Cap banks - the pre-emptive answer

[tlandauer]

Wow, yes, it looks very intelligent! Now for the unintelligent stupid question I have: suppose you still use your "T" connector and "save" one pos. and one neg. for a cap bank, would that work?

[rickwess]

It would work, but it is another connection, which in practice you want to avoid. I think it would be better to just bind another set of wires into that splice for the cap bank.

[drwayne]

The less individual joins or loops or bypasses or extra traffic on the leads is always best.
rickwess's wire wrap idea is a frequently utilized idea, and is good to see it represented here.
Do use a large tip high wattage iron to quickly put solder through that join, else the solder will wick up the leads making it a most unsatisfactory product.

Yes, Id solder leads from a cap bank to that same location...

[rtodd1405]

Hi,

I've read all these comments and great advise and have to say that I'm impressed by the detail but still a little confused. I wonder if you may be able to help. I'm building a boat 56 inch carbon fibre cat with twin drive. I have bought Castle 2028 (740Kv) motors and still to buy the esc's and batteries. I am thinking of Swordfish Pro+300A esc's and twin Entropy 6S in series to give 12S on each side.

I already have some 63V 470uf RB capacitors and not sure just how many I need to use on each side. From your photos etc. I think I need two capacitors side by side in series (one row) but I'm not sure of how many rows in parallel? I'm not sure if it is 6 rows (12 caps in total) or 4 rows (8 caps in total)?

The other thing I'm not sure about is whether the two sides (ie. the batteries) should be connected in parallel (at the capacitor bank) or left completely independent? I've been told that this helps balance the loads on the batteries?????????

Any assistance would be greatly appreciated.

Russell - Brisbane Australia

[rtodd1405]

Ps. one more thing, do you know what size resistor I should use in the spark arrester??????

Russell - Brisbane Australia

[drwayne]

Gday

if you hope to race this inside AMPBA rules, 12S1P for the whole boat is your limit.
A pair 2028(780Kv written on back of mine btw ) is too much for 12S1P

resistor is 100 ohm 5W ceramic ...
63V470uf 105c caps available in Au from Jaycar RE6210

here is the last capbank for a SF300 feeding castle 2028 in sprint hydro.
All cables are AWG8, plugs 8mm with cables when entering the plug are doubled so more wire less solder ... ergo I stripped more insulation from outside wire, folded the exposed and forced into plug.. then soldered
16 caps in total set as 8 series pair connected in parallel ( wtf ? lol )
The Sf300 here is my old faithful

20140219_221554_resized.jpg

Here are 3 pair of series caps connected in parallel

--||--.--||-- is a pair of caps connected in series...

capbank.jpg

[rtodd1405]

Wayne, thanks very much for the info.

Your right, the motors are 780Kv.

Much appreciated

Russell - Brisbane Australia.

[Fluid]

...I'm building a boat 56 inch carbon fibre cat with twin drive. I have bought Castle 2028 (740Kv) motors and still to buy the esc's and batteries. I am thinking of Swordfish Pro+300A esc's and twin Entropy 6S in series to give 12S on each side...

Another issue with your motors, 12S is too much for the Castle 2028 motors. First, they are rated to 30,000 rpm and 12S will be at their limit. Second they will need some relatively small props, and that hull will move better with large props. Unless you want SAW-type running only best to limit voltage to 8S or 10S per motor.



.

[drwayne]

Another issue with your motors, 12S is too much for the Castle 2028 motors. First, they are rated to 30,000 rpm and 12S will be at their limit. Second they will need some relatively small props, and that hull will move better with large props. Unless you want SAW-type running only best to limit voltage to 8S or 10S per motor.

.

Hi Ray.
The 608z bearings inside these castle 2028 are 8mmID 22mmOD 7mmWide
They are in fact skateboard bearings made in Singapore...as labelled and later identified from manuf.
Do yourselves a favor and replace these wheels with better.
Bearings are the failing of this motor.
I went BOCA
Be aware there is a bloody o-ring on the shaft internal as a spacer !

Seriously wtf ? hahaha

regs
W

[Fluid]

What about the rotor wrapings doc, that is a more common BL motor failure point due to over-revving than bearings are.


.

[rtodd1405]

Hi, many thanks for your comments and good advise.

Thanks

Russell - Brisbane Australia

[mekzoid]

I just bought a swordfish 300 with the castle recommend cap bank which is http://shop.rcboatbitz.com.au/index....roducts_id=868

Would that be sufficient?

[drwayne]

it depends on your loading.
for a 1515/1Y on 4S likely ok ..
for a 2230/1Y def not.

What motor + expectations ?
W

[mekzoid]

Sorry dur, I should have given more info, CF cheetah, TP 5660 1420 kv running 8s with a prather. Should I add another cap bank looking for the fastest cheetah out there so 75mph plus with a Prather 245 and Prather 240. I already bought 1 cap bank as stated.

[drwayne]

higher volts and lower Kv would make things easier ..

If you already have motor and packs..Id rec another the same cap bank and play gentle .

Talk to SteveB or DavidK in Qld about your needs ... :)