I want to build my own UPS for my computer and appliances. Something that works just like the APC UPS that you can buy but I want to built the pack with LiFeP0 batteries. I want to be able to feed primary with my 110V power company feed and switch automatically to my pack in case the power fail just like an APC works. Can somebody guide me on this process?? I would greatly appreciate any help. Thanks!
Seeking Guidance on Building a Custom UPS with LiFePO4 Batteries
- Thread starter ZEUS-FL
- Start date
BentleyJ
Solar Wizard
A quality UPS does not Switch, it powers the load 100% of the time and uses utility power to float charge the battery. So if the grid goes down there is zero momentary loss of power to the sensitive load.
An inverter on the other hand normally would just pass-through utility power and the switching process does take a few milliseconds. Three solutions to get UPS like protection from an inverter with LFP batteries.
1) Purchase an inverter that has true UPS functionality.
2) Use an inverter with no AC input feature so its running on the LFP battery 100% of the time and use utility power with a stand alone charger to simply keep the batteries topped up.
3) Use a grid-interactive inverter that has a Peak Load Shave function. These are the most expensive type but are capable of blending utility and inverter power with user settable values for how much utility vs. battery power is used. If grid power is lost, the inverter is already running and the batteries will pick up the load with virtually no power disruption.
An inverter on the other hand normally would just pass-through utility power and the switching process does take a few milliseconds. Three solutions to get UPS like protection from an inverter with LFP batteries.
1) Purchase an inverter that has true UPS functionality.
2) Use an inverter with no AC input feature so its running on the LFP battery 100% of the time and use utility power with a stand alone charger to simply keep the batteries topped up.
3) Use a grid-interactive inverter that has a Peak Load Shave function. These are the most expensive type but are capable of blending utility and inverter power with user settable values for how much utility vs. battery power is used. If grid power is lost, the inverter is already running and the batteries will pick up the load with virtually no power disruption.
DIYrich
Solar Wizard
What is your budget and power needs?
Brucey
Solar Wizard
The Delta pro may or may not switch from AC grid to battery fast enough for PC ups purposes, can take up to 30 msec in "EPS" mode. If your PC power supply is highly loaded it may glitch out.
EcoFlow Delta Pro Through Manual Transfer Switch - Full Time Pertinent Circuits Home UPS
I have an existing manual transfer switch for pertinent circuits in my house, all under 2000 watts max and all 120v. Currently use a WEN 56200i with the transfer switch in a power outage that can handle the loads from these pertinent circuits with no problem. Our bigger issue lately isn't long...
diysolarforum.com
I had no luck trying to charge my Delta 2 max from an external 36V battery, so doubt 48V would work either. Maybe Delta pro with it's higher solar input does bettér. 24V works fine with my d2m
DIYrich
Solar Wizard
EG4 3000, or Growatt 5000
signaturesolar.com
signaturesolar.com
EG4 3kW Off-Grid Inverter | 3000EHV-48 | 3000W Output | 5000W PV Input | 500 VOC Input
Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL
signaturesolar.com
Growatt 5kW Stackable Off-Grid Inverter | SPF 5000US | UL 1741
Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL
signaturesolar.com
Maybe connecting a small 650VA APC to the Delta Pro so can act faster for the computer and then the Delta Pro will supply the APC. It should work. Just thinking loud.The Delta pro may or may not switch from AC grid to battery fast enough for PC ups purposes, can take up to 30 msec in "EPS" mode. If your PC power supply is highly loaded it may glitch out.
EcoFlow Delta Pro Through Manual Transfer Switch - Full Time Pertinent Circuits Home UPS
I have an existing manual transfer switch for pertinent circuits in my house, all under 2000 watts max and all 120v. Currently use a WEN 56200i with the transfer switch in a power outage that can handle the loads from these pertinent circuits with no problem. Our bigger issue lately isn't long...
I had no luck trying to charge my Delta 2 max from an external 36V battery, so doubt 48V would work either. Maybe Delta pro with it's higher solar input does bettér. 24V works fine with my d2m
Brucey
Solar Wizard
Yes that will work.
Brucey
Solar Wizard
One thing to be aware a fair few people seem to be having problems with their Delta pros.
If you already have 16 105Ah cells, build a 5.12kWh 48V battery assuming you have a BMS.
If your budget is $1000, get this inverter/charger and you are done. Has built in fast transfer switch and huge configurability. 10 year warranty if you buy through current connected who is a well regarded vendor with great reputation for customer service.
www.currentconnected.com
Or bump up budget to $1250 or so and get the 3000VA model (UL listed version also available).
If you already have 16 105Ah cells, build a 5.12kWh 48V battery assuming you have a BMS.
If your budget is $1000, get this inverter/charger and you are done. Has built in fast transfer switch and huge configurability. 10 year warranty if you buy through current connected who is a well regarded vendor with great reputation for customer service.
Victron 48V MultiPlus 2kVA Inverter - 25A Charger | Current Connected
The Victron MultiPlus 48V 2kVA Inverter - Empower your energy system with adaptive tech, remote monitoring, and seamless backup power solutions.
www.currentconnected.com
Or bump up budget to $1250 or so and get the 3000VA model (UL listed version also available).
KevinC_63559
New Member
Actually doing this exact project right now. Per my existing APC, my primary load is around 530W. I've opted for a Victron Compact from the kind folks over at Current Connected. It has a 2000VA inverter (call it 1600 watts to be safe), more than meeting my need. I opted for the 12V model with (2) 12V100A LiFePO4 batteries set up in parallel to feed it.
Along with the inverter I bought the required cables, a Victron MK3-USB, fuse holders and fuses. Spent a bit over $1100 plus tax and delivery (which would obviously vary based on where your at).
Yes, this system will drop power for about 20ms during an outage, but expect all my equipment to be able to ride through a 1/50th of a second outage, and Victron claims they will.
Nice thing I'll be able to do is current limit the recharge rate after an outage. Since I, like many in the USA, pay a peak demand, that should help minimize peak charges when power is restored. I plan on setting that to around 10amps, since I'm normally pulling half of that - plenty to cover the running need plus slowly recharge the batteries. I will feed it with a 20amp power cord out of my 20amp wall sockets, and have it feed a surge protected power strip I'll plug all the equipment into.
ps. I opted to go with the 12V system since I have some 12V needs in the area.
pps. Victron's 3000VA units are UL1741 listed, the 2000VA I went for is not; I'd probably do the 3000VA unit if I was ordering today.
Along with the inverter I bought the required cables, a Victron MK3-USB, fuse holders and fuses. Spent a bit over $1100 plus tax and delivery (which would obviously vary based on where your at).
Yes, this system will drop power for about 20ms during an outage, but expect all my equipment to be able to ride through a 1/50th of a second outage, and Victron claims they will.
Nice thing I'll be able to do is current limit the recharge rate after an outage. Since I, like many in the USA, pay a peak demand, that should help minimize peak charges when power is restored. I plan on setting that to around 10amps, since I'm normally pulling half of that - plenty to cover the running need plus slowly recharge the batteries. I will feed it with a 20amp power cord out of my 20amp wall sockets, and have it feed a surge protected power strip I'll plug all the equipment into.
ps. I opted to go with the 12V system since I have some 12V needs in the area.
pps. Victron's 3000VA units are UL1741 listed, the 2000VA I went for is not; I'd probably do the 3000VA unit if I was ordering today.
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I really appreciate the response and options. I forgot mentioning that I need something more portable since this options looks like are large in size and more like stationary device for homes. I live in an apartment for the moment and I like to have portability around the apartment or If I want to move the device for camping etc.... I am really interested on the Victron option for a future.
Brucey
Solar Wizard
In that case I can recommend the Delta 2 max. Fans are pretty quiet for locating close to living quarters.
robbob2112
Doing more research, mosty harmless
For this sort of project I am using an Expertpower brand charger/inverter. It has a UPS function to it with a 5ms switchover on AC preferred or you can set for battery prefered and it runs the batteries down 40% then tops the batteries up. I am using the 2000w 12v unit, but they have other wattages and voltages.
6 months in and so far so good. It appears to be really similar to the sungold units externally. But, they claim usa design and mfg.
6 months in and so far so good. It appears to be really similar to the sungold units externally. But, they claim usa design and mfg.
DIYrich
Solar Wizard
16 eve 105 batteries are not what I would call "portable".
If you do a 12v system, then moving a case of 4 batteries would be portable. Hooking the case back up in parallel with the others is annoying (have to be all at the same voltage).
If you do a 12v system, then moving a case of 4 batteries would be portable. Hooking the case back up in parallel with the others is annoying (have to be all at the same voltage).
robbob2112
Doing more research, mosty harmless
For mine I am connected to a LiTime 200ah plus battery. Seems like it is 4s4p setup inside from the teardown video but I could be not remembering correctly. Either way the battery is 45lbs and the Expertpower unit is about that. So far from 'portable' if trying to carry it around. I put a powerpole SB350 connector in the line so I can separate the two parts to move it when needed.
Basically a bigger version of this, same general wiring diagram with different larger components and wiring. And the inverter also is charging so no separate charger. For the smaller cpap backup I have the charger on a timer so it comes on at noon when nobody is in the bedroom.
The other thing I did was paint the ends of the shunt with liquid electrical tape since I don't have a cover over it. I wish the mfg would include a cover or over the exposed metal. I suppose they don't expect the shuts to be used in a setup like this.
The precharge resistor is a 30ohm 25watt connected with 16awg wire and a fuse inline. It is connected across the switch so I push it for 10 seconds or so, then turn the switch on.
edit:
Attached a picture of my UPS setup - I forgot I reworked things with smaller wires and without the connector. I intend to put in a SB175 between the battery and inverter, but haven't done it yet.
Basically a bigger version of this, same general wiring diagram with different larger components and wiring. And the inverter also is charging so no separate charger. For the smaller cpap backup I have the charger on a timer so it comes on at noon when nobody is in the bedroom.
The other thing I did was paint the ends of the shunt with liquid electrical tape since I don't have a cover over it. I wish the mfg would include a cover or over the exposed metal. I suppose they don't expect the shuts to be used in a setup like this.
The precharge resistor is a 30ohm 25watt connected with 16awg wire and a fuse inline. It is connected across the switch so I push it for 10 seconds or so, then turn the switch on.
edit:
Attached a picture of my UPS setup - I forgot I reworked things with smaller wires and without the connector. I intend to put in a SB175 between the battery and inverter, but haven't done it yet.
Attachments
Last edited:
KevinC_63559
New Member
I'm not sure portable, and using even a single 12V100amp LiFePO4 battery are compatible conversations. A single battery weighs about 25lbs. You could just hook it up to a cheap charge controller, and say a 500W full sinewave standalone inverter and have basic functionality. Package it all up and maybe your at 30 lbs. Just make sure the charge controller is designed for LiFePO4 batteries.
I'm thinking something like this inverter and a larger version of this charger. Add a cheap voltage display as a sanity check. Depends on your power requirements of course. Point is the charger could be smaller than your load, presuming you turn your PC off (or let it go to sleep), when not in use. Personally, I prefer the sleep option since it can be easily automated via Windows settings.
This would be a "poor mans" solution, but would come in at a few hundred dollars vs. a thousand. OK if you only use your PC a few hours a day. More than that, and you would need more battery and/or a bigger charger.
robbob2112
Doing more research, mosty harmless
My cpap UPS is a LiTime 12v 100ah mini, 19lbs. With the small 300w inverter I've had for years and the Litime 20amp charger. I went with the 20a charger because I tried a 10a charger first that was fanless, it was in a plastic case and it got so hot it was warping the case and releasing the adhesive under the stickers.
At any rate the battery + invert + charger will all fit inside the plastic case that holds hanging file folders. Put a strap around each end with a strap between and it weighs in at around 25lbs. It is capable of about 3 nights use in a pinch it might do part of a 4th night.
Weighs less than any number of my older "small" UPS like the apc backups 650 in the white case and weighs FAR less than the old 2200. My computer UPS weighs about the same as that old 220 (100lbs) but has 8 times the runtime when used.
So depends on what the OP means by portable.
Now in my case I run my cpap off the 12v direct with a car adapter. So I don't need an inverter at all and I leave the charger outside the case for ventilation.
At any rate the battery + invert + charger will all fit inside the plastic case that holds hanging file folders. Put a strap around each end with a strap between and it weighs in at around 25lbs. It is capable of about 3 nights use in a pinch it might do part of a 4th night.
Weighs less than any number of my older "small" UPS like the apc backups 650 in the white case and weighs FAR less than the old 2200. My computer UPS weighs about the same as that old 220 (100lbs) but has 8 times the runtime when used.
So depends on what the OP means by portable.
Now in my case I run my cpap off the 12v direct with a car adapter. So I don't need an inverter at all and I leave the charger outside the case for ventilation.
