Common caps for two escs?

[Jesse J]

It would be best to keep this a twin motor thread, since there seems to be a lot more to consider working with twins than I thought.
Thanks!
Craig, I'm using for now, a pair of those opto gadgets posted on page 2 or 3. Seems to be working.

[golfito]

Opto_Board_2_Input_2_Motor_Power_Schematic.pdf #160
I could find only two ps2501-1. Armed as the PDF of post 160.
Working correctly for the flysky GT3B radios, it was running 3pv4 / 4pls and an old spektrum DX3s.
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[CraigP]

That looks good Golfito! I got about 80 of the PS2501-1 from an old project I did. They are still available. Maybe you can go over the spec sheet and find an alternative.

[MG1234]

So you guys are 5 steps above my pay grade regarding cap banks so I’ll jump in here and ask ,I read that I’m supposed to leave the stock cap bank when adding a set of caps but I just don’t have the room on a twin fighter cat ,I have 2 HW 180 amp ESC,ran them last year on 6 s each,they gave me a little trouble at the end of the season ,sent the boat up on the shore full throttle,it’s happened before with other boats using HW ESC running them hard,so I want to add a cap bank but need to remove the stock one ,I’ll also add a BEC, I read that that helps theses ESC also,I was going to install the castle creations capacitor pack that has the 4 caps and 2 posts to connect to,your opinion please ,my other boats have room to leave the stock caps in place ,I’ll be adding the extra caps there also,thank you,

[CraigP]

Sorry to hear about the troubles, nobody likes seeing their pride and joy heading toward the shore with a mind of its own! The problem sounds more to do with “glitching” of either the ESC or Receiver. A glitch is a term in electrical systems like the word “bug”, which means a critical system (usually the microprocessor in either the ESC or Rec) gets an electrical disturbance, normally on the ground of the electrical system. If you read through this post, you’ll see that some of us have started using Opto Boards to keep the ground clean between the ESC and Rec.

Also note that the BEC’s internal to many ESC’s (like the HW ESC) can shut down due to high servo current draws or electrical noise “glitching” the over current detection in the switching regulator. Bottom line, I don’t use the internal BEC and always install and external unit that can supply at least 3A continuous and 5A surge. ESC’s often state their BEC is in that range, but there are many reports of problems.

There is an unintentional ground loop formed which has been discussed earlier in this thread. I’m pretty sure you’ve been a victim of that. It’s NOT an easy topic! There are schematics posted on this thread that should give you some ideas to get it just so...

[MG1234]

Thank you for explaining the glitch,I knew it had something to do with pushing those HW ESC too hard,I’ll install external bec,now I just need to know if I can remove the existing cap bank to install an extra ,or maybe only because there is no other way ,installing the extra cap bank with extention wires maybe 3” long max,it’s really tight inside this boat ,anyone?..thanks ,

[srislash]

As close to the ESC as possible is the rule. If you can replace the old ones so be it.

Any chance you can marry the negative wires as shown previously in the thread?

It has been a given that any of the HW ESC’s would cook their BEC on 6s. At least it was on the old ones.
It is just to hard to reduce voltage and current that much in such a small space. There is no cooling provision for an onboard BEC either.

[MG1234]

Thank you ,I’ll look again at that diagram and see if I want to give it a try ,thanks again ,

[CraigP]

Switching regulators running at 200Khz and above won’t give you a heating issue. Most of these external BECs I’ve checked out are that speed and above. But they do emit noise! So they should be at least 2-3” away from your Rec and that goes for the inlet power wire as well. I use the type that have a metal shield over the noise emitting elements on the circuit board. They usually refer to those as “fully shielded”.

[MG1234]

I’m going to use a castle BEC ,just because it’s all I know ,thanks ,

[dasboata]

THT good reading

[CraigP]

Response to Jesse: Some receivers don't like them, but I've had good results with all of mine. My dual hydro has a silky smooth throttle response (no sudden lurches) and it cleaned up a servo mixer I was using for the rudder/starboard ESC. I slowed it down slightly on right turns. The only way I could get it to really dig out on a turn!

[CraigP]

Thanks Craig, I think I'll do something similar, but bring the batteries in series. I'd like them to get drawn down together. This may require separating the cap banks completely. I'll post a picture when I get it wired.

Jesse, you can make it a 2-plate system, all caps in parallel. Two sets of batt leads coming in, and two sets of ESC leads going out. Batt leads to cap bank can be longer, but cap bank to ESC needs to be short as possible. Bring one of the batt leads into one side of the cap bank, the other on the opposite side. Both ESC lead sets come from the middle of the cap bank. This forces even current sharing among the capacitors. So it looks physically like a T with batt leads coming from each side and the ESC leads both coming from the middle. I hope that helps you... oh, and all caps MUST be the same type..