| Electronics > Projects, Designs, and Technical Stuff |
| Switch from flat to charged battery while under load |
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| gnif:
Hi All, I am looking at building a solar charge solution to try to save a bit on my power bill for my soho server. I obtained a 1KW solar array for extremely cheap but due to austalian law with regards to PV and grid tie in, as well as the abysmal byback rates, I have decided to try and go another route. I already have a enterprise grade UPS I use to protect my equipment with which works great, I also know that I consume more then this solar array can generate, so my goal here is to make usage of this system without exceeding ELV (110V DC IIRC) at which point I would require an PV license. My idea is to switch the UPS between two battery banks, one is maintained full for redundency reasons, the other is charged and discharged by the solar array. When the solar batteries are full I intend to switch the UPS over to them and disconnect the mains feed to the UPS, this should be simple, however the switch back is what I am worried about. Switching back would require connecting the still charged UPS battery back to the UPS, however doing so will mean that the now flat solar battery bank will try to charge the UPS battery bank at an insane rate. I am looking for a way to avoid this. The reason to use this method is simple, the cost of a large battery bank is at this time out of the question, and since I only intend to power one device, it doesn't need to be huge. Just large enough to cycle on and off solar power as the cells discharge and recharge. I hope this makes sense. If anyone has any ideas it would be greatly appreciated. |
| NiHaoMike:
Just add additional battery capacity and a charge controller will take care of maintaining the charge level. |
| gnif:
--- Quote from: NiHaoMike on August 10, 2019, 02:57:56 pm ---Just add additional battery capacity and a charge controller will take care of maintaining the charge level. --- End quote --- --- Quote from: gnif on August 10, 2019, 02:23:53 pm ---the cost of a large battery bank is at this time out of the question --- End quote --- |
| NiHaoMike:
Then use what you have for now. The charge controller will take care of it. |
| gnif:
I think you don't understand what I have tried to explain, or I didn't explain it very well.. I have a UPS feeding a server already with a battery bank, I do not want to use this battery bank for solar, i'd like it to continue to remain charged incase of a power outage while a secondary (solar chaged) bank is also flat. This way I wont loose redundency which is the entire purpose of a UPS. I would like to hot swap between battery banks that are connected to the UPS, the change over will be from the flat solar batteries to the fully charged still unused UPS batteries. The UPS will not be using these batteries at this point as it's AC service will have been restored. I believe the UPS will complain and likely shutdown if I just cold disconnect the battery pack from it, as such I need a way to transition over that wont cause a massive charging current to flow from the still charged UPS batteries back into the now flat solar chaged batteries. Edit: it might be possible to just switch them fast enough using some relays, I am yet to test any of this as I am waiting on parts, etc. |
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