Advantages of DC

[keefe007]

What would be the advantages of using DC at a site that has good AC power?

Follow-up: What DC power plants are people using?

[sirhc]

NONE! - IMHO

If I was on grid I would use grid with a Tripp Lite inverter charger and deep cycle batteries.

[keefe007]

Which tripplite are you using?

How do you monitor the runtime and if power is lost?

[sirhc]

http://www.ebay.com/itm/TRIPP-LITE-APS1 ... 33966d806a

Have something at the tower that is not backed up by the inverter charger

We do a stress test

Not the most graceful solution but we know for instance that from the test we have say 8 hours so if power goes out and 6 hours go by with no restore we send a body with a generator

[petecarlson]

You lose about 20% going from DC batteries to AC. There are a lot of standard -48 systems out there that are designed to run in an outdoor enclosure for 10+ years and give great visibility into the status of your power system. We just haven't had much luck with AC battery backup solutions and they never seem to have the run time that they think they have. Our rectifier shelves are set to test themselves every six months and we get a warning if the batteries last longer then designed. I also find it is much easier to control my techs when they can't just plug something in, and it leads to much cleaner racks without a nasty tangle of AC power cords.

[keefe007]

Which DC system do you use?

[sirhc]

We use that TripLite and we LOVE them.

I have only lost ONE unit in 5+ years.

When grid power is there they just pass through AC power and keep the batteries topped off then pull from batteries in brown and black outs.

This allows the batteries to last longer. DC sites that constantly charge and draw from batteries using off the shelf deep cycles get clogged up (The plates) and need replaced every 3 years.

We use 4 of the blue top gel batteries and the average up time on a tower loaded up like only I seem to do stays up about 12 hours on 4 batteries and the batteries last 5 years.

There is no conversion loss with this unit as it passes AC through 99.99% of the time, very efficient for ON GRID systems.

The unit has a built in AC surge protector and Earth ground is bonded to our service/tower ground system. THe only thing we plug into them is the WS-24-400A and the Cisco 2951 router, everything else at the site plugs into a surge strip off AC and then we monitor a device that is plugged into AC direct like a camera or mFi to know when AC power fails.

I would never build a DC site if I gad grid at my disposal but to each their own.

[iggy05]

We use that TripLite and we LOVE them.

I have only lost ONE unit in 5+ years.

When grid power is there they just pass through AC power and keep the batteries topped off then pull from batteries in brown and black outs.

This allows the batteries to last longer. DC sites that constantly charge and draw from batteries using off the shelf deep cycles get clogged up (The plates) and need replaced every 3 years.

We use 4 of the blue top gel batteries and the average up time on a tower loaded up like only I seem to do stays up about 12 hours on 4 batteries and the batteries last 5 years.

There is no conversion loss with this unit as it passes AC through 99.99% of the time, very efficient for ON GRID systems.

The unit has a built in AC surge protector and Earth ground is bonded to our service/tower ground system. THe only thing we plug into them is the WS-24-400A and the Cisco 2951 router, everything else at the site plugs into a surge strip off AC and then we monitor a device that is plugged into AC direct like a camera or mFi to know when AC power fails.

I would never build a DC site if I gad grid at my disposal but to each their own.

What kind of environment are you using these in? Any sites that are not in air conditioned rooms? Our UPS at our main tower actually just died yesterday and I am looking for a replacement. It seems they are not exactly hardened but this UPS lasted a year and a half before the last. We are probably going to go with it either way as I like how this works.

[sirhc]

All of my boxes are out door and just have vents and fan or fans.

I try to put them in shade but most are in direct sunlight part of the day.

I paint the worst ones white which helps a little.

The nice thing about these are they are AC PASS-THROUGH 99.99% of the time so very little heat is generated unless on DC power from a power failure and or right after recovery they are charging hard but the larger units have their own internal fans but most of ours do not but we have no issues

Average summer time high 100F +/-

Average winter time low 0F +/-

[iggy05]

Very good. That is what we are looking for and we have one on order coming our way now. If this works out great we will probably stick with these ourselves.