Hi ! I saw your comments about the wattage VS amps VS Voltage. I still don't understand the difference between the motor wattage (let's take the specs of the E3 Dash so 500W) and the battery volt/amp (48V8.7Ah = 417Wh). Why is there a difference between the 500W and the 417W ? Instead, if I have a battery of 36V with 11.5 amps, I will have the same result (417w) but what's the difference then ?
36 volt vs 48 volt electric bike batteries
- Thread starter Electric Bike Specialists
- Start date
Ravi Kempaiah
Well-Known Member
- Region
- Canada
- City
- Halifax
Every motor has certain wattage (not watt-hours). Watt is the power output and watt-hour is power output over a certain temporal scale (hours or mins).
Motor wattage and battery wattage need not match exactly. You can have 500W motor and have 1KW battery. For example, Tesla Model S has 310KW motor but 85KW-h of battery.
Similarly, for example Stromer ST1 platinum model has 500W motor but comes with 522W-h of battery.
Let's imagine we need to spin a turbine using a water hose to produce a certain amount of energy. Using a 48V system, you could delivery more power (water gushes out with lot of force/speed) at any given point of time but you can run it for for shorter period (8.7Ah/ Amp-HOURS) but the same amount of energy on a turbine can be produced using a 36V system (water doesn't gush at a rate that we see in the other case) but by making it run for longer duration (11.5Ah/ Amp-HOURS). This is a very basic analogy.
Now, on an electric bike, what kind of motor (geared or not), what kind of controller, efficiency of the drive system, bike and rider weight, terrain condition all play a role. 48V means more power i.e., the battery can discharge at much higher voltage but if you have a motor that can't handle such power, again its an issue. Izip dash easily attains 28+mpd speed, as experienced by many bikers and that can be easily attributed to 48V system.
Bike_On
Well-Known Member
Chandlee,
That was a nice write up.
I have been an e-rider since 2006, with the old mid drive Giant Lite, 24V, 6.5Ahr NiMH, 25 mi range, geared up to average 17-19mph. Back then, hub drives were very heavy cupcakes and lead acid batteries were the icing. The Giant L had the best range and weighed 49lbs.
In the 2006-2012 era, Americans didn't want a 65lb bike that might go 15mph tops. It is embarrassing to spend the dough and go slower than the average roadie. So speed begat power, which begat bigger motor, which begat weight, which begat bigger battery, which begat more weight, which begat less speed.... Tidal force was ahead of the day in 2002-2006. They could do 30mph, had NiHm (less wt), but were heavy. Then evolved E+, Optibike and Stealth. All the other OEMs could not get a good system together. It wasn't location, location, location. It was battery, battery, battery. Always is about the battery. Li was the holy grail, but it was unstable, costly, unreliable suppliers, dangerous. Optibike lead the way here with a first OEM, 20 Ahr, 3 year warranty Li, way ahead of the day.
Around 2010-12, the industry started to shift. Lithium chemistry became more energy dense with reliable BMS packs and cells got cheaper. Now bikes could become lighter, and still maintain a 20-30mph top speed. Companies who were making marginal junk, re-invested and started to bring quality. (aka Currie) New players emerged: BH Easy Motion, Stromer, Grace.
Mid drives, that once had a decided advantage with weight, efficiency, handling, began to lose ground to the geared hubs and 48V silent systems. As an analogy, we may be moving away from the 1950's, where you had a family car to do everything, and move into the 2000's where we have 3-4 cars, set apart for different applications. The Optibike, designed by a MX racer (Jim Turner), was one of the first bikes to do-it-all. Made for dirt, but with slicks, made a fast, long range commuter. Now, Haibike will compete for the xc trails, driving Opti prices down, and many OEM offer bikes with good range, power/speed and better reliability.
Endless Sphere forum had a thread over several months about a super-commuter weight weenie bike. A BH like prototype, but better, ahead of it's time. The new genre of people want their bike legs back. They want it to look cool and ride like a bike. They still want to be able to blow past spandex booty. They want it affordable. Mid drive, dd drive, geared drive, cargo, street, commuter, mountain: we may see people starting to own several styles ebikes.
Historic Rambling,
Dan
That was a nice write up.
I have been an e-rider since 2006, with the old mid drive Giant Lite, 24V, 6.5Ahr NiMH, 25 mi range, geared up to average 17-19mph. Back then, hub drives were very heavy cupcakes and lead acid batteries were the icing. The Giant L had the best range and weighed 49lbs.
In the 2006-2012 era, Americans didn't want a 65lb bike that might go 15mph tops. It is embarrassing to spend the dough and go slower than the average roadie. So speed begat power, which begat bigger motor, which begat weight, which begat bigger battery, which begat more weight, which begat less speed.... Tidal force was ahead of the day in 2002-2006. They could do 30mph, had NiHm (less wt), but were heavy. Then evolved E+, Optibike and Stealth. All the other OEMs could not get a good system together. It wasn't location, location, location. It was battery, battery, battery. Always is about the battery. Li was the holy grail, but it was unstable, costly, unreliable suppliers, dangerous. Optibike lead the way here with a first OEM, 20 Ahr, 3 year warranty Li, way ahead of the day.
Around 2010-12, the industry started to shift. Lithium chemistry became more energy dense with reliable BMS packs and cells got cheaper. Now bikes could become lighter, and still maintain a 20-30mph top speed. Companies who were making marginal junk, re-invested and started to bring quality. (aka Currie) New players emerged: BH Easy Motion, Stromer, Grace.
Mid drives, that once had a decided advantage with weight, efficiency, handling, began to lose ground to the geared hubs and 48V silent systems. As an analogy, we may be moving away from the 1950's, where you had a family car to do everything, and move into the 2000's where we have 3-4 cars, set apart for different applications. The Optibike, designed by a MX racer (Jim Turner), was one of the first bikes to do-it-all. Made for dirt, but with slicks, made a fast, long range commuter. Now, Haibike will compete for the xc trails, driving Opti prices down, and many OEM offer bikes with good range, power/speed and better reliability.
Endless Sphere forum had a thread over several months about a super-commuter weight weenie bike. A BH like prototype, but better, ahead of it's time. The new genre of people want their bike legs back. They want it to look cool and ride like a bike. They still want to be able to blow past spandex booty. They want it affordable. Mid drive, dd drive, geared drive, cargo, street, commuter, mountain: we may see people starting to own several styles ebikes.
Historic Rambling,
Dan
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bikerjohn
Well-Known Member
"Historic Rambling" much appreciated!
So, let's take again the 2 batteries (48V/8.7Ah VS 36V/11.5Ah). The same bike with the battery of 48V will speed up faster and reach the max (20 mi/h) easily. However, the Amps will be probably lower so the battery won't last longuer compared to a 36V with a higher amps. Could we say also that the 48V will have more torque or is it linked with the Wattage of the motor ?
You're pretty much there Guy but how long the weaker battery lasts also depends on the weight of the rider + bike and the terrain. If you try to use an under powered 36 volt system to move a larger rider and expect it to go further due to increased amp hours you may be disappointed if the motor struggles and ultimately just goes the sam distance... only slower
I've heard larger guys tell me they prefer the 48 volt and actually go further even with fewer amp hours and I believe this is due to the motor not having to struggle as much.
Also, Dan! Great industry history overview, very much appreciated
calvin
Active Member
After riding my 36 Volt bike for 600+ miles, I think that I would go for the 48 Volt system instead. There is only one reason for this, and that is I would like to be able to match the acceleration of the average car. I have come to believe that it may be safer to get into a regular lane and track along behind a car or group of cars while going through some intersections. This enables me to use them as a shield. When I am in a bike lane and that lane disappears, I am left riding along the cross walk or in the cross walk. This is when I feel most vulnerable. What do you think?
Aushiker
Well-Known Member
- Region
- Australia
- City
- Walyalup, Western Australia
I have gone with 36V on my Bafang BBS01 conversion ... early days but riding it so far is working out good and I feel I haven't lost to much of the bike riding feel.
Andrew
Andrew
FitzChivalry
Active Member
I regularly take the whole lane going through intersections... esp. when they are "straight-or-turn" lanes. In my 48v City Commuter, I get up to speed enough that I'm not making the car behind me wait or, worse, miss a light they'd otherwise have made.
bikerjohn
Well-Known Member
As a 238 pound cyclist, I think the 36 volt set-up on the Zurich 350 ix is perfectly adequate. I can't resist adding my nickles worth of salt on this subject...nicely written. Thank You. I quite enjoyed it. Mind if I ask how much do you weigh ?
I'm 6' 240lbs and I think I need a 48v for a 30 mile round trip commute.
Yesterday I traveled 54 miles at an average speed of 13.9 mph on a single charge! The controller and motor were powered on for nearly 4 hours. Of course there is a technique involving greater rider effort to minimize battery drain. A good share of the ride was done using the e-motor power on an intermittent-only basis.
ride specs here: http://connect.garmin.com/modern/activity/546784605
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Steve Cameron
New Member
Whoa!! I am a CurrieTech distributor and great proponent of the IZIP and Haibike lines but I need to interject now. The IZIP Dash is one of the best street bikes available today for the street with it's 28 mph top speed (with pedaling) and cruise control but it is NOT good for off road. I burn't up a IZIP Dash 500W rear direct drive hub motor going up a steep off road hill while my IZIP Peak mid drive 350W motor bike made it up the same hills with ease. A mid drive is best for off road but if you must buy a hub motor, be sure you buy a geared hub motor like the BH Easymotion bikes. You still have to deal with the lack of gears driven by the motor and the unsprung weight of the hub motor but at least you won't burn out your motor and fry your battery. The post is correct about the added strain on the drive train that a mid motor creates but if this is an issue for you, look at the Haibike. All Haibikes come with Advanced Shift Detection which detects shifting and reduces motor torque automatically during shifting to relieve wear and tear on the drive train. Good post though and good responses.
flymeaway
Well-Known Member
It's a non-issue if you use your left hand brake as a "clutch" when shifting. Prior to shifting engage the brake to the point where the motor disengages. With Bafang mid-drives the motor disengages after only a slight engagement of the brake lever. Continue pedaling shift and release. I ride both a Carbon and a converted Motobecane Elite with a 500W 36V Bafang mid-drive and enjoy both bikes. The Motobecane is a very capable road bike and easily maintains 26/27 MPH while pedaling. It will go faster but 26/27 is about all I need or want.
Court J.
Bike_On
Well-Known Member
As I undertsand (as an EE), torque is porportional to current. Going to 48V will INREASE the current through the windings because the winding impedance should be the same. A higher current, high torque and consequently higher power with the higher voltage.
Nothing is for free. The cost is strain on the battery. The C ratio goes up: Actual amps/rated Ahr. This causes wear on the battery. Since you draw more power, the Whrs get used faster. You also ride faster, so range consequence is not horible, but it will be less for th esame initial whrs.
More power means more heat in the motor dissipated. Make sure it can handle it, and the wiring too.
Some motors are designed to optimize at 36V (I think) and overvolting them will not be as efficient if the core gets saturated any. I am not a motor designer and could be over reacting here.
Bottom line: you go faster and use more power.
Excellent response, I think I got caught up in sizing there... The Peak, Haibikes and possibly Easy Motions would be better. I'm going to update my original comment based on your feedback Steve.
I respectfully disagree... Your controller will limit the Amperage from the battery, and can be programmed to limit the power... And anyone who has ridden a 24 ,36 48 or 50v battery can attest to the proportional repsonsiveness of higher voltage...
now if you use that higher voltage with high amperage, it will definitely work the battery harder, since the absolute battery capacity in Wh is usually the same at the higher voltage...
Shea N Encinitas
Active Member
I ride 48 Volt, PAS level ONE, no throttle all the time - Going for distance, I'm pretty sure I'm getting the riding experience alluded to in the OP, but I also understand nostalgia and old school POVs.
With this platform, heavy assisted bikes, I'm enjoying night rides with good lighting systems, cool fresh air, stars, no sunblock, long dark roads with few cars - this is when it gets mystical for me.
With this platform, heavy assisted bikes, I'm enjoying night rides with good lighting systems, cool fresh air, stars, no sunblock, long dark roads with few cars - this is when it gets mystical for me.
Lenny
Well-Known Member
At higher voltages, the impedance losses and core losses become very high. Especially, in the case of gearless motors, it is one of the reasons Stromer Sport (version 1) had so many problems, along with its faulty temperature sensor.
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