| |
> 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.
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 shorted.
DANGEROUS, as in wires will melt from the heat, and the cells can
explode.
so i DEFINITELY do NOT recommend replacing the fuse with a wire.
if you stick a phone cable of the wrong polarity into the RJ11 jack,
or heaven forbid, a shorted phone cable, you'd be shorting the nicad
pack and BAD, BAD THINGS can happen.
so, the fuse is there for a good reason.
re: the discussion on using 12v rather than 9.6, there's not a big
problem with this.
it would put additional stress on the 7805, so check that it's not
getting too hot.
you would need to up the adapter to 15v, 500 ma (from 12v, 500ma) to
make sure you have adequate charge voltage.
in closing, let me reiterate: DO NOT REPLACE THE FUSE WITH A WIRE.
thank you. please practice safe handy-boarding.
fred
>
> 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
>
|
|
Message is in Reply To:
 | | Re: Just some questions...
|
| (...) 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 (...) (25 years ago, 24-Feb-00, to lugnet.robotics.handyboard)
|
2 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
