[sharky]

i bought one of those rather-new, handheld, black and decker 'auto jumpstart' devices. in other words, those devices that jump start a car battery.

One can use these devices to plug in an appliance,such as a laptop. ANYONE know how long once can run a laptop plugged into one of these devices?? before the jumpstart device goes dead?

[JohnWill]

A typical laptop would consume about 3-4 amps from a 12V battery, you do the math.

[sharky]

As a matter of fact, it is now -20 windchill where i live(im inside),it is expected to go to -40 degrees tonight. Meanwhile there is a stray cat in the neighborhood i have been trying to catch for 3 days now. I leave food and water on the porch that he (or she) eats 4x a day but i can not get anywhere close to catching or persuding the cat to come inside.

i have setup a makeshift doghouse-like shelter on the porch. i bought an auto blanket that warms up like an electric blanket by using a 12volt plug. I plan on putting the blanket in the shelter, powering it by the auto jump start device's 12volt option overnight. (there is a safety shut off of the jump start claps). i like to know about how long the heated blanket will last running off the auto jumpstart device.

the blanket uses 5 volts,or 5 amps i cant remember what the packaging said.

(i used laptop to avoid writing a long post of what i was doing)

[Mavirick]

wait.. what happened to the laptop?

im assuming thats not for the cat as well?

[sharky]

i just checked with the blanket,it uses 5amps.

as i made the shelter outside, i was working in -20 windchill including winds of 25mph including coming back inside and posting with frozen fingers

[O111111O]

Please don't burn your house down trying to save the cat.

A typical car 30ish pound car battery is going to be roughly 75-125 amp-hours @ 12VDC.
In the cold, you can easily say 15-30% loss.

If the heater draws 5 amps and you want to run it say 8 hours, that would be 40 AmpHours @ 12VDC.

Chances are the AH rating of your jump starter (using sealed lead-acid batteries) is around 40-50. Considering loss, you'll probably get 5-6 hours off the jump starter @ 12VDC.

By the way, to offset heat loss for a 3x3x3 area (i.e. raise it 1 degree) you'll probably need around 110BTU per hour, or roughly 32.33 watts per hour of energy. That's 2.6Amps at 12VDC. Assuming your heat blanket is 100% effiecient. You'll raise the temperature of a 3x3x3 enclosure 2 degrees......



All of this is very rough math. [Close enough for goverment work]

[sharky]

my wife said the same thing, 'dont burn the house down saving the cat'. the autojumpstart device will be outside,the heated blanket will be outside plugged into the autojumpstart device. there is no chance of rain/snow, i will be up most of the night. this stray cat is skiddish, he(or she) will not come into the house

again, its -25 windchill out,25mph winds, i got to do something for the cat. its a stray, we get them all the time in this very rural area.

This is the device i am using: (the device has a shutoff feature so the claps have no power when the 12volt socket is being used)
http://www.blackanddecker.com/Produc...roductID=15581

[cwwozniak]

The B&D Tech Specs page shows the battery as "Battery - 12V, 9 Amp hr, sealed lead-acid" and the circuit breaker is rated at 5 amps.

At room temperatures, your blanket would get about an hour and 45 minutes of continuous operation. As O111111O mentioned, leaving the jumpstart device in the cold will cut the available capacity of the battery. You may get about an hour and 15 minutes or so of continuous operation.

[sharky]

Originally Posted by cwwozniak

The B&D Tech Specs page shows the battery as "Battery - 12V, 9 Amp hr, sealed lead-acid" and the circuit breaker is rated at 5 amps.

At room temperatures, your blanket would get about an hour and 45 minutes of continuous operation. As O111111O mentioned, leaving the jumpstart device in the cold will cut the available capacity of the battery. You may get about an hour and 15 minutes or so of continuous operation.

well its the morning,that is just about what happen, the blanket stayed warm for about 2 hours at most. today i should be able to capture the cat and have him cared for...at least stop his suffering.

thanks for the help