A Boy and his Miata

I have done something that I haven't seen discussed on this board before, and I'd like to share it with everyone, for two reasons:

1. So others can try the idea, if they wish to.

2. So someone smarter than I can let me know if there is a reason I shouldn't be doing this.

I originally put a power inverter in my car to power the a VCR and a book PC. Unfortuntely the inverter was INCREDIBLY noisy, causing problems for the video on my Alpine cva1000 headunit. I was racking my brain for an alternative, and the answer came when I was shopping for a UPS for my computer. The battery in the UPS was 12 volts, 4.5 amps. My car battery was...12 Volts, 4.5 amps. A plan began to form. I talked to the old man electrician at my local electronics shop about what I wanted to do, and he said that it would work, in theory. I purchased the UPS, and after a bit of surgery I had the UPS battery removed , and had wired the contacts, which had gone to the UPS battery, to the car battery (8 gauge wire, with inline 20 amp fuse). In this way, I figured that I could fool the UPS into continuously running on battery power. Since the battery is continuously charged by the alternator, it just never "runs out" of battery power.

I drove the car around with the new power supply for over 5 hours straight. No noise, no badness occurred. It has been going strong for over three months. One thing that I didn't expect...The charging circutry allows me to charge and "jump-start" my car using an extension cord and wall outlet power.

Any comments?

Don.

MP3Car.com

 

Fosgate

Dude this idea has been discussed many times b4 and i know few people who actually using this sort of setup. But the idea it self never took off as some some down sides where found.
First of all UPSs are more expensive in most cases then the DC converters... Some need serial port to be connected to. Others use different voltage than 12volts...
But i guess if i was to choose between Inverter or UPS i would go for UPS for sure!!!
But then again nothing beats DC converters!!!

But hey thanx for sharing your ideas with us

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Fosgate

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Fosgate

System Comp V3 - In progress.
Low power MB with C7 CPU, DC-DC PSU, car ECU link, USB TV, GPS, 7" TFT, Wireless, Voice.

blkdragon6

That was one of my original plans, but then I thought of costs of the ups and I said screw it.

I wasn't going to respond but I had to after seeing your username.. I love it.

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www.geocities.com/blkdragon6

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www.geocities.com/blkdragon6

Craig Chatterton

I went to BestBuy and found some UPS for as little as $29.99. Since it was BestBuy I know I could find them elsewhere for even cheaper.

But I don't know if those cheaper ones would work - they didn't say what voltage the batteries were.

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Aaron Cake

Your car battery is not 4.5A, but anyway...

There is nothing wrong with this setup. However, it would be a good idea to loose the original UPS battery. Why? Because your car battery and the UPS battery are of a different type, and therefore charge and discharge differently. Most likely, your car battery is discharging into the UPS battery. Under certain circumstances, this small sealed lead acid gell cell can overheat and explode. That would ruin your day.

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Aaron Cake
London, Ontario, Canada

Player: Cyrix 200, 32MB RAM, 10.2Gig Quantum HD, Onboard EtherNet/Sound/Video, Custom Lexan Case, Arise DC-DC, Win95 Kernal w/Custom Player
Car: '86 Mazda RX-7 w/Basic Performance Upgrades

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Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
"If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

A Boy and his Miata

Thanks, I actually did lose the original UPS battery. The UPS I bought was the Connext one from CompUSA, it was $60 bucks, so not too expensive. It is also pretty compact - after the original battery was removed, you can saw (dremel) off half of the casing, making the whole thing about 6 inches long, 4 inches wide and 2.5 inches deep.

Craig Chatterton

Was it This one?

Here's the BestBuy one I saw for $29.99:
http://www.bestbuy.com/detail.asp?e=...t=575&scat=577 It's also 300VA, maybe it's similar enough to the Conext you used that it'd be worth a look.


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Awol][

If i understand this correctly you just took the circutry (sp) of the UPS (that converts the DC into 120v AC) Sounds pretty interesting. Please keep us informed on how it works and any problems you run into. This sounds like a good way to use those ATX computers without an traditional inverter.

Awol][

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Awol

my $0.02 cents (value is based on the intelligence of the person reading this message)

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