I thought we were talking external caps here....except for my SW 8th (which has an external capacitor between the power leads), none of my other Castle ESC's had an external cap. Dont all ESC's have caps on the board inside the casing? I didn't think this is what we were discussing....

If the caps are not mounted on the inside, they're on the outside like the Tekins, Novaks, Hobbywings etc. Having them built on the inside makes the ESC more compact.
Thread started as "are caps necessary". They're there for a reason and if the ESC fails and caps was not used, there goes your warranty. Consider it protection.

I have owned and used every surface Castle Esc since I've been in this hobby. I've ALWAYS used a Castle 10A external BEC for every application and just remove the center red wire off the ESC bypassing the internal BEC.

We all know Castle ESC's are prone to high temps, weak internal BEC power, and usually my servos are 300 oz/in. to 600 oz/in. since most of my rigs are crawlers or huge monster trucks so a separate external BEC is a must.

If I run a Cap pack do I need to run also another Castle 10A BEC? This is for a Savox SA-1230SG digital servo 500/oz in @ 6.0V on an 1/8 OFNA GTP2e on road GT basher.

Roelof correct Filtering. But only in AC power. RC uses DC power. Capacitors in DC is a storage for voltage like 4-6v, which mostly all ESC and servos run on. What it does Voltage fluctuates, The caps keep voltage in storage to keep it constant. That why electrolytic capacitor(polarized) are use in RC's. That why most Failsafes and Flight ESC you see capacitors in them. Electrolytic caps when charge it keep voltage in them in definitely, until they are discharge. Most ESC manufacture uses Caps on their products and voids their warranties if not used. Failsafe install b4 the RX on Nitro. Capacitor function hasn't since it invented, filtering in AC, Storage in DC.

I'm not sure if I understand your question correctly. But the caps being discussed for the power section of the ESC do not require an additional BEC. But as mentioned should be used.

Semantics, different way of viewing the same thing. Voltage fluctuations in DC systems equates to AC content that has measureable frequencies. When caps are used to help stabilize the voltage it is also filtering out some of the frequency content. Frequency dependent same as in AC use. For example the output caps on DC power supplies are sometimes to frequently referred to as filter capacitors.

The voltage rating of the capacitor is just how much it maximum can handle. Even if you want to use a 100v capacitor on just 8.4v no problem but it will be bigger. If you want to go small just use a voltage just above the battery you will use although with 2S batteries I would use 16v instead of 10v capacitors. Tolerances are wide with capacitors so it is not wise to sit close on the limits.

All of our ESCs have them built in. They are very important to the survival of the ESC, so we don't give customers the option to remove them. In 17.5/21.5 setups it might be okay to remove them from some ESCs because the current is so low and there shouldn't be much ripple, but anything more absolutely needs them if you want the ESC to survive.

Our newer ESC's have a much better BEC. The Mamba X and Mamba Monster X both have an 8 amp BEC and can run digital servos with no issues. I recently used a Monster X BEC to power a 1/5th scale Savox servo in a Losi 5ive-T and had no issues with brownouts on a Spektrum radio. The BEC on the Mamba Max Pro and Mamba Monster were designed before high current digital servos were common and were appropriate at the time.

The only disadvantage to capacitors is that they take up space and add a very slight amount of weight. There is no negative side effects to ESC operation of running input capacitors.

Edit: Just noticed this thread had been bumped from 2015, sorry to quote you and give you a notification from 4 years ago.

This reaction I have missed....
Are fluctuations on the DC line not just AC voltages? High frequency ripple from the switching FET's will cause a high frequency but small AC voltage on the DC line. That ripple will heat up things like the batteries and also the FET's. The capacitor has a lower resistance on higher frequencies and so acts as a shortcut fot the AC part and wipes away the ripple.

The only changes I've noticed when switching between a single capacitor and a capacitor bank is the esc runs a little cooler and the brakes are a touch more consistent with the capacitor bank.

As far as I've ever known the capacitors on esc are to absorb ripple current generated under braking.

i have order capasitator 3caps

can i just have it to any esc , add more ? they have alreade capasitators, more is better or wrong?

is this okey do with cheap shit china tsky esc ? add more
i have couple old cars and old combos i want build them to work good again just for fun.

does the extra capasitators help old shit esc from china?

HOW DO I SOLDING extra capasitator bank ?
same as the stock capasitator is? soldèring them there ?