I asked them about this, citing that my products are designed for =20 automotive 12V battery use, and they checked and said yes this is =20 fine. I won't have access to it for the 4 days (enclosed in a glass =20 case), so this is why I will set it up to come on during show hours. Cheers, -Neil. Quoting Bob Blick : > Sounds like it should work, just don't tell anyone what you're doing, > it's probably not allowed :) > > Bob > > P.S. My rule of thumb for car batteries is that the advertised capacity > is actually double the real 20 hour rate. So your 50 AH rated battery is > good for 20 hours at 1.25 A when new. > > Second rule of thumb is that a car battery takes some damage if you take > more than 1/2 of its useful (25 AH) capacity. So you do some damage > taking over 12.5 AH. A little here, a little there. > > 16 AH seems a reasonable amount from a new battery. You should be able > to do it a few times and still have a battery good for use in a car for > several years. > > Make sure you turn it off every night, charge it soon after the show and > you'll be fine! > > > On Mon, Oct 14, 2013, at 05:33 PM, Neil wrote: >> Yes, 10.5V is what I've calculated too. But I'm wondering if the AH >> rating is to that voltage, or to a safer voltage. If I go to 11V, how >> much of the 50AH can I get? Is the drain relatively linear from 12.6 >> to 10.5V, so I can expect about half of the 50AH? >> >> Either way, some of these shows provide electricity, but at this show >> I want to power some electronics in a different section of the show, >> where they can get me an extra electrical outlet costs for ~$135. I >> can buy a new car battery instead for $70 and dump it (yes turn it in >> for the core charge) when I'm done. >> >> At this point, I have another bonus: instead of powering the devices >> with 12V and letting the linear regulators in each drop that to 5V, I >> can easily run a 12V-5V buck switcher after the battery and drop by >> power requirements by about half. My calcs with this method is now >> 16AH required. > > > -- > http://www.fastmail.fm - Or how I learned to stop worrying and > love email again > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .