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bshoring · 11-02-2015, 04:58 AM

I saw the page below on the web, and I am wondering if anyone here has had any experience with this seller or the battery pack adapters that he sells. The site is:
HP Classic AA Battery Pack Adapters at
Bob's Calculators and Slide Rules

at:
https://sites.google.com/site/bobscalcul...ck-adapter

Thanks!

Sadsilence · (This post was last modified: 11-04-2015 08:50 AM by Sadsilence.)

No experience with it so far but a nice idea. Wish I would have come along it before.

I was looking for a posibility to use RTU cells with my classics as self discharge rate of normal NiMHs and NiCDs forces you to reload packs every 3 months, no matter how often you use your calculator(s).

Normal AA cells does not fit into original pack case cause of high tops. But if you do not mind open your existing battery pack case and replace cells there is a already prebuild pack:

tecxus AA-3 RTU Pack

e.g.
http://www.reichelt.de/Batteries-NiMH-So...ANGUAGE=EN

or
http://www.amazon.de/Tecxus-NiMh-Akku-mi...s=aa-3+rtu

Really high quality flat top cells pack for around 10 bucks. Just open case, remove contact tails from original pack carefully with pliers , clean them and arrange them correctly in case together with tecxus pack. You even do not have to (of course you can) solder tails as pressure is enough for contact and closed case with a drop of super glue prevents any accidental shift.

One charge is good enough for a 12 hour timer test with HP 45.

Nominal and real capacity: 2100 mAh
Recharge time for discharged pack with AC adapter: 48 hours
Recharge time for discharged pack with external rc battery charger: 2h 15 min

Best regards,

Werner

Sylvain Cote · 11-02-2015, 12:27 PM

I bought one and it works as expected.
The great thing about it, is that you can use normal AA cells.

The only draw back is that it's fragile.
I drop mine with batteries in it and the unit completely disassembled itself.

Sylvain

BobVA · (This post was last modified: 11-03-2015 01:53 AM by BobVA.)

If you use low self discharge NiMh they'll sit for months and still work OK. These are typically sold as "pre-charged" re-chargeables at the consumer level.

I haven't found them available as flat-top, but you can use button tops if you make your own "shell" out of heat shrink - I had a local battery shop make me up a 3 AA pack (welded connections) and heat shrink it, then I attached some DIY copper connectors. Don't try to solder directly to the batteries - it's dangerous and wrecks the cells.

Katie shared this idea awhile back and it works great: modify a 3xAAA cell holder to make appropriate contact with the battery connectors in the calculator, then load it with low self discharge AAA batteries.

bshoring · 11-03-2015, 08:13 PM

Thanks for the info & ideas!

**Katie Wasserman** · 11-04-2015, 03:24 AM

Here's an old thread on this topic.

bshoring · 11-04-2015, 06:19 PM

(11-04-2015 03:24 AM)Katie Wasserman Wrote: Here's an old thread on this topic.

Thanks, Katie!

I might just see if I can get a battery holder like that at Batteries Plus.

**Katie Wasserman** · 11-05-2015, 03:26 AM

(11-04-2015 06:19 PM)bshoring Wrote:
(11-04-2015 03:24 AM)Katie Wasserman Wrote: Here's an old thread on this topic.

Thanks, Katie!

I might just see if I can get a battery holder like that at Batteries Plus.

If you still have a Radio Shack near you, they might have it. Almost any on line electronics store will have them too.

Derek W · 11-05-2015, 10:28 AM

I bought one of Bob's adaptors two years ago and was fully satisfied - it's maybe not quite as neat looking as the website photos but the difference is marginal and in no way affects serviceability. It enabled me to use normal AAs in an HP35, and I've been powering it that way ever since. He replied quickly to my initial e-mail enquiry, and dispatched the adapter within a week of me placing the order - it took a further two weeks to reach me, but that was down to transatlantic transit and UK customs clearance.

bshoring · 11-13-2015, 11:21 PM

(11-05-2015 03:26 AM)Katie Wasserman Wrote:
(11-04-2015 06:19 PM)bshoring Wrote: Thanks, Katie!

I might just see if I can get a battery holder like that at Batteries Plus.

If you still have a Radio Shack near you, they might have it. Almost any on line electronics store will have them too.

Thanks Katie for the idea. Radio Shack didn't have any but I got a bag of 5 from Amazon and they fit. I don't plan to keep batteries in my HP-35 that long, but it is nice to know that should any leakage occur the battery holder offers some protection, I think. My calculator is working just fine! Thanks.