The mystery remains !

Hopefully we have a resident electronics expert who can explain this to us ?

What is the purpose of this small device (pictured below) that comes buried under black shrink wrap and is fitted across the positive and negative power supply wires to the ESC?

….and of much more interest (as far as this particular farce is concerned), why does it prevent the brushless motor being able to rev when the power supply is dropped from a pair of 2C LiPo batteries (wired in parallel - same voltage) to a single 2C LiPo battery .

Both power supplies provide the motor with 7.4 volts whether they are plugged into the “Y” lead harness or plugged in singly and it is the same 5000 mah LiPo battery packs being used in each instance.

As the video shows - after I cut this device out of the power supply wires, the same motor powered by either one of the same LiPo batteries allows the motor to rev freely and power the model perfectly.

This strange device acts like a “choke” on a single battery supply, but allows free passage of power on a two battery supply of the same voltage.

Problem solved - as far as getting it to work with one battery goes, but understanding why is entirely another matter!

Bob.

It’s working alright now with only one battery!

The video is probably a bit too long so if begins to “buffer” a little part way through (it does on my iPad) but it does get going again - it is not an ESC fault 😂

I added an earlier (shorter) video that should play better for anyone that cannot view the first one on their device.👍

This little circuit board was the culprit, the reason why the ESC would only deliver full power from a pair of LiPo batteries.

It was the “lump” hidden under the black heat shrink that can be seen on the black and red power supply wires.

The ESC would not allow the motor to rev with only one LiPo battery connected.

The “Y” lead was soldered in parrallel to double the endurance (not to double the volts) so in theory the motor should be able to run equally well on one LiPo or two LiPo batteries.

…….and it does now that this circuit board has been removed.

I previously owned an Alpha 1000/ Inception RTR that was a very fast one metre long boat that used a Seaking 90A ESC.

A spare Seaking 90A ESC was bought later as I found that I was using the boat quite a lot and thought that it must have been working overtime to handle all that power and a pair of 3 cell LiPo batteries.

It never failed, so I thought that it would make an ideal size of ESC to fit in the Remora that I was working on. I made a custom shelf to fit it and it all looked very neat and tidy.

I didn’t want to carry two heavy LiPo batteries in this craft, so I chopped off the “Y” lead that had two XT90 plugs on it and fitted a single XT60 plug to connect to the single 3 cell 5000mah LiPo that I planned to use in it.

Everything looked really neat and tidy and I was really happy with the boat on its first outing on the Southport lake - until I opened the throttle.

The boat ran at a nice brisk walking pace but it would not rev very well. Different size props were tried - all to no avail - the motor would not rev.

The motor was also changed, and the new one also refused to rev.

The “Y” lead was soldered back on and a pair of LiPo batteries were connected and the motor screamed!

Meanwhile I had made a bigger sized shelf in the engine bay to take a 180A Seaking ESC that I had spare at the time and the boat then ran beautifully, with either of the previously used motors.

Eventually the penny dropped ! The little circuit board that was on the ESC supply wires must only allow it to work on two LiPo batteries.

I cut out this circuit board and soldered on the XT60 plug again - and this time the Remora positively flew around the lake - no problem with not being able to rev now….but nobody that I have spoken to can understand this or why it happened.

The first picture shows the spare ESC in its packet as supplied new,

The second picture shows one ESC with the “Y” lead and one without.

The third picture shows the ESC as it was delivered with its “Y” lead attached.