Lee Haefele wrote: > I don't think there is anything to be gained using 2 controllers, > especially considering that each needs a minimum amount to get efficient. > My controller at 50A is too big, (and not as efficient as it might be) but > the 25A size was too small. > It is best for battery life to leave the 2 banks connected together, > forever. A battery monitor, like a Xantrex XBM that counts amp hours down > and up is an essential item on a cruising boat. Use that to monitor charge > state of the entire battery set. I see solar companies selling an amp and > voltmeter as a battery monitor, but that is NOT the same. > Next best tool for a tinkerer is a hand held clamp on DC ammeter. > Lee > Here's my thinking and I don't know how the controllers work so I may be off base. If you have two voltage sources in parallel and one of them is generating a higher voltage, current will flow from the higher voltage source to the lower voltage source and the load. Kirchoff's law holds for a pure resistive circuit. Now in the case where there is effectively a diode preventing current from flowing into the lower voltage source, it seems to me that the current from the higher voltage source flows into the load and the lower voltage source doesn't contribute at all. This is for an ideal system.
So I'm guessing that the input impedance (resistance) of a controller is very low such that the panels are almost short circuited and there is almost no measurable voltage at the input of the controller. Then current from both sources would be available. That analysis didn't come to the conclusion I was aiming for, but that's OK. It supports Lee's suggestion. If there is a marginal advantage to two controllers, it's probably not worth it. Jim. _______________________________________________ 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
