1

I’ve estimated watts drawn by all our servers and balanced them across several UPSs, balanced on 20 amp circuits. One thing I didn’t account for, and thought of after the fact, is how does recharging impact the power draw. It must draw more current in addition to the server, to charge the batter after an outage.

3 Spice ups
2

Correct. Watts during charging = watts used + watts for charging.

1 Spice up
3

Great question,

Charging can often just be short term, but you can still strip your breakers. Also, if you have a higher-end UPS, you may even need to consider efficiency loss from the UPS.

IMO, if you are balancing and worried about charging, ask the manufacturer for their charging specs. The amount of charging current can vary greatly by manufacturer and model. They aren’t usually posted - just be tenacious, they shouldn’t be confidential.

Also, in North America (as well as most of the world), you don’t want to be placing more than 80% continuous current on your circuit. So in your case, 16A or less for the 20A breaker. If you use this 80% rule, you will:

  1. Meet National Electric Code (always a good thing)
  2. Won’t have to worry as much about tripping your breaker when the charger turns on

[Then again, this is always easier said from a cubical than done by an actual user with limited infrastructure!]

4

Yep, I do follow the 80% rule, as long a charging doesn’t eat up another 20%, I should be OK. Might be hard to find the info. I have a bunch of this model:

and this one:

5

I don’t want to speculate too much, but in our comparable model, the Eaton 5110 , you can assume a maximum about 12W of charge per an internal battery. So that would translate into a whopping .1A to .12A per a battery in excess current.

The BP1100 and BR1500 have 2 batteries. I think you are in the clear!

6

windso (Eaton) wrote:

I don’t want to speculate too much, but in our comparable model, the Eaton 5110 , you can assume a maximum about 12W of charge per an internal battery. So that would translate into a whopping .1A to .12A per a battery in excess current.

Where can I read this? I was looking through the documentation you linked to, but couldn’t find it.

7

We don’t publish it for several reasons. Mostly because it’s too confusing for a normal end user plugging it in and leaving it be for a couple years.

So the question is how would we publish:

  • what the current draw is
  • how much current will actually be drawn in relation to what percentage of charge already exists in the battery
  • how long will the charge last depending on all sorts of battery characteristics including temperature, charge, battery health, etc.

We’re not trying to hide information, we just don’t want to create more confusion than it’s worth.