Hi, Wrenchies~ Darrel wrote about his wish to dump excess battery energy via AC diversion loads. Part of his "wish list" is to maintain smooth control instead of a coarse on/off.
Mick says: Morningstar's Relay Driver can sequence relays based on the PWM duty cycle of a networked Tri-Star PV control. Some DC diversion load is still required in my suggestion below, so that's why I say "mostly" in my subject line. If only one RD is used, 80% of the energy could be diverted in four stages into four AC loads. The TriStar would keep things fairly smooth via pulse width modulated diversion into a relatively small DC load. Temperature compensation and three stage battery charge regulation (complete with float) would all happen automatically courtesy of the Tri-Star logic. The AC diversion loads would act as slaves which come on line (and off line) in proportion to the DC diversion behavior of the Tri-Star. If a second Relay Driver were networked in (with four more AC resistors), the AC diversion could happen in eight finer stages instead of four, and the amount of AC diversion wattage would increase to 89% of the total. Diminishing returns come into play, however, so I suggest using just one of the RD's, because remember that the Tri-Star is also doing a fine PWM diversion into the DC load. I have never actually built a setup like this. I don't happen to have a matching customer, but I think this arrangement would work well. Darrel: if you're willing to try this, I would be pleased to discuss the control wiring and other details with you, because this needs to be figured out and I'd like to get feedback on how it works. Contact me off list if you want. The Windows software to control the Relay Driver is available as a free download from the morningstarcorp.com website, and one can toy with the software without actually owning the Morningstar hardware. The RD instruction book is also available as a free download. Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675 _______________________________________________ List sponsored by Home Power magazine [email protected] http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org List rules & etiquette: www.mrsharkey.com/wrenches/etiquette.php Check out participant bios: www.mrsharkey.com/wrenches/
