- Oct 7, 2016
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Youngseal said:One of the elements of these projects that I find wasteful is the charging and discharging of the cells. Can I suggest that the charging is done by a solar/wind/hydro input option, that the discharging current is used productively to run the system via storage to a battery pack and that that pack can then be used to run the arduino/diagnostics element of the system!
pelecypod said:The problem with discharging cells to charge more is that current runs down hill as it were. As the battery discharges the voltage drops and as it charges it goes up so what you end up with is the transient current dropping to 0 as the batteries equalize in voltage (somewhere around 3.5V probably), this is effectively battery balancing.
Maybe with some clever circuitry you could use the beginning of discharge to initial charge a cell but it wouldn't be much, you'd still need a charging circuit and you'd be making it much more difficult to measure the discharge current accurately. We're not really talking about much power here either, for a 2200mAh cell, 4.2V x 2.2Ah = 9.24Wh (upper limit as voltage drops over discharge), for perspective this is a 1kW kettle running for about 3 seconds. Even over 6000 cells this is only 60kWh or about 7.50 and these cells are going to "save" that much energy every complete cycle for 100+ cycles so losing that little bit of energy would only account for an additional 1% efficiency loss still far better than a coal/gas station when you assume solar/wind is 100% efficient.
I also don't think this keeps with the KISS mentality. I thought 1.0 was awesome, 2.0 was novel, but when 3.0 was shown I could immediately see it was going to be the superior solution. Probably the best use for the discharge energy is going to be as a 60W fan heater in the shed