300W Online UPS for less then $200
I was wanting a way to keep my internet and a custom build security system running in the event of a power failure. I plan to plug everything in my data rack into a 3000W UPS but the battery life on rack mount UPS are not very long and I wanted to extend the life after my servers and other less important things run out of juice. So as part of the custom security system I build a 300W online UPS.
The UPS is made up of:
*SLA battery charger.
*6x 6V 7Ah SLA batteries which are series paralleled into 12V 21Ah.
*300W Inverter with built in low voltage drop off.
I could have built my own charger and inverter but this way is cheaper and gives me full CSA approval on all the high voltage stuff. The inverter as a 2.1A USB port which I will use to power the brains of the security system.
I went with 6 small batteries because I originally wanted to package the entire thing in a 1RU case but the inverter is thicker then 1.55"(space inside 1RU case) so I will have to got a 2RU anyways.
Have not done complete testing on how long this can keep router, and switch operational after the UPS fails. Will find out some time in the new year when I start setting up my new server rack.
The UPS is made up of:
*SLA battery charger.
*6x 6V 7Ah SLA batteries which are series paralleled into 12V 21Ah.
*300W Inverter with built in low voltage drop off.
I could have built my own charger and inverter but this way is cheaper and gives me full CSA approval on all the high voltage stuff. The inverter as a 2.1A USB port which I will use to power the brains of the security system.
I went with 6 small batteries because I originally wanted to package the entire thing in a 1RU case but the inverter is thicker then 1.55"(space inside 1RU case) so I will have to got a 2RU anyways.
Have not done complete testing on how long this can keep router, and switch operational after the UPS fails. Will find out some time in the new year when I start setting up my new server rack.
1024 x 768 - 80K
Comments
Do they have external PSUs?
If so, it may be a goo idea to pick up 12V 'Travel PSUs' instead of having the 12V-to-AC-to-WhateverDCVoltage chain.
Even the best PSUs are rarely better than 80 - 85% efficient, and the 12V-to-AC inverters really, really, suck unleaded...
Some in that size has a 'quiescent current' of 1A... In other words, they suck 1A even when not supplying a load with power.
Anyway, even if we assume an 'ideal' 85% efficiency at each stage, you still only get 72.25% when going through two stages.
Add a possible third internal stage inside the boxes, and yeah, battery power dropping fast.(you'd be down to 61.4% )
Best option, if you're willing to hack a bit is to replace the internal PSU in the boxes with good step-down DC converters running on 12V.
That way you keep 80 - 85% of the battery power.
Who knows; that way you may actually manage to keep it within a 1U box.
(I prefer to call them 'Pizzaboxes' Probably had one too many late night at the office, working on a misbehaving server... )
Unfortunately modem is 120v and I don't own that so strictly 12v system is not possible. I have not purchased the router or switch yet but most 24 port rackmount switches are 120v
A lot of Cisco equipment has a 48V DC connector. not that it helps much, though.