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Help - Powering the BS2e??? — Parallax Forums

Help - Powering the BS2e???

Peter RandPeter Rand Posts: 20
edited 2008-01-17 16:41 in BASIC Stamp
On a separate 24 pin IC carrier, I have been powering the BS2e using a 9V battery at Vin - and driving one Parallax servo motor separately with 6 separate AA batteries, using only the ground Vss as common. - I'm using the following simple program

Temp15 VAR WORD
start:
DO
DEBUG "starting",CR
nm = 250
FOR Temp15 = 0 TO nm STEP 1
PULSOUT 15,748
PAUSE 20
NEXT
PAUSE 8000
LOOP

So this runs continuously, the motor on about half the time. In 6 or 7 hours the 9v battery is "drained" to a level that won't power the BS2e! Is that how much power the BS2 requires?? Or is there something wrong here?

Post Edited (Peter Rand) : 1/16/2008 11:02:17 PM GMT

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2008-01-16 23:54
    The BS2e draws about 22mA while running (see: emesystems.com/BS2power.htm). The PAUSE is not a low power statement. NAP or SLEEP would reduce this for periods of time (with some issues ... read the statement description in the manual).

    A 22mA drain for 6-7 hours is 130-140mAh. The datasheet for a 9V Energizer battery gives 600mAh as the capacity at a drain of 25mA. If you're using a similar 9V alkaline, you should get a higher capacity.
  • Peter RandPeter Rand Posts: 20
    edited 2008-01-17 00:29
    Mike - many thanks. I'm trying to save space in a piece of art and trying to get the 'thing' to run as long as possible without wires, days if possible.

    I quote below your answer to a similar sort of question of some time ago.
    Do I take it then that as well as using NAP or SLEEP to reduce power to the Stamp, I would be better off to drive both Stamp and servos from the same alkaline pack? How high in voltage can I drive the servos and Stamp with (I have a 10-12 volt 'stack' of AA's), and will that gain me extended time? Any other solutions? I sure appreciate your replies.

    Thanks, Peter.

    ... you from earlier
    "The best thing to do is to set the jumper to power the servos from Vin and to use the 6V battery for Vin. When the BOE is part of a BOE-BOT, the whole thing (Stamp and 2 servos) is powered via Vin from a 6V alkaline battery pack and works fine that way. If you use 4 AA NiMH batteries instead of the alkalines, the voltage is really 4.8 which isn't enough for the Stamp's regulator to work properly. I assume that your battery pack is made up of 5 NiMH cells which would give 6V (5 x 1.2V)."
  • allanlane5allanlane5 Posts: 3,815
    edited 2008-01-17 15:25
    The BS2 can work fine on 6 AA NiMh rechargeables (6 x 1.2 == 7.2 volts). 7.2 volts is a little 'hot' for a servo designed for 4.8 or 6 volts, but should work ok. I think 9 volts would burn out the servo pretty quickly, but that's not what you're doing. Note I wouldn't use 6 AA Alkalines (6 x 1.5 == 9 volts) for this purpose.

    Are you using an on-board Linear Regulator? Or only using the BS2e's on-module regulator (by driving Vin)?

    Were I you, I'd remove the 9-volt, and drive the BS2e AND the servo's from Vin.· And power Vin with 6 AA NiMH rechargable batteries.
  • Peter RandPeter Rand Posts: 20
    edited 2008-01-17 16:41
    "Are you using an on-board Linear Regulator? Or only using the BS2e's on-module regulator (by driving Vin)?"

    I guess the latter since I have nothing 'extra'?? Do you know the ma draw of the servo?

    I'll do as you suggest - and use "sleep" instead of 'pause' - and I see also that the BS2 is far less power hungry than the BS2e.

    Many thanks for the help.
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