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Old 12-30-2007, 11:23 PM   #601
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Shawn you PM
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Old 12-31-2007, 12:12 AM   #602
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Shawn you PM
Hey
You s/b in bed.....
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Old 12-31-2007, 12:22 AM   #603
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Capacitor tech:

I've explained what caps do above, so lets get into exactly what they are, and how to qualify them.

A capacitor is best looked at like a tiny little battery, as they are indeed just another "electron storage device". The standard "can" caps are actually built much like a NiMH cell, as they are two conductive plates (anode (-) and cathode (+)) rolled up with a dielectric between them. Unlike NiMH cells though, the dielectric between the plates of a cap is in most cases just a patina layer of aluminum oxide on the aluminum strips. If you've ever seen a blown cap, it basically looks just like a tiny blown NiMH/NiCad cell - as in tightly rolled layers of metallic material expelled from one end.

So if we think of them as tiny batteries, we can understand how they are rated (in simple terms) by their "ESR" and "uF" ratings.

ESR stands for Equivalent Series Resistance. Think of this as the same as the internal resistance of a battery. The lower it is, the better the cap and the battery performs. Lower ESR in a cap means it "charges" or takes voltage faster. The faster it charges, the more voltage it has to give back up to the ESC during the "on" pulses at high switching rates, and the less voltage difference the ESC sees between the "on" and the "off".

The uF (micro-farad) rating is the "capacitance" of the capacitor. Think of this just like the Mah capacity of a battery. The more uF a cap has, the more capacity it has to absorb current/voltage from the battery when the ESC is "off" and then supply it to the ESC when the ESC is "on".

So when you're looking for a cap for your ESC, you want the lowest ESR and highest uF you can either afford, or will fit in the car.

When shopping for caps, always cross-check with the Digikey catalog/website to make sure of specs and prices. One of the good things about caps is: Unlike most other power electronics in the hobby, you can actually generally trust the ratings given for them in the Digikey catalog. And the rule that "you get what you pay for" also generally applies.

Caps are also rated by: Q, TSR, and Ripple current, which can account for price differences among brands/items with the same ESR and uF rating. Again - you generally get what you pay for, so the performance difference (of the cap) between a $1 cap and a $5 cap can be quite astounding.
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Old 12-31-2007, 12:34 AM   #604
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The next gen of capacitors now appearing in RC are: "Super Caps"

Super Caps use an electrical "double layer" where the dialectric is only nanometers thick. This allows two main advatages: The ESR is extremely low due to the physical proximity of the anode and cathode, AND the capacitance (uF) is many many times higher than a comprable sized standard cap due to it's far more tightly coiled components.

Super Caps have one more big RC advantage - they are "flat" shaped, instead of "can" shaped. So you get more uF, lower ESR, and get it in a smaller and more easily managed package.

***Shameless plug alert***
We're bringing in Super Caps from Speed Passion in our next order



And of course all this coolness comes at a higher price than standard caps...
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Old 12-31-2007, 12:38 AM   #605
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Shawn,

Keep posting the tips, these come in handy and good to read. I am new to BL but have raced BR for years, mostly mod. My question is when you speak of advancing or decreasing the timing are you mostly speaking of the ESC software where you don't actually have the ability to change timing on the actual motor itself, Like 10.5 or 13.5 BL correct?

On Mod 3.5 BL where you can alter the timing on the motor when should you do this as opposed to software timing change? Do the same basic principles apply?

Is my question clear enough?

Steve
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Old 12-31-2007, 12:44 AM   #606
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Shawn,

Keep posting the tips, these come in handy and good to read. I am new to BL but have raced BR for years, mostly mod. My question is when you speak of advancing or decreasing the timing are you mostly speaking of the ESC software where you don't actually have the ability to change timing on the actual motor itself, Like 10.5 or 13.5 BL correct?

On Mod 3.5 BL where you can alter the timing on the motor when should you do this as opposed to software timing change? Do the same basic principles apply?

Is my question clear enough?

Steve
Hi Steve
Good question.....I've being watching Brett and JB doing some testing their New GT esc and SP10.5 and 9.5 as well...
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Last edited by Goingfast; 12-31-2007 at 01:25 AM.
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Old 12-31-2007, 12:55 AM   #607
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Corrallyman:

Simple question, but the answer with the advent of the GT ESC can be quite complex. The GT has some tricks up it's sleeve I'm not prepared to talk about publicly just yet, but give me a call in the office and I'll fill you in on them privately if you'd like.

Generally though, yes - the same basic principles apply, although the "hotter" the motor (as in higher Kv/lower wind) the harder the break and finer the line is between "acceptable" advance, and "motor melting temps" advance.
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Old 12-31-2007, 01:00 AM   #608
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At some point I will do that Shawn, at the moment I have a big learning curve ahead of me. One that I am looking forward to though.

Thanks for your help.

Steve

If I find it easier to PM you or email instead of calling is that ok with you?
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Old 12-31-2007, 01:02 AM   #609
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Get to bed Shawn, it's 3am in the morning!!!....you must have speedo on the brain
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Old 12-31-2007, 05:31 AM   #610
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Hi Guys,
I've just received my 6.5 motor and looking through the instructions/user guide the part number for the motor isn't listed ?

It's #13865 (Competition 6.5R) the part number for the 5.5R is listed

Is there somewhere I can look the details up, or does anyone have them ?

Thanks
Chris
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Old 12-31-2007, 06:26 AM   #611
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Steve: PM is just fine

Chris:
Which details are you looking for?
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Old 12-31-2007, 06:29 AM   #612
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Shawn,
Watts is the main one that I'm after, but and explanation of "Rotor Performs (ROM/Temp) would be great too

Thanks
Chris
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Old 12-31-2007, 08:12 AM   #613
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Look guys i found this 11.5t motor, could be from the same production line as Speed Passion, called Roche.
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Old 12-31-2007, 09:19 AM   #614
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Chris:
~350W

ROM/temp:
I'm not sure what they're designating by ROM, but I'll find out. The "temp" part is regarding the rotor magnet's performance at high temperatures. The stronger the magnet, the lower it's critical temperature. However most magnet strengths in BL motors don't near critical temp until around 190-200+F.
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Old 12-31-2007, 09:22 AM   #615
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Shawn,
Thanks for that much appreciated
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