Both. Outages when the PW is charging have caused disturbances. We didn't notice a two hour outage when the sun was down, and tests with load > PV opening the breaker have also been seamless.
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20 second UPS?
- Thread starter Cosmacelf
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- Tesla Energy
Ulmo
Active Member
I'm collecting prices on some good UPS's. Since I am tailoring this for momentary outages, I was hoping SuperCapactitor UPS's would work well, but it seems their price points are still quite high. I found one that is tailored to run for 15 seconds or less, I hope perfect for dealing with a PowerWall cutover for my computer server that has a large power supply:
I might be looking at the above solutoin with capacitors, or try going with an exsting battery brand UPS from somewhere. I would want high quality, a fairly healthy KVA rating, and handling only very short outages of seconds in length (as opposed to the old UPS battery regimine of "enough time to do a proper shutdown and transfer all clients to another cloud provider off-site"). I think requirement begs more for capacitors than batteries.
Marathon Power, SuperCap UPS System, made up of two parts: part# ARTE-3000-01, SuperCap 3kVA (2100W) NEMA IN/OUT Electronics Module (the inverter) (they also have a 1kVA (700W) model), and part# ACPR-1058-96-120, 3kVA SuperCap Energy Storage Module (the capacitors). (They also sell hardwired (no plug) or plug (NEMA), 120VAC or 240VAC (single phase), 700W or 2100W.) I got a quote from Arrow.Com for those for $1,350.38 for the ARTE-3000-01 plus $2,575.29 for the ACPR-1058-96-120 for a total of $3,925.67 (not including sales tax and shipping). I'm waiting for a quote back from my official distributor which may or may not be much different. Literature at Marathon Power - Supercapacitor UPS - Battery-less True On-Line UPS
Marathon Power told me "The initial cost (for the SuperCap UPS System) is higher than a comparable (battery UPS) of the same VA rating, but there is no battery replacement, major system maintenance or hazard waste disposal." Also, I think the supercacitors are supposed to last longer than the batteries, but we don't have a lot of data on that yet.
I might be looking at the above solutoin with capacitors, or try going with an exsting battery brand UPS from somewhere. I would want high quality, a fairly healthy KVA rating, and handling only very short outages of seconds in length (as opposed to the old UPS battery regimine of "enough time to do a proper shutdown and transfer all clients to another cloud provider off-site"). I think requirement begs more for capacitors than batteries.
Ulmo
Active Member
Following up on my post:
Buckles-Smith (my local distributor for Marathon Power) has them for about half the price of Arrow.Com. For $2,295.55 including all tax (the Arrow quote didn't include tax), I could go pick them up in town. I'll have to seriously consider it! I'll probably get them in a few months, and then I'll let you know how it works out. Lead time is 10-12 weeks, so it may be 2019 when I get it.
Ulmo
Active Member
I also received a quote direct from the manufacturer:
Model
Part #
Description
Price Each
3000RT UPS
ARTE-3000-01
Rack Tower UPS Electronics, 3000VA, 120V, LCD, 2U, 120V
$1,320.00
Capacitor Pack
ACPR-1058-96-120
Capacitor Pack, Rack Tower, 10 x 58F, 96VDC, 4U, 120V
$2,652.00
Subtotal $3,972. There’s no stock; they probably have to make them. If they were less expensive, I’d ask if we want to do a group buy.
Personally, I would buy a used UPS off eBay without batteries and put in some high C-rate LiFePO4 batteries rather than the expensive SuperCap system listed above. I will do the LiFePO4 conversion when the AGM batteries in my UPSes need replacement.
I have a number of 1500VA APC UPSs around the house on all the electronics. We have a lot of computers (both of us work from home and I'm a programmer), so I have 8 UPSs. Each one costs less than $200 and last for many years. I think the oldest one in use is about 10 years old now.
The 1500 VA is overkill for most of the computers, but it gives a long run time if necessary. They also work as a good surge protector, better than the power strips which are only good for one power surge.
The 1500 VA is overkill for most of the computers, but it gives a long run time if necessary. They also work as a good surge protector, better than the power strips which are only good for one power surge.
Frankman60
Member
What is the advantage of “high C-rate LiFePO4 batteries” compared to lead AGM batteries in a UPS in a home with Powerwalls?
Jigglypuff
Member
If your server has a good power supply, which it should, or two power supplies, which it should, then a typical server-grade UPS should do the job. The capacitors on the power supplies will bridge the momentary gap until the UPS kicks in, and a typical UPS will last long enough for the PowerWalls to kick in. When I last flipped the main, just to experiment, the only thing that turned off was our TV. My Supermicro server with only one power supply plugged in hummed along happily, hard drives a spinning without a hitch. None of the clocks reset, either.
NinjaVece
Member
This mirrors my set-up. We run a business out of the house that uses 12 computer systems with their 4k monitors - along with two internet provider modems, two routers and a QNAP NAS as well as sundry internet devices like switches, Kevo controllers, etc. I have all of this nestled behind seven APC UPSs throughout the house where the various components are. Its meant as a fully redundant system for continuous internet usage fail-over. The UPSs are there (they are over-kill from a time prior to the Powerwall 2) to provide for the momentarily loss of power that can occur when the PW2 Gateway relay switches over from grid loss to the self-contained house circuit.
This has worked well for me through a couple of power outages in my area - even as the APC UPSs are so over-powered for the function they are now used for. However, if anyone should find a good surge-suppressor unit that provides 5-10 second power conditioning that would get through any relay switch-over for a good price, I'm always listening.
AGM UPS batteries have to be replaced every 3-5 years. If you are not concerned with runtime, like with a Powerwall, then you can use a small number of high current and low energy LiFePO4 batteries in place of the AGM. Those lithium batteries should last indefinitely because they're not being cycled.
That's a good idea. You'd want to design the electronics a bit differently though. You can't let a l-ion battery discharge too far like an AGM battery can, or else the lithium battery will be permanently dead.
Right. You need to add a cheap BMS board between the cells and the UPS so that it will do the low voltage cutoff for you.
And I presume the BMS takes care of the high voltage cutoff as well because trickle charging isn't good for lithium batteries.
Frankman60
Member
This sounds great to me because I have a half dozen UPS devices in my house and was thinking that I would no longer need them when my PWs are installed. But it seems that I will still need to have the UPS devices on PCs, and AV equipment. I’m going to assume that the BMS board and the LiFePO4 battery can fit inside the UPS where the AGM batteries would normally be? I would like to try this on a UPS that currently needs the AGM batteries to be replaced. Do you have a source for the BMS board and LiFePO4 battery and a schematic as to where to place the new components?
mspohr
Well-Known Member
Here's a couple of boards which could be useful.
https://smile.amazon.com/gp/product/B07DC3LH9C/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
This can monitor up to 8 Li cells in series and alert when voltage is too low.
https://www.amazon.com/Micro-USB-5V-Battery-Charger/dp/B01LHD9D7E
It's best to charge each Li cell individually even when they are connected in series.
https://smile.amazon.com/gp/product/B07DC3LH9C/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
This can monitor up to 8 Li cells in series and alert when voltage is too low.
https://www.amazon.com/Micro-USB-5V-Battery-Charger/dp/B01LHD9D7E
It's best to charge each Li cell individually even when they are connected in series.
bkp_duke
Well-Known Member
I run multiple servers running off a 1Gbs fiber line to my home. No UPS installed on any of them.
I have 3 Powerwalls, and we have experienced 2 prolonged outages since I have had them installed. I have never had a computer reboot or any other problem during those outages and transitions from grid-backed power to all-PW power, and vice versa. The transitions were instantaneous.
This sounds to me like a solution in search of a problem.
I have 3 Powerwalls, and we have experienced 2 prolonged outages since I have had them installed. I have never had a computer reboot or any other problem during those outages and transitions from grid-backed power to all-PW power, and vice versa. The transitions were instantaneous.
This sounds to me like a solution in search of a problem.
Yeah, when you get into lithium ion batteries, it gets complicated quickly. Those chargers, for instance, while cool, are meant for 18650 cells, not big LiFePO4 cells. And individual cell chargers work great until one of the many chargers you now have fail (power electronics, like power supplies, are a frequent failure point). If your BMS works correctly, it'll shut off the whole pack before the affected cell gets discharged. If the BMS doesn't do its job (it can fail too), you'll soon have a dead cell. Speaking from experience...
I do like the individual cell charging idea because it eliminates the cell balancing problem. But it introduces other problems...
mspohr
Well-Known Member
Here's another charger which can handle all different types of Li batteries.
https://smile.amazon.com/dp/B075GHLF8X/ref=pd_luc_rh_crh_rh_sim_04_03_t_img_lh?_encoding=UTF8&psc=1
You would have to verify how the UPS charging circuit interacts with the LiFePO4 batteries and the BMS. If it does a simple Constant Voltage regulation (float charge), it will probably be fine. However, if it wants to push a small current regardless and counts on the battery to absorb it, then it would destroy the LiFe batteries. If the charger in the UPS is problematic, you could use a BMS with separate charger input and find a way to separate the UPS's charging circuit from the direct battery connection. The BMS will cut off the charger when the batteries are full. Worst case, you disconnect the charging portion of the UPS and use an external CC/CV charger. These thoughts are all related to standby type UPS. With a double conversion UPS, if the internal charger is not suitable, then you just run a separate charger full time and leave the original UPS plug disconnected.
I have two 24V APC units that I've been intending to do this mod with. One is a very old SmartUPS 700 (SU700NET) and another is a larger SmartUPS 1000XL. The latter could use any size battery because it has an external Andersen connector. Either one could use a 8S1P string of A123 26650 LiFePO4 cells for a short runtime. To reduce the amp draw per cell on the 1000VA unit, you could make a 8S2P pack. That would still fit in the 1000XL battery compartment.
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