On Mon, Jun 22, 2009 at 06:28:27AM -0500, Rick Morel wrote: > > From extensive experience with DC motors... The motor will run > hotter at 12V, so that's probably why the tech said it won't last. DC > motors really don't have a set voltage rating, but the lower the > voltage the higher the losses and the higher the current for the same > power output. At 12V the volume output of the pump should be less, > but the current should be higher because it's the same load to get > that 800 PSI.
I agree with most of the things that have been said here, with one note of caution: running a motor on a lower-than-nominal voltage is very, very dangerous. As I unuderstand it, EU recently passed a law requiring bus manufacturers to add in a low voltage detection circuit - it seems that the chief cause of buses catching on fire was low voltage to the cooling fans. As best as I can reconstruct the scenario, the voltage drops, the current goes up, eventually the fan motor stalls (i.e., draws maximum current) and catches fire, which jumps to the engine. I'd strongly recommend "in-lining" another battery, as Rick recommended. Depending on how your PUR unit is powered, you might even be able to trip a DPDT relay from its power switch; that would automatically put the batteries in series while the unit was running, and in parallel for charging when it was off. -- * Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET * _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
