Long duration UPS without completely breaking the bank

Jammminjay

New Member
May 23, 2022
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Hello,

The short version - I'm looking for a UPS system that isn't going to be *too* expensive and will allow me to sustain ~600W or so of power from batteries without overheating no matter the runtime, as I plan to hook the UPS up to external deep cycle batteries. If I could find a good working solution that I'm happy with, I'd like to implement 3 of them, so the price adds up.

The longer version -

A lot of cheap UPS systems that you can buy are designed to run out of power right before they overheat and start damaging things/starting a fire (at higher power draws). Some even have timers that activate to help with this. So, if I wanted a longer runtime out of cheap units like this, the battery capacity simply isn't the relevant factor.

There's a few mid tier units from Tripp Lite and APC which allow for external battery addons. Is it safe to presume that these would be capable of supporting (potentially) infinite runtimes without heat related problems? Here's a few example products:

ttps://www.amazon.com/APC-External-Battery-BR1500G-BR24BPG/dp/B003Y24DEU/

Tripp Lite has some similar products that don't advertise the addon battery compatibility (XL in their product name), but I don't know if they're otherwise the same inside or not (read: able to avoid overheating).




Does anyone have advice for me?

Would the products which support external batteries also be likely to avoid overheating with a ~600W constant power draw?

Would anyone know if I could just add on to the similar Tripp Lite products that are much cheaper without the XL in the product name (~180 vs ~280 USD)?

Other than buying a power inverter and constantly running off of it, are there any other solutions that I could use?

I've read mixed things about PWM sin outputs vs an actual sin(ish) waveform - Does this really matter with computer power supplies made in the past ~20 years?

Thanks.

Edit: For anyone hoping to do this same thing yourself, I ended up doing the following:

I found the APC BGM1500B "gaming" UPS on a good sale and tried it. The closest, "non-gaming" themed one is the BR1500MS2, I think. They're both, "pure sin wave" outputs on battery mode, which creates significantly less heat than the stepped/approximated sin waves do. I would imagine internally they're likely identical, or stupid close. The externals are probably just a difference of RGB and the rear light if I had to guess (didn't look into it - the, "gaming" model was cheaper at my time of purchase).

I didn't time myself, regrettably, but I hooked the battery input up to a car charger + car alternator and got close enough to the expected 24V (+~3) DC input to simulate a large battery's runtime. I hooked up a load of ~595 Watts, and I went for a bare minimum of 20 minutes, probably closer to 30 before calling it quits. I didn't rip my UPS's case open, but I did stick a thermal gun in the side at every angle I could. In a room which was about an ambient 80 degrees that day, I was reading a max of around 140F through the small open grill of the plastic case. I never reached a thermal error message, which supposedly my UPS should tell me about, so this was plenty acceptable for my use case.

If someone reading this wants to run for longer than ~25-30 minutes at ~600W load, you could look into adding a 24V fan to the case and dremeling / melting a few holes into the plastic case for air flow. The model I have appears to have a lot of fin slotted air vents, but almost all are fake, and just an external design thing. But anyways, for my use case, I'm perfectly happy with the runtime and temperatures I found. It should be noted that the battery lead wires themselves got very hot since they're incredibly thin for the amount of current that they're drawing, so do mind the heat there if you're pulling more than ~600W for any length of time.

My conclusions are that getting a proper true sin wave UPS on battery mode is going to create a lot less heat, and just go from there as a starting point. Perhaps my unit has a hard built in timer like I was previously discussing, but if so, it only kicks in at higher power outputs. If one wants to expect higher performance than what I tested, my recommendation would be to go for pure sin wave, ensure you have a power overhead (so, if you wanted more than ~600W, get a stronger unit, or double up your units if possible) between what your unit is rated for and what you're actually pulling, consider adding fan vent holes and a fan, and ensure there's no overheating occurring or a hard built in timer on your unit.
 
Last edited:

Sean Ho

seanho.com
Nov 19, 2019
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seanho.com
UPSes are not there to provide long-term runtime but to tide you over until your generator spins up. There are smaller gennys that are affordable for home use.

Having said that, I did do what you propose many years ago with a marine deep-cycle battery for a single low-power desktop; got a little over an hour out of it if I remember correctly.
 

Jammminjay

New Member
May 23, 2022
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UPSes are not there to provide long-term runtime but to tide you over until your generator spins up. There are smaller gennys that are affordable for home use.

Having said that, I did do what you propose many years ago with a marine deep-cycle battery for a single low-power desktop; got a little over an hour out of it if I remember correctly.
I'm not looking for a generator. When I say that the UPS should, "run for an infinite runtime without overheating" I'm not stating that I plan on running it for hours or even days at a time. I state this because most consumer UPS systems would overheat at high power demands in just a few minutes. I would like the freedom in this solution to add batteries to increase runtime if necessary, as each of my three targeted systems have different use cases.
 

Tom5051

Active Member
Jan 18, 2017
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I use an APC 1500 with 2x 100amp SLA batteries in series (24volts). I get about 1.5hrs out of it before low battery shutdown. Been using this setup for 15 years with no issue. If you don't want to cut holes in a brand new ups, I took the front off the ups and connected the external batteries straight to the anderson connector.
 

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Jammminjay

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May 23, 2022
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I use an APC 1500 with 2x 100amp SLA batteries in series (24volts). I get about 1.5hrs out of it before low battery shutdown. Been using this setup for 15 years with no issue. If you don't want to cut holes in a brand new ups, I took the front off the ups and connected the external batteries straight to the anderson connector.
Awesome, thanks. I think the trend I'm seeing is that the wider frames tend to have better cooling included.

I would also imagine that true(ish) sin wave machines generate less heat too, so I wonder if the tall and slim true(ish) sin wave units would work well, too. They'd cost a bit more but would be more power efficient when running off of battery so I could get a longer runtime on cheaper batteries.
It's nice to see others having success with this. I tried this years ago but the unit I tested with had a built in battery runtime timer, if I'm remembering correctly. Roughly speaking, what kind of power output are you using to get your 1.5 hour runtime?
 

T_Minus

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I run APC unit + external battery bank, when batteries are new I can run my desktop (two monitors, nvme, ssd, optane, etc, etc) for around 1hr.
 

Jammminjay

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May 23, 2022
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I run APC unit + external battery bank, when batteries are new I can run my desktop (two monitors, nvme, ssd, optane, etc, etc) for around 1hr.
CPU and GPU are by far the biggest sources of power consumption - drives (SSD's especially) are nearly negligible in the grand scheme of things.

Would you mind checking what model your APC is? There's quite a lot of differences from one to the next. It's nice to see what models other people have success with within this context.

Thank you!
 

Rdr

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Jan 26, 2019
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If you are using your own battery's, look at the Victron Multiplus Inverter/chargers, i use a 800VA version as my 'UPS'.
 

Jammminjay

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May 23, 2022
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If you are using your own battery's, look at the Victron Multiplus Inverter/chargers, i use a 800VA version as my 'UPS'.
I've considered this, but for my use cases I don't think it's in my favor to go this route, so long as the other route is viable. With the AC -> DC -> AC conversion 24/7 like in your case, you're spending a lot more on power usage than you would be with a standby UPS system due to the inefficiency of the inverters in play. It can be quite substantial depending on what hardware you're using. I don't need the 0ms activation time that a 24/7 inverter would provide, and I'm pretty sure that the standard sub 12ms activation found in even low end UPS's is fine for me.

Luckily I don't have power outages frequently and when they do occur, they're not usually for extended periods of time. But if someone lived in an area where they are common, your solution is pretty much the best possible one. You can have the inverter system setup and can activate it when you lose power manually from a different, cheap UPS.

Thank you for the suggestion and information all the same! I do appreciate it.
 

T_Minus

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Feb 15, 2015
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CPU and GPU are by far the biggest sources of power consumption - drives (SSD's especially) are nearly negligible in the grand scheme of things.

Would you mind checking what model your APC is? There's quite a lot of differences from one to the next. It's nice to see what models other people have success with within this context.

Thank you!
Maybe for consumer drives.. but my system uses enterprise SSD and NVME, they're not a GPU power hungry but they're not negligible either ;)
Also running an AMD 5950x and 2080 TI with a 27" 2k and 24" 4k screen and more, just to compare against :)

It's the BackUps Pro 1500 with extra battery bank next to it.

To go big though, the victron setup would be my go to :)
 
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Stephan

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Apr 21, 2017
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Am still also using lead-acid-based batteries and Eaton/APC UPS.

For new stuff I am paying the premium for power supplies with long hold-up-time. In most recent instance for a side-project I bought three Seasonic Prime Titanium Fanless 600W which deliver 35 milliseconds of power after AC-in goes away. Expensive, but really good imo. ATX standard demands 16 ms. This way I can use a Victron Multiplus II 48/5000 as an UPS, which claim a switchover time of below 20 ms. Battery will be a seplos.com DIY kit called "MASON plus" for 280 Ah LiFePO4 cells with total nominal power of 14.3 kilowatt hours. There are new Eve LF280K cells out with 6000 cycles instead of the old 2000. Innovation out of China, can you believe it? Estimated runtime at 400 watts average load will be around 35 hours. The battery will go into a separate 19" rack for later expansion to 230 volt 3-phase island mode. No idea yet how to bridge the dark european four months, maybe build a wood gas drizzler and run 2-3 Honda generators to load batteries.
 
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Rdr

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Jan 26, 2019
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I've considered this, but for my use cases I don't think it's in my favor to go this route, so long as the other route is viable. With the AC -> DC -> AC conversion 24/7 like in your case, you're spending a lot more on power usage than you would be with a standby UPS system due to the inefficiency of the inverters in play. It can be quite substantial depending on what hardware you're using. I don't need the 0ms activation time that a 24/7 inverter would provide, and I'm pretty sure that the standard sub 12ms activation found in even low end UPS's is fine for me.

Luckily I don't have power outages frequently and when they do occur, they're not usually for extended periods of time. But if someone lived in an area where they are common, your solution is pretty much the best possible one. You can have the inverter system setup and can activate it when you lose power manually from a different, cheap UPS.

Thank you for the suggestion and information all the same! I do appreciate it.
I run my setup as a standby UPS, the standby power usage is comparable with a modern standby UPS.
 

Tom5051

Active Member
Jan 18, 2017
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Awesome, thanks. I think the trend I'm seeing is that the wider frames tend to have better cooling included.

I would also imagine that true(ish) sin wave machines generate less heat too, so I wonder if the tall and slim true(ish) sin wave units would work well, too. They'd cost a bit more but would be more power efficient when running off of battery so I could get a longer runtime on cheaper batteries.
It's nice to see others having success with this. I tried this years ago but the unit I tested with had a built in battery runtime timer, if I'm remembering correctly. Roughly speaking, what kind of power output are you using to get your 1.5 hour runtime?
1653487498981.png
 

nabsltd

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Jan 26, 2022
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my system uses enterprise SSD and NVME, they're not a GPU power hungry but they're not negligible either
It depends on how many you have. ;)

I'm just getting started with U.2 drives, and I was shocked to see a single Hitachi SN100 could draw 40W of power. But, that sweet 3 drive writes per day (so about 9TB per drive) is worth it.
 

T_Minus

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Feb 15, 2015
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It depends on how many you have. ;)

I'm just getting started with U.2 drives, and I was shocked to see a single Hitachi SN100 could draw 40W of power. But, that sweet 3 drive writes per day (so about 9TB per drive) is worth it.
Yeah, that's why I stopped using 4x p3700 on my home storage... power cost for those were more than the system itself :D
 

Loto_Bak

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Mar 10, 2011
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I use a marine inverter/charger Magnum MS2812 but there is a smaller MS2012.
It'll run continuous duty (2000w for the MS2012), has a 30A @ 120v input and a big charger (200+ Amp DC).
I work in the marine industry so am familiar with them. I got mine used.