Cap banks - the pre-emptive answer

[drwayne]

Thank-you for the honest upfront approach. I am dismayed to hear that you haven't had success with a cap bank to fit the needs. I did throw the hard launch thing in there hoping to put together something more robust than 98% of my driving requirements. It's the last 2%.... You did recommend a castle 2028 at one point, have the trials with your dragster changed your outlook?
The 5660 is 820kv and 6s may be used for the initial pack or two to make sure things are solid mechanically and electrically(8s will be run for the same checks). Once all systems are a go and data logging is running correctly it will a 10s boat from there on.
Propping will start small and baby steps will be taken each step of the way, I don't mind spending the better part of a season getting there. Getting the most the boat can offer each step of the way There's fun in that to, another veteran boater taught me that. Going hellbent to find the limits and maximum speed is not the objective (have another one here to do that:-) Starting out with a solid base for a reliable boat is. This will never be a 90mph mono but 50mph will not keep me interested in the boat other than rough water days. Working up to a 65-70mph speed would meet my expectations and I will putt the time needed to get there and change my setup if this motor isn't up to the task. Until I build my experience base with a larger/faster boat I only have others experience to draw from. The castle 50volt 880uf capacitor board I have in my hand that's much smaller than my thumb doesn't feel right for building that solid base:-? Based on what I have read the Rubicon 63v 470uf would be the cap to to build my bank from, please correct me if I'm wrong. If I have to do some experimenting with cap banks so be it.When I say experimenting I really mean guessing:-) I see these setups run successfully with no cap banks, the castle 820 uf:4-220uf in parallel, etti 63volt 5000uf:5-1000uf in parallel and all the way up to the 50volt rc boat bitz 12000uf (fightercat board):10-1200uf in parallel. I hope that was readable! The only one I don't have is the etti cap bank and if I was to pick one of the three, of course it's the etti!
To start the guessperiment (it should be a word) I am thinking 6x2 or 8x2 with the 63 volt 470uf would be a place a start. Any other wisdom you can share will be most welcome. The novel above should give you an idea of my approach or your asleep. Any experience you can offer wouldnt ever come back at you should a cap blow or even catch fire. It's just one component is a series of them being pounded and abused beyond there design limitations. I choose what to do with advice and recommendations I receive from others. You don't want me to put 2 of the rc boat bitz 15000uf cap banks in the boat, one for each positive and negative wire the esc has, do you;-) Yes, I bought two of them. Somewhere in all this there must be a place to start. Thanks for reading this much! It's the medication, really it is. Look at it from a harm reduction standpoint:-D

The FC/RCBB/TFL cap banks are designed where biggest was thought the best .. BLING.
Massive capacitance will certainly reduce ripple to near zero, but the overall response for surge/recharge is based solely on the battery's ability to keep up to the demands of the capbank.. a heay demand of power from the esc will see the bank discharged hard.. and if that demand remains high the bank will draw power from batteries for a recharge rather than feed that towards the esc ... and the esc will see a reduction in available power after the initial surge has been passed...
We want a capbank design that is optimized for flow to the esc ... not detrmined to keep itself charged with little care for the load.. lol
However 80% of electric boaters dont push their setups hard.. so whatever capbank ( or none ) will suffice for their needs.

The 3 or so of those massive banks Ive handled for others, Ive literally cut in half with a dremel .... allocated half to each side of an independent twin setup for eg ( eg where the twins have individual battery sources ) .
Anything >6000uf really is a waste of effort electrically.

Hope this clears the medication haze a little.....

[olwarbirds]

Wayne, some of my military electrical circuit training came back to me as I was building cap boards. I was wondering why we dont put in a fixed style inductor in our cap boards. Would it not then almost completely eleminate any ripple voltage ? DJ

[drwayne]

:) Please illuminate me with your thoughts.

[Fella1340]

Thanks again, i had to laugh at myself when I opened the box up and realized the actual size of the fc cap bank. That was quite awhile ago before i had found any sound reading on the subject. Perhaps they'll get cut down and used one day after i get through the the fifty 63 volt and fifty 35 volt bags of capacitors i have here! Keep us posted with any new updates on hv cap bank arrangements that will stand up to serious abuse, enjoy the warm weather. Snow is just around the corner here:-(

[3-UP]

Quick answer.... 4....

Thanks for helping out, would it be OK to solder the bigger caps into the factory t180 aux cap bank board?

[olwarbirds]

:) Please illuminate me with your thoughts.

It might darken them It has been a long time since my military electronic days, I will try. I know that in modern hitech setups charging and using multiple lithium ion and polymer batteries. They are using various single stage PFC converters. In these setups their using caps along with BV inductors to control ripple voltage and to keep the DC voltage at a more constant level IE: no voltage drop until the preset cutoff.

Our lipos start out 4.20v-4.25v per cell and drop in voltage rapidly. For me if I could keep the voltage constant on a "SAW" setup then I would have more consistent timed runs IE: one up one down the course, so its feasible. In heat racing I dont think there is enough stored amperage to support this with the current max battery mah rules.

How to use these BV inductors in my "SAW" setup is where I'm rather unsure about the placement. Can I add them in the capbank or would this have to be something actually added to the board on the ESC ? ... DJ

[drwayne]

Thanks for helping out, would it be OK to solder the bigger caps into the factory t180 aux cap bank board?

physically impossible.. std caps have 3/16→1/4 leg gap .. the little tackers much less .. dont bend pins to suit the boards .. start again new board and space correctly.

[drwayne]

It might darken them It has been a long time since my military electronic days, I will try. I know that in modern hitech setups charging and using multiple lithium ion and polymer batteries. They are using various single stage PFC converters. In these setups their using caps along with BV inductors to control ripple voltage and to keep the DC voltage at a more constant level IE: no voltage drop until the preset cutoff.

Our lipos start out 4.20v-4.25v per cell and drop in voltage rapidly. For me if I could keep the voltage constant on a "SAW" setup then I would have more consistent timed runs IE: one up one down the course, so its feasible. In heat racing I dont think there is enough stored amperage to support this with the current max battery mah rules.

How to use these BV inductors in my "SAW" setup is where I'm rather unsure about the placement. Can I add them in the capbank or would this have to be something actually added to the board on the ESC ? ... DJ

most inductors I placed into circuits were to limit (power) rail ripple ..they are made/wound to target specific harmonics.... dont truly offer a wide frequency coverage ..more a 'choke' effect on the circuit for the frequency they are wound.
eg in DC/AC inverters they could hold the input voltage stable for conversion to 120VAC60Hz through switching.
in rc ESC, also DC/AC inverters, where we have variable output frequency..the inductance would need rate change to benefit the circuit .... here we look into toroids with movable primary/secondary coils ..which is already in the too hard basket for this miniature work with such high draw.

[olwarbirds]

Wayne, ok now I do understand why we dont do this. It was a thought anyways. Yes the setups I was referring to are alot bigger than our rc units... I dont care what they say about you Aussies being upside down all the time, it must help blood flow through the brain. again tks for explaining why it wouldnt work and how it does work... DJ

[drwayne]

Wayne, ok now I do understand why we dont do this. It was a thought anyways. Yes the setups I was referring to are alot bigger than our rc units... I dont care what they say about you Aussies being upside down all the time, it must help blood flow through the brain. again tks for explaining why it wouldnt work and how it does work... J

It's all a matter of perspective, mate .. we are not upside down, you lot are.
You are not on top of the world, we are.
Contrary to popular belief the earth rotates west to east, orbits the sun in direct conflict of path as first determined by Galileo.
The Catholics were right to question his results.
The sooner you Northerners all accept that reality, the better we will all be.
regards
W


btw, if we were upside down, the backflush from our backsides would fill our heads with....

[ray schrauwen]

Top of the world to ya Wayne! lol...

I thought there was no top of the world and if there was it would be the rotating surface of the equator area but, how would I know what angle and or direction our universe is traveling in?? lol... I'm stupid.

[Fluid]

Top of the World Hotel - 3060 Eben Hopson Street, Barrow, Alaska 99723 Barrow, Alaska

http://travel.rbth.com/travel/2013/02/12/the_antarctic_russians_make_themselves_at_home_at_the_south_pole_22777

[drwayne]

Top of the World Hotel - 3060 Eben Hopson Street, Barrow, Alaska 99723 Barrow, Alaska


http://travel.rbth.com/travel/2013/0...uth_pole_22777

Been Antartica for work. !
Douglas Mawson base.. all of 10 days turnaround before the ship returned for more vegetables and beer

There's a tourist mob here in Au who hire a 747 or 767 or something, and fly gawkers down and around the place for a ten hour total flight .. never touching down... easy way to spend $2k+ ....
A mate ( Jamie ) offered them full fare for a one way trip, intending to wing suit down to Mawsons.. but they seem uninterested his adventurous nature, or the media sensationalism it would bring topromote their flights.
lol

[kfxguy]

So......I'm wasting my time what what I've done? I have a t180, (3) 50v 1000uf caps on the esc (repacking the stock ones of 35v) and then 5 more additional ones of the same 50v 1000uf.... mainly hard saw passes but rolling into the throttle. Maybe ditch Two of the caps? (Setup is a neu 1524, 32" cat, 7s, 1860kv)

[drwayne]

So......I'm wasting my time what what I've done? I have a t180, (3) 50v 1000uf caps on the esc (repacking the stock ones of 35v) and then 5 more additional ones of the same 50v 1000uf.... mainly hard saw passes but rolling into the throttle. Maybe ditch Two of the caps? (Setup is a neu 1524, 32" cat, 7s, 1860kv)

The cap bank ADDS to the existing capacitance onboard an ESC.
Most ESC support around 1000uF total... +3 or 4x 1000uF caps =~ 5000uF ± 500uF

As you already have 3x1000uF onboard.. 3 more is a good total.
Capacitor and battery temps will identify if this is the sweet spot.
'5 second rule' ..if you can hold a finger on cap crest for 5 seconds without burn.. that's ok .. if burn !! .. need more.