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

[Zephrant]

Sure-

A fast blow fuse has a lower mass, so it heats up a "blows" faster. A slow-blow fuse can have a ceramic center, with the wire wrapped around it. This acts as a heat sink, and keeps the element from heating up as fast.

Note that in a direct short, a LOT of amps flow, and EITHER fuse will blow in a fraction of a second. The slow blow is useful for surviving the (softer) spikes that a starting motor can cause, without popping.

Fast-blow fuses are normally used for electronics, where you are trying to protect the electronics from destroying itself. (Even though all fuses are insanely slow compared to the nanosecond electronic rates...).

So to recap, if you are running a motor, a slow blow that is rated at least at it's peak draw, or about 20% above it's normal draw (whichever is higher) should provide decent protection.

[Icepic]

on your fuse blowing problem

here is a quick ohms law formula for ya

Amps= watts\volts

let say 800 watt just incase you want to add something later devide it by 120 volts
= 6.66 amps so about 7 amps give or take a little

would work for your fuse to keep it from blowing

[JEMichael IV]

Have any of you thought of using the Optima Gell Cell batteries? These dont contain Acid, and could be mounted upsidedown if needbe and since there is no acid I would assume there would be no fumes? Maybe I am wrong. I am looking into doing this and I have a couple of these batteries from my last stereo system.

[minfinger]

This one only powered my 55Gallon Reef for about 25 minutes.

Belkin 800VA

I've got a 65watt hood and 2 poweredge 402s the switch back and forth for wave making. I think it's a Mag 500 (?) in my Wet/Dry and i just added a little skimmer.

I didn't think 25 minutes was that bad for the whole system, but I was expecting at least 1 hour. I've got bad power in my neighborhood, so I left the whole thing hooked up to the UPS.

I may get another one and seperate some of the equipment between them, at least it will last longer. I think

[Russ]

I'm building playfair's DIY battery back-up today. I've got the same relay (120VAC 4pdt). I'm planning on running 5 things off of it: Heater (250watt), DIY wavetimer (Reeftech/MJ powerhead), 5volt DIY powersupply (to run 555-timer circuit in the DIY wavetimer), Mag7 return pump, airpump.

I've got a 500watt Cobra HG inverter (w/rebate it only cost me $40). I've opened it up, so that I can put the third leg of the relay in series with the inverter's power switch.

For the fourth leg of the relay, I was thinking I would put a small airpump that I had lying around in series. Then, when the power goes out, the small airpump will turn on automatically for oxygenation -- since my skimmer won't be running during power outages.

QUESTION: I guess I'm going to put a 5amp slow-blow fuse in series on the output. Do I put the fuse on the neutral or the hot side? Or doesn't it matter? Maybe I should go with a 7amp fuse?

[Russ]

Well... Things are getting a little bit more expensive than I thought.

For the same charger playfair used cost me $30.
For a battery... $80.

Since they don't rate batteries in amper-hours (ah) anymore, I was a little confused about which to buy. Thankfully, I went to this place called the Battery Warehouse in Reisterstown, MD, where there was this guy who knew everything there was to know:

For a ROUGH approx of a battery's amper-hours:

ah = crank / 5.25

My battery's crank was 625, so my ah=625/5.25 = 119ah.

I should finish hooking up the relay and building the rest of the contraption tonight. I'll let you know how I make out. Keep your fingers crossed!

[minfinger]

Ok so from the 119ah how do you figure out how long your stuff will run?

[techy]

Hi Playfair,

I read your posting on the DIY UPS with interest and I want to build one. I managed to buy one relay switch (Brand: Omron, model: MK3P-S which is the same as MK3P-I, S) which is very hard to find one in Singapore. But being not an 'electrical' person, I have no idea on how to connect the various wire to the switch. I downloaded the switch specs from Omron web site but it did not mention anything about the connection.

The switch comes with 11 pins and according to the store person, it is a 3PDT type. Would you be so kind to share with me what needs to be connected to the 11 pins. Based on your circuit schematic posted to Mobert dated 18 Feb 2002, if you could number the dots, that will be great. Thanks in advance for your help.

[Playfair]

Glad to see people are still using this thread! I don't get over hear much when I'm not building something! lol

Originally posted by Russ
QUESTION: I guess I'm going to put a 5amp slow-blow fuse in series on the output. Do I put the fuse on the neutral or the hot side? Or doesn't it matter? Maybe I should go with a 7amp fuse?

The fuse should go on the hot (black) wire. It is not used to protect the inverter (safety is built in), but instead the relay. Since the contacts are only rated at 5A, we need to guarantee they don't see more than that with an easilly replaceable fuse.
Good idea for using the 4th leg of the relay! You could also use one of the other outlets on the inverter for "emergency only" power.
As far as the battery, last I checked, all deep cycle are rated in Ah... Yours sounds like a starting battery; not the best choice, as they do not like to be discharged, even if the capacity is adequate.

Techy, I think you should find someone who will understand the schematic and draw you a new one for your particular relay. PM me if you want to send the dwgs of yours and I'll give it a shot.

I still have yet to get real use out of this thing!

One note on deep cycle battery maintenance that I've run across is that they need to be slightly "over charged" (bubbled) every few months for an hour or so to prevent the acid from stratifying, which would reduce their capacity and life. I'm trying to make a point of running the backup long enough to partly discharge the battery, then charging it off a "heavy duty" car charger with deep cycle capabilities once in a while.

To figure out run time using a 100Ah battery as an example: P=IV
12V@100Ah=1200Whrx90%(inverter efficiency)=1080Whrs.
So, if you have a 100W pump, 1080/100=10.8 hrs.
At least, I hope this is how it works!

[techy]

Hi Playfair,

Thanks alot for your prompt response. I managed to figure out all the 11 pins connections my self (with the help from the sales person who sold me the relay switch) via the 'see-thru' casing of the switch. Initial testig of the switch (ie. energizing it, supplying AC current for output and placing an AC led light for testing) proved that my connections are correct. The next phase of the test is to link the inverter's AC supply to the switch and the cut-over of the AC supply from AC wall outlet to the inverter.

Couple of questions.

1. Are all regular car batteries has about the same Ah ratings (not sure I'm using the correct terminology; I'm referring to the rating where how much energy a battery can stored. For eg. an AA size battery can range from 600 mAh to 2000 mAh) ?

I intend to use a regular car battery (12V, 15 amps). Those that need to top up with distill water type. I read about your comments about, such battery is not suitable for this job since car battery does not like to be discharged in this manner.

2. If you can explain a little on what is a 'deep-charge' battery, that will be great. Such battery is usually for what purpose (eg. for boat, etc.) ?

Thanks in advance for your help.

best rgds,

[minfinger]

Playfair, if your math is correct, that's just simply amazing. Now I'm going to have to build in a seperate cabinet in my new fish stand for 2 of those batteries. BABY I WANT TO RUN THE WHOLE TANK! LOL Well at least the pump and the Heaters.

[techy]

Hi Playfair,

I've completed the entire project over the weekend. The only thing short on the list is to find a deep-charge battery. I managed to learn about differences between SLI and deep-charge batteries via 'Optima batteries' web page. It will be a tough quest to look for deep-charge battery in Singapore. Anyhow, thanks alot for your sharing on this DIY UPS. Without your contributions, I don't think I can come out with this idea cost-savings and effective method. Once again, thanks alot. Keep up the good work.

cheers,

[Russ]

Originally posted by Playfair
As far as the battery, last I checked, all deep cycle are rated in Ah... Yours sounds like a starting battery; not the best choice, as they do not like to be discharged, even if the capacity is adequate.

Actually, it is a deep-cycle marine battery (says so right on the battery)... I got at at the "Baltimore Battery Warehouse"... where all they sell is batteries. I was surprised when the guy said they don't rate batteries in Ah's anymore too. They manufacture their own batteries, so maybe it's just them. Anyway, it's a deep-cycle marine battery.... so, I'm all good.

Thanks again for all your advice Playfair! My DIY battery-backup is complete, and works flawlessly. Just a few lingering questions:

Question #1: I have the battery maintained on the same trickle charger you do. I don't have a "heavy-duty" charger around to "overcharge" the battery every few months as you suggest. Do you think I could just hook it up to my car's battery and let the car run, so that the alternator will charge/"bubble" it? How long do you think I should let the car run?

Question #2: I haven't opened up the battery yet to look at the fluid level. How high should the level be maintained at? You top it off with distilled water, right?

Question #3: I'm really curious to see how long the powersupply will hold-up in actuality? Do you think it's a good idea to let it run all the way down, until the inverter shuts down (due to low voltage [i.e. battery is drained]), in order to see? Or, will this really kill the longevity/life of my battery?

[Fourseahorsemen]

I started this project by purchasing a 125ah marine battery, a Schumacher 375w Power Inverter, and a Deltran Battery Tender charger/maintainer. Now that I am commited, I am having dificulty understanding how to build the Transfer, and how to wire the inside of the outlet box in the cabinet. If someone could be kind enough to walk me through the wiring in a little more detail, I think I could do it. The inverter has a low battery alarm, but it has a built-in fan so I need to swith it like playfairs. Or if somone wants to build me a transfer, I would buy it from them.

Thanks, for any help.
Jeff

[StirCrazy]

Originally posted by Russ
Actually, it is a deep-cycle marine battery (says so right on the battery)... I got at at the "Baltimore Battery Warehouse"... where all they sell is batteries. I was surprised when the guy said they don't rate batteries in Ah's anymore too. They manufacture their own batteries, so maybe it's just them. Anyway, it's a deep-cycle marine battery.... so, I'm all good.

Russ, Check to see if it has a "reserve" rating should be 200min or something like that. this is how long the battery will last with a 25 amp draw and is another standard ration on Deep Cycle batteries. I am having a hard time finding amp hour ratings also..

so lets say the reserve is 200 min then multiply that by 25 and devide by 60 and you will have amphour ratings. I am looking at a "golf cart" battery which has a reserve of 440 min to make one for myself. This will power my mag drive 12 and a 250 watt heater for a min of 6 hours (if the heater is on constantly)


Steve

[Gerard the fish]

I just take a row and mix that water up till the power comes back on

[Wazzel]

Given the large power outage in the NE I figured this thread needed a bump top the top.

[minfinger]

Yeah Playfair, Did it work

[sixpackrt]

i bet it didnt work as planed he hasnt been on since the 13th
i hope it did

[ByTor]

To quote Playfair from a short and to the point email....

"Thanks man, no problems here. The autobackup kicked in for an hour before I got home, then I got the generator fired up."

Just another day

[Playfair]

Thanks for coming to the rescue, BT

Here's the updated scoop:
I sold my original 1 yr old DIY unit to a guy in my reef club, as the Mag 18 I am using creates pretty severe voltage spikes that damaged the inverter during testing. He has sinced used it several times over 6 months running with a Mag 7 and it's worked great. I figure it is good to at least a 9, maybe a 12. Someday I'll bring a scope home and see what the hey is going on with the pumps...

Anywho, I started looking around for components to make a new BIGGER and BETTER backup. In addition to a higher capacity inverter, I wanted a 3 stage battery charger. By the time I priced the components out, it was close to a commercial extended run UPS...

After MUCH searching, I picked up a Tripp lite APS512, and it's the nutz! It has the old technology transformer style inverter, which produces a cleaner waveform and surges to 1200 watts (500 continuous), as well as multiple battery capability. Price varies to over $400, so be careful. I don't recall where I got mine from, but the above link is the cheapest price I ran across today (Batteries not included).

So, if you have a reletively small system, my original backup is very cost effective and reliable. However, for larger pumps and demands, a commercial unit may be better.

[odenwell]

I'm sure it's been mentioned before, but modified sine wave inverters are not real good at running inductive loads like a motor. You usually get a lot of chatter and little, if any, water movement. The best inverters for this purpose are true sine wave, but they can be a little pricey. For my backup system that I built a couple years ago, I use multiple air pumps with 6" air stones. When the power goes out, the air comes on. Worked great twice this summer when the transformer on our block blew. We now have a new transformer. Modified sine wave inverters have no problems with air pumps and heaters. BTW, as a shameless plug, I have a 300 watt true sine wave inverter that I can sell for $100. I used in my camper until recently. It should work fine for large powerheads or small external pumps. I can test it on a large Otto powerhead and an Eheim 1060 if someone is interested. Email me if interested.

[rmendis]

Total noob questions: How can I calculate what size inverter I will need to power a couple MaxiJets and a heater?

Follow up: If using my car battery as the source, how often will I need to start the car to power this load?

Thanks!

[Mr_Quality]

I'm glad this thread got a bump. I wish I had seen it it time to build one for H. Isabelle. But looks good for the next time though.

Mike

[Russ]

Originally posted by odenwell
I'm sure it's been mentioned before, but modified sine wave inverters are not real good at running inductive loads like a motor. You usually get a lot of chatter and little, if any, water movement. The best inverters for this purpose are true sine wave, but they can be a little pricey.

Actually, IME the modified sine-wave pumps are pretty darn good. Most you can use with the inductive loads used in the hobby without much problem. They claim you can use them on TV and Hi-Fi's w/o interference, but I don't 100% believe that claim. I wouldn't use them to power expensive electronic equipement (i.e., that Pentium 4 computer), but STILL they probably make them a lot better now-a-days. I have a Portawattz, and it's given me no problems with 3 Maxi-jets1200's, a Mag9, an airpump, and heater -- a pretty big load.

Calculate your load by adding up how many watts each device consumes (usually listed on the back as Watts... Remember that [Power = Current * Voltage]... so if just current (Amps) is listed then you can still calculate your Power = Amps listed * 120VAC). Then buy an inverter that can handle 1.5 times your load. Seriously, modified sine-wave inverters aren't that expensive, so buy one that's over-rated for power.

Remember numbers you computed are just for everything once it's running. The START-UP power requirement is a lot more. This is because inductive loads draw a lot of "in-rushing" current when they first start up. Electrons rush into the motor's coil to energize it, and it's not until the coil starts turning that electrical resistance builds up across the coil to reduce current. Because the initial current is so high, the initial power drawn by the motor/pump is high [Power = Current * Voltage]. This initial power draw is called "surge power." So, be sure to by an inverter that's not only rated for 1.5 times the continuous operating power you calculated, but also is able to provide high surge current [Most of the time this will automatically be the case... but, you can see the rationale for buying 1.5 times what you need, as these inverters will also be able to provide higher surge power needed].

For the person who asked about car batteries... They really don't like to be deeply discharged (which is what will happen), and doing so may damage the car batterry. If you have a volt-meter, you can monitor the battery's voltage while it's running the inverter . [Personally, I wouldn't let it get below 10.7 VDC]. You could just leave the car running all the time [do this outside, not in your garage or any place fumes could gather and be dangerous]. Remember to keep the wires from the battery to the inverter short. The wires from the inverter to the pumps can be long. So, you'll need to use heavy-duty [15 Amp] extension cords (like air conditioner or refrigerator cords) to bring that power into the house!