Wednesday, February 20, 2013

Comparing Separation Resistance Between Magsafe Options

As I noted in my last post, I recently replaced my older Macbook with a new Retina Display Macbook. Apple changed its power adapter format on the MBPs to use the slimmer adapter format it previously had on recent Macbook Airs, which means that you have to either use a tiny little $9.99 adapter to use your old power supply or use a new power supply.

Searching the internet there's consensus that the new Magsafe-2 connectors seem to be much less securely attached to the laptop; in conversations internally at work, there was a suggestion that old (Magsafe-1) power supplies with the $9.99 adapter seemed more securely attached than the new (Magsafe-2) power supplies.  So I got curious and conducted an informal experiment.

The laptops
For a Magsafe-2 laptop, I used my own recently-purchased Macbook Pro Retina Display.  For a Magsafe-1 laptop, I used a coworker's 17" Macbook Pro, about a year old.

The power supplies
I used three power supplies: The classic power supply with a chicklet-looking connector, the more modern power supply with an L-shaped/barrel connector, and the new Magsafe-2 chicklet-looking connector.  The older power supplies were tested with the Magsafe-2 adapter (on my new Mac) and without (on the older 17" MBP); the new power supply was obviously only tested on my new Mac.

The tests
I taped a little paperclip about 3" from the connector end of each power supply, then used an RCBS Trigger Pull Scale to measure how much force it took to cause the power supply to separate from the laptop when pulling away from the laptop in three directions:

  1. Straight left from the laptop
  2. Straight away from the laptop (and away from the user)
  3. Up from the plane of the laptop
The results
Up Left Away
Old chicklet 0 3 lbs 1.25 lbs
Old L-style Off the charts .75 lbs Off the charts
New chicklet 0 3.5 lbs 2 lbs
Old chicklet with adapter 0 3.75 lbs 1.375 lbs
Old L-style with adapter 1 lbs 1 lbs 2.75 lbs

"Off the charts" in this case means more than 8 lbs, the maximum capacity of the scale.

Notes and Opinions
It's clear that overall, nothing beats the old L-style connector for attachment strength, though I'm not certain this is a good thing -- at more than 8 lbs, if you pull hard enough on the cord you'll be taking the laptop with you, potentially causing an accident as it falls off the table.  That said, it's important to note that in this testing, I was slowly increasing the stress on the cable; in a real life accident, what we'd see is a quick shark jerk and it's more than likely that the connector would require less of a tug to separate.  

What you take away from the results depends on your particular use case, i think.  In my case, where I have the laptop on a bed or a couch, the biggest concern for me is the ability of the connector to stay in place in the face of pressure up from the uneven surface; in that case, I'd definitely prefer the old L-style with adapter option (1 lbs) to any of the other Magsafe-2 options, which were so weak in the face of upward pressure I could not measure how much force was required to separate the connector from the laptop.  

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