Posted by Max Dunn
Sun, 02 Sep 2007 15:37:48 GMT | 5 comments
After running the Zapino battery all the way down last night, I put the charger on it with the Kill-A-Watt meter to record how much power it would take to recharge. The charging rate started at about 360 watts and then increased to 400 watts. The total power consumed was 2.68kWh.
This is an interesting number and does make sense since the battery pack is rated at 2.28kWh (60v-38ah) and you would expect that there are some losses when charging. Sealed lead-acid batteries typically can be up to 95% efficient and chargers are typically 90% efficient, so combined these numbers lead to the total efficiency we measured of 85%.
Another useful fact about charging is that for every hour that the scooter is being charged, you are adding about 4 miles to the range. (Based on the charger putting out 400 watts, and the Zapino using about 100 wh/mile.) So, for instance, my wife works part time at an office about 18 miles away. So if she is there for 4 1/2 hours, the Zapino will be completely recharged.
Posted in Electric Vehicles
Posted by Max Dunn
Sun, 02 Sep 2007 02:06:40 GMT | no comments
After the excursion with my wife today where we traveled about 20 miles, I went to go pickup my son at the pool which was a little over 5 miles away. I was still taking it easy in economy mode and staying around 25 mph. However, I did go through the neighborhood where there were a lot of stop signs. Coming back home, we got about 3 miles away and the range indicator starting to drop into the yellow when we accelerated. At 2 miles it was dropping into the red, so I started driving 15-20 mph. At about 1 mile away, the engine cut out because the indicator dropped below the road while accelerating. Coasting to a stop, I turned off the key and back on again and was able to continue. I then starting going really slowly, about 10 mph. The engine cut out a few more times, but we made it home. So i consider that we fully utilized all the available range.
Total distance today 31.2 miles. Not bad!
Posted in Electric Vehicles
Posted by Max Dunn
Sun, 02 Sep 2007 00:21:38 GMT | 3 comments
Last Wednesday, after weeks of looking around at electric scooters, we finally bought a Zapino and love it! Today, Suzanne and I took a little excursion around town to see if it could carry both of us and to see how the battery would hold up on a longer trip.
The first thing you should know is that it was hot in San Jose today, getting up to 94 degrees. Riding the Zapino was nice because the breeze cooled us off. However, we were worried that it would overheat because we were pushing its 282 lb weight limit with our combined weight of 275lbs. (And no, Suzanne forbids me to break out our weights separately. ;-)
Since we were just out cruising, we were using the energy saving mode which limits the top speed to 30mph. Most of the time, this is plenty fast, but I did kick it into high-speed mode several times going down Highway 9 to Los Gatos.
The Diagnosis light was flashing its 2-3 combination which means that it is overheating, but I just ignored it and kept going
We stopped at a store and looked around for about 5 minutes. When we got back on the Zapino, the overheat protection kicked in and it made us go really slow. This was probably because after stopping, there was no more wind to cool off the controller and it was so hot out anyways. This slow speed was fine since we only needed to ride a block. We then got off again and walked around for about 20 minutes before getting back on the scooter, at which time it had cooled down.
Going home, we continued to take it easy but the “overheating” warning starting flashing again very soon. This didn’t seem to make any difference, although our top speed was a little lower, around 25 mph in the energy saving mode. Just for fun, right before we got home I put it back into high-speed mode and it sped right up past 30 mph, no problem.
I realized on this trip that the diagnosis light is a little annoying. In order to read the flashing codes, you have to look at it continuously for about 5 seconds, which is very dangerous while driving.
Our total outing ended being about 20 miles and the charge indicator was only about halfway down in the green. So we have now confirmed that driving conservatively with a heavily loaded bike can take you at least 20 miles on the Zapino.
Suzanne and I really enjoyed our little excursion on the the Zapino!
Posted in Electric Vehicles
Posted by Max Dunn
Fri, 17 Aug 2007 05:20:26 GMT | no comments
We didn’t plan a big trip this year so instead, we got in the car and drove. We ended up spending some time in Newport Beach, Las Vegas and San Diego. Here are the things we enjoyed most about the trip:
- Eating hamburgers and fries at In-N-Out
- Frozen yogurt in San Luis Obisbo
- Riding the eGo electric scooter in SLO
- Eating lunch on the cliffs in Laguna Beach at Las Brisas
- Shopping for surf clothing at Jacks in Newport
- Buying cupcakes at Sprinkles
- Surfing all over
- The wave pool at Mandalay Bay in Las Vegas
- Seeing the Blue Man show
- Sleeping in
- Hanging out at the beach in San Onofre
- Paige’s Craft Corner at San O
- Maxie getting coffee at Startbucks
- Seeing baby Mitchy
Posted in Trips and Vacations
Posted by Max Dunn
Tue, 15 May 2007 18:12:24 GMT | no comments
Migrations don’t come with referential integrity directives, best as I can tell. There are some plugins but it appeared to me (ok, after only a brief review) that they were more focused on adding referential integrity for rails object hierarchies (:belongs_to etc.), so that seemed both overkill and insufficient for what I needed to do.
But it turns out that an “execute” statement in the migration lets you issue sql directives directly.
create_table "dvectors", :id => false, :force => true do |t|
t.column "length", :integer, :default => -1
t.column "fvector", :binary
t.column "document_id", :integer, :default => -1
t.column "total_size", :integer, :default => 0
end
add_index "dvectors", ["document_id"], :name => "document_id"
execute "alter table dvectors add constraint `dvectors_fk` " +
"foreign key (`document_id`) references `documents` (`id`) on delete cascade"
(Submitted by Wido Menhardt)
Posted in Ruby on Rails
Posted by Max Dunn
Sat, 28 Apr 2007 16:37:14 GMT | no comments
If you are using the SVN command line, here is a trick that makes it easier to import your files into Subversion. The problem with the usual method is that after importing your files, you have to check them out to a different directory, rather than continuing to work with them in the same location. This methods avoids that problem:
Read more...
Posted in Tech Tips
Posted by Max Dunn
Tue, 17 Apr 2007 19:51:46 GMT | no comments
(Suzanne) If you know me, I’m the one that has to research everything for months before making any kind of big purchase. Trips, on the other hand, can be a different story. Don’t get me wrong, I still love doing research for certain destinations, but there is some sort of thrill that I get out of being spontaneous—this trip being one of them!
Read more...
Posted in Trips and Vacations
Posted by Max Dunn
Tue, 20 Mar 2007 15:49:44 GMT | 2 comments
It is interesting that Apache 2.2 doesn’t include a startup script that is compatible with the Linux ‘chkconfig’ command. Here is how you fix this:
First, add this information to the top of /usr/local/apache2/bin/apachectl:
# chkconfig: - 85 15
# description: Apache is a World Wide Web server. \
# It is used to serve HTML files and CGI.
Then change to /etc/init.d and do:
sudo ln -s /usr/local/apache2/bin/apachectl httpd
sudo /sbin/chkconfig --add httpd
sudo /sbin/chkconfig --level 2345 httpd on
That’s it! Now Apache will start when the computer starts up.
Posted in Tech Tips
Posted by Max Dunn
Mon, 05 Mar 2007 17:12:25 GMT | 1 comment
We had a bad crash yesterday on our MySQL 5.0.22 database. Our guess is that we ran out of hard disk space during a large transaction and the database somehow got corrupted. Worse, restarting MySQL didn’t clear the error, but continued to have the problem. Luckily, we could still read from the database so we were able to do a current backup which allowed us to recreate the database and re-import the data. Here are the steps we used:
- In my.conf use:
innodb_force_recovery = 6
(or lower) to bring the database up.
(See http://www.mysql.org/doc/refman/5.1/en/forcing-recovery.html)
- Dump the tables. For example. to dump the ‘maxwiki’ table use:
mysqldump -
mysqldump --database maxwiki -u (username) -p (password) > maxwiki.sql
Repeat for all other tables
- Shut down the database
- Move all files out of /usr/bin/mysql and put elsewhere
- Re-init with:
mysqld_safe --user=mysql
mysql_install_db --user=mysql
mysqladmin -u (username) password '(password)'
- Reload all the tables from the sql files
- Reset the users
Posted in Tech Tips
Posted by Max Dunn
Tue, 23 Jan 2007 17:51:17 GMT | no comments
I like Linux, I really do. That is one reason why I got a Mac last year and also why I host my web sites on Linux servers. However, for all the talk about Microsoft’s DLL Hell, it is nothing compared to Linux Dependency Version Hell. Those of you that have tried installing new versions of software on Linux know what I mean. Whenever you upgrade one piece it causes a cascading effect of having to upgrade lots of other pieces. And sometimes there is a problem with the latest version of a library so you have to use an older version. Now if you have something like apt-get, yum or urpmi, it can help a lot by installing all the needed dependencies for you. But once you venture outside the official versions, it will take a long time to get everything right.
Take for instance, what should be a straightforward task of getting Subversion 1.4 (SVN) working with Apache 2. Of course, you don’t have to have these working together because you can use svnserve by itself. But this only lets you set access control for the whole repository, rather than the finer grained access you get going through http, and you also need to add all svn users to Linux, which is problematic. So to get the advantage of having Subversion working through Apache using http, I spent a day figuring it out.
In the end, the procedure turned out to be fairly straightforward and to save others the pain I went through, here is the trick:
Use the Apache apr and apr-util libraries when making Subversion.
On a standard install, you will probably have libapr-1.so and libaprutil-1.so in both /usr/local/apache2/lib and /usr/local/apr/lib and maybe even /usr/lib. If you configure Subversion with the defaults, it will find the apr libraries in /usr/lib. And if they are not the exact same version as in /usr/local/apache2/lib, there won’t be any errors but when you try to access the repository, you will get error messages like:
Could not fetch resource information. [500, #0]
Could not open the requested SVN filesystem [500, #2]
Internal error: Can't open file '/var/svn/format': No such file or directory
So the best thing is to delete all the libapr* files everywhere but /usr/local/apache2/lib and then configure Subversion like this:
./configure --with-apxs=/usr/local/apache2/bin/apxs \
--with-apr=/usr/local/apache2/bin/apr-1-config \
--with-apr-util=/usr/local/apache2/bin/apu-1-config
After that, you should be able to follow the Subversion/Apache setup instructions with no problems.
Posted in Tech Tips