Converting UPS to Amateur Use Power Supply

Discussion in 'Homebrew and Kit Projects' started by W2FCP, Nov 16, 2008.

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  1. W2FCP

    W2FCP Ham Member QRZ Page

    I was reading the ARRL Handbook 2008 and in the power supply section there is an article about converting a UPS to a Universal Power Supply by adding binding posts and a fuse holder to the rear of the unit. After reading the article I remembered that I happen to have two APC Smart-Ups 700's in my garage that are not in use. The problem is though that the article says it is best to use a UPS that uses a 12V battery system, the 700 uses 2x12V batteries forming a 24V system.

    My question is what would be the best way to get 12V out of the system and keep the batteries balanced?
  2. W0BST

    W0BST Ham Member QRZ Page

    Just put your posts in parallel with one of the batteries. If you want, add a second set of power posts in parallel with the other battery.
  3. W2FCP

    W2FCP Ham Member QRZ Page

    That solution would work but couldn't it cause one of the batteries to wear out quicker than the other?
  4. W4INF

    W4INF Ham Member QRZ Page

    I can give an umbrella answer to UPS questions, but here is my experience.

    A 12v UPS (Usually the smaller ones) make dang fine chargers, plus they will work as a UPS for stuff like laptops.

    Anyway, I have one here I kilt because I failed to unplug it before I put a load on the battery it was charging.

    So, disconnect the battery while you operate, then reconnect the UPS to charge the batteries agn when your done in the shop.

  5. W2FCP

    W2FCP Ham Member QRZ Page

    kb1oev I would be interested in hearing more about that circuit. The batteries are indeed connected in series, the batteries are wired together at a + and - post and the UPS hooks up to the other + and - posts.

    On a side note, the two batteries are connected together with wire and powerpole connectors.
  6. N9LCD

    N9LCD XML Subscriber QRZ Page

    I have an A P C mod. 650 ups. I tried to power my VHF/UHF receivers with it.

    HASH & MORE HASH!!! And it wasn't even corned beef. HI HI

    I suspect it was the charging circuit, probably a high-speed switcher!

    Check on receive before transmitting. Some conducted noise, like alternator whine, can modulate your carrier even well into the VHF & UHF range.


  7. W4INF

    W4INF Ham Member QRZ Page

    Can I use the same circuit for a 12v UPS? Thank you for the schematic.

  8. W4INF

    W4INF Ham Member QRZ Page

    Okay, no problem. As a matter of fact, I have a 24v UPS on stand by.
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