Does APC lie about the charging times of a smart apc?
Posted by mk_ccna@reddit | sysadmin | View on Reddit | 13 comments
Does APC lie about the charging times of a smart apc?
I've decided to test SMT750IC (I have two of them, from 2023 and 2024) and SMT1500IC (2024).
APC claim:
"Recharge Time: 3 hours" (probably to 90%)
Reality:
from 75% to 90% -> \~1% per 6 minutes for 750va
55% to 90% -> \~1% per 8 minutes for 1500VA
You do the math... my 1500IC spent like 4.5 hours to charge from 50 to 90%... the charging speed of 750IC was only 20% faster. Not even close to what APC claim...
Am I missing something obvious here? No way I got three faulty items ;-)
uiyicewtf@reddit
Before anything else - your test was with no load, right? Or at least, nowhere near max load?
(Now I want to go unplug two identical UPS's, one with almost no load, vs one with heavy load, to measure the difference. They sitting right here.... (The no load one would take forever to drain down)).
mk_ccna@reddit (OP)
APC 1500IC no devices connected - 0% load, 750VA - load 15%...
With all my love towards APC... I do get marketing claims, I really do but they seem to miss the charging time by a few hours ;-)
uiyicewtf@reddit
Once I'm sure I have monitoring set up, I am going to do a full runtime and recharge test on my three 1500's, which have wildly different loads, and compare them to the marketing numbers, and report back. Because you've made me really curious about it.
Of course the problem is my 1500's aren't your 1500's, so my results won't help you any. But they interest me.
Poke me if I don't get back to this thread in 24 hours...
uiyicewtf@reddit
Ok, plan aborted...
refused - state of charge not acceptable
refused - state of charge not acceptable
refused - load too low
I can go pull input cords, but they're not in convenient places. It can be done, but the work involved to discharge them has now exceeded my curiosity regarding how fast they'll recharge.
Ssakaa@reddit
Put a space heater or big fan on the no load one to discharge, then pull it for the test?
NH_shitbags@reddit
charge time for lead acid batteries isn't linear. Its more of a curve. Do you suspect a capacity or runtime issue?
throw0101d@reddit
Do a search for (lead acid) "charging profile":
LimeyRat@reddit
Also, how old are the batteries and how many deep discharge cycles have they been through?
neoh4x0r@reddit
It's just an estimate, like having a contractor come to you home and quote you a price to replace your roof (the actual cost could be more or less than stated).
sniff122@reddit
The time given by APC will probably only be an estimate
Immortal_Tuttle@reddit
Dont worry about it. They have slow charging like C/10. Since typically you don't want to discharge acid battery more than 50%, ideally just 25% is used to shutdown whatever load is connected, hence the listed time.
Over half of this time is usually spent on topping the battery up - usually overcharging it.
Vesalii@reddit
Are you on 110 or 220 V? This could possibly impact charging. Maybe APC limits on amps pulled. Batteries could be worn. Or higher capacity than the UPS expects.
iceph03nix@reddit
From what I see, they list 'Typical' Charge Time in their datasheets, which is pretty open to there being some variation, and there are so many variables in battery charging, that I think it would be tough to say it's an outright lie. Most likely they just have a rough formula for battery size vs input wattage.
As others have said, Battery charge rate tends to be a bit of an arc. It can also be affected by temperature, and incoming volts and amps from your main.
Charge time is also typically something most people don't really care too much about, as it's rarely useful for knowing how long it will take to recharge in a real world scenario where you're likely charging it along with a load, and your generally not going to be operating with it draining and recharging regularly.