ESC Wiring Dilemma

[Panther6834]

I have a bit of a dilemma, so I'm turning to those more knowledgeable than me. This is a dual-wiring configuration matter, so I'd like to explain before asking my question(s). To simplify things (at least, as much as possible), I'll use 6S as my 'base'.

As with most even-numeral power configurations, there are two primary Lipo configurations - a single pack of the full voltage, or two packs of half the voltage (ie. a single 6S, or two 3S in series...I'm ignoring the possibility of packs in parallel). As I understand it (and, if my 'understanding' is incorrect, please, feel free to correct my misunderstanding), the primary benefit of a single pack is "less resistance", whereas the promise benefit of two packs in-series is "lower temperatures". Based on my 'understanding', I get to my dilemma.

If someone plans to power a particular boat via both methods (ie. sometimes via a single 6S, and sometimes via that 3S), there are two possible ways of wiring the battery connectors to the ESC:

1) Have 2 connectors soldered to the ESC wiring, with one wire from ESC + to connector #1 +, one wire from connector #1 - to connector #2 +, and a third wire from connector #2 - to ESC -. This wiring configuration sets up a primary use of two packs in-series. To switch to using only a single pack, a loop connector is used.

2) Have the ESC wired for a single battery, with a single connector. To switch to using two packs in series, a Series Harness (see photo, below) is used.



Finally, the questions. First, which is better? Second, which is safer? I realize the answer to both could be different...or, it could be the same answer to both questions. Obviously, if a boat is always going to use two packs, option #1 is the way to go. Likewise, if a boat is always going to use a single pack, then option #2 is the way to go. But, for a boat that has the potential to have an even split between the two powering methods, I'm trying to find out which option is best.

[Xrayted]

It really comes down to personal preference. My boats are set up for a single 6S pack, so the ESC uses a single Q8 connection shown above. However, I do run it on 8S from time to time using 2X4S packs I have, so I use the exact same series harness in your image for 8S to do that, easy peasy. The only reason I would use dual 3S packs in a boat only intended for 6S would be because I had 3S packs laying around vs buying a new 6S pack, otherwise there is zero performance advantage to splitting them up.

Any RC model I build that uses 2 packs in series routinely, either boat or heli in my case gets a similar series wiring setup as above directly from the ESC, but one of the three plugs shown above is eliminated as the primary ESC + and - are used with the two remaining pack connections with a jumper wire between them. My helis for example run 12-14S, so always two packs wired in series, so the ESC is already set up for this with a dual plug setup.

You could still use a single connector on the ESC in this case, but would then always have one extra connection from the ESC harness due the series adapter, so there would be some extra resistance from that third plug vs only 2 with a permanent series wiring from the ESC, and is perfectly safe either way you decide to go.

[fweasel]

All lipo batteries are just 1S cells wired in series. All things equal, a single 6S pack is better than two 3S packs wired in series because there are fewer soldered connections introducing more resistance to the circuit, fewer connectors, and less wire.

That brings us to your ESC wiring question. The more soldered connections, bullet connectors, and wire means more resistance in the circuit. Personally, I prefer ease of use, compatibility with multiple boats, and the safety of a shielded connector like the 8mm anti-spark vs. the absolute minimalist approach to using bare bullet connectors and connecting the Lipos in series without any harnesses. In your specific case, I prefer to solder two connectors to the ESC in a series configuration (one connector soldered to the negative ESC wire, one connector soldered to the positive ESC wire, and a jumper wire between the two connectors) when using two or more batteries. In high voltage, low amp setups like my 12S 650kv Apache, I then plug a Y-parallel harness into each side of the ESC connection so I can double my mAh capacity. The extra connections don't make a difference in that setup due to the low amp draw.

PXL_20240509_000618835.jpg

[Xrayted]

Yep, your ESC wiring in the image above is exactly how any of my models that use dual packs in series is wired. Elegantly simple with the least amount of connectors