At 02:40 PM 8/14/2009, you wrote: >I know I need an inverter/charger and a rectifier. What I haven't >found out is how many batteries and what kind to use.
12 batteries come in deep cycle and auto starting. Get the deep cycle. You will find an amp-hour rating (at the 20 hr rate). This is what a new battery will put out before it is discharged. Multiply by , say 11v, to get watt-hours. Find the watts of what you want to drive and divide into the above watt-hours, then toss out 20-30% to get APPROX. hours the battery will power your stuff. A 60 a-hr batt will run 500 watt for around an hour. Measure your computer - you'll probably find it draws far less than you would expect form the power supply rating. > I see a Coleman >1000 watt inverter on ebay and it supposedly shuts down automatically >when it's about to deplete the battery... Size the inverter for the expected load - computer + monitor +?? All modern inverters automatically shut down on low battery (as well as over voltage.) Be sure to check both Harbor Freight & Fry's - for inverters. Will probably be cheaper than Ebay + shipping. and easy to return. >but how do I signal the >computer that the batteries are about to be drained completely? >I don't know if the Coleman unit is a charger as well or just an >inverter. I have only seen one unit at Fry's/Harbor Freight with a charger and it was not automatic. (There are units with charger & auto switch available from Trace and their competitors.) >A UPS needs surge suppression capability and undercurrent >protection and most of the time power should be applied w/o using >the batteries. > >The nicest way to do signaling would be to use say a PIC micro >controller and put a signal out over the local ethernet line. I am using a setup with a simple 3PDT relay: Use two poles to switch the power out between the wall socket and the inverter out. Use one pole to switch the inverter on (wire across its on-off switch) Remaining item is charger. Ideally it will sense a low battery and take the battery up to 14-14.5v them revert to 13.6 for float. I got one of these form harbor freight a few years back, but they don't seem to have these anymore. >So, what kind of batteries should I use? > > I don't like the typical sealed lead acid because where do you > get them A and how do you revive them without special equipment B? Fry's has sealed lead acid. > Nickel metal hydride batteries are a possibility where the AA > variety are available at most electronic stores. Nickel metal > hydride RC car packs might be ideal. Another possibility is > to see about getting say D cells. NMH = expensive. > There are some AA Lithium ION batteries, but I don't think these > are typically rechargeable batteries. More expensive > There are laptop battery packs, but using these might be a bit of a > challenge and expensive. > >So I am thinking car batteries as they pack a lot of punch, are >available practically everywhere, and they are recoverable without >special equipment. However, open lead acid batteries are not >appropriate for use on a desktop. I've also heard if these >batteries don't vibrate that they will sulfate up much faster. Phone company used to (and may still) use stationary liquid lead acid. Get deep cycle. >So say I start with 2 12V car batteries. One may do - look at the run time required. 200 watts for 2 hrs should be easy for one battery. Thanks JK >A do it yourself UPS doesn't make much sense unless the >UPS you are replacing is say an APC Matrix UPS, so let's >pretend that we are doing just that. > >For the inverter, do I need a 1000 watt capacity? Do I need >more than that? How do I figure out how many batteries to >hook to it? > >For the rectifier/charger, do a typical say car battery >charger if I'm using lead acid auto/marine batteries? >Will the typical marine/auto battery battery charger >stop charging when the battery is fully charged? How >do I monitor the state of charge and report that on the >network? > >Perhaps for the rectifier/charger and inverter I should >build my own, but how do I do that? > >Well, here are the results of a quick google search: > >http://www.dansdata.com/diyups.htm > >http://www.wikihow.com/Build-Your-Own-Uninterruptible-Power-Supply > >http://www.diy-computer-repair.com/UPS-Uninterruptible-Powe-Supply.html > >http://dev.emcelettronica.com/ups-uninterruptible-power-supply-reference-design > > > >_______________________________________________ >PLUG mailing list >[email protected] >http://lists.pdxlinux.org/mailman/listinfo/plug _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
