- Joined
- Feb 17, 2013
- Messages
- 4,406
Well, ya see, I've had this-here vintage Hewlett-Packard 427A volt-ohmmeter for quite some time.
Had it stored away for a few years, finally unearthed it a couple weeks ago. Unfortunately, the battery (an Eveready 763, 22.5 volts) had died of old age (originally installed in 1999). So I went searching. Several sellers on Amazon and eBay must have thought the battery chemistry was platinum-iridium or something, judging by the prices they wanted. Among the lowest prices was one on eBay for a bit under $70 ... sold by Lowes, of all places. Gritted my teeth and placed the order.
When the "Exell" battery arrived, I was taken aback by the weight - about half that of the old Eveready! How could such a lightweight have anywhere near the milliamp hours capacity of the original?
It seemed far from right. I didn't even try connecting it ... figured it would be easier to return if still in the original shrink wrap. Luckily, the local Lowes store was willing to handle the return.
So what to do? AHA!!! I did a bit of figgering and tried dividing 22.5 by 1.5. Got 15. Stacked up 15 AA cells, and found they would easily fit within the same volume as the 763 battery. Luckily, I'd not discarded the old 763. Cut open the cardboard "wrapper" and removed the cell stacks - three parallel stacks of 15 chicklet-sized cells.
I soldered the AA cells together in series, wrapped them with electrical tape, re-connected and re-sealed them in the original battery wrapper, and checked the voltage - right on.
Loaded the "refurbished" battery in the meter, and by golly, it's happy!
I now have a very good mirrored scale analog meter. True, even with the mirrored scale it doesn't give as many decimals of precision as a digital meter. But nothing beats an analog meter for time-varying signals! Furthermore, I have a nice, inexpensive source of replacement batteries! Assuming 50¢ a cell, that's just $7.50 ... instead of $70.00 for a "new" battery!
Had it stored away for a few years, finally unearthed it a couple weeks ago. Unfortunately, the battery (an Eveready 763, 22.5 volts) had died of old age (originally installed in 1999). So I went searching. Several sellers on Amazon and eBay must have thought the battery chemistry was platinum-iridium or something, judging by the prices they wanted. Among the lowest prices was one on eBay for a bit under $70 ... sold by Lowes, of all places. Gritted my teeth and placed the order.
When the "Exell" battery arrived, I was taken aback by the weight - about half that of the old Eveready! How could such a lightweight have anywhere near the milliamp hours capacity of the original?
It seemed far from right. I didn't even try connecting it ... figured it would be easier to return if still in the original shrink wrap. Luckily, the local Lowes store was willing to handle the return.
So what to do? AHA!!! I did a bit of figgering and tried dividing 22.5 by 1.5. Got 15. Stacked up 15 AA cells, and found they would easily fit within the same volume as the 763 battery. Luckily, I'd not discarded the old 763. Cut open the cardboard "wrapper" and removed the cell stacks - three parallel stacks of 15 chicklet-sized cells.
I soldered the AA cells together in series, wrapped them with electrical tape, re-connected and re-sealed them in the original battery wrapper, and checked the voltage - right on.
Loaded the "refurbished" battery in the meter, and by golly, it's happy!
I now have a very good mirrored scale analog meter. True, even with the mirrored scale it doesn't give as many decimals of precision as a digital meter. But nothing beats an analog meter for time-varying signals! Furthermore, I have a nice, inexpensive source of replacement batteries! Assuming 50¢ a cell, that's just $7.50 ... instead of $70.00 for a "new" battery!