K thanks again
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Why don’t you see BMS balancing applied per individual cell instead of sets of parallel cells?
Just curious; Imagine a 12S4P battery pack,
With BMS for balance charging only, bypassed for discharge, you would need 4x BMS for each 12S series string, and for parallel discharge you just bundle the 4 pluses and 4 minuses for the ESC?
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Because each set of parallel cells is already balanced, by definition.
“balancing” is all about differences in voltage. But if you have two cells with their positive and negative ends connected together (parallel), there is no way for one cell to have a different voltage than the other. Ergo, they are balanced.
You can still have differences in current sharing, either from differences in capacity or internal resistance (or external resistance for that matter), but that is not covered under what a BMS handles anyway, so the point is moot.
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Yes, this.
Series strings need to be balanced against drift, parallel groups are already connected together and cannot drift at all.
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It’s enough spaghetti in my enclosure already with 17 wires coming out of the pack. No more…
P groups self balance themselves very well, and being assembled brand new, they experience almost identical wear and resistance increase. Towards their end of life it would be expected to have those differences grow, but still not enough to start melting stuff
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What would happen if a cell gets faulty, for each case?
For BMS-parallel it means the remaining 3 cells wear out faster?
For BMS-individual-cell it means the cells in the complete string wear out faster?
If one cell in a p-group goes bad, it will take the whole p-group (four cells) down with it (assuming it heads for 0 volts, which is the most common).
If instead of 12 groups of four cells, you have four 12s1p strings each with an individual BMS and only connected in parallel at the main leads, then yes, a single cell failure will only take out the one cell. However, that whole string (12 cells) is now one cell lower than the rest, and the other three will dump power into it until that once cell either explodes, or goes open circuit without an explosion, or the abuse damages more cells in the string. Not a good scenario, plus you now have four times the wiring and BMSs to worry about failing as well.
Either way, you’re going to have to rebuild your pack. You can’t just replace a single call (or a single P-group), because the new cell(/group) won’t match the rest in terms of capacity/wear/IR. The best method (assuming you don’t just chuck the pack and buy a new one) is to break everything down to bare cells, then replace a multiple of 12 cells. In the conventional pack, you reshuffle the p-groups so there’s one new cell in each p-group to guarantee a matched capacity across all the p-groups. In your proposed method, you have to replace the entire string that had the one dead cell. Either way, you’re replacing one s-count’s worth of cells at a minimum, so you’ve spent an extra 3 BMSs’ worth of money, and not saved any money on replacing cells.
Long story short, not worth the extra hassle and cost, especially in a space- and weight- limited application like an LEV.
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can you drop-through the BN baseplates on a hummie? iask because on close insection they have bolt though the middle and have a stepped section
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Okay, thx. I have the picture why it is the established method.
And if the whole p-group (four cells) is going down its noticeble so you can investigate.
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Yup. And no matter which way you do it, you’re going to have to replace a minimum of one s-count’s
(12 for a 12s pack) worth of cells to get everything back to being properly matched anyway.
The stepped section is what messes it up. I used it dropped and it started creaking after a while, making funny noises. You can probably cut out the stepped part in the deck but i didn’t bother, just sold it. The bolt poses no problem, just don’t expect to slide out the entire truck
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ah right. i just spoked to Kevin and he said that compared to 44 Cal 2 baseplate the BN ones are about 20mm taller (at 40 degrees) which makes it more likely to have to work drop-through with the geardrives.
are any other baseplates that work with Caliber-profile hangers?
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Thing is, the height changes with the angle. At 30° it’s about as tall as a normal 50° baseplate, and on the back you kinda want the 30°.
Just… wait till i get them i guess? I will show what works and how once i figure things out, just like with the 12s4p p42a on a hummie deck
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Does anyone have experience with these tires?
My only concern is they list the bearings as having an interior diameter of 10mm, while street trucks have a diameter of 8mm. Has anyone been able to switch our the bearings in these wheels? I ask because I’ve heard of other cheap wheels with glued bearings, so I’m a little concerned.
Thanks!
Sure 
. Ah sorry yhought it was a question 
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with regards wheel pulley’s, the larger the wheel the more T(eeth) required. I see people running 50-60 pulleys on Bergs, but what happens if you run 44T pulleys on bergs? more/less torque? High/lower speeds?
44t pulleys on bergs mean high speed but 0 torque
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Ok, thanks 
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to achieve 30-35mph on bergs without sacrificing torque, how many teeth is recommended?
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