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Battery life v Weight and Terrain

Discussion in 'Electric Bicycles' started by ElectricOwl, Jul 11, 2017.

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    ElectricOwl

    ElectricOwl Just Joined

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    apologies if this has been covered elsewhere .

    So my Carrera Crossfire is reputedly able to cover 60 mile on a charge ? So how do the makers come to this figure ? I suppose if you were 7 stone and lived in a area with no hills would it be possible ?

    If the makers used a formula for this assumption would there be any way of inputting different weights and terrain choice to come to a guesstimate for say light medium and heavy ? also terrain easy medium hilly ?

    The reason I have brought this up is that I am around 16 stone and live in a hilly area , best I can achieve is 46 kilometres = 28.5 miles

    I was looking to do the coast to coast bike ride and would be limited to distance on 1 battery and having looked on Halfords website the cost of a back up is £400.00

    Also my local dealer was telling me my battery needs servicing and I should store the battery indoors during low temperatures

    Are they making things up because the batteries are not achieving their figures ?

    Also has anyone achieved anything like the 60 mile range on a crossfire ?


    PS

    While I was in Halfords I noticed they had a new E Crossfire mountain bike for £1000.00 it proclaimed the range on that one was 40 miles ( and its the same battery according to the sales guy ?
     
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    Tabs

    Tabs Pedelecer

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    I think the battery range that gets quotted is a bit the mpg figures that car manufacturers come up with and basically don't happen in the real world cause there's to many variables.
     
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    d8veh

    d8veh Pedelecer

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    Good questions. The range they quote is just an estimate using pretty optimistic parameters. Never take any notice of what anybody else gets. range is always personal to you and your rides. It can be anywhere from 20 miles to 200 miles on a bike like yours - or on any other bike. The only thing that would make a difference is the capacity of the battery, though, obviously, you'd get some difference between a MTB with wide knobbly tyres and a thin light bike with a crouched riding position.

    No magic wand will help you. If you want to go further, you need to get a bigger (or extra) battery or pedal harder.

    Actually, I lied. This magic formula will work, but try not to let the secret out. Ride an average of at least 10 miles a day; stop drinking everything but tea, coffee and water; and eat only salads for the next 12 months, then you'll have no problem doing that coast to coast ride on one battery charge.
     
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    kangooroo

    kangooroo Pedelecer

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    Is this the bike with an 11.4Ah battery? If so, 60 miles sounds optimistic to me.

    I have a 15.6Ah battery on one of my bikes and have managed 56 miles in a hilly area (Wales borders) with some headwinds and still had about a third of the capacity remaining using power levels 3-5 of 5. I weigh 52kg and carry about 5kg.

    On a 8.8Ah battery, my limit is about 30 miles along similar routes using power levels 1 & 2 of 3.

    The quoted 60 miles must surely be on flat roads with a lightweight rider carrying no/little load, no headwinds and on the lowest power mode eeking it out as far as possible.
     
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    d8veh

    d8veh Pedelecer

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    I did 129 hilly miles on my bike with 11.6 Ah battery when I weighed 100kg. What does that tell you?
     
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    Benjahmin

    Benjahmin Pedelecer

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    You had Mo Farrah pushing you?
     
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    kangooroo

    kangooroo Pedelecer

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    - either you were very very fit and those 100kg were pure muscle or your bike's 'puter wasn't working...?
     
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    ElectricOwl

    ElectricOwl Just Joined

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    All down hill ?
     
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    ElectricOwl

    ElectricOwl Just Joined

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    Yes 11.4 Ah .......maybe I need a different bike , are there many with 15.6 Ah batteries ? Whats yours ?
     
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    d8veh

    d8veh Pedelecer

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    You just turn down the power. When you come to a hill, use a low gear. On an MTB, you can pedal up even the steepest hills using the third (inner) chainring and bottom gear. You don't need an electric motor. All the motor does is make you go faster in a higher gear. My pedal effort is always the same whatever I do. I've done 44 miles on my other full-suspension MTB before I even switched the motor on. You don't need to be fit. You just need time because you'll be pretty slow up the hills.
     
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    anotherkiwi

    anotherkiwi Pedelecer

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    To add to the above: when you are asthmatic you can climb just about any hill seated and MUCH faster than without a motor and in granny gear.

    My hub motor bike could climb pretty much anything at cut off speed (you learn to ride at 1 km/h below 25 km/h cut off) and I was using down to 5.35 W/km which lead some here to remark that I didn't really need a motor. I do need one because I couldn't do that at all without one it is just the tiny little bit of help needed to prevent stopping twice on a 3.4 km climb and gasping for air...:eek:
     
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    ElectricOwl

    ElectricOwl Just Joined

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    I always turn down the power and try to use the gears until i find it to hard to pedal , the other day I turned off completely for ages because my battery was on its last legs but that was on the flat as soon as i come to a hill i do need assistance because the weight of myself and the bike , anyway thanks for making me feel inferior to your prowess .
     
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    d8veh

    d8veh Pedelecer

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    What gears do you have?
     
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    ElectricOwl

    ElectricOwl Just Joined

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    Shimano Acera 8 gears .
     
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    d8veh

    d8veh Pedelecer

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    You need a double or triple chainring to climb hills without power from the motor or with low power.
     
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    Danidl

    Danidl Pedelecer

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    .. will we get into the no man's land of using crank drive and the gears... Going real slow in a very low gear with a crank motor allows the motor develop its full mechanical power. Going real slow on a hub motor is wasteful as the majority of the electrical energy is converted to heat...
     
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    Danidl

    Danidl Pedelecer

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    .. except if you were eating only salads for a year , you wouldn't have the energy to lift the cup of tea.... You need a few spuds.
     
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    d8veh

    d8veh Pedelecer

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    Potato salad?
     
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    Danidl

    Danidl Pedelecer

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    .. they are not really making it up as regards battery maintenance. But that's no problem, just charge it up every three months even if the bikes not used, and keep it at moderate temperature.
    The other question, as d8veh, has referenced is much more complex. To answer it you have to add together all the energy loss mechanisms on riding a bike and compare it to the energy stored in the battery.
    Bosch have a calculator on their website and you can play with the variables. Schwab have a nice graphic showing power losses as a function of speed etc.
    The most important variables are.
    1. Speed and wind resistance. Power loss increases by the cube of the speed. That means whatever power was lost at 10 kmhr it is 8 times more at 20kmhr. The riders stance and clothing affect thus
    2. Weight of bike and rider.. the rider being the most significant this affects in two ways. Rolling resistance of the flexible tyres is dependent on weight. That's why railways use steel wheels. And work done going up and down hills. You never get back going downhill what you put in going uphill, as wind resistance matters.
    3. Numbers of stops and starts.
    4. How much energy you the rider are prepared to contribute.
     
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    Danidl

    Danidl Pedelecer

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    With lashings of salad cream Fair play!!
     

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