P-spec tunnel

[James E Beasley]

I have not seen anybody address the issue of adding / using capacitor banks to the P Spec rules specified motor and ESC system? From what I have seen this added component is where people get a lot of the extra punch and speed. As far as I can tell the WTC rules and the D12 IMPBA rules do not address the matter, either allowing it or prohibiting it. My initial thoughts were that if the rules say all you can use is motor XYZ and ESC 123, then that is all of the electrical components that should be in the system. I'll confess and it's no secret that after getting skull-drug at the WTC, I bought my supply of CAP Banks! I'll be interested to see what the audience says on this topic. What you say Chilli? Respectfully, James Beasley

 

[Chilli]

Hey James, We've got you covered. If you check out the link below, we do specifically allow cap banks in the D12 FE rules. It's at the bottom of the page under rule 8-F. After our winter meeing last year, I tweakled the new FE Spec rules to align with the ones used at the WTC. You and Dick already had Spec tunnels, you run at the WTC and you both attend all the district races so it was a no brainer. http://www.impba.net/index.php?option=com_kunena&Itemid=153&func=view&catid=17&id=65

http://www.impba.net...&catid=17&id=65

Now we can start the debate on extra capacitors (cap banks). First, what is ripple current? It's a small variation of the current traveling from the battery pack to the esc. The capacitors job is to act as a conditioner to smooth out these variations providing a more consistant current to the speed controller. Now all speed controllers already have capacitors installed from the factory. But if the ripple current is excessive, the controller will be put under alot more stress and the stock capacitors will heat up trying to do thier job. Eventually the caps and/or the controller will blow, resulting in a redecorated interior for your boat. Extra capacitors take some of the load off the ESC's capacitors, keeping the controller happy and the stock caps cool. A little side note- Many FE boaters check the temperature of their motors and speed controllers immediately after a run when trying a new set up or proping up. The usual accepted standard is about 130-140 degress F as a max temperature for motor and the body of the speed controller. Caps will usually be much hotter and I believe 160 degress is the maximum acceptable temperature. But the bottom line is the cooler you keep your equipment. the longer it will last.

Ripple current most often occurs when the ESC is demanding more current than the battery (and associated wiring) can provide. Causes include battery packs that have an insufficient "C" rating, packs that are old, low quality bargain packs that do not have the specs that are advertised on their labels, to much wire length between controller and battery (keep it 7 inches or less when possible), using too thin a gauge wire, using connectors that are too small, bad solder joints and dirty connectors.

Are cap banks really a necessity??? Doug Smock in D13 doesent run them in any of his Limited (Spec) boats and he whipped all our butts at the ODMBA race last year. He also took District championships in the three limited (spec) classes last season with no failures. I have run them on my high amp full "P" powered boats for a little insurance but I don't run them in my spec boats. I hope you guys coming into the FE side now realize why many of us recommend getting the best quality cells you can afford. You folks that run internal combustion boats wouldnt feed cheapo bargain fuel to your race boats. Don't feed junk to your boats electrical system either. You'll be hurting your equipment and your performance will suffer.

Now, I'm not a EE and there are alot of people out there with a ton more knowlege and experience than I have. I hate giving out bad information so feel free to correct any of my misinformation and kick in your 2 cents........

 

[Dick Loeb]

Lets just go racin some where. :wacko: :wacko: :wacko: :wacko:

 

[Chilli]

I'm more than ready to get my boots on!!!

 

[John Crouch]

I just got my motor, controller and cooling cap for the motor from offshore electrics on Friday. I plan on running without extra caps and use good batteries. Just waiting now for the adapter to fit the electric motor to the lower unit and the shaft adapter to get here and then I should be good to go. Hope to get some testing done later this month since it is finally warming up some around here.

 

[Dick Loeb]

Will race for food :blink: :blink: :blink: :blink:

 

[Paul Traufler]

The capacitors (cap banks) will NOT improve performance that is not what they are for, they will make your hardware last longer by reducing the surge that the ESC will see. The surge (high current draws and backing off the throttle are the hardest part for the ESC). One other part that really can hurt the ESC is if the boat jumps or hops on the water, loading and unloading the motor and driving the current up and down. All the capacitors will do is act as a small storge unit (kind of like a battery) with VERY small current run through them and either give the charge back to the ESC or bleed it off according to the deman at the time. The capacitors are only a filter to the supply voltage, so no real "gain" in power is provided. For you nitro guys it is like the hopper tank to keep the fuel flow even.

Paul

 

[Doug Smock]

I wish capacitors gave us a performance advantage. I'd build a boat out of them. :lol:

Well said fellas. I like the hopper tank analogy Paul.

Doug

 

[Flyguy55]

Up till a couple yrs ago escs were often not keeping up with battery and motor performace. Adding caps helped them live longer.

Most manufactures now have adaqute caps. It doesn't hurt anything to ad them , but often isn't needed .

You'll see some of us with older escs that have added caps .Often if an esc quits working the caps will look bulged or burnt . Adding new caps often makes them work again. Some times bad caps are not easily removed. Its not necessary . Just add new caps .

Dick

 

[James E Beasley]

Thanks for the education and clarification guys. I dig the hopper tank analogy. Dick, get us a lake and we will go racing!!!!! Beas

 

[chuckg]

I am looking forward to the tunnel racing as well in D12. I have a VS-1 with a K&B just about ready to go and I am working on a Lynx with an O&S. As far as the caps go I like to add 2 or 3 just to be on the safe side.