No Load Inverter Current Draw, how long till it kills my battery

**clean customs** · 01-12-2005, 11:06 PM

I have a pretty good size inverter, and I am trying to figure out if I can leave this regulator running with the PC hibernating for a period of time without killing the battery. It says its no load current draw is <0.3ADC. I don't know what that means, or if that is enough to worry about. It is a XPower 1000 inverter.

**fishy** · 01-13-2005, 12:47 AM

it will mainly depend on what size battery you have in your vehicle.

this means it will use "less than" 0.3Amps per hour.

If you have a 600 amp battery (if it was charged to peak, and in A1 condition) it would theoretically last 2000 hours until it drains the battery flat.

How long you can leave it on before the battery wont start your car is another thing. How much amperage is required to start your car? and bare in mind normal Lead-Acid batteries (like in most cars) arent designed to be ran flat, recharged, ran flat, etc etc. They are there too handle quick heavy loads (like starting a car) and then being recharged by the alternator thru trickle charge. I have 2 x 600 CCA batteries in my 4wd, with an invertor that has a <0.5A rating in idle mode and its been fine for a week with the PC in hibernate, but leave the laptop on full time, with the screen, my car wont start a day or so later, due to my 4wd's huge starting requirements.

most small cars require about 250amps to start them, and if you have a 400 amp battery, expect it too output about 300-350 after some use, so, really, its hard too say how long will it last...

**kiltjim** · 01-13-2005, 12:49 AM

You need to give us a little more information. Specifically, the information on the battery. What you really need is the standby current available. And you also need to find out what the total drain on the battery is. This includes things like the ECU (the actual car computer), radio standby draw, security system, stuff like that.

You could measure the current being drawn by the car when the engine is not running by measuring the current with a multimeter.

**clean customs** · 01-13-2005, 12:52 AM

Thanks man, glad to know .3 wasn't higher then normal. I drive an Acura RL, I think it might be a V6, but nothing serious, although it is a big car. I am thinking about adding a second battery just for the hell of it. The cost of one battery with a little cable versus all the other money I have spent doesn't seem like much. Are there any accessories still being powered while your computer is hibernating? I assume when the computer hibernates, it cuts the power it supplies to USB ports, but I dont' know that for sure.
K

**clean customs** · 01-13-2005, 12:59 AM

Originally Posted by kiltjim

You need to give us a little more information. Specifically, the information on the battery. What you really need is the standby current available. And you also need to find out what the total drain on the battery is. This includes things like the ECU (the actual car computer), radio standby draw, security system, stuff like that.

You could measure the current being drawn by the car when the engine is not running by measuring the current with a multimeter.

Really I was more concerned about just the inverter itself right now. I didn't even think about the fact that the inverter has a draw when nothing was being run off of it. It just didn't cross my mind when I decided to go this route for power. I had read alot about people leaving it hibernating with DC-DC PS, but couldn't find anything about inverters, and didn't know if it was like parking lights on. When I get it all installed, I will check out my current draw, and will most likely change my power setup.
thanks for the help

**KyferEz** · 01-13-2005, 12:59 AM

use this calculator: http://www.thecarpcstore.com/link.ht...alculator.html
Click the "Battery Discharge Time" link towards the bottom on the left menu.

Then you can figure it out yourself.

KyferEz

**rando** · 01-13-2005, 01:03 AM

Blah, I'll make it simple for you. 300mA is probably going to drain your battery in a matter of days and will certainly lead to premature battery failure also.

**clean customs** · 01-13-2005, 01:06 AM

Originally Posted by rando

Blah, I'll make it simple for you. 300mA is probably going to drain your battery in a matter of days and will certainly lead to premature battery failure also.

Thats what I didn't want to hear, but I needed to know. You have any recommendations for max amount of time leaving your computer hibernating with no power to any other accessories? Would a second battery be a definite, or would a DC-DC give me the lowest amount of draw.

**KyferEz** · 01-13-2005, 01:17 AM

Well, something needs to be cleared up here:
Did you mean shutdown to hibernate OR shutdown to standby? Shutdown to hibernate does not require any power at all. Shutdown to standby is when the inverter must remain on to power the PC's standby voltage line.

So the inverter can be off when you shutdown to hibernate.

KyferEz

**kiltjim** · 01-13-2005, 10:09 AM

Here I am worried that the overall draw will exceed his battery, and that the battery isn't going to live for very long with such a draw, and rando just rains on all our parades. rando has is right.

A second battery, specifically a battery designed for deep draw (like an optima or the like) would be the best bet. But then you have to worry about isolating it from the other battery and all that stuff. This is one of the things I'm working on now. It's not that its difficult, but its expensive. And I'm afraid of ruining things doing it on my own.