HP 3457A Battery - Page 1
Forum section: electronics / testgear

author: BertSP
author_rank: Contributor
timestamp: September 06, 2017, 06:44:16 pm
content: I know this has been covered in the distant past. I am a newbie at this and just purchased one of these DMM. From the serial number, this seems to be a '87 model. I opened it up to find that some of the bigger caps were changed in '96 (good start). Looking at the dreaded backup battery, I find a yellow panasonic 3v Li battery, which looks fairly new and shiny. I have included pix of the board and battery close-up. Looking at the service manual, the battery PCB board number is different than the board I have. The manual calls for BT501 and my board shows BT601.The questions I have for the experienced members that are familiar with this model are:1) Is this an upgraded board? (considering the step-up in BT #)2) Is this a newer battery or changed battery and should I risk changing it? (let sleeping dogs lie)3) If I should change, what would be the recommended model. the PCB has three holes on one side and a single on the other for the battery tab. I cannot see the battery info due to the orientation.Any wisdom or insight would be greatly appreciated.

author: BertSP
author_rank: Contributor
timestamp: September 06, 2017, 07:15:46 pm
content: Poking around I found this potential match on digikey:https://www.digikey.com/product-detail/en/panasonic-bsg/BR-2-3AE2SP/P270-ND/64350The question is how old are these, or are they newer than 1987?

author: BradC
author_rank: Super Contributor
timestamp: September 14, 2017, 01:59:54 am
content: Quote from: BertSP on September 06, 2017, 06:44:16 pmHaving just been through this here's what little I know.There is a later rev PCB easily identified by the major ref part numbers being 6xx rather than 5xx (I have one of these). The biggest issue with that is correlating the board against the schematic as I've never found a revised service manual. You have the same board.Have you measured the battery voltage yet? That's the first place to start, although these batteries have a relatively flat discharge curve which drops off sharply toward the end of life.Is the meter still calibrated? When you power up, does it log an error (little flashing triangle above the 'err' mark on the front panel)?You'll get a better indicator of device age checking the date codes on some of the ICs. Yours are around 88/89, mine are around 92. I don't think that 96 written on the cap is a date code. That looks like the original cap and mine had a similar scribble.Have you run the serial number? Many HP devices had the manuf date encoded in the serial number. I can't help further with that as mine had the serial number removed before I bought it, but I'm sure I spotted a serial number decoder somewhere.Replace that IEC input filter before it spills its guts. They are notorious for making a mess, although more so in countries with > 110V mains.Oddly enough RS no longer stock the battery I bought from them 4 weeks ago, but it was one of these :http://au.rs-online.com/web/p/speciality-size-batteries/2033894/...except with welded leads rather than terminals. I fitted a couple of big PCB pins and soldered the battery to those to make it easy to replace next time around.

author: wiesl
author_rank: Contributor
timestamp: March 16, 2021, 02:30:47 pm
content: Which battery can you recommend for replacement?

author: maxwell3e10
author_rank: Frequent Contributor
timestamp: March 16, 2021, 03:32:42 pm
content: At some point I looked into the properties of these batteries. The upshot is that if the battery measures over 3V its probably fine for a few more years.https://www.eevblog.com/forum/projects/panasonic-br-23a-chemistry-change/