Need some advice on bolstering batteries in APC UPS

[chrisjinla]

Hi there, first time posting  here so forgive me if I am not doing this the best or right way...

 

I currently have a UPS which I use to power my Wifi Router and a fan in case of power cuts, it really helps as it generally gives me about 25 minutes of power which is enough for me to make sure anyone expecting me to be available online is aware I am in a power cut.

 

I have recently seen a bunch of videos of people hacking these machines to give themselves more than the 20 minutes which for me would be a godsend.

 

This is the UPS I have - APC - BX1400U-MS - https://www.apc.com/shop/th/en/products/APC-Back-UPS-1400VA-230V-AVR-Universal-and-IEC-Sockets/P-BX1400U-MS

 

I can see it has two 12 volt batteries inside (APCRBC 113) in series so I am wondering if I can remove these and integrate two larger deep cycle 12 volt batteries and if that would work.

 

The part that I am unsure of, is how to understand if those would blow the transformer in the UPS, how to work out what my technical limitations are for extension.

 

Any advice would be amazing, I was considering some batteries like this - https://www.lazada.co.th/products/200ah-deep-cycle-deep-cycle-gel-battery-lvtopsun-12v-200ah-i800192177-s1614028329.html?spm=a2o4m.searchlist.list.61.52b93330Wd8kc7&search=1

[bankruatsteve]

You could get a 2kVA generator for less than the batteries.  Just sayin.

[Moonlover]

Not recommended. This unit has Intelligent battery management. (mentioned in the specs) This system will be fine tuned the specified batteries and If you stick  unfamiliar batteries in there, you're liable to screw up or maybe even damage the circuitry.

[chrisjinla]

Thanks for the heads up! back to the drawing board then!

[Crossy]

I have almost the same unit which is running on an external 10Ahr LiFePO4 pack.

 

Details are in this thread - 

 

There are a number of caveats in the thread. 

 

The main issues you are going to run into if using larger, but still lead-acid, batteries are charging and heat dissipation.

 

You could probably double the capacity of the batteries without too much trouble, of course it would double the re-charge time. Otherwise you are going to need an external charger.

 

The heatsinks in these units are optimised for the expected run time they were designed for. Running longer obviously will generate more heat, you may need to add fans to keep things in check.

 

I've modified a number of UPS's over the years, I don't recall ever actually frying one.

 

 

[tjo o tjim]

Another thing to be careful about is overloading the inverter; many of the APC units are only designed to operate for a limited duration and will fail quickly if overheated in a longer duration run.  If your outages are infrequent it will have enough time to recharge the battery, but if they happen very often it will destroy the life of your battery quickly as well.

 

The best ones to use have a 24VDC connector on the back, as the inverters are rated for continuous duty, and you should be able to run a second charger off the independent battery bank.

 

All that said, it is a painful way to solve your problem.  The UPS is good for the Wifi, but maybe you are better off getting a 12V fan and just using a separate battery and charger for it.  Size the charger large enough that it can run the fan directly.  There are products that can power 12V electronics like your wifi router as well directly from a lead-acid battery if you go big enough.

[Led Lolly Yellow Lolly]

The problem with these consumer UPSs is they drain the batteries so low it permanently damages them, even after a few charge/discharge cycles. Yes, they're called deep cycle batteries but this is a misnomer, you should never drain less than 50%. In my own system I never drain below 70% state of charge. This gives me very long battery life, 5 years+ even with frequent power outages (server room, critical system with their own extended run UPS systems designed by myself). . .

These little UPS units you have under your table get their '20 minute' specs by hammering the battery down to near zero. You will be wasting your moeny putting big batteries in them just to have them wrecked by excessively deep discharges.

 

On 2/12/2021 at 10:02 AM, chrisjinla said:

I currently have a UPS which I use to power my Wifi Router and a fan in case of power cuts

 

That APC model you have is a Stepped Approximation to a Sine Wave output. You risk wrecking your fan motor running it on that. You need a pure sine wave inverter for motors.

[BritManToo]

On 2/12/2021 at 10:02 AM, chrisjinla said:

I have recently seen a bunch of videos of people hacking these machines to give themselves more than the 20 minutes which for me would be a godsend.

I built my own with a 100AH battery, cost around 9,000bht and runs my entire entertainment for 2-3hrs.

I should add some more battery for best results.

 

 

Deep cycle batteries are supposed to run their load over 20 hours, so my 100AH battery is only supposed to supply 50w.

The 7.5AH battery usually found in the home UPS is only really rated for a 5w load.

Edited February 24, 2021 by BritManToo

[beddhist]

I have done exactly that with my APC CS500: doubled the battery size. Found a detailed explanation on the web, but didn't keep the link, sorry. The important thing supposedly is not to run it at the rated capacity, as the inverter will get too hot.

If you put in a LiFePO4 battery with protection circuit then it won't get discharged too far.

[Crossy]

Yeah ^^^. 

I don't think I'd go above double the existing capacity without doing something with the charger, and defintitely look at extra cooling if running anywhere near rated power.

[OneMoreFarang]

On 2/12/2021 at 10:37 AM, Moonlover said:

Not recommended. This unit has Intelligent battery management. (mentioned in the specs) This system will be fine tuned the specified batteries and If you stick  unfamiliar batteries in there, you're liable to screw up or maybe even damage the circuitry.

Correct, and maybe the electronic will detect that the other batteries are not what it expects and it won't work at all.

[OneMoreFarang]

On 2/12/2021 at 10:02 AM, chrisjinla said:

I currently have a UPS which I use to power my Wifi Router and a fan in case of power cuts

"a fan"? What kind of fan? Many UPS don't like inductive loads = fans!

Better check in the manual.

 

 

[OneMoreFarang]

On 2/12/2021 at 4:26 PM, Crossy said:

I have almost the same unit which is running on an external 10Ahr LiFePO4 pack.

 

Details are in this thread - 

 

There are a number of caveats in the thread. 

 

The main issues you are going to run into if using larger, but still lead-acid, batteries are charging and heat dissipation.

 

You could probably double the capacity of the batteries without too much trouble, of course it would double the re-charge time. Otherwise you are going to need an external charger.

 

The heatsinks in these units are optimised for the expected run time they were designed for. Running longer obviously will generate more heat, you may need to add fans to keep things in check.

 

I've modified a number of UPS's over the years, I don't recall ever actually frying one.

And always be careful with Lithium batteries!

LiFe are not too bad. Especially LiPo should be handled with care and by people who know what they are doing.

[Crossy]

45 minutes ago, OneMoreFarang said:

"a fan"? What kind of fan? Many UPS don't like inductive loads = fans!

Better check in the manual

Our APC doesn't seem overly concerned by a fan, the fan however definitely does not like the modified sine from the UPS and makes a most unpleasant noise. It doesn't seem to overheat but it's certainly not a happy bunny.

 

[Crossy]

49 minutes ago, OneMoreFarang said:

LiFe are not too bad.

They also score in that a 4 cell LiFe pack is sufficiently close in voltage to a 6 cell lead-acid that the stock charger will do a "reasonable" job (it won't quite get the pack to 100%).

You still need a BMS on the pack to prevent over-discharge but a simple plug-n-play replacement does work pretty well. 

[OneMoreFarang]

23 minutes ago, Crossy said:

They also score in that a 4 cell LiFe pack is sufficiently close in voltage to a 6 cell lead-acid that the stock charger will do a "reasonable" job (it won't quite get the pack to 100%).

You still need a BMS on the pack to prevent over-discharge but a simple plug-n-play replacement does work pretty well. 

Let's say it like this: As far as I know people can't do much wrong with lead-acid batteries. Obviously it's a good idea to treat them like they should be treated but as far as I know they are not dangerous if treated badly.

Lithium batteries are very different in that way. Charge them with too much voltage or too much current and bad things might happen. Use them below the minimum voltage and they are dead. Shortcut them and again, bad things might happen. How bad is not sure. But anybody who wants to get an idea just google Lithium batteries and fire and you will have many many interesting links. And it's not possible to extinguish those batteries with water. In fact lithium and water is one of those risks which should be avoided.

Summary: Be careful with Lithium Batteries! They are dangerous! 

[tifino]

going back 10 yrs ago I had been flustered that outages were usually either millisecond flickers or blackout for hours

So, using the idea that the UPS i had had the facility to Repowerup itself upon resumption of Mains power i.e it had Stopped due the battery flattening before the mains came back.

The same US also had a selectable Green Mode where the UPS will power itself down when the battery was 'almost' flat

Now I had four of these units, with capacity each of 500VA - and I'd been using them independantly running a rack of different DTV DvDrecorders, a number of set top boxes and some TvSenders for relaying AV throughout the home... 

In reality, with power outages exceeding the obviously low powered UPSs, I'd often lose a lot of TV recording data. 

The individual housekeeping VA of the recorders was pretty low @ approx 35W max each

So what I did instead, was to combine all the recorders to run off a single 500VA UPS; which could support all the recording units for about 15mins total... but wait! there's more...

I also considered that sometimes a recorder would, upon resumption of (Mains & hence UPS power) that even though it was On again, it has locked up. his was common for a number of the recorders, which could not handle the flubbery burst/peaks etc that occurs out of the otput of a UPS that starts up whilst it is actually connected with its electronic devices loads... 

Thinking hat on again... and what I did was to actually Cascade all the UPSs in a daisy chain... #1 feeds #2 which feeds #3 which feeds #4 which then powers all the devices... 

 

what this did was to then give me 10mins + 10mins +10mins + 15mins of stable continuous 240V supplied to the devices ????  

In action, if say the Mains power had gone out for 30 to 40mins, I knew that the recorders were safely still running on continuous stabilised 240V -  upntil the last UPS in the daisychain were to finally give out...

When the power came up, each of the UPSs in the daisy chain would power up and feed power onto the next UPS etc etc 

The Brand of the little UPSs was iCube 

 

[Yellowtail]

You could not dick with the UPS and use a battery & inverter you could plug the UPS into if it runs low.

 

Do power outs often  last longer than a few minutes? 

[Yellowtail]

Or get an inverter that plugs into the car cigar lighter and run a cord into the house...

[Jan Dietz]

As mentioned briefly before, the 20 minutes runtime is enough to get a cheap Honda (or knockoff) generator running and switch over to it.

It will then run indefinitely powering way more than the little UPS.