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  • Rusdy commented on Rusdy's instructable Charge Electric Bike Battery with Solar Panel1 year ago
    Charge Electric Bike Battery with Solar Panel

    hi BeeeSB,Mine is 80W panel with 22Voc and with 17-ish Volt at MPP with 4.7Amps. Obviously, this is at ideal condition (which is never).Regarding calculation "How many hours to charge..." and so on, the short story is, multiply your panel rating by 4, and this is how much you will get out in Wh per day (this figure is conservative, in reality, you might get 5 to 6 times depending where you are). Obviously, if you want to be accurate, you need to consider where you are in the world. But hey, we don't want a thesis out of this right?So, let say with my panel of 80-Watt, I will get 320Wh per day (80 x 4). My battery is 416Wh. So, it's not enough to fully charge my battery using 80-Watt panel in a single day. In reality, I don't use full 416Wh out of my battery. So, my 80-Watt pan...

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    hi BeeeSB,Mine is 80W panel with 22Voc and with 17-ish Volt at MPP with 4.7Amps. Obviously, this is at ideal condition (which is never).Regarding calculation "How many hours to charge..." and so on, the short story is, multiply your panel rating by 4, and this is how much you will get out in Wh per day (this figure is conservative, in reality, you might get 5 to 6 times depending where you are). Obviously, if you want to be accurate, you need to consider where you are in the world. But hey, we don't want a thesis out of this right?So, let say with my panel of 80-Watt, I will get 320Wh per day (80 x 4). My battery is 416Wh. So, it's not enough to fully charge my battery using 80-Watt panel in a single day. In reality, I don't use full 416Wh out of my battery. So, my 80-Watt panel is sufficient to date.Now, let's get to your proposed battery:Your battery is 48-Volt 20Ah. This translates to 960Wh. If you want to fully charge your battery in a single day, you'll need 250-Watt panel.If you want to use my instructables as the MPPT, there is a problem here. My current component selection maxed out at 5-Amperes output (due to the blocking diode limitation). Also, since I'm using linear voltage regulator as an input, this limits maximum input voltage to 20-ish volt. Without being too technical, what I'm trying to say is, you only can use 22Voc panel (which you already found) and around 100-Watt maximum.So, without changing the schematic, you only can use 1-off 100-Watt panel (with 22Voc) with my instructables to charge your 48-Volt battery. You'll need 2 days to fully charge the battery from completely discharged state.Or, you can parallel them all. So, you'll end up with 4-off panels with 4-off MPPT. You'll probably end up cheaper in buying an already existing 48V MPPT.

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