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Which rechargeable battery you prefer for the HP-41?
08-21-2018, 05:28 PM
Post: #1
Which rechargeable battery you prefer for the HP-41?
I had the green ones from China with the extra-large positive pole. This product is now longer available.

[Image: akku.jpg]

Please share your rechargeable battery with best experience.

Many thanks
Patrik
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08-21-2018, 05:54 PM
Post: #2
RE: Which rechargeable battery you prefer for the HP-41?
(08-21-2018 05:28 PM)CY-CL Wrote:  I had the green ones from China with the extra-large positive pole. This product is now longer available.
...
Please share your rechargeable battery with best experience.

Are you asking for N-size batteries that are used in the standard HP-41 battery holder? May I ask how you charge these?

Dieter
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08-21-2018, 06:27 PM
Post: #3
RE: Which rechargeable battery you prefer for the HP-41?
Hello Dieter

Yes I talk from rechargeable batteries (Akkus) N-Size in the standard HP-41 battery holder

I charge them with the following charger and adapters:

[Image: 02.jpg]
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08-21-2018, 08:20 PM
Post: #4
RE: Which rechargeable battery you prefer for the HP-41?
Could someone post a link where those cells and the charger might be purchased? :-)
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08-21-2018, 08:29 PM
Post: #5
RE: Which rechargeable battery you prefer for the HP-41?
Amazon Germany:

Charger
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08-21-2018, 08:32 PM
Post: #6
RE: Which rechargeable battery you prefer for the HP-41?
Have someone experience with ODEC N Rechargeable Battery Ni-Mh 600 mAh?

ODEC
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08-21-2018, 11:45 PM (This post was last modified: 08-24-2018 12:55 PM by rprosperi.)
Post: #7
RE: Which rechargeable battery you prefer for the HP-41?
(08-21-2018 08:20 PM)Gene Wrote:  Could someone post a link where those cells and the charger might be purchased? :-)

Charger: https://www.amazon.com/Crosse-Technology...B000RSOV50

Sleeves to hold N cells in AA/AAA charger: http://ogazent.com/store/batteries-and-a...pter-n-aa/

N-Sized NiMH Cells:

N-Cell 500mAh NiMH Rechargeable 1.2v Battery (NT50NH) (LR1)

http://www.smallbattery.company.org.uk/sbc_N_NiMH.htm

Note 2nd cell supplier is a UK-based while the other 3 are US-based companies but will sell/ship overseas.

Edit: Revised to include link for N cells from Ogazent (same supplier as the cell-holder sleeves) found by Sylvain, to have all links in the same post. Thanks Sylvain.

--Bob Prosperi
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08-22-2018, 12:26 AM
Post: #8
RE: Which rechargeable battery you prefer for the HP-41?
I've been using NiMH cells in two HP-41's for many years with no problems at all. In a halfnut CX with no card reader they last forever. I recharge them in an external smart NiMH AAA charger by adding magnets to the cells like this:

[Image: NplusMagnets.jpg]

My source disappeared soon after I bought them, but the 500 mAh and 600 mAh cells mentioned above would last even longer than mine I guess.

By the way, the 41 can use cells with or without nipples, so if you find ones without nipples, go ahead and buy them. They'll work fine.

<0|ɸ|0>
-Joe-
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08-22-2018, 01:16 AM
Post: #9
RE: Which rechargeable battery you prefer for the HP-41?
(08-21-2018 08:32 PM)CY-CL Wrote:  Have someone experience with ODEC N Rechargeable Battery Ni-Mh 600 mAh?

I've used these and they worked well. Foolish me though, I recharged them in a unsuitable charger and continued to do so even after noticing how warm they were when removing them. One eventually leaked slightly but caused no damage.

Use good equipment!
~Mark

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08-22-2018, 01:09 PM
Post: #10
RE: Which rechargeable battery you prefer for the HP-41?
(08-22-2018 01:16 AM)mfleming Wrote:  I've used these and they worked well. Foolish me though, I recharged them in a unsuitable charger and continued to do so even after noticing how warm they were when removing them. One eventually leaked slightly but caused no damage.

Use good equipment!

Use suitable equipment!

The point is that N-cells require a much lower charging current than AA cells for which most chargers are designed. It's roughly 1/4 of the comparable AA current. That's why the BC-700 charger was recommended here: it defaults to 200 mA which for a 500 mAh N-cell means 0,4 C. This is a rate that is low enough for most current NiMH batteries and high enough to provide the required voltage drop for end-of-charge detection in a smart charger.

On the other hand, if you put such a 500 mAh cell (with an adapter) into an AA-charger that is set to 1000 mA you'll fry the battery with 2 C. This is a rate that exceeds the limits for most N-cells. You described what can and will happen then.

Dieter
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08-22-2018, 02:22 PM
Post: #11
RE: Which rechargeable battery you prefer for the HP-41?
I have bought through Robert a couple years back, several (20+) 500mAh NiMh 'N' batteries and 8x N-to-AA sleeves from Ogaz.
I am using with great success my smart battery chargers (BC700 & BC1000) from La Crosse Technology configured at 200mAh.
Sometime the smart battery charger does not see a battery because it is too low and report NULL.
When that happens, I put the battery into a dump charger for 30 seconds, then put it back into the smart charger which normally sees it and start the charging process.
Sylvain
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08-22-2018, 03:29 PM (This post was last modified: 08-23-2018 12:50 PM by smp.)
Post: #12
RE: Which rechargeable battery you prefer for the HP-41?
(08-22-2018 02:22 PM)Sylvain Cote Wrote:  <...snip...>
Sometime the smart battery charger does not see a battery because it is too low and report NULL.
When that happens, I put the battery into a dump charger for 30 seconds, then put it back into the smart charger which normally sees it and start the charging process.

Yes, I've experienced this same thing, and I solved the issue the same way. I never leave the battery in the dumb charger for more than a minute, and it's always enough to get it going properly in the smart charger again.

smp
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08-22-2018, 04:54 PM (This post was last modified: 08-22-2018 04:57 PM by Dieter.)
Post: #13
RE: Which rechargeable battery you prefer for the HP-41?
(08-21-2018 05:28 PM)CY-CL Wrote:  I had the green ones from China with the extra-large positive pole. This product is now longer available.

Isn't it? Take a look at amazon.de – here it says "on stock".

The picture in your initial post seems to show an Accucell battery – which sounds logical since you're using a charger/battery/adapter set by Accucell. So why not just get some new batteries of the same type?

Dieter
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08-22-2018, 05:05 PM
Post: #14
RE: Which rechargeable battery you prefer for the HP-41?
(08-22-2018 03:29 PM)smp Wrote:  
(08-22-2018 02:22 PM)Sylvain Cote Wrote:  <...snip...>
Sometime the smart battery charger does not see a battery because it is too low and report NULL.
When that happens, I put the battery into a dump charger for 30 seconds, then put it back into the smart charger which normally sees it and start the charging process.

Yes, I've experienced this same thing, and I solved the issue the same way. I never leave the battery in the dump charger for more than a minute, and it's always enough to get it going properly in the smart charger again.

smp

If you don't have a dumb charger, another option is to "jump start" the dud battery by connecting it in parallel with one of the other discharged batteries for a few seconds.

— Ian Abbott
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08-23-2018, 02:44 AM
Post: #15
RE: Which rechargeable battery you prefer for the HP-41?
I can't find the source for these, at one time they were on Amazon US.
   

Check out NQ41!
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08-23-2018, 03:08 PM
Post: #16
RE: Which rechargeable battery you prefer for the HP-41?
N cell NiMH batteries I've used w/o problems for several years are still available in USA/Canada from Interstate Batteries, however they cannot be purchased online, they have to be ordered through your local IB store, and paid/picked-up there. I assume this is a result of the general fear and loathing of mailing batteries, even though this does not apply to NiMH, but could not get an answer as to why no online sales.

Spec: 1.2V 500MAH NIMH N CELL
Part number: ASC1055
Price: $3.90/ea. in qtys. of 20 (but possibly the same even in low qty.)

Not cheap, but good quality, reliable, and above average capacity.

Here is a list of the Interstate Battery store locations, there are a lot more than I expected.

--Bob Prosperi
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08-23-2018, 05:05 PM
Post: #17
RE: Which rechargeable battery you prefer for the HP-41?
Hello Everyone, I am new here and was passing thru the other day when I was searching for N-Cell batteries and Adapters to charge them. I thank you for the link to the ogazent.com website. I did order 8 adapters from them. They are on their way to me now. I just got an e-mail from them that they are finally getting the 500mAh N-Cell batteries back in stock. I clicked on the link they sent me and it looks like they are letting you order in advance now.

Just wanted to let people know there is another reputable company to get N-cells from. They shipped my Adapter order the same day.
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08-23-2018, 06:04 PM
Post: #18
RE: Which rechargeable battery you prefer for the HP-41?
(08-23-2018 05:05 PM)mrcntry Wrote:  Just wanted to let people know there is another reputable company to get N-cells from. They shipped my Adapter order the same day.
Thank you!
I just looked at their web site: N-Cell 500mAh NiMH Rechargeable 1.2v Battery (NT50NH) (LR1)
and this is what they have posted: Batteries will be BACK in stock Sept 7th. 2018. You can pre-order now or wait till they come in. Might come in early.
Sylvain
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08-23-2018, 09:59 PM (This post was last modified: 08-23-2018 10:00 PM by rprosperi.)
Post: #19
RE: Which rechargeable battery you prefer for the HP-41?
Thanks for the updated info; $2.35/ea is a LOT better than the $3.90/ea quoted by IB. In mid-2016, they were $1.99/ea in qtys of 10+.

--Bob Prosperi
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08-24-2018, 12:44 AM (This post was last modified: 08-24-2018 04:06 AM by Garth Wilson.)
Post: #20
RE: Which rechargeable battery you prefer for the HP-41?
Are there any that give much over 1.2V per cell? Because that's where my 41's BAT indicator comes on, and that's a pretty standard voltage for rechargeable cells that are supposed to be 1.5V substitutes; IOW, I basically can't use them. However, I did recently buy 20 Energizer alkaline N cells, expiration date 2022, for $17 ($.85/ea) including shipping, and I saw even lower prices if you want to buy 50 or 100. I got these: https://www.ebay.com/itm/Lot-of-20-Energ...2749.l2649 . (My ebay ID is wilsonmines, and I have no connection to this seller.)

http://WilsonMinesCo.com (Lots of HP-41 links at the bottom of the links page, http://wilsonminesco.com/links.html )
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