Are you confident they’ll handle that many amps? Have you got any kind of temperature monitoring working with them? I’ve got mine at 340 but I feel like it may be pushing it already
Not sure, I’ve seen others push similar amperages on the 560kv 70125’s so I figured I’d just copy those as baseline settings for these since I thought the thicker windings could take a few more amps, I’ll keep an eye on temps for a few track sessions before making a decision on if I want to push more, no onboard temp sensor is a bummer but I’ve been just touching the outside of the motors to keep track of temps. They’ve stayed very cold but it’s also freezing in Jersey atm, I’ll keep testing as weather gets warmer and plan accordingly
Haha, appreciate it, yeah I specifically started working on the thread so I could have it posted by the new year
so when it comes to voltage I initially wanted to go 14s using 50pl cells because they had enough amperage headroom to let me keep similar battery amps without as many cells in parallel, the issue came when it turned out that 50pl’s were questionable quality and I still needed a pack to race with
I had a bunch of spare p42a’s left over from various projects so said screw it and figured I’d just use those to at least have the build running while I figure out an alternative to 50pl’s, the downside there is that the p42a’s have substantially less amperage headroom so I had to bump up the P count to get close to what I thought I’d need amperage wise, even now after seeing what battery amps other inrunner users are pushing I don’t think the p42a’s are enough but 10p means I can get close to a decent amount of total wattage, 12s10p had close to enough discharge without going too low in voltage that I’d be limited in top speed in the pursuit of more amperage headroom. I also considered 8s15p or 10s12p but 12s looked decent to me, helps that I also have a charger on hand
The downside is it’s heavy, 120 cells total is about as big as I could see myself going on a board, and funny enough it’s the same number of cells as both my euc’s 
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Increasing the battery voltage reduces how many battery amps you need for the same power. Compared to 20S6P for example, 10P gives you two thirds more battery amps but since 20S is two thirds more voltage you use that many less battery amps.
Instinctively I think more battery voltage would make it run just a little bit cooler and be safer (especially with the single input for the 2xG300 and how powerful your build is) but I know lower voltages are used when more rpm isn’t necessary, so I am mainly trying to learn what it is I haven’t found out. (Something around higher mosfet pwm/duty cycle being better?)
The main advantage to 20S6P imo would be if you wanted a D100S on the front with lower kv motors in future for braking.
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Also depends on what motor. High voltage on those Hobbywing motors is mental, scary high ERPM.
4 poles makes it more manageable if these were outrunners with this high of a kv though yeah the erpm would be absurd
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Yeah heat in the ESC is significantly reduced at high voltage. No downsides as long as enough voltage headroom is kept.
I’m considering possibly doing 15s8p when I can justify the investment in a new pack+4wd, same number of cells and more watt hours if I can get those new 5ah tabless cells in, tricky part now is I reckon I don’t wanna go through changing gearing for a while since I’ve already got the custom pinions ordered, maybe something worth playing with later on
350A 650kv is actually around half the torque on the motor shaft compared to 200A 175KV though.
Wow yeah that’s crazy to wrap my head around
18s 135a had my 173kv 6485’s cooking in vegas, I’m surprised you can push 200 without it being problematic temp wise
That swings back the other way with gearing though
I just don’t have the sensors wired up. Ignorance is bliss if it continues working 
That said I’m pretty sure I’m close to cooking them and I want to run more battery current. Switching to inrunners sometime during spring when I have the time to make the double stage drives I designed. Unfortunately unlikely to be done with that for esk8con. Aiming to have just the new chassis done.
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The force that the gear transfers is calculated from the equation T=F*radius; the final ratio has nothing to do with this. In fact if you change to higher mod same teeth count (increasing diameter), the force transferred decreases, even if you have the same ratio.
In the 200A 175kv mod1 17T case its
10.9Nm=F*0.0085m
F=10.9Nm/0.0085m=1282N
Thats a lot of force to be transferred by a single teeth.
This is assuming the motor has 100% efficiency and that 10.9Nm is actually 10.9Nm of course. I won’t even try predicting efficiency at such high torque but chances are its not anywhere near 100%.
But physics says that at ~11Nm torque, the 17T mod1 pinion is also destined to fail, but instead of from undesirable wear characteristics, it’s from fatigue accumulation this time.
Actually chatgpt is pretty decent for mechanical engineering calculations if quoted well so here’s what it spit out
TLDR we are past the 25-30% strength of the material where steel has 10^8-10^9 cycles, hence fatigue accumulation is quite quick and only 10^5-10^6 cycles are expected at max load, for the calculated stress ratio which is over 1.
Note that here for cycle life it assumes that full acceleration at 10.9Nm shaft torque is the only valid state of the skateboard, in practice it lasted me around 2000km of riding.
The key to sizing the diameter of the smallest pinion for “infinite” cycle life is to look at shaft torque and stay under ~25% material strength. For ~11Nm torque, I’d need about 27mm diameter to stay under the stress limit (mod1 27T / mod1.5 18T)
650kv at 375A is around half the shaft torque so gives a stress ratio well below 1. So actually math says for this build mod1 17T is strong enough to not fatigue early.
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Ah yep yep was more referring to the torque at the wheel once they’re geared to the same top speed and that motor current becomes the main lever.
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Sooooo on the topic of pinion wear, this was after 20 miles of track practice/street riding, I think my pinions might have been unhardened
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Looks about right for pinions that aren’t hardened properly
Pretty sure you should be able to find a shop that can do hardening locally. If I remember it correctly the BN pinions are 4130 case hardened (carburized) to 55-60 HRC (then tempered to relieve stresses), so that should be a good baseline to ask from the supplier. I didn’t dive deep into metallurgy though.
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