powering a computer

[clintonddk]

Hi everyone, my laptop is older and the battery use to hold a dmall charge. I did install a power converter so I could plug it in if needed. The problem is, while starting the car with my laptop plug in the power drain kills my computer and now the laptop's battery is dead. Is there a good way to prevent this from happening?

[volksbugly]

A capacitor would probably work, something like this:
http://www.sonicelectronix.com/cat_i6_capacitors.html

[clintonddk]

Okay, that's kind of what I was thinking. Thanks

[woodsbuggy1]

I have bought laptop batteries on ebay for $20 shipped, my current one is almost a year old and still holds a charge well. Might be an option for you.
Kenric

[clintonddk]

Hi Woodbuggy, I did just that last year, I bought a new battery and everything worked just fine until I had it plugged in and hit the ignition. Now the new battery is DOA. The old battery use to hold a charge too.
Thanks

[jhoefer]

Go find a car charger* for your laptop. Install a cigarette lighter socket and make sure it is connected to the constant hot (red wires) of your fuse box. This will eliminate the inverter which if it's not a good one, might not actually be charging your battery properly or could be causing issues with the laptop power supply. I drive one vehicle around here with an inverter that will run some laptops and not others because it doesn't output enough amps. Other laptops might run but then not have enough amps to actually charge the battery. A DC car charger is also less sensitive than an inverter when the input voltage drops during cranking so would be less likely to shut off the laptop. Wiring the socket to constant hot will also make sure you have battery power to the laptop even while starting because depending on year/how it's wired, power to your existing socket may be turned off while cranking.

You may also be having battery problems if your laptop is always in the car where it gets large temperature swings, especially cold.

*If you can't find one from a simple google search like "dell laptop car charger", try searching for "laptop dc-dc converter" and see if you can find one specific to your laptop model.

[clintonddk]

I'll give that a try jhoefer.
I thought it could have been a temperature think after all I do live in Michigan and I did leave my laptop out in my garage one winter. I have always charge it in doors but, since it is an older laptop the battery life was short. I was hoping that the new battery would help but you know the rest of the story.
Since my car is a 56 I already did the 12v cigarette lighter install just as you described.

[jhoefer]

It's possible the "new" battery was crap too.

Personally, I'd try the dc-dc adapter first. And for the capacitor size you'll need, it's probably cheaper to just get another laptop battery or two. But if you do want to try to add a capacitor, first, you also need to have a diode between it and the battery so it only feeds the laptop and not back into the starter. And second, you'll need to get one big enough to hold a charge long enough while cranking. That really depends on the amp draw of the laptop and the lower limit of the voltage required to keep it on. I'd say you're looking at between a 4 and 10 Farad capacitor. What's working against you most is the cranking time. Capacitors aren't good at long duration loads.

[Dale M.]

Sounds like multiple problems First and above all you need good battery in LT... 2nd a disconnect between LT battery and cars electrical system to disconnect computer from aux charge circuit when "A" starter is cranking, "B" when engine is off... May be as simple as add a relay that is only activated when engine is running or key is in "on" position...

Basically it appears you have two different problems but both related...

Dale

[clintonddk]

I just wanted to give a update. I finally got around to purchasing a audio capacitor and a 12v power adapter. This worked perfectly.

[madmike]

5 months ur fast JK
gonna have it at the Bug Run? ???????????????????????

[clintonddk]

It's looking good, you willing to line up against me