USB Battery Array -> Power 36v Motor

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Discussion Overview

The discussion revolves around the feasibility of creating a 36V power source for a speed controller in an electric vehicle using multiple USB device charging batteries. Participants explore the technical aspects of connecting these batteries in series and parallel configurations, as well as the implications for amp hours and watt hours.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • The original poster (OP) inquires about the possibility of connecting USB charging batteries to achieve a minimum of 36V and whether this can be prototyped with an Arduino.
  • Some participants explain that when batteries are connected in parallel, amp hours add together while voltage remains constant, whereas in series, voltages add but amp hours remain constant.
  • One participant notes a potential discrepancy in watt hours due to voltage drop during discharge, suggesting that the conservative watt hour rating per unit is likely accurate.
  • Concerns are raised about the necessity of a charger for the batteries in a vehicle application, questioning the practicality of using such batteries for continuous power supply.
  • Another participant clarifies that the device mentioned by the OP is primarily designed for charging portable devices, implying limitations for vehicle use.

Areas of Agreement / Disagreement

Participants express differing views on the practicality of using USB charging batteries for powering a vehicle, with some focusing on the technical configurations and others questioning the feasibility of charging in a vehicle context. No consensus is reached regarding the overall viability of the proposed setup.

Contextual Notes

Limitations include assumptions about the discharge characteristics of the batteries, the specific configurations of series and parallel connections, and the operational context of using such batteries in a vehicle.

vanillabass
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I'd like to take several of these (or similar) usb device charging batteries (http://www.ianker.com/product/A1271011 ) and connect them into an array to create a minimum of 36V and channel that to power a speed controller for an electric vehicle. Is this possible? Would I be able to prototype something like this with an Arduino or similar? Any advice/direction would be really appreciated.

Question 2: if this is possible, do the amp hours added together per battery or does that stay a constant? For example, a battery has 2 amp hours - if I have 5 is it a total of 10 amp hours or is it still 2 amp hours?

Thanks!
 
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The Watt hours add together. 72 Whr x 7 = 504 Whr
If they are in parallel, the amp hours add together, but the voltage stays at 5V. parallel 7 x (5V , 20 Ahr) = (5V, 140 AHr) equivalent 700 Whr
In series the voltages add, but the amp hours stay the same. series 7 x (5V, 20Ahr) = (35V, 20Ahr) equivalent 700 Whr

I assume the discrepancy in Whr is due to the fall in voltage during discharge. The conservative 72 Whr per unit is likely to be correct. So
in parallel 504 Whr / 5V = 101 Ahr
in series 504 Whr / 35V = 14.4 Ahr
 
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maybe I'm missing something but a charger needs to be plugged into do anything. wouldn't that be an issue for any vehicle application?
 
The device linked to by the OP is a battery pack that is designed to charge portable devices. Thus a charger. It also likely comes with a plug in type charger. Thus a charger charger.

BoB
 

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