Using a UPS and Deep Cycle battery(s) to make a reeaaal man's 120 VAC backup

[K1JJ]

Notice how fast the standard UPS (uninterrupible power supply) dies during a power failure? Mine lasts about 5 minutes at most and then the computer dies.

I have several needs if the power goes out - my SDR receiver, the computer and other assorted low power 120 VAC uses.  This is for low power stuff, not for running the house.

I've been thinking of how to inexpensively assemble a UPS (battery and AC inverter) to extend the range by maybe a day or two during a power outage. A standard computer UPS doesn't cut it due to the small internal battery. But what if we used the same UPS and one or maybe TWO large deep cycle batteries? (two in parallel) I would think we could get a day or two out of it.

Before assembling it and spending some cash, I first wanted to see what others here thought of the idea. The only issue I see is if the UPS charger can handle the charging capacity if the battery starts from a low state. It's probably current limited and would take a long time to charge, but that's OK. Also there are dangers to having a lead acid battery in an enclosed room in the event of overcharging, etc.

I did a search and eventually came up with this excellent summary of what I want to do. Check it out:

http://revision3.com/systm/hackedups

I like the idea that this UPS will allow any plugged-in 120AC system to operate - it is not just a battery designed only for a specific piece of gear.

Another downside is that the overall system efficiency is not stellar. The inverter is maybe 90% and drops lower at lower power levels - is this true?  Either way, it is just for emergencies, so OK.

Ideas?

T

[K6IC]

Hi Tom,

Glad to see you posting here again ...  had wondered what you were up to ...  know you were/are busy.

A couple of things.  Most UPSes are Modified Square Wave inverters,  not the best,  but should be fine for computers and the like.

Running Flooded batteries to a low State Of Charge is not good,  especially if it will take a long time to recharge them.  You might want to come up with a charger that will recharge the batts in 6-8 hours not days.

Most UPSes are designed for Gelled electrolyte batts,  and so the charger voltage is lower than ideal for Flooded batteries,  but it you redid the charger for higher charge currents,  you could fix the charge voltage.

Flooded batts DO outgas Hydrogen,  and Oxygen when they are becoming fully charged,  so venting outside is a good idea.  Flooded batts are considerably less expensive than Sealed Lead Acid batts.

There are some UPSes with real manly cababilities.  Some use 192 volt battery strings,  and can supply a number of Kwh for days.  Some of these do show up on the auction sites,  BUT,  of course,  the cost to re-battery them is high.

OR,  why don't you just do a Hybrid Grid Interactive system,  where you use PV to charge your batts,  and sell the excess PV power to the Grid?

With the WX many in North Central and NE  have had this year,  seems that many,  many folks there are thinking about backups -- and not just generators.  Opinions may differ,  GL,  Vic

[K1JJ]

Hi Vic -

Good to see you around.

I've done some more reading and see there are strapping pure sine wave inverters available cheap - that will run right off a deep cycle battery. Also I see some chargers that can be set to charge to a certain voltage and then turn off.  So maybe a combination of these components will be a better choice.  I like the modular approach.

Some of my stuff requires  pure sine wave AC, so glad you mentioned this point.

Thanks for the extra info, OM.

T

[K5WLF]

Tom,

For indoor use, you'll want the AGM (absorbed glass mat) sealed batteries. No outgassing or boiling over. I've been using a pair of PowerSonic 100Ah for several years now to power my gear set up in a 12 VDC UPS configuration. They can sit right in the shack under the desk or whereever with no worried about explosion or acid damage.

ldb

[K1JJ]

Tom,

For indoor use, you'll want the AGM (absorbed glass mat) sealed batteries. No outgassing or boiling over. I've been using a pair of PowerSonic 100Ah for several years now to power my gear set up in a 12 VDC UPS configuration. They can sit right in the shack under the desk or whereever with no worried about explosion or acid damage.

ldb

Yes, I've been seeing "AGM" mentioned a lot in my web reading, but wasn't sure what it meant yet.  100Ah is a pretty good capacity too.  I did a search and see they aren't cheap - but a very FB battery.

http://www.atbatt.com/product/3617.asp?utm_source=frog&utm_medium=cpc&utm_content=textlink-sealed-lead-acid&utm_campaign=frog1&utm_term=PS-121000&gclid=CPeIyfiezbICFQJp4Aod7gcANg

I have been reading about some guys running the stnadard flooded marine deep cycle batts in their house for 15+ years with no problems, as long as they take the precautions. Like, just a trickle charge, in a strong vented box, keep on the other side of the room, etc.

Well, I just bought a 300W 12V to 120AC pure sine wave inverter and a precision 1.25A battery charger, so just need the batt and case and we're golden. 


T

[Ed/KB1HYS]

So, are you going to use the UPS circuit to detect the power failure and switch in the external battery and inverter? Or will this be a manually switched system? 

Just wondering, as I've considered the same thing my self, just to run critical items during an outage. 

[K1JJ]

Hi Ed,

First, this system is mainly as emergency power backup for a medical device needed by an elderly family member.

So I will have this device on a standard computer-type UPS in case of short term power outages or quick drop-outs.

But once the outage becomes longer, I will switch over to the inverter and big battery manually. I expect the inverter system to last at least 2-3 days.  I will also be able to transfer this system over to the SDR or computer if needed.

What kind of system are you considering?    Frank sent me a message suggesting a solar panel charging system. Interesting idea, since we have had outages last 10 days here.    We do have a 5 Kw power generator, though I hate to run it more than a few hours each day.

[w6dhk]

just a note from past experence.  you may want to check the duty cycle, most ups systems are not designed to supply backup power for extended times past what could be provided by their internal battery

[Ed/KB1HYS]

I am thinking that a PV panel mounted on the roof, with several (3-4 high amp hour) sealed lead acid batteries and an inverter. Enough to run say just the gas heat on during an outage.  And maybe a little radio while the 'electrical quiet period' was in effect

Luckily the longest outage we've had in 18yrs here is 2.5 days, which was last octobers ice storm.  I had a Kerosene heater which kept the house warm and provided hot water for cooking & personal hygene.  We cooked most stuff on the gas grill (electric range is Not So Good) and a coleman stove.  Lights were hurricane lanterns.  Very 1850's-esq.   Still we were a lot better off than most folks with no generator (and some with).  In fact my Father in law stayed with us because we were warm and eating good.

Anyway, the gas appliances don't need a heck of a lot of power to operate, and it would be nice to keep the place warm and have hot water for a 48 hr period or so.

[W1RKW]

T,
I've been considering something along the lines that Ed is suggesting. I have a couple of 90 watt panels and a genset hook up that goes to a 10 position transfer switch. I figure taking 2 inverters and connecting them to L1 and L2 to power lights and any other light devices with at least 2 1000w inverters with batteries and batteries charged by the PV panels.  I haven't bit the bullet to purchase the inverters or the batts yet.  One thing I was considering was split phased synced inverter(s).  Haven't found anything yet but syncing may not be critical since I'm not interested in powering anything that is 240VAC.  Not sure if it matters or not. But would like to take some of the watts off grid so to speak. I would like some thing that is true sinewave vice modified just because.  

The thing that kills me though is the price of some of this "green" stuff.  The green weenies are as greedy as the non-green weenies. The prices are ridiculous IMO. I was thinking of just running 12v through the system instead of an inverter just to run 12v CFLs.  The 12vCFLs are $12.00 and higher. And those the buy them from these "green" places complain about them not lasting.  Seems silly when one can purchase a 120V CFL for a $1.50.

[K1JJ]

just a note from past experence.  you may want to check the duty cycle, most ups systems are not designed to supply backup power for extended times past what could be provided by their internal battery

Yep, plus they use a simulated sinewave that may not work well for certain types of gear. So I decided to use a UPS JUST for the sudden shut down and then manually connect in the inverter and big batt.


Ed:  Sounds like you've got in covered. You'll be able to charge the batt using the solar even when power is down. I'll think about the sloar later on. It sure is getting popular.

Bob:  Two 1KW inverters is "awesome."  (as the kids say)  Are you going to use the simulated sine wave for more efficiency?

I've already committed to the 300w pure sine wave unit but still need a big batt.

What is a good deal on solar panels these days to handle a 1KW inverter unit?

T

[W1RKW]

just a note from past experence.  you may want to check the duty cycle, most ups systems are not designed to supply backup power for extended times past what could be provided by their internal battery

Yep, plus they use a simulated sinewave that may not work well for certain types of gear. So I decided to use a UPS JUST for the sudden shut down and then manually connect in the inverter and big batt.


Ed:  Sounds like you've got in covered. You'll be able to charge the batt using the solar even when power is down. I'll think about the sloar later on. It sure is getting popular.

Bob:  Two 1KW inverters is "awesome."  (as the kids say)  Are you going to use the simulated sine wave for more efficiency?

I've already comitted to the 300w pure sine wave unit but still need a big batt.

What is a good deal on solar panels these days to handle a 1KW inverter unit?

T

T,
No, want true sinewave is what I want to go with.  I have many CFL's in the house and figuring that modified sine wave might wreak havoc with them like alot of other digital equipment. 

I picked up a pair of panels from a guy at work for a song and dance.  They seem to be in pretty good shape and can deliver said power.  Just need to get it into a battery bank.  I haven't been to receptive to the cost of AGM batteries and inverters just yet.  But I keep looking.  I'm hoping that if I can find the right deal for both in addition to cutting the light bill by 25% or so with just eliminating lighting cost it should be worthwhile. And any reserve can be used for shack purposes.

[Opcom]

I have run five 92AH AGM batteries in parallel for over 9 years with no loss of performance. I charge @ C/10 and float at 13.65V for maximum lifespan. It is done with a current regulated laboratory type DC power supply. The float voltage must be related to battery temp for max. life. AGM batteries like clean DC power for charging. Throwing one in a UPS and letting that unit continually charge it to 14+ volts will ruin the battery. They are each tested once a year @100A for 30 seconds and have stayed pretty close. It is worth the extra cost to use AGM batteries for UPS. They are not designed for cranking.

[KF1Z]

I used an old ups inverter in my shack ( living space, not radio room.. :-) ) and that's all I had for AC power.
4- 110 amp-hour , 6v golf cart batts. ( 12v ) charged by 2- 55w solar panels.

I had one crucial motor that was pulse-width controlled..
The "modified sine wave" that the inverter in the ups claimed to have created havoc with that motor controller.
Was very jumpy and unstable.

I dropped a 25 watt incandescent bulb on the output, and it cleared right up, and ran smooth.
I guess a little resistive load is what it needed.

[WBear2GCR]

I have not done this for a few years now, but one of the local "recycler" companies around here does all electronics. They ship the stuff out by the truckload. Big machine to pull rare earth out of CRTs and bulbs... anyhow they get old computer stuff. I got a rack UPS from a server farm from them. It had two chassis. Each about 100lbs or more, about 6" high 19"w and 24"deep. One is the UPS + basic batts, the other is ALL batts!! That one is more heavy. 120vac power cord too. Some fairly large KW rating.

It ran when I tested it last, and I may have screwed the sealed batts by letting them run down... but I would check around if there are places like that around you, and schmooze a bit. Mine was like $75 bux. I figured the batts were worth the price of admission alone, even with bad ones in the pack... plus the base unit seemed to work fine... you might find them.

                   _-_-bear

[K6IC]

As has been touched on,  to make real split-phase 240 VAC from smallish inverters,  they must be stackable,  and few are.

Current generatrion largish inverters  4-6 KW outupt can/do output 120/240 from a single unit,  and are stackable for more power.

There are a number of good True SineWave inverters on the market.  MorningStar makes a nice 300 W job, and Samlex/Cotek and several others are good units,  as I have read.

The following company (in which I have NO interest of any kind),  does a good job,  with reasonalbe prices on quality products,  and have been in the biz for a few decades supplying off-grid,  and grid connected parts/systems:

http://www.solar-electric.com/

They have a very active Forum,  with a number of reasonable and well informed fokls,  and those at all levels.

If the above link is not permitted,  just shoot me.

The only other thing that I'd add is that most battery charge controllers and all inverters,  anymore,  are SWITCHERS.  Many are LARGE switchers,  and DO generate  RFI.  For the most part CM Chokes do wonders,  as does running wires to/from them in metal conduit.

Our Grid is not very reliable,  and really cannot be,  even if well maintained,  when most of the distribution is above ground.  This is too bad, as it seems that many,  many folks are buying gensets,  fuel storage and PV/battery systems for these ever-increasing long power outages.  I would do the same ...

As has been mentioned here before,  a smallish Inverter generator can do wonders in running a refer,  TV,  AM radio and a few lights.  And could probably run weeks from fuel stolen from one's vehicle.  The little Honda EU-1000is,  here runs all of the above for a pint an hour or less of fuel.  Keeps my AM mode RX humming!  YMMV,  GL,  Vic

[K1JJ]

I had no idea that so many were using UPS or solar charged inverter systems.

Question:  How do we regulate the solar cell charging rate? Do we go into some kind of "smart" regulator?      I understand that battery charging is critical and even a trickle charge that stays on will kill a battery over time - especially the cheaper thin-plated car batt types.   

T

[K6IC]

Hi Tom,

For smaller systems,  PWM type Charge Controllers do a very good job,  and create less RFI than MPPT CCs, which are switchers.

MorningStar probably makes the broadest line of CCs,  altho anyone wanting a large CC,  should look at the Midnite Classic.

A link to many  CCs:
http://www.solar-electric.com/chco.html

For sealed batteries like AGMs or,  especially Gell Cells,  a Battery Temperature is important,  unless the batts are in a very temperature stable environment.

Yes,  the problem with using an unregulated charger,  connected for days to months,  is as the battery becomes fully charged,  its voltage rises due to decreased charge current.  This,  is very bad over a period of time,  as this is when the water from the electrolyte is broken down into H and O2.  This is an ineficient process,  generates heat,  increases the SG of the electrolyte (which can corrode the + plate of the batt),  and in time will reduce the electrolyte level to the point where the plates are exposed to air.  These things ruin batteries.

When using sealed batts --AGM & Gel,  it is fatal to do the above,  as the water cannot (really) be replaced,  as the batt is sealed.

Flooded batts -- ones with removeable caps --  are less expensive than sealed,  and one can actually measure the Specific Gravity of each cell,  and determine how well charged the batts are.  Sealed batts are nice,  as,  normally they do not emit gasses,  and require less maintenance,  although determining charge level is more difficult.  Altho taking a sealed batt off charge and off discharge for 3-6 hours rest,   and measuring batt terminal V  is a good indication of charge state,  if batt temp is known  ...   and so on.  Yammering done,   GL,   Vic

[K1JJ]

Hi Vic,

Thanks for the precautions and extra info.  Yes, I'm learning that charging it correctly makes a big difference in longevity and even outgassing for safety.

I will most likely get an AGM battery and that shud do the trick. Put it in a vented batt box and also put a tray under it in case of spill. I've also seen it suggested to put a layer of baking soda in the tray so that in case of a spill, the acid gets neutralized. In case of an explosion, then that's a different matter...

I shud have the 300w inverter and charger here in a day or so and will get the batt next. Might add some solar stuff later.

T

[N0WEK]

Back about 15 years ago I was at a hospital auction and bought a pure sine wave UPS for $5.00. It weighed about 150 lbs, lots of iron in it and it came with two 100+ lbs 96 volt battery packs which were dead. They had motorcycle sized 6 volt batteries in each 96 volt pack. This rig was good for 14 amps at 120 volts.

What I meant to do was use 4 of our expired24 volt lead acid aircraft batteries for a really big UPS. This had no switch over time, there was a 96 volt charging system which floated the battery packs and the inverter always ran the load. It sat in my basement for about 10 years and the aircraft batteries that I had went bad over time. I finally recycled the batteries and gave the inverter away.

Wish I had it back!

[K6IC]

Hey Tom,

Am sure that you will find the 300 W TSW Inverter very useful.

The AGM battery has "all" of the electrolyte Absorbed in a Glass Mat.  So, in theory,  even if the case broke or was cracked,  no electrolyte would escape.  They are in a non-hazardous category for shipping.

It would be very rare for an AGM to outgass.  Should only occur when significantly overgharged for a period of time.

With a good,  V regulated charger it should do fine.  Most AGMs,  I believe,  have a catalyst recombiner that converts any gas back into water.  But for large overcharge events  there will be some outgassing,  as I read it.

Have never seen any of the large UPSes that run at HV.   Sure a lotta batteries,  but they can supply a lot of power for an extended time.   GL  Vic

[K1JJ]

Well, there ya go.

Went to Walmart and bought a 114 AH marine deep cycle battery for $109.  (not AGM)   The battery is pretty heavy, maybe 50-60 pounds?

The plastic container was $5.  It has baking soda at the bottom in case of acid leaks, to neutralize.  Notice the vent holes, even though this is a sealed batttery.

The inverter is a $109 300 watt pure sine wave unit and the charger is an automatic $65 "smart" type that shuts off at full charge.

I added a 20A fuse to the battery as well as a disconnect 20A standard light switch.

Tried it out for a few hours with both a light bulb and the SDR radio and all seems to work well.   I don't plan to use it often and should not see a lot of discharges, thus, should last for years.  Maybe add a solar panel charger later.

Total cost: About $290.


So, if this is a 114 AH battery and I am pulling 2A, then it shud last about 57 hours continuous, right?   114/2 = 57.  Consider the pure sine inverter efficiency of about 80% - then let's make that about 45 hours (almost 2 days) at 2A, 10-roger?   The full size computer will take more current, of course, and might last 12 hours at best.


Another use I just thought of...  it could be used to charge any device that uses a 120 VAC wall wart, like cell phone, lap top, etc..

Whenever I need it, just slide it out of the closet, and plug in whatever.  I'll keep the smart trickle charger on it to keep it topped off.
Shud work out FB.


T

[W4EWH]

So, are you going to use the UPS circuit to detect the power failure and switch in the external battery and inverter? Or will this be a manually switched system? 

Just wondering, as I've considered the same thing my self, just to run critical items during an outage. 

I'll add a note of caution: most UPS units are very finicky about the frequency of the AC at their input, so if you're going to use a genset to provide long-term survivability, you most likely will not be able to use it to recharge batteries via a UPS.

I found out about this the hard way: those who want to read the long, sad story may visit https://groups.google.com/forum/?fromgroups=#!topic/rec.radio.amateur.moderated/Gs3wr8WgV6Q.

HTH.

Bill, W1AC

[WA3VJB]

Bill the units from American Power Conversion that were built in Rhode Island have a "sensitivity" toggle on the back panel.  

Frequency variance is among the parameters the APC is designed to protect against. In applications where frequency isn't critical, you can step through low-med-high sensitivity to keep the UPS within a range you consider tolerable.

I have a generator and four of the APC units, from 450VA to 2200VA. All are on "low," and all remain in charge mode when on the genset, applying the load to the generator and not kicking out until I shut down when it's time to refuel.

To get the most power efficiency, I supply 24V from two marine deep-cycle batteries (YEAH TOM, WAL MART's the deal!) to a smaller APC, the 650VA job.  All it runs is the fiber optic box for the internet and TV, and the wireless router that serves Pam and my laptops, tablet and smartphones. Only one or two "load" LEDs light up.

I put a 1500VA on the board in the Radio Lodge (3 LEDs load) have a 1000VA here on the compooter and monitor (one LED load), and have a cool little switched UPS that runs the scope and the audio gear.  You turn on any of the connected devices, and the UPS powers up.

The APC put out real sinewave.  I came across a TrippLite, new in the box, and quickly got rid of it when I realized it's either a square wave or a "modified" sine wave. Nice way of saying dirty waveform.

[K1JJ]

I have a generator and four of the APC units, from 450VA to 2200VA. All are on "low," and all remain in charge mode when on the genset, applying the load to the generator and not kicking out until I shut down when it's time to refuel.

To get the most power efficiency, I supply 24V from two marine deep-cycle batteries (YEAH TOM, WAL MART's the deal!) to a smaller APC, the 650VA job.  All it runs is the fiber optic box for the internet and TV, and the wireless router that serves Pam and my laptops, tablet and smartphones. Only one or two "load" LEDs light up.

Sounds like a well thought out emergency system. I like the idea that the generator is always charging the APC units.  Since none of us like to run a generator 24/7, this is an efficient way to "push-pull" it.

We have a 5Kw generator here, but have yet to set up multi-Kw APC units.  Maybe the next major power outage will give the required kick-in-the-ass.


Question:  What is the overall efficiency of a 2KW pure sinewave inverter - and a 300 w unit?  Do they get less efficient the larger they are?


T