On Tue, 27 Jun 2000, Dan Michaels wrote:

> Scott Dattalo wrote:
> >On Mon, 26 Jun 2000, Dan Michaels wrote:
> >
> >> Funny thing you should mention exercise machine here. You've
> >> probably seen the Polar heart rate monitors. The h.w. inside the
> >> chest belt will signal heart rate to about 200 bpm - and run for
> >> months off a sealed-in lithium battery <-- presumably Li, since
> >
> >Try years. I just replaced the battery in my (Li CR2032 IIRC, $1.20 at Fry's)
> >after 5 years of use. I knew it was about time to change my battery when my
> >respiration rate started exceeding my heart rate. Also, I've never sprinted
> up a
> >200' hill and kept my h.r. below 80 bpm!
> >
>
> Scott, I suspect the Polar ckt design is so efficient - with say 3
> bps each producing a 5 msec long pulse in a class C amp - that the
> battery probably will go for years. [I used to use mine on 8-hour
> long hikes in the CO mtns - helps an old wheezy body get up those
> 14ers - anything for a gimmick, huh!].

The sprint referred to a bicycle... I suspect that the long life of the battery
is due in part to it's lack of continuous use. These batteries have very long
shelf lives. So I may've been demonstrating that behavior (I don't use it every
time I ride - seldom during commutes).

>
> But was this actually the belt battery or the watch battery you
> replaced? If indeed the belt, what did you see inside, viz-aviz
> electronics, after you slit it open? Also, how did you reseal it
> afterwards?

There's a quarter-sized (that is 25 cents) lid that's slightly bigger than the
CR2032. An o-ring is present to keep out moisture. When you open the back, you
really can't see much. So I have no idea what the circuit looks like.

> I don't know if my suggestion helped out Russell, but all in all,
> the Polar device is very clever, plus extremely simple and cheap,
> electronics.

and expensive!

>
> [what the heck is IIRC ???]

if I recall correctly

Scott