Re: Using a Laptop from My Car Battery?

Barry Watzman wrote:
Maybe, but more likely not.

First, you must not connect your laptop to the electrical bus of the CAR. The car's power bus is incredibly dirty and has huge spikes as things cut on and off.

As to a car battery (disconnected from the car itself, or with the car engine not running), it's a good source of 12.6 to 13.5 volts. The problem is that your laptop most likely runs off of 15 to 19 volts DC from it's power supply and a car battery is probably too low.

It might be possible to jury-rig a connection to where the laptop battery connects to the laptop, but on most laptops the battery has an onboard microprocessor that talks to the laptop, and the laptop may not work without this data connection; simply providing power may not be enough.

Again, don't under any circumstances try to connect the laptop to the car's electrical system with the car running.


W. Watson wrote:
Is it possible to somehow tap into the auto battery of my car to power my laptop?

Here's my experience of "living dangerously" -- since the early '90s.

From the early '90s until 2005 I routinely plugged Thinkpads (500, 760, & 380) into either the cigarette lighter or GM's "auxilary power outlet" in several cars. I had no failures with any of these machines attributable to power. (The backspace key on the 760 failed.)

In 2005 I started using a Tpad 600e for data capture from my Corvettes ECM/PCMs and was concerned about noise affecting the data. So, I re-considered the 'hash' issue and added a simple choke-capacitor filter between the cigarette lighter adapter and the Thinkpad connector. Since 2005 I've used my Tpad R31 on over two dozen trips in the passenger seat of my wife's Buick. The Tpad 600e has seen regular service in a variety of Corvettes (1886 through 2004), either working from a cigarette lighter or from an auxilary power socket.

I've thought about adding a MOV to the hash filter but haven't got around to it.

Generally, the R31 and 600e will not draw power from the car's battery when the engine isn't running -- particularly when battery voltage is below 12 volts. They 'report' charging on "AC power" after the car system voltage rises above 13.8 vdc.

Only precautions I take: I don't run these machines without the internal battery and, I only plug the computer adapter into the car after the engine is started.

All this works because these Thinkpads use 9.6 or 10.8 volt batteries with 16 volt charging bricks. Neither my HP Pavillion or my wife's Apple notebooks will work this way since their voltage requirements are in far in excess of what an automotive system will provide.

Suggestion: To be really safe, go with a DC-to-AC power inverter and use the 'brick' that came with your notebook.

If you own a 10.8v Thinkpad, you might try what works for me.

--
pj
.

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