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# Is there an easy way to run a computer/laptop, almost directly from a car battery? Has anyone got some good ideas? Answered

This one has had us stumped for a while. I'm currently thinking along the lines of side-stepping the transformer.

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There is no need to worry about the amperage rating as the voltage is the constant and the amps are the variable. For example . . your household appliances run on 120 volts and they all use different amounts of amperage but the circuit they run off is controlled by a 15 amp breaker. Just as the amp output on the adapter and the circuit breaker are maximum outputs and only the voltage remains the constant the device being used will run on the set voltage and use the amperage it requires up to to maximum available if it is supplied by an adapter . power lines. A generator or any other power supply. Just remember that constant voltage is required but amperage varies on demand. Like a loud stereo uses more amps than a quiet one but they both run on the same voltage. Hope this helps you understand volts and amps . take care

I have an hp laptop input voltage is 19v and the current is 4.7ah.and laptop battery gives 10.8v and 55wh to laptop but I want to use a motorcycle battery for my laptop. Because motorcycle battery gives better backup time. Motorcycle battery voltage is 12v and the current is 7ah. I know how to convert 12v into 10.8v. but do not know how to convert 7ah current into 4.7ah current. Please help me.

Probably the simplest most efficient solution would be to use a DC-DC converter/regulator of some sort. In my personal experience for other similar projects I have found that buck converters are probably your most reliable solution where you will probably be getting approximately 95% efficiency stepping up the voltage from 12 to 18V (Probably more efficient than your AC charger). One thing I would recommend however is that if you are buying a cheap buck converter (off ebay perhaps) that you ensure that you either connect the outputs up to an oscilloscope to check for any large high frequency components to the output. If you don't have access to an oscilloscope I would recommend you also buy a fairly large electrolytic capacitor say ~200uF and put this in parallel between the positive and negative terminal, this should filter out most damaging high frequency DC voltage spike. Another thing to keep in mind is the power rating of the buck converter. Make sure its going to be able to power your laptop.

How about 12v battery Plus + 6v battery and connect them so they
make 18v current , I'm not really good in electricity and I want to ask
about the amperage , what if my battery is 60AH can I use transformer
to step up the voltage to 18 V or 14 V

It depends on what voltage the laptop requires. If you have a notebook that requires 12v, you probbly are in luck depending on the amperage, but if you have a laptop that demands 18v, you would need a transformer to step up the voltage and possibly the amperage. As stated below, and inverter isn't practical unless in is necesarry. You are simply going from 12v DC to 115v AC, back down to around 15v DC.

It seems like it would be a waste to use an inverted considering that you have a DC battery that you would run through an AC inverter in order to go to an AC to DC converter through your laptop charger. Maybe you could use an 18-volt linear regulator?

I have been studying this idea for some time because the power hungry laptops I have suck all the power out of a normal car battery and the inverter goes off much too soon. This method will not hurt the charger or plug. 1 Unplug the charger. 2 Cut off the output wire (about 1/2 way, i.e. in the middle) 3 Separate the two wires and bare the ends 4 plug in the charger and check the polarity (don't let them touch each other) 5 bare the wires of the other cord and note the color code for polarity 6 wire (3) 6 vdc batteries in series to get a total 16 vdc (+ to - to + to - to+ to -) 7 attach the + of the first battery and the - of the last battery to the computer 8 charge the batteries with a solar panel with an output of greater than 16 vdc The trick is to get total efficiency by eliminating any resistance factors using inverters or electronics. Use a voltmeter to monitor the voltage of the batteries. A vintage laptop should run for hours on this solar powered industrial grade setup. In fact, you can run your laptop directly without an internal battery so save money buying a new laptop battery.

Correction The total voltage of (3) 6 vdc batteries wired in series should be more than 18 vdc without a load and the laptop load should bring the voltage down to 14 - 16 vdc. The batteries should also be equal in size and quality to eliminate any imbalance. The solar panel should also be sized to keep the batteries charged but not overcharged.

Go to Jaycar or similar and lash out \$44 on a voltage inverter.

there are many convertors that you can get on the web and in alot of shops, they come with a ciggarette adaptor for in the car but this could easily be taken off and put straight on the battery, then you just plug in your laptop!

There are a few ways to do this. If you have the car charger for it you can wire that to the battery and it will charge. Another way, you already suggested was to use the transformer. The last way you could do it would be to either step up or step down the voltage to what your computer would usually use. You can do this with some simple electronic components

One more for the just buy a cheap inverter, you can use it for any low power appliance, and a lot of them come with a usb port for charging gadgets. Though I would leave the inverter intact and buy a cigarette plug to clip adapter for 3 bucks. That and laptops are rather sensitive to the input voltage range, don't go frying your \$\$\$laptop by being to cheap to buy an \$\$inverter.

Like others said, just get a car adapter for your laptop. Then cut off the car plug and wire it straight to your battery.