Subject:
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Re: Just some questions...
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 24 Feb 2000 18:19:12 GMT
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Original-From:
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William Bain <MONTANAWILL@YAHOO.stopspamCOM>
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Viewed:
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947 times
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--- Eric Davis <Eric_Davis@mindspring.com> wrote:
> Is there a general guide to what fuse I should have with a
> certian current?
The self-resetting thermal fuse that's part of the HB ought to
be just fine (see item F1 on the HB schematics). I think that
if you use a 9.6 V NiCd battery pack with less than a couple
thousand mAH capacity, you probably have nothing to worry
about.
Be aware, though, that not all HBs ship with the F1 fuse. I got
mine from Patrick Hui of the Robot Store HK, and it had just a
wire where the fuse goes. Not that I had any problem with that
-- he told me before I ordered the board that it wouldn't have
the fuse. Just for my own peace of mind, I ordered the fuse and
installed it myself. You might want to verify that you have
component F1 before you experiment with bigger batteries.
Another thing to consider is that a 12 V battery pack would
probably not damage the HB, except that it would be a hassle to
recharge, because the HB internal charging circuitry is not
designed to deliver a high enough voltage. You'd have to unplug
it from the HB each time and plug it into the proper charger. I
looked into this, because I have a camera and video transmitter
that runs on 12 V, and I wanted to use a single battery pack
for everything. Unless I can figure out how to hack the HB
charging circuit to charge a 12 V pack, I figure it's not worth
the trouble.
> Would the internal resistance of the battery be shown if I
> measure the
> resistance across the terminals (my DMM does not display the
> batteries
> resistance, out of range)
>
> Should I really be taking my measurements from the
> capacitor(?) which is
> the first component the trace leads too?
I don't really know how to measure the internal resistance of a
battery pack. You shouldn't need to, though, because your HB
and motors will probably blow the fuse long before the internal
resistance of the battery starts to be an issue. Best of luck!
-- Will
=====
Any sufficiently advanced technology
is indistinguishable from magic.
-- Arthur C. Clark
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Message has 1 Reply:
 | | Re: Just some questions...
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| (...) you are confusing mAh capacity (the amount of energy stored in the battery) with how fast the batt can deliver the power. the two are not the same. the fuse is in the design because nicad cells can deliver a *DANGEROUS* amount of power if (...) (25 years ago, 24-Feb-00, to lugnet.robotics.handyboard)
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