Cap banks - the pre-emptive answer

[srislash]

Top of the season to you Doc, it has been a while. Just read the whole thread(for the most part) and now have a bit better understanding though now the brain is overloaded.LOL

So the current project is an AC R-42 with twin 1717's and FC 8s300 ESC's. Am planning on running 5-6s2p per side(Dinogy 3300mah all) and am now at the point to consider a good cap arrangement. This is to be the
Hull that rips 70 or so around the course just for fun(4-5 laps). So I am looking for a recommendation. Thank you for taking the time, Shawn

[drwayne]

Top of the season indeed !
Weatherman predicts something around 41'celcius for my new year's eve
Im getting a few in early to prevent dehydration

Why limit to 6600 a side when you can blow out to 10,000 ?..

1717/1580 are Y winds which demand more from a 100% launch than possible at 100% rpm .. so bottom end surge capability is what you should aim for.... with a little ripple coverage higher up.

Expect all those 8S300A can handle if you spin big wheels...

I advise 3000→5000uf as the vague magic number for capbanks ..but how that is determined depends on your application.

In your case of high demand on launch, and ripple clipping later on, use 8x 63V1000uf per esc as below

+.batt.-
+.......-
+o-+o-
+o-+o-
+o-+o-
+o-+o-
+......-
+.esc.-

zoom zoom

best of your wintry season to you, mate .. your welcome to the cold !!!

[srislash]

Thanks Doc, It iis not TOO cold here but certainly not 41 Celsius. We have a small desert/lake region not far from here that can see 40 degrees in the summer, I used to live there so I suggest the hydration. I used to go with a nice Pale Ale

Happy New Year to you and best wishes for the coming builds

[drwayne]

Thanks Doc, It iis not TOO cold here but certainly not 41 Celsius. We have a small desert/lake region not far from here that can see 40 degrees in the summer, I used to live there so I suggest the hydration. I used to go with a nice Pale Ale

Happy New Year to you and best wishes for the coming builds

Not too uncommon here for 40+'c for week or more at a time.. nights of 35'c .. love the weather here .. :)

Im 100% sure USA no longer has God looking over them, because he is down here brewing beer at Cooper's brewery...
Im less than 3 miles from this Chapel of beer, and often scent him brewing more of his nectar ... that Coopers plagiarize as their own , labeled Coopers Pale Ale ... pure bliss ...

Waiting on MichaelB to start/finish the new plug and mold for my next drag hydro build .. photos somewhere on OSE under his name . Zoom Zoom

[srislash]

I can't wait to see the Problem Child, I have been lurking my friend. I really dig the Drag Hydro concept. Or flat bottom for that matter.

[Nikolas Andriop]

Hello.
I have the Seaking 120A esc and i have replace the stock caps with Rubycon 35v 1000uf Capacitor (http://www.offshoreelectrics.com/pro...k-cap-35v-1000)
i just desolder the stock 2 pieces caps and solder the new ones at the same places and polarity...
Is that good tip for my esc???
I run the esc with 4S and some times 5S with a TP Power 2100KV Apparition Cat

Thanks so much!!!!!!!!!

[dmitry100]

Guys, instead of using the big 1000uf rubycon capbanks ... would doubling up on the 560uf caps work just as good as the bigger ones? I have these on hand and was thinking of just soldering up my own cap banks for much cheaper (bought a bag of like 12 of them for $5 bucks) instead of buying the pre-made swordfish cap banks for $15 bucks a pop...

[ray schrauwen]

You are better off with using two you have than a single 1000uf cap.

Many of you're questions are already answered in the earlier pages of this thread. It's good reading and you can learn lots.

[ray schrauwen]

The type of capacitors makes as difference too. ZL Rubycons are a choice of some top saw guys. The goal is to decrease ripple voltage as much as possible so your esc lasts longer under heavy use not to increase its capacity or ability to pass more current than rated.

[Jamey]

After reading this I have concluded that if you compare two banks with the same total capacitance the bank with more capacitors is more effective at controlling ripple than the one with a less number of larger capacitors. Does it work this way because there are more capacitors, or do the smaller capacitors actually work better? It seems we are just assuming the smaller capacitors work better and maybe that IS the case.

This is important because if it is total capacitor count that gives the advantage then maybe everyone is dropping down to smaller caps for no real reason? Instead use the same number of larger. For example 8x 460 is a better bank than 4x 1000; but is it better than 8x 1000? Using the larger caps takes the same amount of soldering and only a little extra space.

[Ken Haines]

Also search for "Low ESR" and a "Hi Temp" rating.
These options are listed on electronic sites like
Mouser, MCM, Newark, Digi-Key etc.
They are important factors in getting the best Capacitors
for our high demand applications.

[dmitry100]

So I have read the entire thread and my take on it is that ... a cap bank made up of smaller caps that is arranged in series and parallel will allow the caps to recharge fast enough to keep a constant flow of voltage to your ESC to avoid drops when under load. Does that mean it'll actually allow it to go faster and reach higher RPM under load (for a high RPM setups-- 50-60k rpm) when theres no voltage drop compared to a scenario where you are not running w/ a series cap bank ?

drwayne: Would 4-8 count of rubycon 35v 560uf ZLH caps be suitable in parallel & series for a 6s 2050kv (50k rpm) twin cat setup? and would it be beneficial to share that bank among both sides?

Looking at my data log below -- is it normal to have a voltage drop like this? I'm using the 4x1000uf rubycon zlh 63v swordfish cap bank with this one...
Shows lowest voltage as 23.4v and this was only using 45mm cnc props at the time as well with same tp 4050 2050kv on 6s as mentioned above.

[drwayne]

Oh my .. Ive not ventured here in 9 months .. a most pregnant pause LOL
more smaller Vs less bigger.
smaller caps will give a much faster refresh than larger ..although delayed.. the larger will feed more energy back
In the data above .. there is simply not enough total capacitance .. if you check the graph .. the caps hold voltage for around 1/3 the acceleration period before the voltage drop commences .. and the delay to recover afterwards is when those starving caps recharge..
Smaller caps generally combat high freq ripples .. larger caps control large voltage drop
and ... TP4050s are unlikely to survive >4000W for long.. the graph touches 4750

tp-ouch-sb.jpg

regs
W

So I have read the entire thread and my take on it is that ... a cap bank made up of smaller caps that is arranged in series and parallel will allow the caps to recharge fast enough to keep a constant flow of voltage to your ESC to avoid drops when under load. Does that mean it'll actually allow it to go faster and reach higher RPM under load (for a high RPM setups-- 50-60k rpm) when theres no voltage drop compared to a scenario where you are not running w/ a series cap bank ?

drwayne: Would 4-8 count of rubycon 35v 560uf ZLH caps be suitable in parallel & series for a 6s 2050kv (50k rpm) twin cat setup? and would it be beneficial to share that bank among both sides?

Looking at my data log below -- is it normal to have a voltage drop like this? I'm using the 4x1000uf rubycon zlh 63v swordfish cap bank with this one...
Shows lowest voltage as 23.4v and this was only using 45mm cnc props at the time as well with same tp 4050 2050kv on 6s as mentioned above.

[dmitry100]

Thanks for the response, DrWayne... I was wondering when you might come around here again!

What kind of a cap layout should I use for this particular twin cat setup setup in parallel? (6s on 2050kv)

I recently bought some Rubycon ZL 470uf 50v caps (from Newark) and am in the process of making a bank consisting of 18 caps total in parallel/series like you have outlined in previous posts for a total capacitance of 4,230 uf to be shared between the 2 sides.

Should I use even smaller 35v ZL caps for this setup? Like 330uf instead, or 220uf even?

Also, do the age of caps effect their performance? I have found good deals on them by US sellers on Ebay but they are from around 2007, 2003, etc.

[drwayne]

Hi.
Im not receiving notifications from here about new postings, sorry for delay.

if you're setting 18 caps into parallel / series pair .. you have 9 sets of series pairs in parallel ?

see attached pic fo eg .. lol..
a series pair of 470uf totals at 235uf .. where total = (C1xC2)/(C1+C2)
so 9 sets of those is not your aforementioned 4230uf.. more like 2115uf

35V caps for a 6S (22V) setup is better than 63V rated caps, yes... but youalways need +10% minimum headroom above the total voltage else the caps will perish.
smaller than 470uf Ive found togive less than optimal recharge ability

re old capacitors ..old stock is cheap because good electronics assemblers wont trust them for longevity or correctness in application

8x2capbank.jpg