Cap banks - the pre-emptive answer

[drwayne]

Yes, current limiting IS power reduction. But this would be an effective tool to get the setup right, so you can take the current limiter off and have confidence what power levels you will be running. I want to use it in tandem with the data logger and fix the set up so it runs on the power budget.

My end goal is to master the use of high voltage packs and make power with higher V, instead of higher A. This reduces the stress of the entire electrical system and helps to prolong battery life, since the current draws will be lower. But these BLDC motors are most unforgiving in trying to reach that goal. I want a tool that will minimize my electrical failures. I see it as a perfect tuning tool to reach no current limited AND no broken parts! I ain't made of money Doc! Thanks for the advise, hang in there with me...

A thing with power availability. . The nore there is, the more people will push those limits.
With esc now capable 12s+ 300A+ , we need support the higher end demands of this market also..ETTI 5x35v1000uf banks suits most every 6s or lower setup.
Access to higher voltages leads to higher amps and the associated expectations of more of what this sport is about -> Fun .
What i detailed initially catered more the upper end of our hobby, and although taken up by lower cell count runners, that wasnt the aim. .
Latest battery construction generically support more kwh than our 90%+ users demand...
I see 90%+ of this hobby as plug and play experts .... Lol
.
Indubitably there are refined capacitor arrays producable for independant applications ..
.
This thread started as an introduction to a generic idea supporting the high end users who had clouded thoughts over unexplained repeatable failures :grin:
From there this has grown into a long diatribe... which is good for the hobby !

Stay in touch ... :)

[CraigP]

Those that want to stay abreast of battery tech and amperage capabilities will have to come to terms with the problems associated with switching so many amps. 1-1/2" of #10 wire is enough inductance (about 0.8uH) to really start causing problems. 12s at 300A, crazy KW levels in such small form factors! But the larger classes (1/8 and 1/6 scale) could certainly use the power.

My goal with the DF33 Hydro is to achieve WOT turns, in race water and run about 60-65MPH on the straights. Above that, and it gets out of my reaction capabilities, though I'm sure some young bucks got the reactions times... I just turned 60, so I'm not what I was in the old nitro days. But I love this stuff Doc, God knows I love it! Keeps me young

[ray schrauwen]

It has been a thought of mine for some time that why mosty Suppo esc's burn up is most likely due to faulty caps they buy in massive quantities not caring if they are way out of spec or just not made right at all. I mean, the fets on Suppos are a discontinued fet in USA that was shipped in container loads to China like many other obsoulete electronic components.

A while back I grabbed a near new HK SS100 esc and the cap wires nearly fell off from inside the caps?? I replaced the caps with blue 1000uF 35V-130* Rubycon RX30's right onto the board. It works very well now.

I remember Etti used to use the Suppo base board BUT, they used the blue Rubycon's instead.... wonder why.

+1
ditto CC240LV 3+ years back... use to burn cap leads ... 4S 1515/1Y - pop .. changed to upmarket caps.. 6S1527/1.5Y
around then decided to design own esc.... never looked back
W

THis esc is still running well even when I use it to test iffy or bad motors on bench.

Cool... $20 esc....

[golfito]

There seems to be a lot I should read, subscribed! .Thanks Wayne.

[CraigP]

Yes, there's 150deg C caps too with high ripple current. They are NOT cheap! If you buy your own, remember there are 2 ripple specs, 60Hz and 100KHz. You want to look at the 100KHz number. Good caps aren't small in size, they need some mass to handle the heat. Some of these little dinky caps they are installing in these ESC's are a joke!

It's not necessary to replace, putting good ones in parallel will bolster them up. I buy my caps from Mouser, spent a lot of time researching specs.. If anyone is interested in some part numbers, just let me know...

[dasboata]

Yes, there's 150deg C caps too with high ripple current. They are NOT cheap! If you buy your own, remember there are 2 ripple specs, 60Hz and 100KHz. You want to look at the 100KHz number. Good caps aren't small in size, they need some mass to handle the heat. Some of these little dinky caps they are installing in these ESC's are a joke!

It's not necessary to replace, putting good ones in parallel will bolster them up. I buy my caps from Mouser, spent a lot of time researching specs.. If anyone is interested in some part numbers, just let me know...

you have a PM Craig

[gearhd48]

My question here after reading this is what mathematic calculation is needed to figure out how much Uf you need for what amp draw & voltage to get the optimal capacitance?

[gearhd48]

Here is some great video info on youtube calculating your needs. Capacitors (1 of 11) in Series, Calculating Voltage, Charge and Total Capacitance look it up.

[drwayne]

My question here after reading this is what mathematic calculation is needed to figure out how much Uf you need for what amp draw & voltage to get the optimal capacitance?

Hi
After reading all this. you would be aware that cable length/inductance.. battery quality.. plug resistance .. motor efficiency etc etc etc are a mixed bag..
There is no single complicated? calculation to provide an answer for the best capacitance array suited any setup.
One needs consider multiple factors which could be potentially different across differing situations, and consider your own setup when reading this thread.

For eg
Im currently running pair [ HIFEI X300 to 5692/780Kv ] from 12S1P65c5000 source ( Au class limit )
The amp loading here is impressive, driving 1665 wheels.. the initial launch draw(250A) is harsh as I launch hard , and at high rpm the voltage spikes are abhorrent..thus the cap bank caters to both the initial voltage sag, and upper rpm frequency buffering.

Thus I use 10x 470uf 63v low esr 103c rubycon.. fast reply, adequate voltage support, and fast recharge.
5x 1000uf do not offer fast recharge, and consecutive draw attempts may see a degradation.

Sorry..no magic calculation ... just a direction for you to take towards a solution

regs

[gearhd48]

I thank you for your time to reply this. As you said this will be leading me into a new direction for knowledge! I'll be heading to OZ to ask the wizard, Oh wait you are in the land of OZ! I've got a mate in Queensland....Well I'm of to learn more and do some testing! LOL Tim

[dmitry100]

Any of you guys know what this cap bank is and what is the difference between this and regular caps?

https://www.offshoreelectrics.com/proddetail.php?prod=etti-e081

[drwayne]

Hi
Just revisited this after countless years .. still holds !
W

[ray schrauwen]

In general yes it does. So far with the new Castle ESC's they are saying a cap bank is NOT required.

[TRUCKPULL]

In general yes it does. So far with the new Castle ESC's they are saying a cap bank is NOT required.

It Not just that it is NOT required,
If used it can damage the new type of circuits that stop excessive heat.

I am pulling 400A on 8S with a Castle XLX2 - Ripple is 0.61V
Why would I want an extra cap bank.

I do use Cap Banks on all my older ESC's.

Larry

[Steven Vaccaro]

It Not just that it is NOT required,
If used it can damage the new type of circuits that stop excessive heat.

I am pulling 400A on 8S with a Castle XLX2 - Ripple is 0.61V
Why would I want an extra cap bank.

I do use Cap Banks on all my older ESC's.

Larry

Larry who said it would hurt them? the guys I know locally using the xlx2 also used cap banks with no problems.