irockflipflops

iTrader: (33)

are you an electronics engineer?..I tried to wiki a lot of your answers, but I would appreciate layman's terms, sir!

howardcano

iTrader: (37)

Yes. I was born with a hot soldering iron in my hand... my mom said that hurt.

ufoDziner

iTrader: (39)

Oh, duh. After I read your response I realized that he was referring to capacitors on the ESC and not on the receiver for issues with the ESC. Thanks.

1mrdad

iTrader: (48)

While I understand some of your explanation, which I appreciate the detail by the way,and muddled through a portion of it, will adding more capacitance, lowering ESR, increasing cap voltage, increase ripple current capabality vs the stock cap provide the benefits that the Murffdogg Octane booster claims on its description "... Use of the MurfDogg OCTANE BOOSTER will provide the racer with more punch, better braking, cooler motor and ESC temps, more run time, better battery voltage deeper into the run..." ? If so then I want to build my own custom "octane booster" that will fit my car and needs.

Thanks

ariwere

iTrader: (4)

Along with mrdad at what point is it overkill? I know you can see 10+ caps in audio to clean up signals but for RC is there a formula or is it feel? I know adding 2 more caps to RS pro seemed to effect it but I'm also getting better at driving so I don't really notice. I'm faster cause I'm on all 4 wheels.

irockflipflops

iTrader: (33)

I remember reading an article about Masami Hirosaka and how he adds numerous caps to his cars to adjust the feel. Now granted he was racing every mod class available, so because of the speeds I guess he could sincerely feel the difference in his ESC's feel when adding a bunch of caps.

howardcano

iTrader: (37)

Part of the fun of this hobby is experimenting with stuff! If you have the proper caps at hand, then it won't cost much to try them out. But PROVING that it will increase performance requires tightly controlled testing, with repeatable conditions and results. That simply won't happen on the track, as there are too many uncontrolled variables. While some guys enjoy doing controlled experiments in a laboratory with proper equipment, I don't think the average racer would. (It always seems like work to me!)

I think the largest improvement you'll see is in battery temperature, and that likely won't be much at full throttle. Showing a change in motor performance, if any, will take a very good dynamometer. That is a rarity.

If you intend to purchase caps to try the idea, simply buying a battery with lower ESR might give you more bang for your buck.

Some audio guys can go a bit crazy-- well past the realm of science, into superstitution and magic.

Given enough information, all of this stuff can be modeled and calculated, but I'm no wizard at math, so for me it would be easier to do the measurements. (Measurements are necessary in any case to verify that the equations and modeling are accurate enough.)

ariwere

iTrader: (4)

I like math . However sounds like I am over thinking it here when I can concentrate on better lines and proper maintenance to improve performance.

Maybe a rule of thumb is more of an answer I would be looking for.



Thanks for all answers

1mrdad

iTrader: (48)

Last questions. Is there such a thing as using a capacitor(s) whose voltage and/or capacitance rating is too high to the point that it would be harmful to the esc? I want to experiment with 2 in parallel with higher values than the stock cap. Also, does it matter if they are rated at 85* or 105*? It seems like the caps rated at 85* have a higher ripple current rating.

howardcano

iTrader: (37)

No, but you can get some pretty spectacular sparks when you first connect the battery. That isn't good for the connector.

As long as the caps stay below their rated temperature, go for higher ripple current rating first.

1mrdad

iTrader: (48)

I originally posted this question to learn the purpose of esc caps, and if changing the stock cap would have some kind of advantage. Thanks to replies and especially to Howard Cano for a lot of useful/helpful info, here are the results of my experiment. The stock cap was a single Chinese, 2200uf, 25v, 105* cap. After some Google research and Howard Cano's input, I used four Panasonic 560uf, 35v, 2470mah ripple current, .018Ω impedance, 105*, 5000 hour caps wired in parallel. I was limited in physical size to 10mm diameter, because I wanted to mount 2 on each side of the centrally mounted esc in the triangles of my b4. I wired 2 pairs of 2 caps in parallel to pc boards. I used 18ga wire (instead of the stock 22ga wire), and wired the 2 sets in parallel to the esc.

Unfortunately, most of my results were inconclusive because it is very difficult to test a variety of parameters in controlled conditions in our hobby. Motor and esc temps (114* and 123* respectively) were about the same with the capacitor "bank" vs the single factory cap. However, ambient air temp was a little higher, and the track had more bite, so I think everything is actually running cooler, but I can't empirically prove it. Punch is very subjective, but visually I don't think there was any difference ( despite Murffdog's Octane booster claims.). I was able to confirm that 3 sets of batteries after 6 minute qualifiers, all had 8.0 to 7.98 volts left with the capacitor bank. That compared to 7.81-7.85 volts with the stock cap. Also, the batteries only took 997mah to full charge.

All in all, I think the car runs a little cooler, and the battery has more charge left after a 6 minute race. It was a cheap experiment. The caps were only 70¢ each, 2 pc boards 74¢, plus the wire. For those wondering, the car is essentially a B4.2, 17.5 motor w/12.5mm high torque rotor, max timing, SP Reventon Pro using Stock 0 software, and a 5.13 FDR.

Here is a pic of the installation.

WindDrake

iTrader: (13)

Not surprising that the batteries came off with more juice left to go. Reducing ripple currents means you aren't wasting energy as heat (Lower Voltage = Higher Amperage for the same Wattage = More I²C Losses.)

steam

iTrader: (10)

Would running capacitors in series create more punch.

Dave H

No you want them in parallel.

asw7576

How do i know capacitors are still working ?

If i change the capacity value eg. 500 to 1000 or 2000 , is this higher capacity means better performance for esc ? Or same performance but with added weight to car ?