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Belkin F6C800 UPS

So your Belkin F6C800 UPS died and no longer holds a charge? Does it give you like 5 seconds of run-time and then quit? Probably the battery is dead. They typically only last 3 years or less. That’s exactly what happened to me recently. So… what do you do with something that states “no user serviceable parts” on the cover? Take it apart of course!


Before you start any disassembly be aware of this. Even disconnected from the AC power the UPS still holds a large amount of power. This is something you don’t want to approach lightly. Even unplugged you could be shocked, burned or worse. You must proceed with the disassembly at your own risk!

Now to proceed, unplug the unit and remove the screws holding on the cover. Once you’ve got the screws removed, place the unit
face down on the ground and carefully lift the cover straight up. It should slide right off.


Here’s what you end up with when the cover is off. The main thing to note is that there are two batteries in this unit. There is a good chance that only one of them is dead, not both. Even if only one is bad, you’ll basically have to take them both out to get the unit apart.


With the cover off, remember the electronics are still energized by the battery. So your first step before doing anything else is to disconnect
the battery hot lead from the rest of the circuit. You still need to be careful. Don’t short the battery terminals and be aware there may still
be charged capacitors in the circuit, so even with the battery disconnected it’s still dangerous.


The next step is to remove the circuit board. You don’t need to completely detach the board, but you do need it disconnected enough
so you can slide it to the side to make room for battery removal. Start by removing the screws holding down the circuit board.


Remove the 3 connectors attached to the circuit board. There’s one on the left, one on the right and one in front. Can you see the mistake I made in the middle picture? Right, I left my ring on. Bad move when working on potentially energized stuff like this. Remember to remove all jewelry before you begin!




Now if you try to move the circuit board to the right side, you’ll find it’s still won’t move far enough. You’ll need to remove the large ground wire connected to the heat-sink.


With sufficient stuff detached, you should be able to gingerly move the circuit board over to the right side of the UPS unit.

To get either of the batteries free, you’ll need to remove the metal bracket holding down both batteries. Start by removing the two screws on the top of the bracket.


Then you’ll have to remove the nuts at the bottom. You can see them here down at the bottom right next to the transformer.


It’s a bit of tight fit. I ended up having to use a socket wrench with several extensions to eventually get down far enough to remove the required nuts.


This is what it should look like with the batteries removed. Note that you don’t have to completely remove the battery bracket. Just make it loose enough to slide the batteries out.


One thing you’ll probably notice is that if you throw a multi-meter on each of the batteries, they may both still read 11-12VDC so it may not be obvious which if either of the batteries is dead. What you need to do is apply a little load to the battery you’re testing. In this
case I just used a large muffin fan while reading the battery voltage. This one read over 11.8VDC under load so there’s a good change it’s still ok.


However, the second battery is another story. Without a load this one was still reading over 11 volts, but notice what happened under load. Way down to under 4 volts. This one is obviously bad and needs to be replaced. Check the markings on the battery and use that information to locate and appropriate replacement battery. For this you’ll probably be looking for a 12V, 7Ah replacement battery. A 12V 8Ah will probably work too.


Reassembly is straightforward, just walk the steps backward. One thing I suggest is labeling each battery with the date it was replaced. I will give you one caution while reassembling this UPS. make sure you slide the cover on. Don’t try to bend the shell open and just wrap it around the case. If you do “just wrap it around” thing, there’s a good chance you’ll miss and the bottom edge of the cover will come into contact with the battery terminals. Check the pic and you’ll see what I mean.


Once it’s all back together, label the case with the last battery replacement date, plug it in and let it charge up.



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    • arjan on July 5, 2010 at 12:03 pm

    cool. Just replaced the bateries in a nother UPS at our company at an age of 5 years. In a load thest they react fine. (4 of ’em) Pretty useful things

    • Barry on March 9, 2011 at 1:58 pm


    I just want to thank you for the great step by step instructions. As well for the great pictures. Just finished carefully replacing both batteries. Took 40 minutes from start to finish.

    Thank you for your assistance. You just got to love the Internet. 🙂

    • Alex on August 12, 2011 at 4:25 pm

    So what if replacement battery has a higher Ah? Will this screw up anything i.e charging or melt transformer, or will it simply add more uptime once power is down?

      • admin on August 13, 2011 at 2:23 pm

      I actually did that on a smaller UPS, replaced w/ the next size up Ah battery. Didn’t seem to be much of a problem in the case I tried

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