Dana I have always wired the PV negative all the way to the charge controller. That way, the battery negative of the charge controller that happens to go to a shunt has a proper representation of the current flow. I guess you could put that PV negative at the same side of the shunt as the battery negative since internally the negatives are tied together on the charge controller.
Did the charge controller come AFCI? If so, you likely have to bring both PV cables through the current sense of the AFCI. Also check to see if you have global charge control coordination turned on, if so, turn it off and also check restart mode to set to two which means restart after 90 minutes no matter what. Thank you, Maverick Maverick Brown Off-Grid Solar Commander since 2006 Maverick Solar Enterprises, Inc. • Solar Commander Remote Power • SunFlow Systems Cathodic Protection maver...@mavericksolar.com 512-460-9825 > On Sep 7, 2024, at 5:50 PM, Dana Orzel via RE-wrenches > <re-wrenches@lists.re-wrenches.org> wrote: > > OK, you wise guys. > I am upgrading my home off grid system from two FM 80s to two FM 100s. > The FM 80s were able to share the negative wire so you didn’t have to pull a > second negative wire. > I wired the FM 100 typical of how my FM 80s were wired with a number four > battery negative assuming and yes, I know what happens when I assume, that > the PV negative on the battery negative are common and I could just pull one > number four since going through those double 1” - 90° is a bitch. Currently I > have two # fours for output to battery, the number eight ground and 1 # six > PV input. > I got this all together and it’s charging just fine but once the battery got > full charge controllers continued to produce full output. The battery dropped > to a float and I had 2800W on each charge controller continuing to be > produced at which was turning into heat so the FM 100s were getting very > warm. The fans had not turned on, but the heat sinks were definitely very > very warm to the touch. The battery voltage is fine. > I Read the manual it doesn’t talk about being able to use one negative so I > am assuming that my problem is that the PV needs a negative and they do not > share the negative. > Has anybody else seen this or done the same wiring maneuver. > thanks in advance > > Dana Orzel - d...@solarwork.com - 208.721.7003 > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
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