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

Pulse Width Modulated sine wave. Visualize a sine wave, but made up like a stair-case going up and down.

PWM is not as good as a sine wave. Each "step" throws high frequency noise on the wire, but they are much cheaper.


Zeph
 
I not so sure my post belongs on the DIY site, but it may really interest folks here nonetheless. Right now Belkin is offering 50% off on their website" www.belkin.com

When you order, you need to enter this code to take advantage of the savings: 35491 This deal is good through the end of January 2004.

This may interest people, because they have UPSs for sale. I picked-up 2 of the 1200VA for well below $200, including shipping. Some of the pertinent specs:

ââ"šÂ¬Ã‚¢ Battery load capacity: 1200VA (670 Watts)
ââ"šÂ¬Ã‚¢ Provides 6 Outlets: 4 battery backup outlets w/surge protection and 2 outlets w/surge protection only

While I was at it, I also bought a few of the heavy-duty surge protectors.

What's the group concensus? Do you think 2 of these babys should keep an 85 gallon tank circulating for a while (1 pump for the skimmer, and 1 return pump)? How long do you estimate?

I'm not overly concerned about keeping the lights on, the fish can deal with the candlelight like their human friends. I just want to keep the filters running until I can get home and hook-up an inverter to the car or until the power comes back on.
 
Beagly, I'm sorry I couldn't help you out after all our emails. At least you found this bb, and that's a good thing!

For the people not wanting to DIY or that need to provide more than 100 watts of auto-backup power (even with a larger inverter, this DIY design does instant switching and greater currents cause severe arcing) I highly recommend the tripplite APS series, like the 512 model which has a 3 stage charger and can handle parallel batteries. An old style transformer inverter allows surges of 2x the rated supply.
 
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I just bought a 750 watt inverter yesterday, and was going to get a relay from all electronics to finish this project. My intentions were to hook up a 250 watt heater and a MAG-7 (soon to be a 9.5) to it incase of power failure.

What's this about sever arcing over 100 watts? Please elaborate.
 
Do off the shelf UPS's have a relay built in? The most difficult part of this DIY appears to be finding a relay that can handle the power, then wiring it so that it dosen't arc or blow. Could you just take a cheap UPS apart and use it's relay?...we are the borg...resistance if futile...

4C
 
Re: Re: fuse question for DIY backup

Re: Re: fuse question for DIY backup

Playfair said:
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.
Click to expand...
Which hot (black) wire are you referring to here?
Is it the black wire coming from the wall (line AC) that goes into the relay, or on the wire coming out of the relay that goes to the pump?
I don't see your fuse on any of your pictures.
Jeff
 
Re: Check out my new DIY power back up! (400k of pics)

Playfair said:
ups_open1.jpg

Click to expand...
I don't see the line AC coming into here, where is it coming from?
And I'm confused what the cord labeled "to battery charger" is for.
I thought that would be plugged directly into the wall.
 
"A Reef Scene", Yes it has been called for service on a few occassions. I mentioned in here somewhere that my original backup know belongs to another guy in our club. I needed more capacity so I ended up getting a commercial unit.

Music Maker, you could probably add the heater once the pump starts with no problems, but turning on both together could be trouble. I don't have a heater running off my backup in order to maximize the time it can run for (heaters gobble up the battery fast, you'd be looking at 3 hours instead of 10)

Grochmal, there's a reddish connector at the right of the box which gets AC in and supplies AC out either from the line or the inverter. I remotely located the backup in my basement and ran a double corded line up to the tank. AC in was provided off my tanks GFI, and AC out ran to a plug that the main return pump is powered from. The fuse is at the other end not shown in that picture, and is located on the output.

As far as the "arcing", what I think happens is this: The relay contacts weld from an instantaneous high current draw produced from a motor, resulting damage to the inverter when line power comes on. I was running a mag18 when this happened (twice), and I didn't have the resources to persue the perfect solution.

However, with a replacement inverter I tested a mag9 MANY times and ended up selling the unit to someone who uses one. It's worked several times flawlessly for him.

I don't know what the computer backups use to switch or if they solve this problem. It's possible that a large inductive load would do similar damage to them.
 
Thanks, Dave. I was thinking about this since my last post, and I think the problem could be solved by using multiple relays. For me 3 hours is cool (for now), because by then I can get it all hooked up to a running vehicle.
 
Another option to consider. I purchaced a used APC 1400 on ebay. With shipping cost me $43 (no batteries included). New batteries for it on ebay $62. For $105 I got a unit that will carry 900 watts and protect against surges. My 6000 btu chiller pulls about 750 watts.

Jeff
 
old threads die hard!!


i read this whole thing and a few people mentioned something very very important and only a couple people touched on it.

the battery.
you do NOT NEVER EVER EVER want to use a regular car battery from Farm & Fleet (lead/acid) in your home.. or anywhere where there is a potential for a spark (like the relay that you have on top of it).

when these batteries charge or give off energy, the chemical recation produces both a toxic and an explosive gas (the reaction is larger when charging, but also present when discharging/using the battery).

if these gasses are allowed to build up without proper ventalation they will be dangerous.

a couple people suggested venting to the outside, which is a good idea but can be expensive if you're setup is not near an outside wall.

The correct solution was also mentiond, but never touched upon.

using a Gel-cell sealed battery. I do beleive the marine type might be, but im not 100% sure. I am 100% sure that the Optima line of 12v batteries are 100% sealed and do not give off explosive gasses

Also, the bigger optima batters can last for hours under full load. Considering that indy and stock cars use optima batteries to save on alternator wieght and hp drain, but drive the car for 2-3 hours or more at full load, they can handle an inverter drawing 25 amps or so.

http://www.optimabatteries.com/publish/optima/americas0/en/config/home.html

get a yellow top battery.
 
The "gel-cell" batteries are not well suited to deep discharge cycles. They are not a good choice for UPS situations. Deep cycle "marine" batteries are the standard. A single 12v deep cycle battery will not pose a threat in a "normally" ventilated house or open area.

Most UPS systems use SVLA batteries. These are "sealed valved lead acid" cells. The batteries are much better than gels and almost as good as standard lead acid types.

Gel-cels and SVLA batteries have a very short usefull life. You will find that they will last you betweem 18-36 months. Kinda expensive to say the least. Standard lead acids last at least twice as long.

You also need to be aware of the recomended charging and discharging cycles for the selected cells. You wil find that they need to be discharged and recharged from time to time. Otherwise they will cease to function as efficiently. However every battery has a finite charge/discharge lifespan... so each time you use it.. the battery deteriorates a bit more.

Bean
 
I don't think a build up of hydrogen gas is a concern unless you are using a 10+ amp battery charger and the battery is in a tightly enclosed area. I small 1 - 2 amp battery maintainer will not cause a build up of gas. Period.
 
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