Bit of context, batteries first: I have a 10S2P 30Q pack that I’m using at the moment, getting about 15-17km. I also made a 12S3P LG HE4 pack that has been sitting on a shelf because it doesn’t fit in my enclosure and I later realised it’s very badly made and probably not very safe. I have a couple of extra HE4s and a bigger enclosure now.
Motors: Currently using a single Maytech 6355 170Kv, 14T/44T on 120mm Cloudwheels. I’m fairly heavy (around 225lbs), so the torque isn’t great. I don’t really have any desire to go above 30 km/h right now - the board can reach it but I can’t handle it at that speed at the moment, might be a truck or setup issue but I’ve swapped in whatever the stiffest bushings I could find were (I think 95A). I do however really want more torque for fun, and kind of need it for breaking. I’m either going to get a Flipsky 6384 140Kv and add it alongside the 6355, or get two 6384s. Until then I’ve ordered a 12T pulley but it’s aluminium so if anyone has links to steel ones/can vouch for aluminium that’d be appreciated. Similarly I couldn’t find ABEC/cloudwheel pulleys above 44T but if they’re common somewhere I’ve missed please let me know.
ESC: Unity
First question: Am I ok to put two fairly different motors on the board? I think I’m inside the ERPM limit with 170 and 12S. To match the speed I was going to keep the 170KV one at 14T and put the 140KV at 17T. If there are some noob mistakes in here please correct. What I will most likely do is buy one 6384 and then add a second if needed later.
I can rebuild the pack as 12S3P or 10S4P. The cells are as best I can tell more optimised for discharge current than capacity, they advertise 20A continuous and 35A burst. The 10% difference in capacity doesn’t make much difference to me with 40 vs 36 cells (I think anyway? I’m fine with the existing range because I live in the city, the question mark is just if adding the extra power is likely to tank my range). This leads to the second question:
Should I go 10S4P or 12S3P? I’m leaning 10S because I don’t need the extra speed and it can’t hurt to spread the load current over 4P instead of 3P even if I don’t strictly need it - I don’t think I’ve drawn more than 15A from the battery because I don’t go very fast or try to do hills at top speed or whatever, so these cells should be good for that in 1P. What I want to check is related to a spirited conversation a few of us had in the ESC thread about voltage vs current loads in an ESC. Does 12S up the risk for a unity considerably? Does the increased current draw of 2 chonky motors at 10S bring its own worse risks?
I’m going to second Brian’s question. Can you get us logs of both the motor and ESC temps for a “cold start” cut-out as well as a “warm-up”? Also, do you have any faults being reported? What do you use for logging?
My money’s on a wonky solder connection that remakes itself with heat (tens of amps through a tiny area will hot it up right good) and it can only reliably sustain the current once it’s been “reflowed”. Would be a relatively easy fix with a good bit of flux and a hot air gun but it could be attached to something delicate like an electrolytic cap or something with a lot of mass so that complicates it
