I have several Belkin Model F6C120-UNV UPS units in need of repair. These are 1200VA UPS units designed for 120VAC type operation. Can anyone recommend where schematics for these may be obtained?
If it turns out that the repair needed is simply to replace the sealed lead acid batteries in these units is it generally considered cost effective to do so or is one better off just getting a new unit.
The most common fault with small "domestic/SOHO" UPS is battery dying due to overcharging and drying of the electrolyte. Assuming the behaviour of these units is consistent with that, replace the batteries.
Sometimes fuses fail, sometimes the electronics fail. But batteries are far more often the issue.
Quickest test is to substitute an automobile battery (or as many in series as is required to achieve the DC system voltage) and test the system.
I'd always replace the batteries rather than the whole UPS if:
. the rest of the unit is sound and provides the capacity and functionality required; and
. there aren't "bells and whistles" on current models that are considered desirable.
The only other matter - which does require a schematic - is to determine whether the charge regime is being unnecessarily brutal on the batteries and causing their premature demise.
My Belkin UPS came with 2 12 volt batteries in series to make 24 volts. The batteries died so I put 2 motorcycle batteries in series and put them beside the UPS. Drilled a hole in the UPS and ran a wire to the battery terminals. Works like a charm though it DOES tend to Overcharge the batteries. They bubble all the time and dry out. Have to keep adding water. Maybe running it on the batteries more often would be better. I don't know how to reduce the charging system.
Thanks folks for the replies. I disassembled one of the UPS units (a unit in service since 2004 or so that failed about 4 months ago). Inside it looks clean except the batteries are completely dead. If particular interest is bulging of the sides of the battery cases. I'll try getting two of units of these 12V/7.5AH sealed batteries (appears like a bog standard type of battery) and see how that works.
I want to watch battery cost even though these things were about $180 US when new. A quick look seems that locally at Batteries Plus the replacements are about $33 US each for the "Werker" brand. Mouser web site shows an equivalent Panasonic unit at $39 US each but then there is shipping on top that.
It's probably smarter to put about 4 car batteries in the basement on a trickle charger and use an inverter and put USP outlets near your computer stuff. You can use a relay to switch on the inverter and outlets to backup power on power loss.
If you keep out the relay you get an on-line UPS, but you need a 12V supply that can provide the required amps. I have found that regulating the voltage to 13,5V keeps the batteries charged without gassing.
A sure sign of overcharging, electrolyte drying, and heat damage.
If you don't attend to the charging circuitry you'll get the same outcome.
The comment from Van Chocstraw illustrates the problem:
"I put 2 motorcycle batteries in series and put them beside the UPS. Drilled a hole in the UPS and ran a wire to the battery terminals. Works like a charm though it DOES tend to Overcharge the batteries. They bubble all the time and dry out. Have to keep adding water."
The manufacturers aim to recharge the batteries in the absolute minimum time (often with the absolute least-component-count chargers) with the argument that the next AC supply outage could be very soon. The casualty of this thinking and poor charger design is battery life expectancy.
Hell, I have a piece of communications test equipment that was ~$US18K new. The battery charger in these was sub-standard and all owners I know have to replace the batteries every two or three years. I reworked the charge system many years ago and haven't had a problem since.