Check out my new DIY power back up! (400k of pics)

[Playfair]

The quest was for a reliable, cost effective backup system that would come on automatically in the event of a power failure and run my MAG18 return pump for 8 hours...

The result cost under $175 total, and consists of a 95ah deep cycle battery, power inverter, automatic trickle charger/maintainer, and a DIY transfer switch.

The main unit is in the basement, with only an outlet box in the cabinet.


This outlet has a cord that plugs into the main GFI, and routes power through 2 legs of 4 conductor wire down to the UPS. Either house current is sent back up, or it is switched over to inverter power.


Here's a top view of the backup

The heart of the system is a transfer switch that consists of a relay normally energized with house power, and when that is absent, it turns on the 300w AC power inverter, and sends that power back up to the outlet.

There are a few other bells in there, like a test switch, audible alarm, and indicator lights.

It took quite a while to design, build, and debug, but so far it has tested out perfectly, and at a fraction of what a similar commercial UPS would have cost

[mobert]

Playfair, that looks pro! I have a generator but I still have to be home or awake to turn it on. (not to mention how fast it would use up gasoline). Do you think you might be interested in building a transfer switch for sale? I can probably figure out the rest but that transfer switch is beyond my capabilities.

[GH Sniper]

I just use an APC UPS 1400 to power my stuff in the event of a power outage.

[deReef]

Do you have a parts list and a drawing on the switching system?I would really like to build a system like that too.At present I am using a UPS backup power supply but it will only keep the reef running for 30 minutes before it dieds out.
I do have all of the major components and thought about doing the same thing that you have done.Looks really nice and compact.

[Playfair]

GH sniper... A true UPS is great, except the one you mention is over $500 new (>$200 rebuilt on ebay) and would only power a 100w pump for about 2.7 hours.

Mobert... I'm kind of burnt out from DIY right now, however, there are a couple of people who would like me to build them one... Unfortunately, may labor aint cheap cause there aint enough hours in the day... prolly looking at $75 for the xfer switch alone, and a 2-3 week lead time

Here is the scematic of the relay, which is the main component.

I added a buzzer (and switch) across the AC from the inverter to let me know when it was running, a couple indicator lights, and a test switch that cuts line ac power to the unit for testing. Also, the whole thing is fused at 3 amps.

feitelb, it may be worth looking into increasing the capacity of your UPS, perhaps by adding more batteries in parallel? This may get tricky for the charger, and those Gels are $$. I know that the chargers are different for UPS gel batts vs. lead acid.

Here's the total parts list:

-Marine 95ah deep cycle battery $45 (auto zone)
-Battery case $10 (auto zone)
-Schumaker auto trickle charger $25 (auto zone)
-Inverter- I used a really nice one that runs about $75, but you can get a 150w for about $40
-120v 3pdt relay (I found cheap 4pdt) $5 (all electronics)
-Extension cord for line in/out of the xfer box $5 (HD)
-misc. components... electrical and project boxes, ac outlet, wire, spade connectors, in-line fuse holder and connectors $20 (all electronics, radio shack)
___________________
~$150**


**without some of the "extras" like the expensive inverter (running a full 300watts would only last 3 hours), 4 conductor cord, alarm, indicator lights, etc.

The only "off the shelf" item that was modified was the inverter. I didn't want it on all the time, so I wired the power switch in series with a leg of the relay so it could be remotely turned on when the power failed.

FWIW, the next size up battery is 110ah, which for $16 more gives you 15% more run time. I just wanted the thing to work until I get home from work and hook up the big inverter to the car (or generator someday)

[erich]

Is the output of an inverter safe for a pump? Most inverters I've seen don't produce true sine-wave output, just step-wave. Will that damage the pump?

You can get UPSs that produce sine-wave output, but they cost more...

[Playfair]

I've run mags and rios off "modified sine wave" supplies (most inverters and UPS) for up to 9 hours at a time (last years power failure) and they are still running fine today. I do notice they run a tad louder do to the "abrupt" waveform shape, but no warmer.
It's not like they are precision motors, just a magnet and coil...

[mobert]

Well, once again, I have fish gear envy. Looks like I'd have convert the guest bedroom behind the tank for this and the new 100 gallon refugium (in my dreams).

Playfair, thanks for the food for thought. At least I can run a cord to the garage and manually plug it into the inverter in the car. Any idea how long I can run a 55 watt pump before my car runs out of starting power?

[Mako]

Playfair - Very nice! Thanks for sharing that great setup.

I have been toying with the idea of a DIY UPS that I could configure for my requirements and not have to drop the big bucks into for awhile now. I pretty much invisioned this exact setup and was getting ready to start till I found this. The pricing on it is not too bad and I was just hung on what my time would be worth to do my own. Decisions, decisions!

[Playfair]

Mobert, I would think the pump would run for several hours, but car batteries don't like to be discharged like that. I have a 600w inverter that I can run my return pump, skimmer, ph's, and VHO lighting or heater... During a black out last year I ended up just leaving the "leased" car idling for 9 hours. The alternator puts out about 50amps, which is what I was drawing.

Mako- That device you linked to is what MADE me DIY! Same thing, for less than 1/2 the cost... And it doesn't include the battery(ies).

That unit does have 500w capacity instead of 300, but it would take a lot of juice to last very long sucking that much power. (500w=~45 amps@12v, which means one 90ah batt would only last 2 hrs). I choose to be realistic at running only my pump and cabnet light, but overrating just a little.

One other difference I see is the "delay" feature. Sounds neat, but I probably won't incorporate it right away.

[odenwell]

Playfair,

I can't see your pictures. Can you re-post them?

Here's a thread showing my system .

[Playfair]

Odenwell, sorry about the pics, there was a prob with the server that is all fixed now.

I checked out your system... I missed the original post! (must have been back when I thought the power never went out lol) Could have saved some time based off your experience! I thought about running 2 batts, or even 1 larger, but for the amount this thing will be used (hopefully never) I couldn't see spending the extra. That opinion may change though...

The only major difference in our designs is that I use a 120v relay to cut both neutral and hot to the pump as well as switch on/off the inverter through the low amperage power switch instead of cutting the main supply leg (25 amps!). This allows me to run equipment off the same outlet for both house power and backup power.

If I build another one for someone, I may just use a 150w inverter that has no fan and can be left on all the time, requiring an easier to find DPDT 120v relay...

[ByTor]

Very nice!! Dude, your like...... soooooo intense!! Job well done!

[deReef]

Playfair
I just finished building the unit.It is awsome and works great.I did upgrade a few of the components but I have the advantage that alot of people don't.Pull in a few of the favors owed me and it got it done.Inverter from a amublance (1000watt), aircraft gel battery with its charger and a AllenBradley relay and some other componets.Thank you for the info it was great.

[GROSSR]

Concerning a UPS, I have an 800 watt UPS. I have a server that needed it, and got rid of the server. I have a RIO 2500, 2 small power heads, 150 watt heater and an air pump on this UPS. No lights, no UV.

I lost power this morning, the UPS alarm went off, and I said, AHHH, I am feeling good, the power backup Gods are looking kindly on me.

I stepped into the shower and took about a 20 minute shower. I came back to nothing, the UPS drained.

I got my POWER BACKUP from the car, those bricks if you leave the lights on, connected it to a power converter and ran a 1 amp pump.

That lasted about 3 hours, enough time for the power company to get its act together.

Moral of this story : A UPS is good only if you have it setup correctly.

I like your idea of only running the pump. For me all I need it water circulation. I would put my device on one or two powerheads. Forget the skimmer, airpump, UV or whatever. Just get water moving past those beautiful corals.

Thanks for listening.

Bye the way, very nice setup.

[odenwell]

I think Playfair's system is very cool. It's nice because it works just like a UPS and will keep his pump running for a moderate amount of time and nothing in the tank will miss a beat. Nice design, quite a feat of engineering if you ask me. The system I designed was for more of a long term outage. Mine could go for a couple days, perhaps longer, unless I plug in a heater. I only use a couple of Hagen Maxima 4.5 watt air pumps, each connected to a 6" airstone hidden behind the rock work. When these things come on, there is a pretty substantial current in my 200 gallon tank. The fish might stress a little, but nothing is going to die from lack of oxygen. I also have 4 fully charged batteries that I use in my camper that I could use if the power were out for a really LONG time.

[Ermin]

Both Playfair and Odenwell,

I've email both of you before on your backup designs (Bob, a long time ago)...... are you guys concern about the fumes given off by the flood cell marine batteries? I'm going to finally build mine in a couple of days....I'm concerned with the acidic fume produced, since the setup will be inside the home.

From what I've read online, the new AGM type will produce very little, if not, no fumes at all when charged properly. The drawback is the cost.

55AH AGM battery is about $120 versus the 95AH deep cycle marine battery for $50.

What do you guys think?

[Snailman]

The fumes are not acidic they are hydrogen and the problem is an accumalation of hydrogen and a spark can mean ....boom. The question about the AGM battery is it deep discharge like a marine battery?

[odenwell]

The only significant fumes that could occur are while charging. Since this battery is constantly at a full charge state, there are little or no fumes ever given off. In any case, the back of my stand is open. The battery will only give off a significant amount of fumes if you are sending it lots of amps and it is near or at a fully charged state. The battery will make a boiling sound when this happens. The little battery maintainer that I use doesn't have enough amps to do this, plus it automatically reduces the charge rate to nothing as the battery becomes fully charged.

[Ermin]

Snailman,
I asked you about wiring up two float switches for top-off couple of weeks ago. It worked great! I didn't have the chance to thank you on the other post, so I'm going to say thanks here!

And yes, the AGM battery I've found are deep discharge like marine battery. Accumulation of hydrogen to cause explosion.....if the room is moderatly ventilated daily, would that be a problem? Basically how much fume does it take to BOOM? Also is hydrogen deadly when inhaled? This is more of a concern than explosion to me.

Bob,
I'm planning to just a 750ma charger to charge and maintain the battery. It switches to float charge automatically when the battery is almost full. I'm assuming charger capable of boiling a battery outputs at least, at 2A?

"Is it true to assume the battery will produce fumes regardless of charging amperage. Significant fumes is ONLY produced when the battery is overcharged and is thus boiling? Battery charged at low amperage produce negligible fumes?"

Thanks for you help. This will really make a big difference to the total price and amount of backup time I'll get depending on the battery I use.

[GreatLakes]

Great idea. I would be sure to opt for the 300w inverter however, I have had poor luck with the smaller ones...Kudos

[Bart]

Playfair and Odenwell,

I am planning on putting together a power backup for my tank. I have been doing some comparison shopping as was going to take a trip to Radio Shack and some electronic stores. I have two questions.

What does "pdt" mean (3 pdt relay)? I will add it to my reference list...

Most of the power inverters I have seen have a voltage lower than 120v, usally 115v or 110v. Is this normal?

[kcolagio]

3pdt is Triple Pull, Double Throw.

Dave, Great job on that unit. Makes me want to dig out the soldering iron again...if I could find it.

[Ermin]

Playfair,
Aside from my questions on the last post....I am also wondering what to do about the ground. Most big pumps have three prong plugs. I've noticed that you have included that in your transfer switch setup. But, where does the ground wire connect to on the relay?

Also, what is the "mode switch" for?

Thanks again!

[Playfair]

Above comments are correct about the fumes, I've read there is no problem trickle charging as long as the battery is free to vent. However, if the battery does fully discharge during usage, I may hook up a larger charger to bring it back up in a shorter amount of time, and will aim a small fan at it to disperse any gasses.

115v inverter will be fine, I would stay away from the 110v ones though (sounds like they are being cheap). Lower voltage produced means the current draw will be higher to get the same power. This means if a motor is rated at 1A at 120v, then at 110v it will draw 1.1 amps.

I was thinking the same thing as GreatLakes about using the larger inverter, I would rather the thing coasts along driving my pump than pushing it's rated limits. Plus, you could always add a second battery to extend run time/load capabilities without much trouble.

A far as the outlet ground (good question, gave this a lot of thought!) The house ground is tied to the output ground directly all the time (doesn't go through the relay). This means the inverter ground is not tied to anything. Even when the power fails, your house ground still works