wesnewell wrote:A 20ah 12s rc lipo pack (888Wh, 5x5x7", 14lbs) will cost $280-$350.
john7700 wrote:36/20 $518 +$109 shipping = $627
Plenty to do the job here. Includes charger but upgrade to the faster charger for $44
Total with fast charger $671
Goathead wrote:Any way to quantify "power" in the 48V rather than 36V? Is it torque, which for hills would help?
wesnewell wrote:Goathead wrote:Any way to quantify "power" in the 48V rather than 36V? Is it torque, which for hills would help?
Sure, VA=W. Simple. Using the same controller, a 48V pack will provide 33% more power than a 36V pack. Assuming a 20A controller;
winkinatcha wrote:Hey Goathead,
Yup added Torque
Power/wattage/kinda sorta torque is calculated in a simple form as I mentioned in post above....
winkinatcha wrote:there are many threads that talk about upping the voltage to up the wheel speed here on ES... this pretty much works under no load at least in my own personal experience from 250 watt through to 2kw... So you can theoretically just up the voltage to get the higher speed... with current... you are not changing your controller so increased "power" is part of the package of increased voltage (not withstanding the ability of power source (batterys) to be able to provide the current demands asked from the controller... )
If yer controller is listed as being able to run 48v then that is good n saves ya pulling it apart n checking the components <=== meaning often enough fair quality controllers can accept a range of voltages above their "rated" voltage... and the rating is based on a set battery voltage...EG a "typical" 24v 30amp controller based kit rated at 500 watts with a top speed of around 27 kph, can alse be run as a 36v 800w kit with top speed around 35 and a 48v 1kw kit with a top speed around 50 kph (assuming the components etc of controller are high enough rated generally determined by voltage rating of capaciters IE ya need 63v rated capaciters to do this)
What others said about SLA Though sometimes budgetry constraints and short distance travel means you can "get away with it"... I have used SLAs on a range of kits from 200w to 2kw...for reasons ranging from budgetry, to original form, to just see if I can... and ultimately the added weight is the killer, not so much cause ya got to haul it but the amount of stress it will put on your frame/rack/bearings etcetera, let alone if you have it high up and want to be able to use a kick stand to keep your bicycle up right when you are not on it....
d8veh wrote:The question I have is: When a controller is limited to 20 amps, does the motor see a higher current with a 48v battery than a 36v one - assuming that you didn't limit phase current in your programmable controller?
Jeremy Harris wrote:Increasing voltage does NOT increase motor torque.
wesnewell wrote:Jeremy Harris wrote:Increasing voltage does NOT increase motor torque.
It does on all the hub motors I've used. I'm not sure where you are coming from here.
winkinatcha wrote:Damn Jeremy I sure do appreciate your high level knowledge...
owever I have some questions re what you say.... And I do understand I may just be a high level n00b, in fact I KNOW I am a high level N00b and I mentioned "kinda sort Torque" because my brain has not yet grasped torque in relation to elctrical motors...
Now this is based on experience...
I increase my voltage on the same controller running the same wheel
I test the build on the same slope (in this case an underground car park so reasonable incline same distance all other factors equal (same bike same tyres no wind....)) using voltages of 24, 36 and 48
WOT from start
the acceleration up that slope is greater when higher voltage, and the time taken to reach the top of the slope is less as the voltage I use increases
But the slope is too short for me to reach the top speed of the lowest voltage.
So... if the power does not increase with the voltage, when running exactly the same kit, then how come my bike is faster up the slope on greater voltage if not the result of greater power and (this might be where I am awry in my thoughts) greater torque being applied through the wheel.
Not being a smart-ass.. seriously dont see how I can experience this without being able to say "increased power and kinda sorta torque" when using same controller (and thus Presumed Same current) but increasing voltage?
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