Long runs for fun?

[sjslhill]

Well, there ya have it...

Excellent feedback

thanks

Steve

 

[crowebar]

Alright, I've got a few questions that I hope Steve or others may have to answer to.

I'm sure these questions have been answered more times then I can imagine, but my guess is there are other ignorant boaters like myself who would like to hear them again.

Are all lipoly's of the same manufacture the same. Not sure if I'm making sence. Lets try this. I have two Thunder Power 2S4P 8000 MAH packs. Is one going to be better then the other? I hope they are all the same or so close we don't notice. It would be really nice if EVERYBODY had cells of equal power.

How many cycles until they start to fall off? Seems like Sub C's are good for 20 to 30 cycles before they just aren't the same anymore. Perhaps the real value is in Lipoly.

I've got more questions, but these will do for now.

Dick

 

[sjslhill]

Alright, I've got a few questions that I hope Steve or others may have to answer to.
I'm sure these questions have been answered more times then I can imagine, but my guess is there are other ignorant boaters like myself who would like to hear them again.

Are all lipoly's of the same manufacture the same. Not sure if I'm making sence. Lets try this. I have two Thunder Power 2S4P 8000 MAH packs. Is one going to be better then the other? I hope they are all the same or so close we don't notice. It would be really nice if EVERYBODY had cells of equal power.

How many cycles until they start to fall off? Seems like Sub C's are good for 20 to 30 cycles before they just aren't the same anymore. Perhaps the real value is in Lipoly.

I've got more questions, but these will do for now.

Dick

Do they need to be matched?, they are suppose to be.

Are there going to be better ones? I would think so. We have new NICADS coming in 2005.

Cycles? My thoughts are (based on expert using them in the field in aircraft), if you use them within the limits, don't charge too fast and if you do not discharge them all the way, i.e. 2.5V per cell, they last much longer than GP3300 cells will.

I would vote for TP with circuit protection at this time. Apogee is coming on with that in the near future.

I hope this helps...

Steve

 

[Paul Pachmayer]

Hey Dick,

3 - I can charge the night before and use the same pack all day WITHOUT recharging or repeaking. I'd just unplug the pack after each heat and plug them back in when it was time to race. The last lap of the third heat was as fast as the first lap of the first heat. Incredible.

WOW, and your still here to tell about it! :blink: I thought for sure you would have blown up your house by now charging those nuclear devices.

Paul.

 

[forresterace]

Hi Dick

Just wanted to clarify something about your super-competitive Lipoly 12 cell class set-up.

Did you run with the two 2S4P packs connected in series? This would make the overall effective pack 4S4P (nominal 14.8V. 8000 mahr)

 

[guiri]

They're known to be more delicate charging and discharging than NiMH or NiCd cells so people tend to exercise more care. Overcharging is nigh on impossible at C/10 so overnigt charging isn't really a safety risk.

Maybe current draw levels aren't as important in sport boating as out and out competition and LiPo's offer real advantages for this, especially the lower-rated previous generation cells. The major problem for competition is the speed of technical development - a couple of years back 3 or 4C was good now it's 10 even 15C. Longer races might be the answer.

I've been following a thread over on the fast electrics section of the e-zone and what's being achieved with a CD Rom drive and small Lipo cells in a 12" rigger is interesting to say the least. Perhaps the auw of under 6 oz helps Runs are long and fast with an X427 but definately hairy, though shorter, with an X430.

 

[crowebar]

Doug, you are correct. I'm basically treating these like two 6 cell packs and running them in series, although I do charge each pack on it's own.

Paul, nothing has exploaded.......yet!

I really like these things. It was so cool to just leave the same pack in all day long and just plug them in when my heats came up!

I still don't know what will happen regarding any rules changes. I hope somebody smarter then me can figure it all out! I'll vote for them.

Thanks for the comments,

Dick

 

[brooks93]

I still don't know what will happen regarding any rules changes. I hope somebody smarter then me can figure it all out! I'll vote for them.

it will be submitted for N2 in the offshore rule change

 

[AirMover]

I noticed in this thread everyone seems tobe consumed by the larger lipoly cells... due to the motors and size boats your useing.... What about the smaller boats and motors..anyone trying them with 10amp or 25amp controlers..? If a 6cell outrigger can get 50mph plus .. what would it do on li poly's ..

lipoly pluses...

more voltage.. ( helps lower amps)

lighter cells

easy charging ( these days there are plenty of good chargers )

Some packs are smaller in size then say a 6cell pack of 3300's

I feel there should be a class of boats for Li poly use..

Two at least since the idea for lipoly is more performance use them in performance based races..

Outriggers for sure..

I know there is heavy concern of miss use.. the larger the cell the bigger the fire if something should go wrong from abuse.. so keep it simple and safe at first .. open up a class that uses only a certain max mah rateing.. such as 2cell packs of 2100's

Another major concern is paralle packs... unbalanced cells are very dangerous .. the big puff happens or the boom and flame trick .. to avoid this.. start off with just 2cell raceing classes.. at least people will have something to work with and through use and time more classes will be added.

Im sure its nice tobe able to buy large high dollar lipoly cells for your large amp hungry motors .. but most of us cant afford them ..nor the risks if they fail..

a smaller set of cells keeps the cost down and if they do fail the fire wont be as bad... .. I have read some of you say you can take one pack out and run the whole day without needing to recharge.. thats great but geez if you can run all day your packing too much weight..I would rather use sizes that are good for running each race..and then swap out for a fresh pack for the next race... A lighter boat runs faster always... we abused nicads and nmh cells in the past when they where first being used .... just a matter of learning how to use the lipoly cells.

This pic here shows a rigger that only uses 2cell packs of TP860's - 1320's..

speeds are very fast.. and able to run clean on the prop hub... 860's get close to 10 min runs.. useing cells this size is very safe .. if a fire should happen .. it wont be near the magnitude of the large cells mentioned in this thread.. If you guys really want them to open up Lipoly use .. I feel we should start small and prove there safe .

View attachment 2912

 

[Kevin Whitehead]

Is that the 12" rigger mentioned in Guiri's post?

Cute.

Might work for racing. If you're racing indoors.

KW

 

[sjslhill]

I still don't know what will happen regarding any rules changes. I hope somebody smarter then me can figure it all out! I'll vote for them.

it will be submitted for N2 in the offshore rule change

Great....I think this is a great idea.

 

[AirMover]

Here is a link to one of my Video's.. this vid shows my small rigger running with a X427 on a single stator cdrom motor .. useing 12 Neo mags I wound it for moderate amps with a 2cell pack of TP860's .. .. the vid shows my smaller 11.75in rigger.. the pic I had just posted is a double stator motor I put together.. custom wound on 12 neo mags .. 2mm thick N50's.. allowing my new design 15in rigger to go 40mph plus on 2cell packs of 1320's.. features only one drive shaft from motor to prop.. uses the only mag floated thrust increaser .. completly removing the need for thrust bearings..and ups the rpm!!!... all up wieght is under 5.5oz ... And yes im the guy with the only and fastest rigger in the world that uses a cd rom motor and lipoly cells... wanna race? B) heehe humm im useing a 10amp esc so a good test would be up against anyone with a rigger controled by a 10 amps esc.

http://www.rcpics.net/view_single.php?medid=32831

 

[sjslhill]

Here is a link to one of my Video's.. this vid shows my small rigger running with a X427 on a single stator cdrom motor .. useing 12 Neo mags I wound it for moderate amps with a 2cell pack of TP860's .. .. the vid shows my smaller 11.75in rigger.. the pic I had just posted is a double stator motor I put together.. custom wound on 12 neo mags .. 2mm thick N50's.. allowing my new design 15in rigger to go 40mph plus on 2cell packs of 1320's.. features only one drive shaft from motor to prop.. uses the only mag floated thrust increaser .. completly removing the need for thrust bearings..and ups the rpm!!!... all up wieght is under 5.5oz ... And yes im the guy with the only and fastest rigger in the world that uses a cd rom motor and lipoly cells... wanna race? B) heehe humm im useing a 10amp esc so a good test would be up against anyone with a rigger controled by a 10 amps esc.
http://www.rcpics.net/view_single.php?medid=32831

Cool stuff, LiPoly is great for these small boats.

 

[AirMover]

Thankyou!

Boats with the smaller cells maybe what it takes to get lipoly use in the races.. just like there are standard 6cell races, perhaps we could start with a limit on the speed controlers... keeping the boats from being loaded down with the larger cells.. if the worst should happen.. and a cell does fail, the boom and flame bit wont be impressive enough to cuase a scandal... The 10amp CC Phoenix 10 has mofits rated for 15amps.. so TP1320's would be plenty to work with .. Im looking forward to showing you vid of my new 15in rigger with the double stator motor.. the new design has alot going for it ... and yet I will still be able to get away with a 10 amp esc and the smaller lipo cells... If the 10amp controlers seem toooo wimpy allowing 25amp controlers with lipoly cells would have tobe the max for now.. a 2cell pack of 2400's can make a bigggggg booom boom.. also if we are limited to useing only 2cell packs we do improve the chances of smooth operation.. big reduction in cell imbalance. <_<

 

[crowebar]

Your video looks great. Any shots of the interior. I'd love to see what it looks like in there. I'm not sure how it would stack up against current 6 cell riggers. My 6 cell boat with B50 6S pushes 50 MPH in oval trim. It's also pushing 65+ amps. The efficiancy of your boat is just incredible. I like the direction you are going.

Good luck,

Dick

 

[guiri]

Your video looks great. Any shots of the interior.  Dick

link go to the last page as its a long thread. :blink:

The link is for the last page. Dooh

 

[Andrewg]

Dick

that information is great

there are several manufacturers of LiPo and the numbers are growing. Kokam is out front for discharge rates. However, the high discharge ie 20 c packs are expensive and of lower capacity.

Firms like Apogee (the ones Steve Hill psoted on) source their cells from anther manufacturer and have medium rate but larger capacity - so 2.1AH*20C = 42amps or 4.1AH@10C = 41amps. At the moment the lower tech hi capacity cells look better value because they can provide the amps but have twice the runtime.

In short for LSH and offshore we have LiPo technology which can perform as well or better than GP3300's.

I explain in more detail why I believe new rules should mandate cells in series only.

PERFORMANCE

It is possible now to run LSH and offshore classes on a single string of Apogee 4.1ah cells. And the pack weight is 1/2 a set of 3300's. So boat acceleration will be improved and runtime extend toward 6 minutes.

Steve Neu just published figures on smaller Apogees and found they were rated at 10.5 c but could be discharged at 15c and on 10C gave 90% of capacity. 4.1's are rated for 40amps continuous - more than the NAVIGA guys can pull from a pack of 3300's for a 6 mono or 5 minute hydro race, and they are not slow.

In short they are an excellent option for 5+ minute racing. (who wanted 10 minute enduro''s?)

Second several manufacturers already have LiPo cells ranging up to 40AH. however most of the capacities over 4ah are limited to 5C discharge rates. They only have to push those cells to 10 or 12 C which seems to be very doable given that Apogee has done it and a 5ah pack is a 60A constant draw.

At current rates of improvement those cells cuould be here in anoither 12 months.

COST

LiPos remain expensive to purchase relative 3300's but everyone is saying that in racing 3300's pack it in after 25 runs. Whereas from the flight boards no one is sure about 500 cycles but seem confident enough to suggest a 100 cycles at full performance is valid - Apogee are conducting long term tests on their cells now.

Using the Apogee4.1's and GP 3300

At $42 a Lipo cell = GP3300's for 100 cycles 4200/100 = 42c per cycle.

At $4.70 for a stock GP3300 - 25 cycles = 3*4.70/25 = 56.4c per cycle

Heres the crunch (if racer reports of 3300's loosing the edge at 25 cycles are correct) for racers.

At 40A a 4.1AH LiPo's give 5.5 mins runtime or in 100 cycles 553 min of runtime

At 40A 3300/s give 4.52 mins runtime in 25 cycles that 112.5 min of runtime

That means LiPos cost 12.5cents/min of runtime. Lipo's cost 7.6cents/min. and Lipos are getting cheaper at a much faster rate than the mature NiMH and Nicad technologies.

OK SO WHY SERIES

Paralleling erodes any cost advantage and paralleling provides a performance gain of 26% max if the second pack is used to the maximum current capability.

The 700BB and offshore classes with more laps and timed races are perfect in terms of current draw for existing LiPo technology. And as the most popular classes possibly the best arena to try it in. Alternatively as you have twice the enrgy density maybe LiPo could be declared a Pro class for a year or two until setups and cell tolerances in marine use are established?

On the other hand a series only (4*$42=$168 for P-Class pack) and a parallel only ie 1S2P class would provide for hi amp setups (at $336 a P-class pack) with current technology.

Even in aircraft where current draws are lower, particualrly in hi performance aircraft it is not unusual for the paralleled cell packs to cost as much as a model itself.

Are LiPo dangerous?

As with many new technologies the problems seem to relate mainly to people not changing their behaviour to suit the new technology. Perhaps they forget how we abandoned burp charging and high delta peak voltages when NiMH became more popular

From the flight boards it is also clear the fragility of these cells relates to impact. In the one verified case of fire in a pack in a car the pack had been damaged and shorted. Other problems have been related to the wrong charger type or charge cycle being used. Anyone here ever shorted Nicad or NiMH cells?

And before any one asks have I used LiPo...... yes and I wrecked them using the wrong charge cycle on a charger! BTW I have made the same error with NiMH too. Luckily i got both while they were just smoking lol Error is just the button press or two I didnt make. I tend not to make those errors now.

 

[Pennywizz6]

They are very dangerous and create fires!! Not safe but hey you get long runtime, ive actually seen like 17000mah ones before, but i cant give ya a link. <_<

 

[guiri]

If treated with due precautions, they are as safe as NiCd's. The problem was that when really new, people were operating them far beyond their rated capacities. The aeroplane accidents were due mainly to that, crash damage, cell imbalance and incorrect charging. Charge, discharge and monitor condition and they are a useful innovation.

Keep an eye on the aircraft forums for the latest in safety.