P Sport Hydro question IMPBA

[Samuel Hagan JR]

I got a ML and I'm going to make an FE. This is my first FE boat. What's the difference in class for

P Spec Hydro

And P Hydro?

 

[brad nichols]

Check your rule book. P spec has battery and motor specs while P open allowa a lot more for motors and batteries.

Brad

 

[bzubee]

There is NO P spec rules for IMPBA give Doug Smock a call he can explain the motors allowed for P Spec or as it is called P Limited class.

 

[MarkScott]

P-LTD is normally limited to these motors: SV 27, Blackjack or UL-1.. Some clubs decide on their own as to what they allow. But there are no official rules for LTD.

 

[Samuel Hagan JR]

Yeah I checked the rule book first and there are no rules for that. I just didn't know what size motor and battery was good combination for P Sport Hydro.

 

[Samuel Hagan JR]

What about battery size?

 

[Buddy Benedict]

Sam, The voltages for "P" is: 11.1 to 16.92 vdc. That means you could use 1 3S battery for 11.1 volts or 1 4s battery for 14.4 volts or 2 2s batteries in series for 14.8 volts. Don't know how you could get to the max voltage with the over the counter packs available. I guess you could have packs made for you but I would bet that's expensive.

Hope this helps, still learning this electric stuff myself.

Buddy

 

[Samuel Hagan JR]

Sam, The voltages for "P" is: 11.1 to 16.92 vdc. That means you could use 1 3S battery for 11.1 volts or 1 4s battery for 14.4 volts or 2 2s batteries in series for 14.8 volts. Don't know how you could get to the max voltage with the over the counter packs available. I guess you could have packs made for you but I would bet that's expensive.

Hope this helps, still learning this electric stuff myself.

Buddy

Thanks for Simplifying that for me. That helps a bunch. I plan on building a couple more FE boats for fun. Our District has was too many classes as it is but maybe for some other places that over it.

 

[Mike Starrett]

A 4s pack should charge up to 16.8v. They are considered fully discharged when they reach 14.4v. Storage voltage is 3.8v per cell. At least that is what I have been told.

 

[Buddy Benedict]

Celina has 2 P Limited classes they run Tunnel and Sport Hydro. Their rules limit the motors to Aquacraft UL-1 and SV 27 also Proboat Blackjack motor. Boat length max is 34 inches on sport hydros.

 

[Samuel Hagan JR]

What is the SV27?

 

[Buddy Benedict]

What is the SV27?

It's a mono that Aquacraft made. I don't think it is in production anymore but you can still get replacement motors.

https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXZGW6&P=Z

 

[HTV Boats]

Namba uses the term P/limited and spec seems to be another phrase that comes up. No official designation or FE class officially in IMPBA. There is an approved motor list and if I had to inspect at a race I could not identify all the motors listed. It seems a few local groups are using a 36mm X 60mm? rule. In our local club we define it as 3661 or 36X61 with any KV rating. For simple inspection purposes the case diameter has to be less than 36.9mm and length less than 61.9mm. If it fits in that box which is easily determined after a race it's legal. 37.00mm or 62.00mm and your out. There may be some others using similar numbers.

When someone says "Full-P" it means no restriction on motor size. In IMPBA "P" class (4 cells lipo) is limited to one motor. Full "P" in NAMBA can use twin engines of any size but limits batteries to a total of 10,000 ma.

For new people buying batteries there are many ways to make 4S but the 3 most common are: One single pack 4 cells, 2 X 2s packs in series (4cells), and two 4S packs in parallel. Say we want 5000ma for our boat. One 4S 5000ma pack, or 2 5000ma 2S packs in series = 4S 5000ma, and finally two 4S 2500ma packs in parallel = 4S 5000ma. Using two packs series or parallel gives you some options for placement of weight.

Once you decide what fits your boat, if you use 2 packs when buying batteries consider buying 3 or 5 if you can afford it. Rotating packs will extend life and I have more than a few singles left over when one pack has gone bad and I can't match the left over of the pair. Sounds crazy but 5 packs will make re-charging in a multiple heat day a lot easier.

Mic

 

[Samuel Hagan JR]

How long does a battery pack typically last if your using them correctly.

 

[HTV Boats]

I don't know there is a typical life, it really depends on how you use and abuse your batteries. When I buy packs I put the month and year I get them with a Sharpie. I have some 5+ year old cells working well and others puff in a year. I guess 100-300 cycles is the expected life and that has more to do with taking care vs quality in my mind. If you push hard and make that extra one or two laps, overheat things they will not last. I check individual cell voltages after every run religiously. 3.8v or above is great. After a 6 lap heat 3.7v means too much prop. Below 3.7 regularly and even premium cell will not last. If you think you've run too long testing you have! so bring it to shore. Store below 80 degrees from 3.75-3.9v and your good. More heat more voltage reduces life. One cell goes down and the pack is toast.

I know some people don't always balance charge. Not a good habit in my mind. There is no industry standard for "C" rating. A lot of hype between sales pitches. Stay above 30C in general. I have some Zippy and Turnigy's that work as well as my Dinogy and Hyperions. Look at the IR (internal resistance) if you have that function on your charger. it will show you how your cells compare.

 

[photohoward1]

There are no special Battery rules for the Class. 4S thats the rule. (No HV Packs) some guys run 1P in LTD. some run 2P. Depends on how the boat balances. Cheap packs, expensive packs they all work. Google MOJO racing he has tons of packs for you. No special order.

 

[Bob Zola]

Hi Sam.

Not sure which ML sport boat you have (331 or 335). I find better performance running a 4S 2P set-up in these sport boats. Running two 4 cell packs in parallel. On the GP-331 a pair of 4S 3300s fit well. I have a GP-335 hull and I run a pair of 4S 3700s in parallel in that one.

As far as limited or full P, there is a big cost delta. You can do a great limited motor and ESC combo on the cheap that will get you speeds in the 55-60 MPH range in oval race trim. Try the TP Power 3630 1950 or 2070Kv motor with a Flycolor 150amp ESC. I found this stuff to be real reliable and affordable! Should be able to get a motor and ESC for about $130-$140.

Going full P with a bigger motor and ESC can get expensive. You need a 200-300 amp ESC which can cost more than the limited set up motor/ESC combined. NEU 15 series motors are over $200 and are very popular with the heat racers in P-Sport. A full P set-up will run 65-70 MPH in oval race trim, but at a potentially much higher cost. Popular battery set-up is a pair of 4S 4000mAh packs. The P size hulls are really getting on the edge of stability over 65 MPH, and tend to stuff or flip quite often. Also full P set ups can consume expensive speed controllers due to high amp loads.

 

[HTV Boats]

Bob makes an excellent point on cost vs performance. That 10 MPH for a full "P" is expensive. I was never a "spec" fan with certain motors and ESC;s dictated. The trend for a motor only limitation like 36X61 allows guys to try new kv and prop combinations to race different strategies. I think you could advance FE racing significantly with a 36X61 P class along with a 40X84 Q option for more performance using reasonably cost effective ESC's and motors.

Mic