Or perhaps I'll call it 2wd FATMON (any of these names taken yet?
) -It's the mongoose steel fatbike I've been working on and this will be the build thread.
In the meantime I have a question before I put the boards pack in their cases and reattach etc etc, hopefully completing the new battery setup, including controller mod.
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Background: The old 12s spun the 29" dia tires way too fast (44mph), and the battery was sagging like crazy anyway on takeoff.
So I went with 9s 30c 15ah zippys, and removed controller LVC jumpers from pcbs for now. I knew there would be less wattage/power on 9s (without shunt mods) but figured the lower gearing would make it a wash, at worst. (I will link all the threads pertaining to this build which includes one on modifying with a trim pot or the proper resistor for custom LVC on non-programmable cheapo controllers.)
Anyway, 9s does 33mph HOC WOT and 29mph-ish WOT when discharged. Here's how I've been testing the battery: Medics hot glued together with neo magnets on back.
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It works great to see the cell levels as I flounce this thing and 'get used' to being the 'bms' for the new pack via total pack voltage Led.
SOo0o, I went from 4.10 avg to 3.85v resting - ~3.75v WOT with brakes on at maybe 10mph quite a bit and nothing got noticeably hot. And although NET I have more torque now than w/12s, that means the front tire breaks loose first when thrashing a hill, alot quicker than before.
With everything staying super cool while pounding on it (. . . what she said?), I figured permanently increasing amperage to the rear motor would make sense on multiple fronts.
So finally, here's my
question:
I have tentatively wrapped 8 strands around the 3 shunts which should easily lower resistance by 33%, guessing visually by the volume of the copper VS the shunts. So I assumed that should give me about 1/3 more amps?
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Results of the testing the mod(read: thrashing, lol):
Battery depletion and sag as noted above, thrashing WOT (even with brakes) the whole time . . . .
70F ambient
75F fets
90F Rear hub
87F Front hub
Short <1ft runs of thin-ass phase wire: 72F.
Seems like I should keep adding copper? Or start adding solder?
But I don't wanna blow anything up. I notice a little increase in torque and better balance rear VS front, but judging from less than a 10% temp increase (3 deg F on maybe 10ah of 'testing'!) for the modded controller , it really didn't do that much.
Maybe I should mod both front and rear??? Hubs can survive fine up past 200deg iirc, so even @ 100F ambient I wouldn't expect the current setup to get much over 140F while thrashing it thru nearly a whole 'tank' of electrons?
I'd like the rear to still have more power VS the front, so IYO (in your opinion?) what should I do and are there any things 'not to do' that this bonehead might stumble upon lol?? Thanks!