Veteran
Location: Guildford, Surrey - UK

Marginal

I think 7.8 Ah cells are marginal on a Logo. 4 x 7.8 = 31amps and I think hovering current is 20 amps so you are going to exceed this with anything other than easy flying and blow your LiPO cells

Does anyone know what a Logo 10 pulls at full pitch, roughly? 40 amps?

David.

05-07-2003 Over year old.

Hivoltage
Senior Heliman
Location: Ohio

Can you give me an address to order one. Providing they wont blow up of course. !!!!!!

I Dont Have No Stink'in Signature

05-07-2003 Over year old.

Dr Lodge
Elite Veteran
Location: Guildford, Surrey - UK

There's a handy calc tool here
https://www.fmadirect.com/site/lipocalc.htm

Using 4 packs to give 14.8 volts, and 4 x 3270 mAh packs in parallel to give 13 Ah, you can pull 52 amps at 4x capacility (4C). But they will cost you $440

ouch

05-07-2003 Over year old.

Reesy
Key Veteran
Location: In the doghouse ... Nottingham UK

Hi Sharam
Could you weigh the batts and keep us posted on how you get on?
I've seen figures of 20-21oz bandied around which MIGHT mean that current draw is less than having to haul a heavyweight 13 cell pack around.
Or am I being too optimistic?

Ting Tong
.... ...... ...from Tooting

05-07-2003 Over year old.

sharam
Elite Veteran
Location: Northern California

Dr Lodge,

I think your 40 amps at full pitch is correct. I have heard or read that in a couple of places. This weekend I will put the heli through some loops, rolls, inverted flight, full pitch climbs to see how it does. While doing these maneuvers will draw heavy current loads, flying around will draw less current due to translational lift. I bought these batts out of curiousity and I am hoping that I will be pleasantly surprised.

Also, I don't believe they are 7.8 amp cells. As far as I know, they are 1950 mah cells (4X1950= 7800mah). I think they can withstand 4 - 5 C discharges which makes them able to give bursts of about 30-39 amps.

Whether they are marginal or not, time will tell.

The Kokam FMA cells you mentioned are way too wide to fit inside the Logo body. I have a couple of those that I use in my electric glider.

Hivoltage,

I ordered them through Charlie Wang at aenergytec@aol.com
Charlie has posted on this and other forums. He charged me about $250 for my batts.

Reesy,

I will weigh them and post that info tonight.

05-07-2003 Over year old.

sharam
Elite Veteran
Location: Northern California

Reesy,

The LiPoly weighs just over 22 ounces.

The 2400 12 batt NiCD pack weighs just over 27 ounces.

05-08-2003 Over year old.

Dr Lodge
Elite Veteran
Location: Guildford, Surrey - UK

sharam

Thanks, useful info. Doesn't matter which way you cut it (7.8Ah or 4x1950), you still get 7.8Ah 4 x 7.8 = 32 Amps but as you imply, these cells can go up to 5C for short periods of time, I was assuming a maximum draw of 4C. So I'll be interested to know if the cells hold up to the current draw or if larger (and more expensive) cells are required.

l8r..

05-08-2003 Over year old.

Reesy
Key Veteran
Location: In the doghouse ... Nottingham UK

Hello Sharam
thanks for that info, there's an interesting comment from Gary Wright, (scroll to bottom and see comments on amp draw) on the forum run by "He who shall not be named" so we'll call him Glen

http://logoheli.com/LOGObb/viewtopic.php?t=116

Of course I'm not allowed to post this link so if anyone asks .. A big boy dun it and ran away

Ting Tong
.... ...... ...from Tooting

05-08-2003 Over year old.

sharam
Elite Veteran
Location: Northern California

Thanks for the feedback guys.

I may get a chance to do some serious flying with my Logo 10 this weekend. I will post my experience and flight times.

The one draw back with the LiPoly pack for me is the charging time. I have a Triton charger that limits me to 2.5 amps. This means that the batts have to sit on the charger for about 3.5 hours. Assuming they will need one half hour to cool down prior to charging, the turnaround time is 4 hours! That's not good.

The three NiCD pack solution is cheaper and might be more efficient. You fly one pack, while one is cooling off and the other one is charging.

05-08-2003 Over year old.

d_wheel
Veteran
Location: Deep in the heart of Texas.

Parallel charging?

Sharam, are you charging your lipoly pack in the 4S4P configuration? All of my experience over the years is that charging batteries in parallel is a huge NO-NO. If it is OK to charge these lipolys without first separating them from the pack and rearranging them in series, I will be very surprised.

Later;

D.W.

05-08-2003 Over year old.

sharam
Elite Veteran
Location: Northern California

d_wheel,

Your experience and what I have read are in agreement. I was under the impression that you couldn't parallel charge these batts without load balance circuitry or that you had to charge them in series as you say.

The manufacturer has told me to just hook it up as is and charge it - no need to separate the parallel configuration!

To be on the safe side, I am charging it while I am in my workshop or I will hook it up outside where it can't set anything on fire, if it does malfunction.

As I said earlier, I am experimenting and am willing to accept a less than perfect solution for now.

I have been through 2 charge and flight cycles now. Not a lot of data but the house is still standing!!

05-08-2003 Over year old.

gwright
Senior Heliman
Location: Melbourne, Fl

parallel charging is fine with the lipo's. I don't know true cycle life yet, but I have over 100 cycles on my logo 10 pack with no deterioration of voltage or capacity.

05-08-2003 Over year old.

HOMEPAGE

sharam
Elite Veteran
Location: Northern California

good information gwright,

thanks. good to know.

05-08-2003 Over year old.

d_wheel
Veteran
Location: Deep in the heart of Texas.

Thanks Gary. Can you offer us any wisdom regarding what to look for if a cell happens to become defective in a pack? From my limited knowledge and experience with these cells charging is straightforward. My chargers start in a constant current mode, where the current is set according to the pack in use. When the pack voltage reaches the maximum voltage, again depending on the particular pack, they switch into constant voltage mode. At this time, the current slowly decreases until the pack is fully charged. I believe that this is probably the safest type of charging that I have seen in my many years of working with batteries! Very simple, very efficient...

My question is this, if a cell in a parallel pack becomes defective, how does this affect the charge cycle? Is there a large enough difference in the charging characteristics that the charger, or chargee, (hows that for cleaver use of words;o)) knows something is amiss?

Later;

D.W.

05-09-2003 Over year old.

gwright
Senior Heliman
Location: Melbourne, Fl

unfortunately (or fortunately depending on how you look at it), I don't know what the failure mode is, or what happens if a single cell has a problem. I haven't had any problems with them so far, but I've only been flying li polies in E3D and later Logo 10 since about november. The E3D pack has quite a few more cycles cause I've had it a couple months longer.

05-09-2003 Over year old.

HOMEPAGE

d_wheel
Veteran
Location: Deep in the heart of Texas.

Thanks again Gary. Sounds like they are proving to be fairly reliable. If the charge rates go up, and the prices come down, the lipoly packs might just take over..

Later;

D.W.

05-09-2003 Over year old.

bjpaul
Heliman
Location: Longwood, FL USA

If you go back to schram's original post he stated that he was getting 20 min of flight time that's 3C (60/20=3). So, 7.8 ah is 468 amp minutes (7.8x60=468) or an average of 23.4 amps (468/20=23.4).

23.4 amps at 14.8v = 346.32 watts

On most Logo10's using 12 cell 2400 mah Nicads the flight times average around 6 to 8 minutes that's 10C to 7.5C. With a 12 cell 14.4v 2400mah Nicad pack thats 345.6 watts (10C) to 259.2 watts (8C).

So that is right in line with what most flyers see. As the ThunderPower are great at 3C to 4C continuous and 5C bursts they fit the flight profile perfectly. And as the all up weight of the heli is lower you should see even lower current rates.

A 5C burst would be 39 amps and again fits the Logo10 flight profile like a glove.

What's holding me back for now is my supply of CP2400 packs work just fine for now, and I will wait for the big drop in LiPo prices rumored for later this year. Also the market needs a good 10amp dual output charger that can handle up to 6 LiPo cells in series.

Brad

05-09-2003 Over year old.

gwright
Senior Heliman
Location: Melbourne, Fl

I've beaten that horse for almost a year now,..it's been dead a while,..I don't think any of the manufacturers are ever gonna wake up and smell the coffee. It'll probably be about the time everyone realizes lipoly is the only way to go,..then all the charger manufacters that don't pay attention to the below statement will be left behind.

***********quote from above
Also the market needs a good 10amp dual output charger that can handle up to 6 LiPo cells in series.
**********

05-09-2003 Over year old.

HOMEPAGE

Jason Merkle
Senior Heliman
Location: Champaign, IL

The new Schulze charger software promises charge rates up to 8 amps and up to 8 cells in series for LiPos on the upper end models!!!

If thats the case, I know what my next purchase will be

For now, I use a Ginzel Spectra (up to 8 amps on LiPos up to 4s, up to 6 amps for 6s, and up to 4 amps for 8s) and 2 Tritons (2.5 amps up to 4s - slow, but VERY accurate and safe charging).

As for the life of these LiPos, Gary and many others have hundreds of flights on these Thunder Power packs at 3-4C continuous and 6-8C bursts and they still deliver 100% capacity and power. All of these packs are charged in parallel as they are configured.

The reason this works fine for these packs is due to the high quality control in cell production and pack construction. These cells are far superior to the other currently available LiPos from other manufacturers and their quality varies very little between batches. But most important, before these cells are assembled into paralleld packs they are cycled and matched, resulting in cells that perform very, very close to one another, even after many cycles.

Ive been using these packs since last year and they work flawless. I have used them on the Logo 10, Logo 20, my Raptor 50 conversion (all deliver flight times of 15-25 minutes), and in planks like my SuperStar EP, flying wings, etc all getting 30-60 minute flight times.

I dont think there is another game in town to compete with these Thunder Power packs right now. They are awesome and are well worth the cost. I just bought 3 more packs yesterday

Jason

05-11-2003 Over year old.

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e-Mikado Logo 400 500 600 > Logo 10 on Li-Poly

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