Greg: Let me say I think the idea is generally bad. Your client would need to be actively involved managing this system on an hour by hour basis or both battery banks are likely to be ruined. If you want to switch between batteries, unless both battery arrays are at a very similar voltage (+/- 0.5 volts) you should not parallel them. In that scenario you would need to shut down the inverter(s), switch battery banks, then restart the inverter. A breaker interlock may be in order to prevent bad things from happening. Like I said, a bad idea. If you have too much battery to match the PV capabilities you need to reduce the battery bank capacity.
If this system includes valid BOS components, and you still want to experiment, integrate within that system by adding a battery breaker. If it does not have a decent BOS (Outback Flexware, Midnite DC breaker panel, for example) that is a problem in itself. Add the BOS. The PV charge needs to have either two battery breakers or be wired on the inverter side of the battery breaker, an arrangement that I do not recommend. Did I mention I think this is a bad idea? William Miller Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985 -----Original Message----- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of greg egan via RE-wrenches Sent: Saturday, June 15, 2024 10:18 AM To: re-wrenches@lists.re-wrenches.org Cc: greg egan Subject: [RE-wrenches] Dual battery bank switch for 48 VDC system Wrenches, I have a customer who has a 2 strings of AGM's @ 48 VDC that we want to split so we can charge them at decent charge rate. Adding more PV and/or larger generator and inverter is cost prohibitive. I've seen Blue Seas (#3002) 4 position 500 amp switches that are rated for 32VDC. Max he could possibly pull at once with his system is less than 100 amps. I would assume the Blue Seas 3002 would work and I'd probably use it in my garage, but I'm not comfortable recommending it to a customer. Any suggestions on a 60 VDC rated unit that could handle say 150 amps and 4/0 cables? Maybe I'm being too cautious since the max load would be < 6KW and the 3002 is rated for 16kW load (32 VDC /500A)? Thoughts? Thank you, Greg Egan Remote Power Inc. Fairbanks, AK _______________________________________________ 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 _______________________________________________ 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
