20 second UPS?

[Frankman60]

Thanks for posting the diagram. This is probably a little too much for me to try without adult supervision . Is a UPS like this available for sale?

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.

 

[miimura]

Thanks for posting the diagram. This is probably a little too much for me to try without adult supervision . Is a UPS like this available for sale?

I didn't know it until a quick search just now, but yes, there are some Lithium UPS available.
Here is a small one.
APC Back-UPS Pro 500 Lithium Ion UPS - APC USA

Here is a larger rackmount one.
APC Smart-UPS Li-Ion, Short Depth 1500VA, 120V with - APC USA
The rackmount one is 87.5% more expensive than an equivalent AGM version. $1,800 vs. $960.

 

[Frankman60]

I couldn’t find the battery capacity on the smaller one, but it is most likely a lot larger than what would be needed to handle a 20 second switchover to PWs during a power outage. APC estimates that the lithium battery will last 8 years which given the additional cost, is not that great compared to the AGM batteries that are fairly inexpensive and last up to 5 years.

I didn't know it until a quick search just now, but yes, there are some Lithium UPS available.
Here is a small one.
APC Back-UPS Pro 500 Lithium Ion UPS - APC USA

Here is a larger rackmount one.
APC Smart-UPS Li-Ion, Short Depth 1500VA, 120V with - APC USA
The rackmount one is 87.5% more expensive than an equivalent AGM version. $1,800 vs. $960.

 

[mspohr]

That's not a charger, that's a passive adapter board.

More properly, it's a BMS (battery management system).
It requires a power source to charge and manages the charging.

 

[miimura]

More properly, it's a BMS (battery management system).
It requires a power source to charge and manages the charging.

No, it's not a BMS. It is literally a passive backplane that allows you to plug in a variety of different battery packs with balance cables, even simultaneously in parallel, so that a balance charger can charge them together.

 

[mspohr]

No, it's not a BMS. It is literally a passive backplane that allows you to plug in a variety of different battery packs with balance cables, even simultaneously in parallel, so that a balance charger can charge them together.

• This lipo balance board lets you charge and balance up to six lipo batteries at the same time.
• The charging time is significantly reduced since all batteries are balanced at the same time instead of balancing batteries one by one.
• Features XT-60 for your batteries main leads and JST-XH balance plugs ranging from 2S to 6S,It can prevent each cell overcharge, so it can improve the balance efficiency. And the later period of the balance charging cycle is shorted substantially.
• This lipo balance board is used for simultaneously charging multiple lithium batteries(including LiPo, LiFe, and Li-ion types) in parallel.
• The lipo balance board can protect each cell when overcharge or short circuit happens

 

[miimura]

• This lipo balance board lets you charge and balance up to six lipo batteries at the same time.
• The charging time is significantly reduced since all batteries are balanced at the same time instead of balancing batteries one by one.
• Features XT-60 for your batteries main leads and JST-XH balance plugs ranging from 2S to 6S,It can prevent each cell overcharge, so it can improve the balance efficiency. And the later period of the balance charging cycle is shorted substantially.
• This lipo balance board is used for simultaneously charging multiple lithium batteries(including LiPo, LiFe, and Li-ion types) in parallel.
• The lipo balance board can protect each cell when overcharge or short circuit happens

None of those published features constitute a BMS. The only thing close is the short circuit protection.

 

[NinjaVece]

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.

Duke, that hasn't been my experience. In fact, with my single PW2 system, should a grid outage occur - or I simply pull the Service Disconnect on the Master Breaker Unit - not only do computers, routers and NASs die in my set up that are not behind UPSs but I get lights flickering and even going out due to the switch over (they are LED lights behind sophisticated radio-controlled switches that are more sensitive to voltage loss admittedly).

It sounds as if you are basing your lack of need for an interim UPS on two outages during your tenure with the PW2. If you manually pulled the Service Disconnect at this point you may find that devices will fail down the chain - that is, unless those devices have capacitors built-in that can handle a 500 millisecond to 1000 millisecond power break.

Just my experience with a number of outages using the PW2.

 

[bkp_duke]

Duke, that hasn't been my experience. In fact, with my single PW2 system, should a grid outage occur - or I simply pull the Service Disconnect on the Master Breaker Unit - not only do computers, routers and NASs die in my set up that are not behind UPSs but I get lights flickering and even going out due to the switch over (they are LED lights behind sophisticated radio-controlled switches that are more sensitive to voltage loss admittedly).

It sounds as if you are basing your lack of need for an interim UPS on two outages during your tenure with the PW2. If you manually pulled the Service Disconnect at this point you may find that devices will fail down the chain - that is, unless those devices have capacitors built-in that can handle a 500 millisecond to 1000 millisecond power break.

Just my experience with a number of outages using the PW2.

A single powerwall has a very limited number of amps that you can pull from load, and I suspect (but don't have the data to prove it) that it is very sensitive to voltage drops, etc. and that it cannot compensate for these as quickly as a larger system (say 2 or 3 PWs).


I've manually pulled the disconnect lever dozens of times, including when the AC is running and other load situations. I never have anything in the house reset or die due to this.

 

[miimura]

Whether your loads experience a drop has a lot to do with the amount of grid draw at the time. If the Powerwall(s) are in Standby and all the load is being supplied by the grid and you flip your main breaker, you will likely experience a brief dropout while the inverters pick up the load. On the other hand, if you are in Self-Powered mode and the grid draw is near zero, then there will be almost no dropout.

The other significant issue for the UPS was brought up in another thread - the overproduction frequency shifting. If the Powerwalls are full and they have to shift the frequency higher in order to shut down the solar and your UPS doesn't like it and it goes to battery, then this whole scheme of using short runtime UPS units really doesn't work. Of course, you could pre-emptively shut down your solar before the Powerwalls become full, but if the system doesn't run automatically and un-attended, then that's a big drawback.

 

[Ampster]

More properly, it's a BMS (battery management system).
It requires a power source to charge and manages the charging.

That connector does not manage anything. As mentioned earlier it is just a passive cable that is designed for parallel LIPO charging. Any management (ie balancing) would come from the charger not this connector. The concept of parallel charging is that a high cell will passively bleed into the lower voltage cells. That is not the same as active balancing.

 

[mspohr]

That connector does not manage anything. As mentioned earlier it is just a passive cable that is designed for parallel LIPO charging. Any management (ie balancing) would come from the charger not this connector. The concept of parallel charging is that a high cell will passively bleed into the lower voltage cells. That is not the same as active balancing.

I need to correct myself. On further investigation, this board is completely passive. It's just a plug set. No fuses or charge control circuits. It cannot balance; it cannot prevent shorts; it cannot control charge.
The description on Amazon is wrong.
Sorry to mislead people.

 

[brianman]

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'm confused by this post. My understanding was that Powerwalls do not offer instant transition.

We currently have solar + lead acid battery back-up. One of my priorities with our setup was that we could banish UPS devices from the interior of our home in favor of whole home UPS. As noted above, I was under the impression that Powerwall could not be used to fulfill that role as a future "upgrade" to our system.

For those that have some expertise in the above, I'd love to hear more.

Our current system was installed in December 2014:

• 8.64 kW solar @ 32x 270W Itek panels
• 3x Outback Charge controllers
  • FLEXmax 60/80 - OutBack Power Inc
• Outback GS8048 inverter/charger
  • http://outbackpower.com/products/inverter-chargers/radian-series
• 12x Outback 200RE battery backup system
  • http://outbackpower.com/products/energy-storage/energycell-re
• Mate 3 display and controller
  • http://outbackpower.com/products/system-management/mate3s

My instinct is to replace only the 12x 200RE with powerwall(s) but I don't know if that option is viable.

 

[miimura]

I'm confused by this post. My understanding was that Powerwalls do not offer instant transition.

We currently have solar + lead acid battery back-up. One of my priorities with our setup was that we could banish UPS devices from the interior of our home in favor of whole home UPS. As noted above, I was under the impression that Powerwall could not be used to fulfill that role as a future "upgrade" to our system.

For those that have some expertise in the above, I'd love to hear more.

Our current system was installed in December 2014:

• 8.64 kW solar @ 32x 270W Itek panels
• 3x Outback Charge controllers
  • FLEXmax 60/80 - OutBack Power Inc
• Outback GS8048 inverter/charger
  • Radian Series - OutBack Power Inc
• 12x Outback 200RE battery backup system
  • EnergyCell RE - OutBack Power Inc
• Mate 3 display and controller
  • MATE3s - OutBack Power Inc

My instinct is to replace only the 12x 200RE with powerwall(s) but I don't know if that option is viable.

Powerwall 2.0 can provide a seamless transition to battery during a grid failure, but it does not guarantee that it will. Therefore, if you have sensitive equipment, you still have to have UPS units inside your home.

Your Outback Radian system is much more flexible and and configurable and can provide true whole home UPS functionality. You can even add multiples in parallel to supply more than 8kW. You cannot remove the 200RE batteries and substitute a Powerwall. The Radian needs direct battery connection and Powerwalls are AC coupled. The closest you could get to a Powerwall battery is probably a LG Chem Resu 48V.

 

[brianman]

Powerwall 2.0 can provide a seamless transition to battery during a grid failure, but it does not guarantee that it will. Therefore, if you have sensitive equipment, you still have to have UPS units inside your home.

Your Outback Radian system is much more flexible and and configurable and can provide true whole home UPS functionality. You can even add multiples in parallel to supply more than 8kW. You cannot remove the 200RE batteries and substitute a Powerwall. The Radian needs direct battery connection and Powerwalls are AC coupled. The closest you could get to a Powerwall battery is probably a LG Chem Resu 48V.

Thanks for the follow-up.

I thought Powerwall 2 allowed for DC coupling as well. Did they cut that?

The New Tesla Powerwall Is Actually Two Different Products

 

[miimura]

Thanks for the follow-up.

I thought Powerwall 2 allowed for DC coupling as well. Did they cut that?

The New Tesla Powerwall Is Actually Two Different Products

They axed the DC version before customer deliveries even started. All Powerwall 2.0 units have had the built-in 5kW continuous 7.5kW peak inverter. So far the inverter supports 120/240V split phase for North American grid or 230-240V single phase for Australia and Europe. There is no 3-phase solution available. The brains that sense solar and grid current and tell the Powerwall what to do are external in a box called the Gateway. There are two versions - the one that provides backup power and grid islanding is called the Backup Gateway and the other that shuts down like traditional grid-tied solar during grid outages is called the Energy Gateway. I think the Energy Gateway is only used in Europe. US and Australia have the Backup Gateway.

 

[cwied]

I thought Powerwall 2 allowed for DC coupling as well. Did they cut that?

Yes, they never produced any DC-coupled units and canceled their plans to do so pretty soon after the release of the Powerwall 2.

 

[Ulmo]

Duke, that hasn't been my experience. In fact, with my single PW2 system, should a grid outage occur - or I simply pull the Service Disconnect on the Master Breaker Unit - not only do computers, routers and NASs die in my set up that are not behind UPSs but I get lights flickering and even going out due to the switch over (they are LED lights behind sophisticated radio-controlled switches that are more sensitive to voltage loss admittedly).

It sounds as if you are basing your lack of need for an interim UPS on two outages during your tenure with the PW2. If you manually pulled the Service Disconnect at this point you may find that devices will fail down the chain - that is, unless those devices have capacitors built-in that can handle a 500 millisecond to 1000 millisecond power break.

Just my experience with a number of outages using the PW2.

I experience both things. It's semi-random which devices will decide to stop working, but generally speaking, my expensive 1,300 Watt power supply in my pieced-together Linux server will bridge most PowerWall backups better than my iMac, my iMac will usually but not always survive it (my last backup event turned off my iMac), and our stove will always show Power Failure. My LED bulbs almost always flicker during any kind of inadequacy at all. I too believe it is entirely regarding the size of the drop and the size of the capacitors. If I have the dryer (6KW) on, it will almost always cause more other items to fail.

 

[MorrisonHiker]

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.

Do you have your Powerwalls set up to Self-powered or Time-based control? I used Self-powered for a couple weeks and never had any issue. I noticed that whenever I'm on Time-based control (and I guess the Powerwalls are in Standby as @miimura mentions above), the UPS devices that I have around the house have to kick in for that split second.

 

[bkp_duke]

Do you have your Powerwalls set up to Self-powered or Time-based control? I used Self-powered for a couple weeks and never had any issue. I noticed that whenever I'm on Time-based control (and I guess the Powerwalls are in Standby as @miimura mentions above), the UPS devices that I have around the house have to kick in for that split second.

I'm on self-powered.