UPS Advice - ME-800-BK timed off

[iByte]

Hey, I wonder if somebody have had this before.

I have a Mecer ME-800-BK UPS - 800. Similar to this one, just the 800 VA version: http://www.comx-computers.co.za/computer-store-specifications.php?products=9513

The internal battery is long dead - it was a 9 Ah 12 V battery.
I replaced that by rewiring a new 101 Ah 12 V deep cycle battery to it.

Now, from my calculations, running my DSL router should take this thing a long long time to run out.

However, I only get about 5 minutes - 5 minutes exactly - and it switches off.

I wonder if somebody has/had a similar experience with their UPS. Is it perhaps something inside it's firmware to switch it off after X amount of minutes? Seems silly to me, but it's the only thing that makes sense.

 

[bekdik]

Probably the charger cannot charge that size battery

 

[iByte]

Hey, no charging is perfectly fine. It started at 12.6 V last night, and now it's at 13.6 V. So charging isn't the issue.

What I mean is, when I switch the mains off - so it goes into supply-mode or offline-mode, it only powers my equipment off of it's battery for 5 minutes then switches off. I can easily switch it on again by pressing the button - then another 5 minutes ensues.

 

[Sinbad]

Fire up the management software and see if you can play with the shutdown settings

 

[sajunky]

I use ME-600-BK, it has the same problem. It is called a "green feature". What happen, many people switch off PC, leaving UPS on with a small load of ATX PSU plus monitor in active off mode. Now during a power cut, UPS activates backup mode, it would deplete a battery completely in one or two hours, as large amount of electricity (probably 80%) is wasted inside UPS. It is why Mecer has a green mode, it has a timer switching off under light load.

I searched Internet on the subject and found that it has a jumper on the PCB to enable green mode. I removed jumper, it works, but it only extends time to 9 minutes. Second test comes with reduced time to 7 minutes, which makes me think that thermal protection comes to effect. Someone posted here information that these cheap UPS's have underrated transformer, so there is a mechanism to protect transformer too.

The other matter is charging a battery. Maybe there is no problem with your new battery, but older one might have larger self-discharge. If I remember correctly on my UPS charging current limit is only 300mA. It is fine for charging 8Ah battery in 8 hours. With your battery this time will extend to a week, assuming no self-discharge.

In conclusion, even you find UPS without "green" feature it will waste lot of electricity. If you want a long backup time for your router, use DC-DC converter with efficiency 85%. Mantech sell Meanwell converters with battery charging function around R300. It is much easier if router is powered 5V DC, as you can use any USB car charger rated 2A.