battery datecode question

[wolfalex]

Hello,

     Does the datecode shown on the primary lithium metal battery below mean produced in the 33th week in 2013? It would be really helpful to get validation from somebody who knows much
    more about this datecodes than I do.

 Thank you very much.

[wolfalex]

I found a document explaining the format of the datecode (attached as a picture) but I am still not happy with the outcome. My battery datecode applied should read as follow:

datecode = 1333

that means:

Wednesday, third week of the month
March  in the year XXX1

but which year? 1991, 2001 oder 2011 (or even sooner?)

Could it really be that the datacode does not explicit contain which year the battery was manufactured? I would have expected that a datecode tells me at least which exact year the battery
was made. Maybe I missed an important point  

[thefamilyman]

My guess would be 1991 from the assumption that it's the original battery and the date codes from the ICs sound it.

[wolfalex]

Thank you for your response and oppinion. I really appreciate it. Unfortunately I do not know if this is the original battery or not, because I got the meter from Ebay, but I think you are right
 with the fact that the battery could be from 1991 (given all the other 1991 parts around it).

 In a second much older 3478A I got some time ago the original battery from HP was still installed, and this one was black (with SAFT written on it). But maybe HP used different yellow batteries
 in newer units during initial installation.

   

[helius]

Saft is mainly known for their Lithium Thionyl-Chloride (LiSOCl₂) batteries, and the Panasonic battery is a BR type. They have quite different voltages: 3.5V versus 3.0V. But both are considered very reliable for memory backup. They need replacement if the in-circuit voltage (not the open circuit voltage) drops below about 2.5V.

[bktemp]

The 0.22uF capacitor in the background of the picture should also be replaced, because those capacitors tend to fail. You can even see the hairline cracks in the picture.

[wolfalex]

@bktemp: Thanks for the info. You mean the two "RIFA" caps, right? Yes, I will change them, especially I am soon moving back to Europe, and my plan is to modify the 3478A for usage at 240V/50Hz. And under the assumption that this caps see then more stress I guess most likely the will fail fast.

I think the line voltage change should not be a big problem: If I am not mistaken there is a cable inside the unit which connection is changed to tap to another transformer winding). What I am more afraid of is that when I set the DIP switch line frequency setting from 60Hz to 50Hz that maybe the ADC changes its behaviour slighlty, and that then maybe a recalibration of the unit would be needed. Could this happen?

@helius: Thank you too for the information about the batteries. I was not aware until now that the SAFT battery is using different chemicals than the Panasonic BR type one. It seems I do not know
 much about this topic Do you also think my battery on the picture posted above was manufactured in 1991? If so I definitely have to change it.

[bktemp]

Yes, those RIFA caps degrade over time and then blow up. And you don't want your board look like this:
https://www.eevblog.com/forum/projects/once-the-magic-smoke-escaped/

[wolfalex]

I better will change them