Problem submitting form in an email

Posted by Max Dunn Wed, 17 Oct 2012 21:05:18 GMT | no comments

For COZMOS, we are implementing an advanced email discussion system where users can type in their responses to multiple posts right on the email and then hit Submit to submit all of them. However, we were running into problems because GMail changed the form submission from the POST method to a GET and didn’t send any of the user input.

It turns out the GMail (and likely other email clients) will only send POST forms to a secure HTTPS address. However, it will send GET requests, with the user’s input included, to a regular HTTP address.

Conclusion: In an email form, use POST only when sending to HTTPS addresses.

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Posted by Max Dunn Sat, 10 Mar 2012 16:22:59 GMT | 1 comment

In getting my MBA at Presidio Graduate School and working with entrepreneurs, I notice that there is usually lot of confusion over market size. In particular, many times the total market size is over-estimated and entrepreneurs don’t have a good idea to estimate how much market share they can get in the short-term.

The standard terms for this are Total Addressable Market (TAM), Served Addressable Market (SAM), and Serviceable and Obtainable Market (SOM). Here is how I explain these:

  • TAM: In the far future, if your company is wildly successful and has a full line of products that dominate their markets completely, how much would your revenues be?
  • SAM: In the future, if your current product offerings are wildly successful and dominate their categories, how much would your revenues be?
  • SOM: In a few years, how much of the SAM can you reasonably expect to get?
    • Top-down: Take the largest, closest competitor and scale their revenues by how much money they have raised by how much you expect to raise.
    • Bottom-up: For a rough estimate, figure that the money you spend each year on sales/marketing will produce 10 times that in revenue in the next year.

Another way to think of this is to realize that investors want to know what your short-term and long-term revenue potential is, and TAM, SAM and SOM is how they do it.

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Long Distance EV Driving

Posted by Max Dunn Fri, 03 Feb 2012 18:03:55 GMT | 1 comment

Some people envision that a network of public charging stations would allow EVs to make long trips. However, I am not so sure.

Even though the Leaf claims a 100 mile range, this is only possible with non-freeway driving. For the normal American driving habits, the EPA gives a range of 73 miles which is in-line with my Leaf experience. Also, if I drive hard on the freeway, then my range can be as low as 60 miles.

This means that when driving a far distance, you could drive for about an hour, then have to stop and DC fast charge for 30 minutes. Since the DC fast charge fills up the battery to only an 80% level, the next leg would be even shorter. Driving the 400 miles LA to from San Francisco normally takes about 6 and a half hours in a gas car, but an EV would require at least 6 recharges and take about 10 hours. Doable, but not very efficient.

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EV Public Charging Cost

Posted by Max Dunn Tue, 31 Jan 2012 16:12:09 GMT | 2 comments

David Herron asked a question today on LinkedIn about the cost to charge an EV at a public station. For those of you not on LinkedIn, here is the answer.

Currently, most public charging stations are free, but you sometimes need to pay for parking. For instance, when I am in SF, I usually park my Leaf at Pier 27 and pay $15 ($10 at night and weekends) to park. A 2-hour charge costs them about 75 cents in electricity, so it is cheap for them. But, they have 2 spaces reserved for EVs and these are often empty and so overall, they are probably losing money.

A company called 350Green is installing charging stations at Walgreens. Walgreens pays for just part of the cost and 350Green will make revenue by selling charging subscriptions for about $70 a month. Coulomb Technologies is also planning on charging too, at about the same rate.

Why does it cost $70 a month? Well it is expensive to install a charging station. EVs take about $35/month in electricity so a $70 subscription leaves $35 for equipment and profit. A networked charging station costs about $2,000 but installation can be expensive depending on how far the power lines need to run. So figuring another $2,000 for installation means a total cost per charger of $4,000. Most people that buy a monthly subscription probably can’t charge at home (maybe they live in an apartment and park on the street) so they will probably want to plug-in while they are at work. This means there can only be one subscription per charger, which will take about 5-years just to pay for the charger and installation before the company makes any money at all.

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Cloud Server Load Testing

Posted by Max Dunn Sat, 07 Jan 2012 20:44:59 GMT | no comments

I have been working on the RealMealz site and am now looking for a suitable host server. Currently, RealMealz is in beta and has just light use, but we expect that once released the use will go up dramatically, so we want to be able to easily scale. I looked at Amazon EC2, Heroku and RackSpace Cloud Servers and the table below summarizes my findings:

Test: Login, hit Discover page 5 times
Use a 5 second ramp up

Average Discover page load time (Apache + Passenger unless otherwise indicated)


1 user

5 user

10 user


EC2, Micro





EC2, Micro, Thin





EC2, 3-Micros, balanced. Apache/Passenger



9s-18s (40s max)


EC2, hi-cpu medium





EC2, hi-cpu medium, Thin










Heroku, 1 dyno, Thin





Heroku, 2 dynos, Thin





Heroku, 3 dynos, Thin



6s (20 users!)




7s (max 66s)



Rackspace, Thin





Rackspace, Unicorn







1. Users are concurrent users

2. I selected the Discover page since this is our most CPU intensive page. This test is not that realistic in actual use, but serves as a worse case example.

3. The Rackspace server had only 512Mb of memory and for the 10 user case for Apache it started swapping out. If I was using their next size up with 1Gb of memory, the cost would have been $44 per month but wouldn’t have suffered this performance issues as drastically.

4. The Amazon Micro instances provide bursts up to 2 ECUs, but if used at a high level for more than a few seconds, get throttled back greatly for about 15 seconds. This is why the 10 user case was so high, even for the 3 instance, load balanced case.

4a. The Amazon servers are a little underpowered. Even the hi-cpu instance that provides 5 ECUs is not all that impressive. My BlueBox server which has 4 VPSes on the server performed better.

5. It wasn’t clear how the Rackspace Cloud Servers could be easily scaled since RackSpace doesn’t seem to provide a load balancer for them.

6. Amazon’s EC2 instances are a bit of a pain to scale. You can’t add an extra instance to an existing load balancer, so you need to delete the current one then create a new one. There is an autoscaling feature, but this only works from the command line and I didn’t test it.

7. Heroku offered pretty amazing performance and was super easy to scale by just typing “heroku scale web=3”. The prices include $15/month for the larger database, although under 5Mbs is free.

8. With 3 dynos, Heroku was able to handle 20 concurrent users where the other tests were only with 10.

9. A disadvantage of Heroku is that it doesn’t offer shell access and there is no way to access the database natively. We do have some table manipulation built into our program, but if there are major changes or corruptions, we will need to export the data, fix it, and then re-import.

In the end, we are going with Heroku because it has great performance, easy to scale and is low cost.

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Vinod Khosla's Five-Second Slide Rule

Posted by Max Dunn Tue, 01 Nov 2011 16:31:22 GMT | no comments

One of my goals while at Presidio Graduate School was to get really good at giving presentations. Since slide decks are required for most presentations, making good slides is vital for good presentations. But the slide deck is not the presentation – you are the presentation. So if your slides are complicated and people need to take time to study them to figure them out, that means that the focus is on the slide and not on you. So it is important to make slides that can be grasped quickly.

How quick? Well Vinod Khosla likes to aply a five-second rule. He puts a slide on the screen and then removes it after 5 seconds. He then asks the viewer to describe the slide. If they can’t, the slide is too complicated.

How about your presentations? Can all your slides be quickly grasped with 5 seconds? If not, then go back and simplify them until they can.

(From: Forbes, Vinod Khosla’s Five-Second Rule)

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EV Electricity Costs With PG&E

Posted by Max Dunn Sat, 01 Oct 2011 16:54:13 GMT | 1 comment

Figuring out how much electricity your electric vehicle (EV) will use is pretty easy. From the wall, 1kWh of electricity will power the Leaf about 3.5 miles (and a similar amount for other EVs). So for a normal 1,000 mile a month usage, it would take about 300kWh of electricity each month (rounding up).

This should add about $35/month for electricity at the average price of $0.11 per kWh. However, for most users it will push them up into higher tiers and be at least twice that. For us, we went from a $70/mo electric bill to $170/mo!

But wait, it gets more complicated. EV owners are required to contact PG&E and go on a special E-9 time-of-use rate plan.

The great thing about this plan is that off-peak, you can charge your EV for $0.05 to $0.06! The bad thing about this plan is that the bottom tier only goes up by 30% and then all times have higher costs. For instance, after 130% of base usage is reached, off-peak charging goes to $0.16 and then at 200% goes to $0.20!

We just switched over a few months ago and are still analyzing our bill, but it looks like it was reduced from $170 to about $120. We think with some reduction (turn off those lights kids!) and shifting our dishwasher to after midnight we can get it down to about $100, which means the EV will cost about $30 per month. Just where it should be!

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Startups in Stealth Mode - Just Stop

Posted by Max Dunn Sat, 24 Sep 2011 14:30:35 GMT | no comments

(Advice from Jason Freedman)

Startups in stealth mode need one piece of advice. Stop doing your start-up. You’re not ready.

Let me a share a few reasons why you don’t need to be in stealth mode:

  1. Execution is more important than the idea.
    This is the easiest lesson. Your ability to create a product is far more important than your ability to think up a product. This is a hard lesson if you’re not the one that will do the building, because it means that your contribution is not as valuable as you thought.
  2. Someone else has the exact same idea.
    The adage is that if you have a good idea, there are 5 other people already doing it. If you have a great idea, there are 15 other people already doing it. One of the reasons you’re foolishly in stealth mode is probably because you haven’t done enough market research to realize that people are already working on this.
  3. Totally unique ideas generally don’t make it.
    If you have a 100% totally unique idea, you’re either too far ahead of the market or you’ve picked a market so small that no one cares. Either way, you’re in for trouble.
  4. The most likely cause of failure is your incompetence, not losing to the competition
    Start-ups are really hard on so many levels. The likelihood that you execute beautifully but then lose out to someone that stole your idea is so incredibly low, you shouldn’t think about it. The likelihood that you build a product that missed the mark, is an almost certainty. Optimize around the problems most likely to shut you down. Paul Graham always told us to focus on the one enemy that matters: the back button.
  5. You desperately need real feedback
    Perhaps the biggest reason not to be in stealth is that you’re robbing yourself of great feedback. Most companies miss the mark on the first product. The great companies learn quickly and iterate. Skipping the learning part by being secretive just reduces the time you’ll have to iterate before running out of money.
  6. First mover advantage is just silliness
    The obit has been written on first mover advantage. It rarely helps. Facebook wasn’t the first to social networking, Google wasn’t the first to search, YouTube wasn’t the first to video, yada yada. First mover advantage was a flawed theory that helped pre-product internet companies raise billions of dollars in the 90s.

I could go on, but this is a fool’s errand. If you’re reading this and don’t agree, you’re probably just not ready to do a startup and all the rationalizing in the world won’t help.

(From Startups in stealth mode need one piece of advice.

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Per Capita GDP and Oil Consumption

Posted by Max Dunn Sun, 03 Apr 2011 17:05:22 GMT | 1 comment

In Peak Oil in 2012, I looked at the strong link between worldwide GPD and oil consumption. But what about per capita oil consumption? It turns out that there is a very interesting story there too.

As reported by Frank Holmes in Seeking Alpha, China currently consumes 2 barrels of oil per per per person. At the same PPP level of $5,000 per year, Japan consumed over 18 barrels, Taiwan 6 barrels and Korea 4 barrels!

Since China currently consumes about 10 million barrels a day, just doubling their per capita usage would require an extra 10 million barrels a day, which is 12% of the world total. Since oil production has been relatively flat since 2005, it is unlikely that additional oil production will ever be able to provide that amount.

This is just another indicator that our worldwide oil supplies will never again be able to meet our total oil demand.

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How Much Oil Do We Use ?

Posted by Max Dunn Sat, 12 Mar 2011 18:43:02 GMT | no comments

How much oil do we use in the United States and where does it come from? This is a question that hasn’t been exactly clear for me until I read this article on the Energy Information Administration (EIA) website. Here is the quick answer.

The US is the largest oil consumer using 19.1 million barrels per day (mbpd). We are the the third largest crude oil producer at 5.5 mbpd. In addition, we produce 3.9 mbpd of biofuels, natural gas liquids and processing expansion. This means we need to import about half our oil, or 9.3 mbpd.

Contrary to popular belief, two of our largest oil suppliers are Canada and Mexico. Overall, Western Hemisphere nations provide about half of our imported petroleum.

Now you have it. While the US uses about 19 mbpd, we produce 5.5 mbpd of crude oil and create another 4 mbpd of fuel products so the 9 mbpd we import is about half our usage.


EIA. (November 29, 2010). How Dependent Are We On Foreign Oil? U.S. Energy Information Administration. Retrieved March 12, 2011 from

EIA. (March 8, 2011). Short-Term Energy Outlook. U.S. Energy Information Administration. Retrieved March 11, 2011 from

U.S. Census Bureau. (March 10, 2011). U.S. International Trade in Goods and Services. January 2011 U.S. Census Bureau. U.S. Bureau of Economic Analysis. CB11-41, BEA11-09, FT-900 (11-01). Retrieved from

Note: All numbers for 2010 except oil additions for 2009.

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