Motherboard Battery?

lastdeadcat · 03-12-2007, 07:36 PM

A few weeks ago I popped the case on my 240 Series 2 DVR that I have had since September 2003. I did that to blow out the accumulated dust and was sort of surprised to found very little. I don't remember seeing anything about this in the forums and I have been checking them for over a year.

My other 240 Series 2 DRV is a few months newer and I didn't open that one because the other one was so clean. I assume that it is much like the older one.

What I did find was that there is a disk battery on the board like on computer motherboards that keep the BIOS working when the computer is off. I suppose that is the same function on the DVR like the computer.

I am wondering what happens when that battery depletes. I think it is a lithium. These are fairly long lived--maybe up to ten years if not used much. I don't suppose it is used very much since these DVRs stay running 24-7-365 except for an occasional unplug to move it or something like open the case (it's on an UPS).

What are the symptoms of a low or dead motherboard battery? Should I change it soon or wait for symptoms? It is like doing it on a computer? (Redo the BIOS)

JimSpence · 03-12-2007, 07:58 PM

Unlike a computer, the TiVo is never really turned off. As long as it is plugged in the battery isn't needed. I believe it is only used to maintain the clock during power outages or when unplugged.

lessd · 03-12-2007, 09:08 PM

Quote:

Originally Posted by JimSpence

Unlike a computer, the TiVo is never really turned off. As long as it is plugged in the battery isn't needed. I believe it is only used to maintain the clock during power outages or when unplugged.

Yes but if you had a bad battery the clock would not reset until the TiVo called home.

litzdog911 · 03-13-2007, 01:43 AM

I've never seen any reports of battery-related problems. Best to just leave it alone.

JimSpence · 03-13-2007, 12:37 PM

Quote:

Originally Posted by lessd

Yes but if you had a bad battery the clock would not reset until the TiVo called home.

Only, if you left it unplugged long enough for the battery to drain and then plugged it back in. Wouldn't the unit then call home to get the current time?

lessd · 03-13-2007, 01:08 PM

Quote:

Originally Posted by JimSpence

Only, if you left it unplugged long enough for the battery to drain and then plugged it back in. Wouldn't the unit then call home to get the current time?

If you have a power loss for say 1 hour in the afternoon and your battery was ok than the clock would still have the correct time and if you had any programs to be recorded that night you would get them all. Except for the Humax DVD TiVo and Series 3 you have no way to tell if there was a power loss (and a dead battery) without turning on the TV, and who would look at the clock each evening to check on the TiVo time. A dead battery is bad news because it may take TiVo up to 24 hours to call home after a power loss, so you would not do any recording in that time. The good news is that you would have to leave the TiVo unplugged for more then three years to kill a new battery, that's why the battery is not a big problem (or any problem for that matter).

JimSpence · 03-13-2007, 01:50 PM

When I said "long enough" I should have qualified that with "a few years".

Cormode · 03-13-2007, 07:48 PM

1. The battery doesn't run the bios.

2. The battery runs a small clock chip that draws less power than a wrist watch. The battery could literally power this chip for years.

3. The battery is only in use after power has been off for about 10 minutes.

4. There is no test for a low battery, only a dead one (unplug, wait one hour, power up and check time)

4. The battery is sold at any walmart or radio shack for about $4. Replace if you like every 5 years. Nothing will be mis-configured if you remove the battery. The tivo will be happy to run even with out a battery (just the time will be wrong after power loss)