I just replaced the battery in my 3457A. From Mouser: Panasonic BR2/3AE2SP
Joe Gray W5JG On Sun, Jan 24, 2016 at 12:54 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <[email protected]> wrote: > I've got a HP 3457A 6.5 digit multimeter - S/N 2703A04579. It's working > fine, but I'm aware the battery must be at least 11 years old, as I first > bought the meter 11 years ago. I suspect its due for a change. I'm trying > to find a *reputable* source for a replacement. I want to avoid eBay, due > to the number of fakes on there. > > Opening the meter up, I see the PCB shows "BT 601". There's no name on the > battery I can see, but the type number of LX 1634. The voltage measured on > my 4.5 digit handheld DVM is 3.03 V. Googling around > > https://groups.yahoo.com/neo/groups/hp_agilent_equipment/conversations/topics/48964 > > would suggest the battery was made by Saft and is a Lithium-manganese > dioxide (Li-MnO2). The size appears to be known as 2/3A. One source > suggests a replacment is the Panasonic BR-2/3AE2SP > > Mouser's uk site > http://www.mouser.co.uk/ > says shipping is restricted, so only available in the USA. > > The nearest I've found to anything remotely suitable is actually a 3.6 V > battery > > "CROMPTON ETERNACELL T32/8AA8F Battery, Single Cell, Lithium Thionyl > Chloride, 2100 mAh, 3.6 V, 2/3A, Axial Leaded, 16.3 mm" > > http://uk.farnell.com/crompton-eternacell/t32-8aa8f/battery-lithium-2-3aa-axial-lead/dp/774017 > > I'd rather not fit a higher voltage battery, although given it provides > power to some 5 V static RAM, I would not expect it to be a problem. That > said, I believe when on mains power this battery is not needed, so there > may be some circuitry that would not like a 3.7 V battery. When power is on > the unit, there is 4.88 V across the static RAM. As mains is reduced, so > the voltage drops to about 2.8 V. I think there must be a Schottky diode > that stops the battery being drained when the mains power is on. > > The battery needs to have either very thin pins or wire-ended. Some I have > seen have tags a 2~3 mm wide, which will not fit in the PCB. Others have 3 > terminals, which stops you putting it in the wrong way around, but they > will not fit properly on the PCB. > > In applications like the 3457A, when the SRAM needs to be kept alive when > power is off, I wish HP would have put two batteries in holders and diode > -OR'ed them. If they had done that, one could just pull out a battery from > holder A, and put a new one in B. Then when B gets old, put one in A. > > My first problem though is finding a suitable battery. Next problem is > changing it without losing the RAM contents, but I don't think that's a big > deal. > > The 3.6 V Lithium Thionyl Chloride is very tempting, as it has a higher > capacity than the Lithium-manganese dioxide and they have a very low > self-discharge (1%/year). I'm just not overly happy about fitting a higher > voltage battery than it is supposed to have, but phyysically it fits, and I > can get one easy enough from Farnell in the UK. > > Dr. David Kirkby Ph.D CEng MIET > Kirkby Microwave Ltd > Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, > UK. > Registered in England and Wales, company number 08914892. > http://www.kirkbymicrowave.co.uk/ > Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please) > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
