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Depends - what do you want to do with it? Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 19 Sep 2003 07:25:29
In Reply to: OT - Portable battery packs ?, ChrisB, Fri, 19 Sep 2003 06:46:29 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I couldn't find a listing for a 801-1900, but there is a -1750 and a -3000. The dash number is the continuous output wattage.
1900 watts will run a refrigerator and a couple of lights. It won't run much more. Of course, you need to be able to isolate the circuit you want to drive from the rest of the house. Otherwise, not only will you be trying to run everything in the house, you'll be trying to power the neighborhood. It's also dangerous for utility workers trying to fix things. So make sure you've got a good isolation switch.
Of course, that inverter will do you no good without a power source - you still need batteries. I use deep-cycle marine batteries. Automotive batteries are not good, because they're not designed to cycle.
As an example, I picked up a 115 Amp-hour deep-cycle battery at Wal-Mart for about $55. 115 Amp-hours sounds great, but I've seen some experiments where in reality, only about 33%- 50% of that power is available; the voltage drops too much beyond that. So assume 50 amp-hours available. At a nominal 12 volts, that's 600 watt-hours.
I've seen no figures on the efficiency of the inverter, but let's assume 80% - that's pretty good. The remainder is heat. So of that 600 watt-hours, 480 is available.
So if you have one battery, and are using the full 1900 watts, you're good for a whopping 15 minutes of operation. OK - that's not going to do you much good. The discharge rate of batteries comes in here too - you'll get more of the power out of the battery if you discharge it slowly - this is pretty fast.
So the solution is to get more batteries, or to pull less current. If you greatly limit your power consumption, your battery (or batteries) will last longer. You can also buy a smaller inverter.
It all depends on what you need to power. For me, I use battery power for my back-up sump pump - I figure that if I lose power in a rainstorm, having a sump pump is best. To avoid the power loss in the inverter, I use a 12 volt boat sump pump as a back-up to my primary, house-current pump.
In winter, I use the inverter to drive the furnace. I have a hot-water gas-fired furnance. This is pretty good for power consumption. Hot air systems have big blower that pull lots of current - a typical hot water circulator pump is only 1/6 hp. And the only remaining power is for the control circuitry, only a few watts. An oil-fired system needs to drive an oil pump, and that takes a lot of power. I can drive my furnance through a small (400 watt), cheap ($50 on sale at Target) inverter. Of course, I can isolate the furnace circuit from the rest of the house very easily.
So, what do you want to do with the power?
posted by 192.249....
, Fri, 19 Sep 2003 07:25:29 <-- Viewing This Message
, Sun, 21 Sep 2003 13:52:39
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