HP-28S battery door
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09-06-2018, 03:02 AM
(This post was last modified: 09-06-2018 03:06 PM by burkhard.)
Post: #15
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RE: HP-28S battery door
(09-04-2018 09:17 PM)burkhard Wrote:(09-04-2018 07:30 PM)jonese Wrote: Ideas on how do I can avoid the battery door issue? OK, I just did confirm it. The "regular" alkaline Energizer N batteries HP expected you to use in the calculator I have measure 29.45 mm long. The "flat top" Chinese generic 2/3 AAA batteries I have measure 28.35 mm. So, each of the "flat top" 2/3 AAA is more than a millimeter shorter than the specified N batteries. I tried out some of these "flat top" 2/3 AAA in a 28C just now and indeed there is noticably less pressure on the battery springs. Remember, the clamshells use 3 batteries, a stack of two and a single in parallel. So the stack of two side is ≈ 2.2mm shorter than a stack of two regular N batteries. That's noticeably less preload on the spring. I'm not sure if that substantially reduces the risk of side door area breakage, but it couldn't hurt. They are a little smaller in diameter than N batteries as well, so no risk of getting stuck. Oh yeah... as a bonus they seem to work OK as well. Everything seems to make contact... the calculator turns on and looks like it operates properly. These are the exact batteries I have, purchased off eBay from a Canadian battery seller. They are *cheap*, only about $1US each *including* Canada → US shipping. They are NiMH as well, so rechargeable with the right adapters rigged up to get them to AAA length and preferably the charging current reduced somewhat. "Flat Top" 2/3 AAA batteries as replacement for type N. |
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Messages In This Thread |
HP-28S battery door - jonese - 09-04-2018, 07:30 PM
RE: HP-28S battery door - Zaphod - 09-04-2018, 08:05 PM
RE: HP-28S battery door - Maximilian Hohmann - 09-04-2018, 08:31 PM
RE: HP-28S battery door - burkhard - 09-04-2018, 09:17 PM
RE: HP-28S battery door - burkhard - 09-06-2018 03:02 AM
RE: HP-28S battery door - robve - 02-24-2023, 05:31 PM
RE: HP-28S battery door - SlideRule - 09-04-2018, 09:20 PM
RE: HP-28S battery door - Jlouis - 09-05-2018, 01:53 AM
RE: HP-28S battery door - burkhard - 09-05-2018, 01:07 PM
RE: HP-28S battery door - rprosperi - 09-05-2018, 02:35 PM
RE: HP-28S battery door - Gerson W. Barbosa - 09-05-2018, 03:11 PM
RE: HP-28S battery door - ijabbott - 09-05-2018, 04:03 PM
RE: HP-28S battery door - Gerson W. Barbosa - 09-05-2018, 04:14 PM
RE: HP-28S battery door - rprosperi - 09-05-2018, 06:11 PM
RE: HP-28S battery door - Jlouis - 09-06-2018, 01:26 AM
RE: HP-28S battery door - jonese - 09-05-2018, 10:01 PM
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