Lipo Lowdown From My POV.

[John Knight]

Joerg,

Since you asked a nitro point of view I will offer mine. I have 2 riggers, powered by NovaRossi's 3.5 cc prepped by master engine builder. Both can turn over 30,000 rpm and I suspect it is more. Depending on the prop one can get more or less. The hp rating is at or over 3 and not 1.5 as you noted. The top 3 engines, NR's MAC's and CMB's are all pushing 3 hp.

As to weight, my riggers weigh in a 3 lbs, 10 oz to 3 lbs, 14 oz. That is in heat race form and not SAW.

BTW, both can do over 70 mph. The majority of those that I compete against in this region are in the 65-75 mph range, heat race trim.

There are 2 variables that I can ultimately control:

1. Weight but hard to do and keep it on the water if it is too light. Speed and stability while racing in a pack is key.

2. Nitro fuel content. I can change it and get more or less speed.

Just some info to munch on.

John

 

[Darin Jordan]

So you are saying although the horse is already dead you need 2 sticks in parallel to beat that poor dead horse?

Not at all... I'm opting to use just one big stick...

 

[JfromJAGs]

Thanks, John.

Rpm is not an issue with electric motors. They could spin much higher (needing even smaller motors for the same power), but I would guess a 35K range is what one would want to use for the above mentioned setup and heat racing. That's why I choose a rather heavy 350g motor. What props are you running for heat racing?

It's kind of hard to compare IC and electric HP numbers. As mentioned above, the setup I described can easily push 2.5-3HP for acceleration and the power band of brushless motors is usually much wider compared to IC engines. I have'nt tested the above setup and I'm not sure if anyone tested it so far on a 5lap 1mile oval, but I still think the above setup should be able to compete. I'm pretty sure we know by the end of the year...

My point was that 4 LiPo cells of 5000mAh cells and off the shelf equippment should be enough to be in the 0.21 range (weight, power and speed). That compares to what Andrew wrote about using 6 similar LiPo cells and beeing competitive to 7.5cc.

I almost wanted to write: "So Paul, if you don't get the job done with 4s1p, then it's you who sucks!", but I don't do it

Joerg

 

[Tim_Duggan]

Typical 3.5cc rigger props for heat racing. (depending on engine)

Octura 1450, 1445. ABC H7, H10, H4, H5, H6.

The big difference between FE & nitro (relevant to props) is the nitro engine produces it's torque at higher rpms than lower in the rev range - effectively limiting the prop to what can be launched and milled with consistently. From what I can ascertain this is less of a factor with FE, if even a factor at all. Current draw and subsequent heat seems to be the limiting factor for FE prop selection.

Having said all of this - I'm very interested in FE riggers that could compete to similar or better levels than 3.5cc riggers in heat racing on a nitro course, as that is probably my fave class at the moment, and FE has many positive merits to it.

Tim.

 

[Paul Pachmayer]

Hi Joerg,

Conclusion:1. A 4s1p (5000mAh) electric boat should be able to compete with a 0.21 nitro boat, similar weight and similar power.

2. A 4s1p electric boat can be run with off the shelf equippment

3. A 4s2p boat would either need to run double runtime (at least 5-6min) or it will be able to output double power (which can't be done with off the shelf equippment at the moment)

Don't take this the wrong way but we already knew this. My guess is your not really beliving me when I say I understand your POV. Nobody ever said you couldn't get the job done on 1P. The problem is when pushing a 1P set at it's maximum levels like in your post it's going to take away lifespan of the cells. There's simply no way around that one simple fact, even a 25C cell run at 100 amps will suffer. I much prefer to run a 2P setup where my cells come in a 100 degrees rather than 140+ like a 1P setup would.

With a 1P setup I would feel comfortable running around 80 amps max, thats why I can do it in my 1/8th scale boat. 70 to 80 amps with a 22 series motor and 10S1P puts me at a competitive speed without taxing the system to hard. Also that system has high voltage working for it, a 4S system will have to work much harder ( pull more amps) to achive the same level of preformance because of it's lower voltage.

When Andrew asked me if I thought you could break your record on 6S I said maybe. On paper it has the potential but I belive all things being equal a 10S1P would be much easier on equipment wouldn't you agree?

All the banter is neither here nor there. Bottom line is 2P is within the rules and will be used. For people who want to use 1P (myself included) they can. I know there's going to be people using 2P setups in their 1/8th scales when I'll be running a 1P setup, this does not bother me in the least bit. As a matter of fact right now in IMPBA a guy could run 4P setups against my 2P setups, I wouldn't be concerned or care about that either.

I'm also not going to concern myself with fantasy paper setups, what happens on the water is totally different than what "could be" on paper. Feel free to build a couple of these fantasy boats and put them on the water for heat racing, this is something I really want to see. I want real world examples of double power from a 2P setup not just talk.

Paul.

 

[JfromJAGs]

Paul, if I recapitulate the previous discussions and the technology available during the last years, people thought it was NOT possible to be competitive with nitro running only 5000mAh LiPo's!!! So this is why there is this 10,000mAh limit now. This is only possible since the 20C 5000mAh cells are available and it will even be easier with the next generation of cells (25C/30C).

You may also read my post about "battery basics and limits". So whatever you do concerning capacity, as long as runtimes or distances require C rates of over 15-20C, either motors, batteries of controllers are expensive fuses. The rules themselfs will never make it safe for the equippment, unless the C rate issue is addressed.

For you beeing competitive with 4s1p in P, I don't think so (anymore). I hear people are already building P monos for heat racing with 2s2p, Neu 1527/1D motors (that would be simular to a Lehner 2250/6). These motor are optimized for 180-200A. I would actually go even stronger and higher in rpm, that would mean a 2250/5 or a 3040/5. It does require a well water cooled Schulze 40.160 though. Remember, this is for what used to be known as P! It jumped instantly to S/T power, hardware and cost (US $1500+). Well, I'm just watching, but have fun.

I'm sure it is possible to compete with the current T hydro SAW record with a 6s1p setup, as it is simply more power than it actually took and less weight. This does'nt push the equippment, as the batteries can handle those short SAW pulses easily concenering heat, the motors are optimized to handle that amount of power and the controllers also. Nothing of the equippment got hot or stressed - it was selected to be perfect for the available power and such short SAW runs.

10s1p would be faster though, 10s2p even faster. Any 2p would require some engineering though, because I expect currents in the range of 600-700A. Anyway, I'm not going to try that, because we (JAG's) believe a 30HP, 10lbs model boat at 200mph+ is too dangerous to even try it - just our personal POV.

Joerg

 

[lohring]

From the number of expensive boats it took to get the two way 140 mph average, I would say that hull design is the limiting factor now. You have the power to accelerate to very high speeds and I'm sure brakes can be designed to stop the boat. The big question is how do you keep the boat from hitting something hard, including the water, during the run.

Lohring Miller

 

[AlanN]

My rule of thumb has and still is not to exceed 75-80% of my lipos abilities.

In testing the 1st gen cells we found if pushed to their max they would suffer. Either a balooning would occur eventually or the pack would start to deform.

That was expensive enough to come to that conclusion.

I wish not to hurt my newer cells in the same way...and hope to be able to keep their cycle life high.

Therefore a 2p setup keeps the amount of amp draw in half per cell.

Even when using Nimh's I would not overheat and vent cells like many others have done.

This stuff ain't cheap and expect to use my equipment for a long time.

 

[JfromJAGs]

From the number of expensive boats it took to get the two way 140 mph average, I would say that hull design is the limiting factor now.

Yes, hull design is the key, but has always been the key for SAWs. Even 50mph boat can flip, it just does'nt hurt as much as at 140.

The lake wanted 2 boats for 140, but we got both back - in pieces though. One was a design and/or setup error, the second was just bad luck with hitting something in the water at full speed. But each of the boats was still cheaper than what will be allowed in the old 12cell heat racing class now (15V class). Because you will be running the same size motors and controllers and a 2s2p LiPo pack is more expensive than 32 NiMH cells - which is not the whole story, but just comparing equippment.

Joerg

 

[JfromJAGs]

Therefore a 2p setup keeps the amount of amp draw in half per cell.

Allan, please take the time and read the "battery basiscs and limits" article.

One half of double is still one.

Joerg

 

[AlanN]

Joerg...are you trying to say that if you have a 100 amp overall pull out of a 2P that each P gets 100 amps pulled from it?

 

[JfromJAGs]

Joerg...are you trying to say that if you have a 100 amp overall pull out of a 2P that each P gets 100 amps pulled from it?

No, not exactly.

I'm saying, if you found that 100A is safe for a single battery pack for 60s, then 2 packs in parallel are safe to provide 200A together for 60s. That's 100A from each pack, but the overall power output is now 200A. Now you need to find a motor and controller that can handle 200A instead of 100A (bigger!) and you are fine with running at 200A. You just doubled the power output with paralleling 2 packs, but it will stay 100A from each pack.

This is exactly what happens right now. People are building P monos with Neu 1527/1D motors - a size that was common for 24 cells last year, just as 2D with 24cells. These motors are perfect for 180-200A continous. All you need is an appropriate controller - which would be a Schulze 40.160 with water cooling.

I mean you can stick to your 100A motor setup and draw only 50A from each pack if you use 2 in parallel. But there are people who understand that they will be faster running at 200A and they know what it takes...

 

[Andrewg]

Paul I guess the 2P setups are at an early stage. I hoped you would be getting a little more.

A 3s2P should be able to hunt with the 7.5's if our 6S1P 25C TP Extremes are a guide. The Lipo is so easy reliable and cool it is joy to use. Our built and raced boats which I use as the basis for my comments here use a similar setup to yours, similar mass motors, same esc, H&Ms and some custom hulls. They are by no means developed, more working prototypes so I feel the performance will improve signifcantly.

I imagine we will have lots more setups data & video etc to share with these good folk. I will get a video of the 6S1P rigger up on its shakedown run - its interesting to count the seconds in each lap.

 

[topfuel443]

7p6S32Clehner2149bNeuwT679kdipc..... whew....my damn head is spinning. I just hope that when I hook up my "battery" to my "Speed Controller" which is connected to the "brushless motor" and "radio"... and I pull the trigger... it moves along the water at a nice clip.

:lol:

~James

 

[Paul Pachmayer]

Hi Guys,

Well Joerg your stuck on the idea that if a person can use 200 amps they will, I have not found this to be the case but like I said before I DO understand it.

For you beeing competitive with 4s1p in P, I don't think so (anymore). I hear people are already building P monos for heat racing with 2s2p, Neu 1527/1D motors (that would be simular to a Lehner 2250/6). These motor are optimized for 180-200A. I would actually go even stronger and higher in rpm, that would mean a 2250/5 or a 3040/5. It does require a well water cooled Schulze 40.160 though. Remember, this is for what used to be known as P! It jumped instantly to S/T power, hardware and cost (US $1500+). Well, I'm just watching, but have fun.

LMAO, I can't wait to see that boat hit the water in oval trim. If whoever is building such a boat can keep it together I aplaud them. It should be a hoot in a 33" mono. The reality of all this is your not going to see these types of boats as the norm, only a few guys I know of are capable of building such a boat let alone drive it. Even less likely will it have any impact in oval racing because how often is this person traviling to races. It's simply not practical and I'm sorry Joerg but your line of thinking is way out there. If I'm wrong I'll be the first to admit it but I'll lay odds I won't be doing so any time soon.
Andrew,

Paul I guess the 2P setups are at an early stage. I hoped you would be getting a little more.

What are you talking about?

Our built and raced boats which I use as the basis for my comments here use a similar setup to yours, similar mass motors, same esc, H&Ms and some custom hulls.

You have no idea of my setups because I haven't given any. The only comments I made were about the 8th scale and a sport 40 boat and all I said was they used a 22 series motor. Unless of course your a mind reader, then maybe you do know my setups. Please let everyone know my 2S, 4S, 5S, 8S and 10S setups are because those are the boats that have been built to date by me. The new 4S boats I mentioned are being built to the new IMPBA rule proposal and have nothing to do with the fact I've been running the combos in other boats.

BTW: you want video of a Q offshore cat here ya go. The cat is a 11 pound 41" Bandit M with twin screws. Setup is 2 8XLs on gear drives with x447 L&R props, 5S3P feeding both motors controlled by 2 Hacker 77s. Run time is over 5 minutes at 50MPH average.

Q Offshore Heat

 

[SReesor]

Hey I remember that boat Paul.... :lol:

For the maiden runs in a race, it ran very well. I may have even pitted for ya. For everyone else that video was shot at CAFE (Cleveland) last fall. One of the first races I have been to where LiPo was allowed in almost all classes. NiMh ran along side of these boats (LiPo) and everyone had a great time.

I have read most every thread on LiPo and boats here and on RR. Cabin fever for those of us in the north has definitely taken ahold of many racers and the keyboard jockying has never been more of a joy to follow.

I have participated in the discussions surrounding the IMPBA rules with LiPo and also the new proposals posted here for class restructuring and hull limitations. Always a hotly debated subject these days. I fully support the new E boat rule proposals even if I do not agree with everything, however it was consensus built, and I see no reason to not play by these rules.

This year I will be runnig some purpose built LiPo outfitted hulls, I do travel to races, and I do support our local E boat racing scene here in Toronto. LiPo boats and M1 boats have been racing in this area, including in Michigan, Ohio, Ontario for the past two years with increasing frequency. The Cleveland guys have been running them for three years.

Could I personally build a 200A fire (no pun intended) breathing monster...sure I could. Would I be able to drive it, probably, probably have the yips doing it (only because I would have built it and realize the cost of such an animal) but my 24 year old son Neil could easily drive it.

When I put together our racing program for 2007, I began with the set-ups that will run comfortably around 80-100 amps without breathing (too) hard. I do have a couple boats for some of the open specialty classes which are designed around 130-150 amps. These set-ups are designed to run 2P LiPo configurations, drawing from 40-50 amps in the first case, and 65-75 amps in the second off each pack. Spit between the paralleled packs allowing me to run well within the guidelines of optimal pack performance and longevity while providing the power and duration for the style of racing which we run in this area. At our nitro venues we run the full mill plus mile plus "post" mill as it were. With the two minute pre-race clock and the race plus post race laps...we are typically running for 2 minutes or thereabouts. We typically launch around the 30 second cut-off for no launch

You can do the math if you like, but the fact remains my set-ups are not radical, there is a factor of safety designed in there as I am not interested in how fast I can go, I am interested in the set-up being reliable, repeatable, driveable, and competitive. I run lehner and Neu motors, Schulze Esc's and Castle for the low amp stuff and have no desire to let the magic smoke out of my fuses. After 17 years of oval racing E powered boats, I've let out enough magic smoke by pushing things beyond their limitations. Around here there is growing support and participation to run longer and farther with Lipo on the larger IMPBA 1/3rd mile oval and join in the fun established by our nitro/gas counterparts with two day district races and 4-5 heats, with plenty of competitive racers and lots of time to spend with our friends while we watch and enjoy (and smell...mmmmm...nitro) what the other types of racing have to offer.

In another month or two, most of will have water we can run on and we all are looking forward to having some fun with Lipo, LiIo, NiXX or whatever. We will race according to the new rules, and we are prepared to make adjustments as necessary.

...Andrew, for comparison my NiXX P rigger was running just over 15 second laps on the nitro oval (in Collingwood last year - course shortened by about 10 feet or so due to weeds off 1-2-3) in rough water last year at our Cdn FE Nats. Should be able to shave a few seconds off that with a 4S LiPo pack

Steve Reesor

IMPBA 14765S

NAMBA 300

IMPBA Asst FE Director

 

[Don Ferrette]

7p6S32Clehner2149bNeuwT679kdipc..... whew....my damn head is spinning. I just hope that when I hook up my "battery" to my "Speed Controller" which is connected to the "brushless motor" and "radio"... and I pull the trigger... it moves along the water at a nice clip.
:lol:

~James

Heard at James' first test run .....

"Damn dudes, there was a boat there a minute ago. I pulled the trigger, there was this bright, blinding flash and poof! "

:lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:

I think if I do go foward eventually with an FE 1/8 scale I'm just gonna ask Paul & Kelly what parts to buy.

 

[Darin Jordan]

I think if I do go foward eventually with an FE 1/8 scale I'm just gonna ask Paul & Kelly what parts to buy.

Usually a VERY good way to get started! You can always expand your knowledge from there...

 

[topfuel443]

I did that, I got a LOT of helpful answers.... I also got a LOT of contradicting answers. Kinda made made head spin then too... hell im just a dumb country boy from South Carolina.

If it goes up in flames I just hope its REALLY big and pretty to put on a show for everyone. Not to mention Ill have another WHOLE YEAR before im able to run it again! Thats plenty of time to scrape the melted plastic off of everything and start fresh.

FE here I come!

~James

 

[JfromJAGs]

Well Joerg your stuck on the idea that if a person can use 200 amps they will, I have not found this to be the case but like I said before I DO understand it.

Well, time will tell if I'm stuck with the idea of "200A+ is possible, so people will use it", or you're stuck with the idea that "although 200A are possible, people will NOT use it". My experience is that at least some people will use what's possible - and more. The rest needs to follow or loose. It's that simple, that's racing.

I got a 33" mono (Hopf Orca), I got a Neu 1527/1D, a Schulze 32.170 (just need to add water cooling) and enough LiPo's to make it a nice 4s2p P mono. I had planned to run it on 18-24 NiMH cells for SAWs and fun and I'd planned to use a different motor, but hey, why not? 4s2p will be ok too. If you got enough butt in your pants to run a S mono, why should you stop running the same mono with the same power, just because it's called P now and runs on half the voltage and double current? It's not more difficult than counting up to 3.

Paul, we'll see what happens during the year. Either me or you will be corrected. I bet a box of beer it's you.

Joerg