Printable View
Here's the answer before you ask.
external cap banks ADD capacitance to your ESC.
When adding a cap bank, DO NOT remove existing esc caps ( replace dead ones with new ones, sure.. rated same )
Just delivered my desk... a new HV ESC where the owner had removed all onboard caps and replaced with an external cap bank.
I know this fellow had the best intentions, so there will be no finger pointing and gesticulating (look it up) for all to see.
Attachment 83341
Question: I plan to add cap bank to Seaking 180 ESC, I bought this one: http://www.offshoreelectrics.com/pro...i-e041&cat=136. The recommended installation is to open up/strip the power wire near the base board and solder the + and - notches onto the wire. That will be difficult in my case, can I open up the power wires at the same location but instead solder two short ( very short , no more than 30 mm) wires and then attach them to the + and - notches on the cap bank?
It is far more electrically efficient to mount the caps further away on the power wires than using a branchQuote:
Question: I plan to add cap bank to Seaking 180 ESC, I bought this one: http://www.offshoreelectrics.com/pro...i-e041&cat=136. The recommended installation is to open up/strip the power wire near the base board and solder the + and - notches onto the wire. That will be difficult in my case, can I open up the power wires at the same location but instead solder two short ( very short , no more than 30 mm) wires and then attach them to the + and - notches on the cap bank?
This is NOT how you do it Attachment 83340
The T180 wires are long enough to allow the capbank mounted further away from the esc.
Thank you very much, that is good to know. My problem is not entirely the length of the wires but rather I have no over head clearance fron the hull, I need the bank to be on the outside of the original caps, the wires now go over the heat sink to the batteries, there is no room above the heat sink. So my only solution is to wire-out the cap bank. It is infact like the T180 V3---how the maker does, two wires to the + and - terminal. But I don't want to over heat the terminal, so was thinking splicing /joining the power wire with the cap bank.
Sorry to be so long winded!
Cheers!
Thank you again for the addition of the pictures , I really appreciate you spending your time here!
[QUOTE=drwayne;447888]It is far more electrically efficient to mount the caps further away on the power wires than using a branch
I understand, maybe i need to rethink my solution, efficiency is important.
Thanks!
[QUOTE=tlandauer;447891]Quote:
Originally Posted by tlandauer
I run some very high demand setups, and the cap banks are anywhere between the Batts and ESC.. the closeness to esc is usually to limit the amount of extra plugs between the esc/capbank....Quote:
Originally Posted by drwayne
Here are 2 photos of 2 different setups for caps in 2 diff builds of same hull.
One has caps on back the SF240HV esc, other has a shared capbank that is attached direct too batts.. with leads out to the SF15S300A esc.
Both drove heavily loaded 5692 with no issues.
Attachment 83342Attachment 83343
You have cleared up alot of misconceptions that I have. Thank you from the bottom of my heart for spending all this time to post and take pictures!
Tim
Of course not, those caps are in series thereby halving the capacitance if they are same.
Did you mean something else?
Quote:
Originally Posted by drwayne
I did not think that large wires are required for offboard cap banks as I am planning to use 14G wire 8" away from esc.
My reasoning: they are only dealing with AC ripple current not full DC load current.
What say you?
I am sure you are addressing to drwayne, but I agree with you, I have done another set-up using 14G wires few inches away from ESC. My misconception was that either the wires has to be very short or if you solder the cap bank on to the main power wires it has got to be close to the ESC.
How else should I say it, Ray ?? "This is NOT how you do it "Quote:
Originally Posted by ray schrauwen
I said what ...Please quote { } where ... :smile:Quote:
Originally Posted by ray schrauwen
Although, purely for the sake of discussion ... from a practicality angle, larger gauge wire decreases EMF, heating and resistance.... and are a heck of a lot easier to handle.
see attached for an example
Is that what you wanted me to say ?
If you mean the large gauge wires from both installed pics above, the middle bank is fed direct from the 12S batt packs ( black plug visible on left, red on right) .. and direct from that bank to the ESCs.. there are no 'patch' leads there.
The esc mounted cap banks in other pic, are large gauge because it offered more rigidity in the assembled units... sizes 14 upwards are okay IME
Attachment 83356
Attachment 83357
edit: these 2 pics are from ''Fabs" setup for his 4S OBT
Here are some details of the shared bank
Attachment 83358
Attachment 83359
for 12S2P feeding 2x 300A esc - 5698/910 - X665 ... child's play ! ( big kids )
How do you get A/C ripple on the DC side? In a car I under stand how. In a boat we dont have an alternator generating ac thought...
I still fal to reason the need for large cap banks in these boats.
Thats what I was asking or trying to find out.
I'm sorry my posts were poorly written. I do that sometimes when I haven't eaten enough.
I didn't want you to "say" anything. My apologies sir. :unsure:
Of course if in-line I'd use heavy guage too but, I wanted mine off the side in flotation so it was out of the way. Since it's not carrying a high amp load as far as I know ??? I was hoping after seeing your posts that I was O.k. and didn't have to change it.
Thanks for your posts!
Quote:
Originally Posted by drwayne
Can I ask why is it bad to remove the old ones as pictured and run it as pictured? What happens? What will go wrong?Quote:
Originally Posted by drwayne
EDIT: That is if they have all gone bad, not if they were still good.
drwayne, where did you get the raw circuit board material?
Here in the States, Radio Shack sells them.
Quote:
Originally Posted by ray schrauwen
If I miss food.sleep/medication I spend next morning apologizing for my last night's posts. :(
Im sure you know this.. capacitors are 'miniature super batteries' that charge and discharge super quick. YES, there is a lot of current/energy
flowing through the wire conduits.. so larger wire on long satellite leads is a must.. ( resistance, EMF, delta Tmp )
Ive evidenced caps under load where the flow is sufficient to burn their own leads away...
Id recommend to 'overcompensate' when adding cap banks.. a few $ more can be the saving grace for your setup.
as pictured ?Quote:
Originally Posted by ray schrauwen
In the first #1 post, that ESC was NEW ( or a few runs old only )... !
If the onboard caps die, Id most certainly add replacements inside or out.. the circuit was clearly stressed with those existing, so ADD MORE !
Remember this, capacitors store energy.
They are waiting to BITE you 'bad'.
W
Doc, Is it possible or "not good" to have too many or too big a cap addition ? (my understanding of basic electronics stops at OUCH :ohmy:)
Attachment 83375
for giggles I searched "capacitor explosion" on youtube. Some crazy stuff there
http://www.youtube.com/watch?v=kjhoePUJ8Vg
Please excuse my interruption here, but aren't cap banks supposed to be made up of "X" of amount of caps arranged in parallel so the capacitance of the bank is equal to the sum of all the cap valves in microfarads? That is added c1+c2+c3 = total. I ask this question because in looking at several of the posted pictures some of the banks seem to be made up of sets of two caps in series and these sets are then wired in parallel. The caps set of two caps in series doesn't add but equals a value less than one of the caps value. In the example I am refering to putting two 1000uf caps in series will equal 500uf. See the following link http://www.calctool.org/CALC/eng/electronics/cap_series
If there is another reason for wiring them in a series and parallel configuration or I am missing something please tell me.
The following picture seem to illustrate what I am talking about. Of the small board pictures one is from underneath and seems to show three pairs of series caps in parallel . If you give a value of 1000uf to the six caps the total capacitance of the board is 3000uf or so and not 6000 as if they were all in parallel.
The larger board seems to show the same thing, but there is no picture of the underside showing the actual solder connections.
Of course I could be completely wrong in my thinking.
Attachment 83376Attachment 83377Attachment 83378
Have you happened to log that combo yet Wayne? I'm curious what kind of current you're pulling with that setup...Quote:
Originally Posted by drwayne
On road atm. 1030am here in South Australia.
More when at desk
I deleted this because it confused even me !
Very interesting DrWayne.
Words Vs pictures
remember these numbers ... ...
C= 470uf cap, low ESR, rated voltage ~ 25% above your pack voltage
2 in parallel c1+c2=940uf
2 in series offers C1xC2/(C1+C2) = 235uF !!!!!!
series (-)---[C1]---[C2]---(+)
That series pair in 3x parallel array offers 705uf
(-)---[C1]---[C2]---(+)
(-)---[C1]---[C2]---(+)
(-)---[C1]---[C2]---(+)
Initial charge of the 6 caps is same as if all were individually charged
OMG Ive written and rewritten this a few times and each time I start expanding on referenced detail that loses most people.
simply..
In this circuit, the charge/discharge speed is 8x the std , thus smoothing the DC line ripple more effectively ... even though the energy return availability is 705/2820 ( std6 caps ) .. it presents 8x speed of charge/return into of those original individual 6 caps.. gives us twice the total energy available, at a far higher return rate than std. ( 705 x 8 / 2820 )
In the 15S300A5698/910 example I used a total of 1410uF as detailed here, and logged ripple <0.19Vdc.
Unfiltered, ripple measured >1.6Vdc .. but I didnt enjoy the lacklustre performance so I went home...
I use cap banks as detailed to cover both yield(battery recharges the caps) and reply(esc demand on power system) needs of the system.
------
I read above .. What is DC ripple ? . When the esc fires a phase, it draws energy from the 'energy sump' .( DC batteries ).. this causes a sudden voltage drop evidenced by a blip on the voltage display of your oscilloscope.
Each 3 firings ( a rotation of the motor ) makes 3 tiny blips ..... eg at 30,000rpm there are 90,000(at least) tiny blips.. a ripple .. an induced frequency.....EMF inciting ESR .....
This ripple.. creates an AC that is not usable by the DC-AC inverter (ESC) thus the esc now sees lower voltage...V x Kv - zoomzoom
Capacitor banks reduce the size of that ripple, the esc sees higher nett voltage = more fun.
If the cap bank is too large, it will induce it's own ripple as it recharges.
Would I recommend this type of cap array if asked .. depends on your application.
Im sure to edit this once Ive seen it in a fullscreen.. and read it as a mini-novel.
W
I guess what Doc is trying to say.... as he has explained it to me a 1000 times is... Because the internal resistance of a battery is much higher than a capacitor. It takes a much longer time to get the same amount of energy from a battery, and the timing is very important. In fact, using a different combination of capacitors/layout can give us the exact control we need. I guess the idea here is time/responce over high numbers of uf. It makes perfect sense..... I wouldnt recommend everyone to just play with caps in series (doc knows what he's doing) as it can have a reverse effect.
(my selective hearing and 10c worth)
Wow. here I was thinking you had learmomg difficulties :lol: :laugh:Quote:
Originally Posted by nata2run
HA! yes, only 1000 times later LOL
Holy Cow! I didn't think it was that complicated!
YOu oviously make good sense from what I read.
I would guess the Etti cap bank is all parellel ? Since only 5 caps...?
Copy & paste in archives...
Thank you! :thumbup1:
Quote:
Originally Posted by drwayne