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Urgent: Need your advise — Parallax Forums

Urgent: Need your advise

JasonNgJasonNg Posts: 6
edited 2009-04-20 17:18 in Robotics
Hi there,
Is there any problem to use normal battery with configuration below for HexCrawler as I'm having problem to have NiMH battery, 7.2V, 3000mA?

1. 4 pcs 1.5V battery (1200mAH) connected in series. So total voltage = 6V, Current= 1200mA.
2. 2 set of 4 pcs 1.5V battery (1200mAH) connected in series where the 2 set are connected in parallel in order to produce same voltage, but with higher current (2400 mAH)

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-04-20 17:18
    The HexCrawler will work with a 6V battery pack, but it won't work for very long. Servos work fine with voltages from 4.5V to 7.2V, but the Stamp and the Board of Education (BOE) is designed to work with voltages from 6V to 9V. Your 6V battery pack will start with a voltage somewhat above 6V and its output voltage will rapidly decrease to 6V under load where it will stay for a while before dropping below 6V. There are graphs from the battery manufacturers that show the output voltage vs. time at specific current drains.

    I recommend that you make up your own 7.2V battery pack using 6 NiMH cells in series. You can easily find AA NiMH cells with a capacity of 2300mAh or 2800mAh made by Duracell or other manufacturers and AA battery holders for 2, 3, or 4 cells are commonly available. NiMH cells are rechargable and maintain their output voltage for more of their discharge cycle than alkaline cells.
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