Hello wrenches, I'm working on 3 off-grid telecom sites. They are designed to operate solar only under most conditions but the project manager ordered a custom-built 48 VDC generators, intended to be used as the battery charger/backup power for the site. These are ~20 kW generators, and can probably do about ~350Adc at 48 Vdc at the elevation that these are sited. The battery banks are 4 x 1000 Ahr GS Nanocarbon 48 battery strings and can gobble up the 350Adc easily when they are discharged.
While discussing the generator operation with the generator supplier, we have found this generator isn't capable of charge control, or limiting its own output. The charge control functionality isn't necessary at this site because we really just need it to keep things online until the sun returns, a simple 54 VDC float voltage would work. However, without the generator being able to self-limit its output, we expect this generator to stall when started because it can't regulate its output current and will immediately become overloaded by the discharged batteries. I am trying to come up with some options to rectify this serious design issue. One idea that immediately came to mind was putting in some parallel solar charge controllers between the DC generator output and the battery bank. If the generator output could be dialed up to around 60-70 VDC, could parallel solar charge controllers be used for charge regulation? It would be kind of like charging a 48 V battery bank from a 70 V battery bank. MPPT isn't applicable, could the max current limit in the charge controller(s) be used to regulate charge rate? Will the charge controllers blow up? If not, what brand might work. Each site has 8 x Midnite Classic 150s but I'm open to other manufacturers if it would work. I am open to blowing up a charge controller in the shop but I thought it best to ask first. What are other ways to put this generator to use, and limit its load? Thanks for your input/comments -- Mac Lewis *"Yo solo sé que no sé nada." -Sócrates*
_______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
