Ups [uninterupted Power Supply]

[jaideeguy]

We get many power drops [fie dop] and blackouts, mostly lasting a few minutes, occasionally an hour or more and altho my computer has a UPS good for 5 min, there are other appliances that I would not only like to protect, but to be able to use and was thinking of simply getting a truck 12 volt battery and charger, then connect that to a power inverter of about 300-500 watts and wire up a separate plug arrangement for those appliances that i don't want to loose. I've replaced many power supplies in tv's computers and stereos due to voltage fluctuations.

I would need some kind of switching system like there is in a standard computer UPS, but I'm sure it can be done.

Is anyone out there doing this??

[Crossy]

It's not difficult to do, you need a few relays. 500W is only a couple of Amps at mains voltage, so conventional relays from Amorn will do the trick (no need for expensive contactors).

But to be honest I'm not sure it's worth it, by the time you've sorted out how it is to work, got the bits and put it together (remember we're looking at mains here so SAFETY is paramount) you may as well have bought a cheap 5-700VA UPS and modified it to use external batteries. That will solve all the issues of changeover sensing and safety.

The only rider on using bigger batteries is that the UPS probably won't be able to charge them, so you'll need an external charger (don't power it off the UPS output, we're not in the business of perpetual motion ). You may also want to install a 12V fan in your UPS as it will be running for longer than it was originally designed for and may run into overheating problems.

I know a couple of other TV members are running UPSs with external batteries, hopefully they'll pop up with experiences.

AH, and if you're going to use vehicle batteries, please make sure they are in a well ventilated area, we don't want anybody being blown up by vented hydrogen

[tjo o tjim]

For your stated need, you are better off getting a generator than trying to use a UPS or battery to do the job. Batteries just don't do a good job on long discharges; you only really can get 25% of its capacity.

You can make it work, but... it isn't easy to do it properly.

[jaideeguy]

generators= noise, gas, breakdowns

inverters= quiet, quick start, no fuel

would prefer to do it electronically...have seen new generation of power inverters that are 95% efficient and produce consistant voltages and frequiency with 'stepped' modified sine wave without producing frequiency hum and compatable with pc's and tv's.

[Crossy]

OK jaideeguy, you need something like this.

All the bits are readily available, RL 1 and RL 2 are 220Vac coil with 3x10A changeover contacts something like these http://www.maplin.co.uk/Module.aspx?Module...lay&doy=1m6 (I've seen them in Chinatown). RL 3 needs to handle the inverter input current, automotive relays are cheap, robust and readily available like this http://www.maplin.co.uk/Module.aspx?Module...lay&doy=1m6

How it works.

Normally with mains applied RL 1 is energised connecting the incoming mains to the load. RL 3 will be de-energised as there is no path via RL 1 contact 3.

When the mains fails RL 1 drops out, contact 3 closes and energises RL 3 which connects 12V power to the inverter, once the inverter is up to voltage RL 2 energises connecting its output to the load via RL 1 contacts.

When the mains returns, RL 1 is again energised and connects the load to the mains, RL 3 drops out and disconnects the inverter power.

SW 1 protects the incoming mains from your wiring and also functions as a 'test' switch.

NOTES

If your inverter will start under load you can omit RL 2.

If you're using a genset, leave out RL 3 and use the RL 1 contacts as your remote start/stop

[Naam]

For your stated need, you are better off getting a generator than trying to use a UPS or battery to do the job. Batteries just don't do a good job on long discharges; you only really can get 25% of its capacity.

You can make it work, but... it isn't easy to do it properly.

we installed 6 years ago an inverter in our holiday home (not located in Thailand) with a deep cycle batterie (124ah) which handles lights and fans in two rooms as well as a TV and a 2 PCs without any problem. until now never any problem although we estimated batterie life time 3-4 years.

[Crossy]

(not located in Thailand) with a deep cycle batterie (124ah)

Yep, it's the use of deep cycle batteries that makes it viable.

Attempting to save money by using vehicle batteries is a false economy as you only reliably get about 30-50% of their rated capacity (so you need bigger batteries for the same runtime).

[jaideeguy]

Thanks crossy, do you think an average Thai electrician could assemble this, or would I need an electrical engineer??

I admit to being a little bit of a dummy when it comes to electricity.

I 've had inverter/battery/solar power on houses, but never off the mains.

[Crossy]

do you think an average Thai electrician could assemble this,

This is of course the acid question, and something I've never considered as I'd always knock this type of thing up myself.

If you can find a professional electrician who does large projects then I'd say absolutely zero problem, however the bod who wires village houses probably wouldn't be able to read the diagram let alone understand how it is supposed to work (when it doesn't)

You'd probably do better talking to your local appliance repair chap to get it built, at least he's going to stand a chance of being able to understand the wiring.

[Naam]

(not located in Thailand) with a deep cycle batterie (124ah)

Yep, it's the use of deep cycle batteries that makes it viable. Attempting to save money by using vehicle batteries is a false economy as you only reliably get about 30-50% of their rated capacity (so you need bigger batteries for the same runtime).

question for you Crossy: do deep cycle batteries render also more peak short time (starting) amps? if yes, why? years ago i bought a second hand yacht and the batteries could not handle the starting amps of the aircon compressor. it turned out that the former owner replaced the original batteries with a set of car batteries with identical AH. after mounting deep cycle ones (based on the inspection and advice of another boat owner) no starting problems.

[Crossy]

question for you Crossy: do deep cycle batteries render also more peak short time (starting) amps? if yes, why? years ago i bought a second hand yacht and the batteries could not handle the starting amps of the aircon compressor. it turned out that the former owner replaced the original batteries with a set of car batteries with identical AH. after mounting deep cycle ones (based on the inspection and advice of another boat owner) no starting problems.

I'm most definately not a battery expert! So the physical/chemical differences between these beasties is outside my experience.

As I understand it, vehicle (starter) batteries are designed to handle very large (cranking) currents for short times rather than constant smaller drains. Starter batteries have many thin lead plates which enables them to discharge a lot of energy very quickly - i.e. to start a vehicle. However, if a starter battery is discharged deeply, its plates can be permanently damaged and the lifetime of the battery greatly reduced.

Deep cycle (or traction) batteries are designed to be drained to lower charge levels without damage. Deep cycle batteries have fewer thicker lead plates, and so cannot discharge energy so quickly, but can be cycled deeply and recharged many times without damaging the battery. Deep cycle batteries are designed to provide a steady current over a long period of time. These batteries have a lower (although still pretty substantial) peak current capability being intended to supply a smaller, more constant load.

When batteries are frequently deeply discharged then sulphation build up occurs. Sulphur molecules from the battery acid (electrolyte) start to coat the lead of the plates. Once the lead is coverered in sulphur the battery is dead and cannot be recharged. Sulphation starts occuring once the charge of a starting battery descends below 75%. I'll bet your yacht batteries (vehicle type) had been shagged by constantly being taken to a low charge state.

Interesting information here http://www.windsun.com/Batteries/Battery_FAQ.htm

[jaideeguy]

Where would one find deep cycle batteries here?? In another place far across the ocean, we used tractor/bulldozer batteries. are they the same same??

two 6volt batteies in series....maybe they have 12 volt now?

[Naam]

Where would one find deep cycle batteries here??

in boat shops. but most probably very few up north.

[Naam]

When batteries are frequently deeply discharged then sulphation build up occurs. Sulphur molecules from the battery acid (electrolyte) start to coat the lead of the plates. Once the lead is coverered in sulphur the battery is dead and cannot be recharged. Sulphation starts occuring once the charge of a starting battery descends below 75%. I'll bet your yacht batteries (vehicle type) had been shagged by constantly being taken to a low charge state.

i don't think that was the case as the yacht had two huge alternators which provided ample amps when the two Volvo engines were idling at less than 550rpm.

[Crossy]

Obviously without seeing and testing the batteries its all guesswork.

Those bloody great alternators do nothing if the engines ain't runnin. If the previous owner ran on the batteries until things started acting up and then ran the diesels to re-charge rapidly, then repeated the discharge, I reckon he'd shag a vehicle battery in a few weeks

[Naam]

Obviously without seeing and testing the batteries its all guesswork.

Those bloody great alternators do nothing if the engines ain't runnin. If the previous owner ran on the batteries until things started acting up and then ran the diesels to re-charge rapidly, then repeated the discharge, I reckon he'd shag a vehicle battery in a few weeks

that must have been the case. i bought the boat from him when it was only 16 months old. had it then for another 1½ years and no problems after fitting the deep cycle batteries. until now i don't understand is why the aircon compressor wouldn't start even when both engines were revved up but the deep cycles could do the trick.

[Gary A]

Where would one find deep cycle batteries here?? In another place far across the ocean, we used tractor/bulldozer batteries. are they the same same??

two 6volt batteies in series....maybe they have 12 volt now?

Having a cabin in the deep woods was popular in the US. Most with modest requirements used golf cart batteries. When more power was required they used fork truck batteries. The fork truck batteries were 48 volts and probably weighed about a ton, maybe more. They were approximately a meter square and a meter deep. They ran the three ton capacity fork trucks for 24 hours. It was the drivers job to change batteries at the first shift starting at 8:00 AM. An electric chain hoist was used to lift them in and out. The batteries must have lasted for years because I don't remember ever seeing any new ones.

[jaideeguy]

We got golf courses up north....so that means we got golf carts, unless they're using buffalo powered carts.

But would a golf cart battery be overdoing it if all i want to have is maximum 500watts for maximum 4 hrs??

Can someone do the math for me please and tell me what would be a reasonable sized battery for my needs??

[Naam]

We got golf courses up north....so that means we got golf carts, unless they're using buffalo powered carts.

But would a golf cart battery be overdoing it if all i want to have is maximum 500watts for maximum 4 hrs??

Can someone do the math for me please and tell me what would be a reasonable sized battery for my needs??

my [uneducated] guess is that a car batterie (48ah) should suffice. but you still need an inverter. have no idea whether one can rig the car batterie to the inverter of a UPS which is around 1,600 Baht and i doubt whether the UPS charger can handle the charging load of a car batterie.

[cloudhopper]

I recommend golf cart batteries for deep cycle use here. Deep cycle batts have thicker plates for slow deep discharge whereas the common auto batt has thin plates and can deliver high current for a short time. 3K makes an equivalent to the Trojan T104, a 6V 225Ah golf cat batt for about 5k Baht. You will obviously need 2 in series for a 12V inverter. I am VERY dubious about sourcing the various 230VAC relays or the tech help in assembling the schematic posted and instead recommend a sine wave inverter/charger like a Xantrex which has an internal auto transfer switch in case of fai dap. As you probably already know any misstep with a generator or inverter can back feed into the mains and cause a lethal shock to line crews...

[cloudhopper]

We got golf courses up north....so that means we got golf carts, unless they're using buffalo powered carts.

But would a golf cart battery be overdoing it if all i want to have is maximum 500watts for maximum 4 hrs??

Can someone do the math for me please and tell me what would be a reasonable sized battery for my needs??

500 watts X 4 hours = 2000 watt hours

/12 VDC = 166 Amp hours (because 1 watt = 1 volt X 1 Amp)

Although the batts I recommended in the previous post have a nominal cap of 225 Amp hours, draining even "deep cycle" batts past 50% will severely shorten their service life. So if you think you will experience many episodes like the one you describe, I would buy 4 T104 batts to give you a nominal 450 Ah @12VDC in series/parallel.

[Crossy]

We got golf courses up north....so that means we got golf carts, unless they're using buffalo powered carts.

But would a golf cart battery be overdoing it if all i want to have is maximum 500watts for maximum 4 hrs??

Can someone do the math for me please and tell me what would be a reasonable sized battery for my needs??

Ok, quick and dirty.

500W @ say 80% efficiency of your inverter gives an input power of 625W

At 12V 625W = 52A so to keep that going for 4 hours we need 208 Amp Hours

We really don't want to use more than 50% of our charge so you'll need 400 AH worth of batteries (if they're deep cycle).

Looking at the specs, the 12MD325 (rated at 325AH) http://www.rolls-europe.com/PDF/12md325p.pdf battery will give you 50A for 4 hours, weighs-in at 90kg and will cost you a cool $1400

Seems obvious why the previous owner of Naam's boat put vehicle batteries in

If you want to use vehicle batteries, I suggest you don't go more than 20% discharge for a decent life so you'll need about 1000AH worth. Be aware that vehicle battery capacities are often quoted as CCA (Cold Cranking Amps) rather than an absolute Amp Hour rating just to add confusion.

[jaideeguy]

maybe time to downsize, after checking prices of inverter/chargers and batteries....in the average year, we have maybe 3-5 days when the power goes out for more than 3 hours, after a storm. most times it is only a few minutes to an hour or so.

my main concerns are running 2 air pumps for the fish, keeping up to 3- 20 watt lites going, my pc, tv/dvd [low priority].

I want to isolate these circuts to accomodate the 'stored' power, so the rest of the house with aircons and big lites are not draining the batteries and 'rough it' during the black-outs, so maybe I could get away with less $ output.

I have a water tower that holds a days+ supply of water, so no drain from pumps and can always take cold showers, in fact enjoy cold, most of the year.

I'll keep googling until i find a unit that suits me. those Xantrex inverter/chargers sound cool, but I'm not a rich boat owner....just a lowly falang on a budget.

[jaideeguy]

to expand on my pc's needs.....I have 2 pc's, router, hub, 2 lcd monitors.....what would be the approximate wattage for that?? it hurts to be off line!!

[Gary A]

to expand on my pc's needs.....I have 2 pc's, router, hub, 2 lcd monitors.....what would be the approximate wattage for that?? it hurts to be off line!!

Here is a system that works like your computer UPS.

Xantrex PowerSource 1800

852-1802 - PowerSource 1800

Our Price: $599.99

1800 watt continuous, 3600 watt Surge

- Built-in 5amp Charger

- Built-in 15amp Transfer Relay

- Includes (1) 60aH Sealed AGM Battery

Battery Backup Power Systems

Alta Power Corp offers a full line of Battery Operated emergency power systems that can supply from 400 wattts to 1800 Watts* of household electricity – enough to run most electronic and electronic appliance you would connect to your wall outlet. These Power Systems store household electricity in an internal battery bank and provide instantaneous power to your critical electrical appliances when utility power fails. Battery Backup Systems are a clean quiet, smart, alternative to a generator, produces no emissions and is safe to operate indoors. *wattage rating depends on model of power system selected.

How It Works

Simply plug your electrical appliance into the Battery Backup System and plug the Battery Backup System into a standard wall outlet. Once appliances are connected to the Battery Backup System, the Battery Backup System will continue to use your utility power until a power failure is detected. Once a power failure is detected, the Battery Backup System will instantaneously begin to supply standard household electricity to any connected appliances. Once utility power is restored, the Battery Backup System will automatically switch your appliance back to utility power and immediately begin to recharge it’s internal batteries in anticipation of the next power failure.

[Naam]

I want to isolate these circuts to accomodate the 'stored' power

mandatory but very difficult if not done during construction!

[Naam]

Our Price: $599.99

1800 watt continuous, 3600 watt Surge

- Built-in 5amp Charger

- Built-in 15amp Transfer Relay

- Includes (1) 60aH Sealed AGM Battery

too expensive for what is offered

[jaideeguy]

I agree with Naam, as I quick googled that model and found it priced just over $300. is gary a selling them??

And yes, naam it will be a little wiring challenge, but I have double walls and can get away with 3 or 4 outlets, all in close proximity.

[jaideeguy]

further reading tells me that it provides 120v. nice tidy little package, but too expensive and small batteries. may source the inverter/charger in 220v version and pick up batteries locally.

[Crossy]

There are a number of el-cheapo low output UPS's on the market, you MAY score by using a separate small UPS for each application, modified to use external batteries to get your required runtime. Obviously your PC will need a decent UPS, but the fish could well be happy with a 1500Baht Chinese unit Doing it this way would certainly simplify your wiring requirements.

For lighting use some rechargeable lanterns, since you don't have particularly regular outages they won't be too much of a problem.

Have a look at this document for adding batteries to your UPS 7954.pdf