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Cyclotricity 1000w kit and a specialized hard rock

Discussion in 'Electric Bike Conversion Kits' started by Scotchgitt, Aug 12, 2017 at 7:53 PM.

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    Scotchgitt

    Scotchgitt Just Joined

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    I test drove my new project. A £40 specialized hard rock sport and a 1000w cyclotricity.

    24mph on the flat , me pedalling but with the very high gearing on the bike.

    Haven't got the derestriction code yet . Is the code unique for each unit or is it simply a hidden menu.

    I have also made a 5ah 48v battery which is doing the job nicely for £90.

    Plan on upgrading the discs and making a second battery to leave at work and I can swap it out when I get there.

    If this all pans out I'm going to put the same unit into my Cube hybrid .

    I'm so impressed with the ease it all fitted.

    Only problem was I needed a washer to space the forks away from the cassette and had to file a little off the upshifter onthetrigger shifter as it was fowlingon the throttle.
     
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    chris_n

    chris_n Pedelecer

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    Good luck with a 5ah battery on a 1000w motor.
     
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    Scotchgitt

    Scotchgitt Just Joined

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    Thanks but don't think I will be running it flat out too often. The weight of the bike needs worked on too. Oh and my 100kg mass.
     
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    d8veh

    d8veh Pedelecer

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    Did you install a BMS in the battery? Without one, 5Ah is very dodgy.
     
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    Scotchgitt

    Scotchgitt Just Joined

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    I'm new to all this, When you say BMS is that to do with a balance charger? I remove the lipo' s and charge then individually on a balance charger. If not that, can you give me more info?

    I charge them outside in a non combustible area as I have read some scary stories.

    Thanks
     
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    d8veh

    d8veh Pedelecer

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    BMS= Battery management system. It looks after charging and discharging to make sure that you don't go outside the safe voltages for the cells. 5Ah lipos for that motor are very dodgy because they go down so fast. How do you make sure that you don't over-discharge them? You can change them from batteries to bricks in about a mile.
     
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    Scotchgitt

    Scotchgitt Just Joined

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    I have a low voltage alarm on them that goes off when it hits the trigger value. I think ( need to check my note and the setting programmed in) they charge to 14.4 v using the balance charger and the low voltage is set to 11.8
     
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    d8veh

    d8veh Pedelecer

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    That doesn't sound right at all. What have you actually got?
     
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    Scotchgitt

    Scotchgitt Just Joined

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    The low voltage is 3.2v per cell so 12.8v per lipo
     
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    d8veh

    d8veh Pedelecer

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    That's much too low for a bike like that with such small battery capacity. The voltage would be going down so fast at that level that by the time you've heard the alarms, your lipos would be bricked. You should set the limit to about 3.5V. The maximum should be set to 4.2v so that you get some sort of capacity from them.
     
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    Scotchgitt

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    Thanks for the advice, I have changed the setting now. 3.5v it is.
     
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    Anthonyexmouth

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    Would the lipos really drop that fast? I'm only used to dealing with up to 6s in my planes but regularly slaughter them drawing up to 60amps and down to 3v-3.2v and only puffed 2 in years of flying.
    Interested to know how using them in bikes compares.
     
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    d8veh

    d8veh Pedelecer

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    I'm guessing that you have a LVC in your ESC, which cuts the power when you get to a certain voltage, so you can't over-discharge. using alarms on an e-bike is different. First, you have to hear them, which isn't easy at 30 mph, then you have to react to them.

    Also, 60 amps will cause a lot of sag, so when you hit LVC, there's still some charge left in the battery. The lower discharge rate on an e-bike would mean that at 3.0v they're really empty and the voltage completely collapses after that.

    Say you had a 10Ah 12s pack. You charge them to 50.4v. By the time you have the bike off your driveway, you see 49v, then they go down slowly and steadily to about 44v. After that, they start to accelerate downwards. The further you go down, the faster they drop. It's like watching water go down a funnel, where the level goes down faster and faster.

    If you look at this graph, you can see how they go down after 3.5v. By the time you get to 3.0v, the graph is nearly vertical.

    The difference in capacity between 3.5v and 3.0v is about 10%, so you're not losing very much, but you gain a lot of safety.

    OP has 5.0AH or 220Wh. His 25A controller can draw 1200w, so that 10% (22Wh) would go in 60 seconds. That's how quickly he'd have to respond to the alarms if he's on full power. He would have no chance if the alarms went off at 3.0. By the time he realised that the alarm was sounding, the lipos would be bricked.
    [​IMG]
     
    #13 d8veh, Aug 13, 2017 at 4:49 PM
    Last edited: Aug 13, 2017 at 5:07 PM
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    Kinninvie

    Kinninvie Pedelecer

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    My Dillenger 1000w kit came with a 10Ah battery and I could run it to lvc in 9 miles.
    5Ah is going to be a short ride unless plenty of pedalling is used.
     

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