On 6/7/2021 5:25 PM, John B. wrote:
On Mon, 7 Jun 2021 09:13:31 -0700 (PDT), Tom Kunich
wrote:

On Saturday, June 5, 2021 at 10:34:18 PM UTC-7, pH wrote:
On 2021-06-01, Joerg wrote:
snip


The game changer, of course, is the Li ion technology since if was so easy
for uninformed users to kill off their lead acid battery pack.


Li-Ion also has its issues. For example, even top brand manufacturers do
not seem to understand that it is not a good idea to top off a Li-Ion
battery at close to 100% charge and then leave the bike in the garage
that way. This results in premature aging and loss of capacity. The
smarter way is to offer 80% or so which is plenty for a short ride into
town. Then let users top it off in the morning when they expect to go on
a very long ride. In the same way, don't ride it all the way down to
where the low-batt cutoff turns it off, at least not often.

"Smart" battery chargers would seem to be in order. Push the button if you
need more than an 80% charge this time for some reason.



NiMH would be more robust, but that chemistry never seemed to catch on
before Lithium came on the scene.


NiMH doesn't have an adequate energy density. A NiHM-battery that can
last 40-50mi would be unreasonably large and heavy.

[...]

pH in Aptos


Is the old stranded concrete ship still there?


Use..the SS Palo Alto.
About two years ago the winter storms broke the last 1/4 of the stern off
and it twisted about 80 degrees from level.

When I was a tad one could actually walk out to the bow. Then it was
fenced off at half way. Then when I came back from college and other things
it was closed off entirely and you can only walk out to the end of the pier
the ship abutts.

Sigh. Things change.
Concrete exposed to water saturation degrades surprisingly rapidly. One of the instruments I was working on detected leaks from degrading concrete is swimming pools. I would imagine that you could make a pool thick enough to delay this for a long time as those concrete barges showed. But degrade they will. The concrete turns back to almost a mush consistency.

Oh, you mean like the Alvord Lake Bridge that was built in 1889 in San
Francisco, CA. This bridge was the first reinforced concrete bridge,
and it still exists today, over one hundred years after it was built!

Or maybe the Hoover Dam? Constructed some 85 years ago and still
standing. Up to this time, the largest scale concrete project ever
completed.


+1
Concrete can be durable if it's done right:

https://www.historicmysteries.com/roman-concrete/

Couple thousand years anyway, maybe longer.


--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971