how to survive a crank with a inverter - Electronic Circuits Projects Diagrams Free

coma · 27th January 2004, 11:45 PM

i want to buy an inverter that will let me run a Pc from inside a car... my only problem is that when i crank the engine the inverter is sure to drop out since the starter motor draw about 300amps, i need to build a circuit that will let me survive a crank so that the PC im runing will not turn off then on....

panic mode · 28th January 2004, 12:35 AM

Well, if you can fit tower case, CRT monitor, keyboard and mouse,
you should be able to find some room for UPS too or switch to laptop.

Klaus · 28th January 2004, 01:11 AM

You have a PC in a car with a 300 Amp starter motor? That must be a big car with a mighty big engine

.
Perhaps the best solution would be a seperate battery for the inverter, charged from the car engine while its running and disconnected from the starter battery when the engine is stopped.
This way you could not flatten your car battery by running the inverter for too long with the engine off.

Or, do as was already suggested, and as most computing in cars is done, use a laptop powered from the inverter. Since the laptop has an internal battery, momentary power glitches from the inverter have no effect.
You still can flatten the car battery to the point when it no longer will crank the 300Amp starter motor if you use your computer for too long :wink: .
Good luck

pike · 28th January 2004, 01:36 AM

you could just run the computer directly off the battery. From there you can you use voltage regulators to power your equipment. The problem is that once you drain the battery to less than 12v the computer dies.

Then you have to find 240v for the monitor...

coma · 28th January 2004, 01:45 AM

there are small 12v LCD screens with VGA input, they are mainly used for GPS systems so a monitor is not a problem nor is mouse since the screens are touch screens, a keyboard is easy to take care of. since you can get some that are flat and made from rubber, beside the aplications im going to use wont realy need a keyboard.
i also found this www.opussolutions.com

what are your comments?

panic mode · 28th January 2004, 01:38 PM

Did you read the datasheet for this unit?

In my experience, battery voltage does drop while cranking
but it is usually in 9-10V range worst case (ok, that's on my car).
The power supply from the website you posted link has wide
input range 7-18V for 12V operation.

And yes, it does have low voltage detection and it is set at 11V but
this initiates shutdown if the low voltage condition lasted 10sec.
I don't know about your car, but my starts in 1-2 seconds.

I other words, this PSU should be able to bridge cranking periods
and if not, maybe you should have your car's electrical system
checked out.

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27th January 2004, 11:45 PM	(permalink)
coma	how to survive a crank with a inverter i want to buy an inverter that will let me run a Pc from inside a car... my only problem is that when i crank the engine the inverter is sure to drop out since the starter motor draw about 300amps, i need to build a circuit that will let me survive a crank so that the PC im runing will not turn off then on....

28th January 2004, 12:35 AM	(permalink)
panic mode	Well, if you can fit tower case, CRT monitor, keyboard and mouse, you should be able to find some room for UPS too or switch to laptop.

28th January 2004, 01:11 AM	(permalink)
Klaus	You have a PC in a car with a 300 Amp starter motor? That must be a big car with a mighty big engine . Perhaps the best solution would be a seperate battery for the inverter, charged from the car engine while its running and disconnected from the starter battery when the engine is stopped. This way you could not flatten your car battery by running the inverter for too long with the engine off. Or, do as was already suggested, and as most computing in cars is done, use a laptop powered from the inverter. Since the laptop has an internal battery, momentary power glitches from the inverter have no effect. You still can flatten the car battery to the point when it no longer will crank the 300Amp starter motor if you use your computer for too long :wink: . Good luck

28th January 2004, 01:36 AM	(permalink)
pike	you could just run the computer directly off the battery. From there you can you use voltage regulators to power your equipment. The problem is that once you drain the battery to less than 12v the computer dies. Then you have to find 240v for the monitor... __________________ www.winpicprog.co.uk - Great PIC language tutorials.

28th January 2004, 01:45 AM	(permalink)
coma	there are small 12v LCD screens with VGA input, they are mainly used for GPS systems so a monitor is not a problem nor is mouse since the screens are touch screens, a keyboard is easy to take care of. since you can get some that are flat and made from rubber, beside the aplications im going to use wont realy need a keyboard. i also found this www.opussolutions.com what are your comments?

28th January 2004, 01:38 PM	(permalink)
panic mode	Did you read the datasheet for this unit? In my experience, battery voltage does drop while cranking but it is usually in 9-10V range worst case (ok, that's on my car). The power supply from the website you posted link has wide input range 7-18V for 12V operation. And yes, it does have low voltage detection and it is set at 11V but this initiates shutdown if the low voltage condition lasted 10sec. I don't know about your car, but my starts in 1-2 seconds. I other words, this PSU should be able to bridge cranking periods and if not, maybe you should have your car's electrical system checked out.