18 inches between ESC and Battery

[Quax]

My ESC is (most likely) telling me there is a connectivity issue. I've got 18 inches of wire between the ESC and the battery. I'm confident in my connections to the point where I am suspecting that the wire's inductance might be freaking out the ESC.

For context, I've got a Seal 150A Opto HV. When I plug it in, it gives me short beeps followed by long pauses (* * * *), which the manual states is either due to
overvoltage (not possible in this case. Using 6s battery on a 6-12s ESC),
bad motors (not possible, as I've tested on 4 motors)
or poor connections.

Could I fix this issue by adding a capacitor bank at the ESC?

Thanks

[fweasel]

That's a lot of wire, but I wouldn't think it would cause you problems on the workbench trying to arm the esc. A properly sized cap bank is never a bad idea, especially on high current setups. Not likely to solve your issue outright.

Have you had this esc working before, or is this a new install?

[Peter A]

Have you used the program card on it yet to set it up? The Seal esc's can be a pain. I did one of these about three weeks ago. You have to follow the instructions with the program card exactly or the program card will not read the esc.

[Quax]

That's a lot of wire, but I wouldn't think it would cause you problems on the workbench trying to arm the esc. A properly sized cap bank is never a bad idea, especially on high current setups. Not likely to solve your issue outright.

Have you had this esc working before, or is this a new install?

It's a new install. I actually have 2 identical ESCs with the same problem.

Do you have any resources on how to size a cap bank?

[Quax]

Have you used the program card on it yet to set it up? The Seal esc's can be a pain. I did one of these about three weeks ago. You have to follow the instructions with the program card exactly or the program card will not read the esc.

I have not used a program card on it yet (didn't come with it). Do you think this could be the source of the problem?

[Peter A]

I have not used a program card on it yet (didn't come with it). Do you think this could be the source of the problem?

It may be. You can set them up using your tx and following the beeps. Why are your batt wires so long? Perhaps post some pics of your set up.

[fweasel]

I have not used a program card on it yet (didn't come with it). Do you think this could be the source of the problem?

A program card isn't absolutely necessary, but very helpful. However, at a minimum, you must perform a throttle calibration on a new installtion. Also, that model is opto isolated and requires an external BEC or 6v LiFe battery pack plugged into your receiver.

[Quax]

It may be. You can set them up using your tx and following the beeps. Why are your batt wires so long? Perhaps post some pics of your set up.

Reason for the batt wire length is partly ignorance, partly circumstance. I need to run them through a controls box since the boat's going to be autonomous. It's a school thing, and no one on the team has ever done anything like this so we're all learning from you guys and various other forums/RC sites.

I did what you guys suggested and got the motors to work. This is a picture of the mock setup. In the end, I'm running a catamaran with 2 batteries in series and 2 ESCs in parallel.

PXL_20210522_190256808.jpg

Here's the wiring for the end setup. 2 6s batteries are hooked up to the green battery connectors. The power lines run in and out of the controls box and is run to the two ESCs. All told, that's about 52 inches (yeah, it's a lot, I know). Based on your past posts, the calculators and such, we estimate that we're going to be looking at between 50-80 amps per motor, or 100-160 amps at the batteries.

I may end up trimming the power wires and lengthening the motor wires if you guys think it's an issue that can't be solved with capacitors.

PXL_20210522_190523719.jpg

The minimum battery wire length length I can have is about 20 inches since it's a catamaran.

Is my setup viable?
How can I size my cap banks?
Will my cap banks interfere with each other?

[plinse]

...
How can I size my cap banks?

Dimensioning is based on experience as the ESC already has caps and in theorie that should be enough while experience shows that quite often it is not .

If you run the components at high load and partial throttle is also planed to be used it is reasonable to place ~2-4000?F as close to the ESC as possible and it is better to use many small caps instead of a few big ones.

...
Will my cap banks interfere with each other?

The more wire you have in between batteries and ESC the more likely it is.

Just have a look at the wiring of a 12s boat I run using 6s packs:

Using bullet connectors I can directly connect the packs without any additional harness or connectors in between.

It depends very much on the current level whether your wiring will cause problems or not. If you expect 50-80amps per motor I would definately shorten the wires to the absolute required minimum (or have the budget ready to buy new components if you burn something up).

You see in the pictures that the required wire length and the wire length you use is a multiple of the minimum. This is what RC-Components are made for. Long wires, XT-Connectors, additional harnesses for batterie-connections are the usual candidates for hunting gremlins
https://www.youtube.com/watch?v=wQ5Xjoq41FQ
The shorter the wires, the less connectors, the better the solder joints the less issues you have to expect

[Quax]

Additional questions:

Can you have too much capacitance?
Are there any considerations to make when running parallel ESCs off of one battery bank?

[plinse]

Not really but you can have inefficiently placed capacitances that do not bring you any additional benefit.

[RaceMechaniX]

Hello Quax,

Your long wire and multiple connections can be problematic. The ESC's you are using do not have a lot of onboard capacitance to buffer voltage sag and inductance in the battery leads. Try to limit the number of connectors in the system to a minimum to further reduce losses. 4000-6000uF of additional capacitance near the ESC will help. You will want to hardware this in by directly soldering the cap bank to the incoming ESC leads. Make sure they are good connections and insulated after installation. Do be cautious when connecting your batteries with the extra capacitance as the inrush current of charging the caps will cause a larger spark. I would highly recommend a soft start resistor to slowly charge the system in several seconds before making the connection. You can also buy connectors with the anti-spark resistor built in. https://www.offshoreelectrics.com/pr...d=ose-qs8-anti These are highly recommended. This is a good example of a cap bank: https://www.offshoreelectrics.com/pr...d=etti-e035-lv