Which batteries for 41CV?

[Zaphod]

(10-17-2018 08:23 PM)burkhard Wrote:  Isn't the rule-of-thumb that the charging current (in mA) should be limited to about 1/10 the nominal battery capacity (in mA·hr)? If so, it's about 4× higher than optimal. Has anyone had any "troubles" from charging the N cells this hard? The page directs you to use 200 mA and not the 500 or 700 mA settings, but even 200 seems pretty high to me for these little cells.

Nicad and lead acid mebbe , but NiMH can be fast charged without problems.. as long as it's an intelligent charger which takes charging current, cell voltage and temperature into account.
You can charge as fast as 1C with these safeguards

[Didier Lachieze]

(10-17-2018 08:23 PM)burkhard Wrote:  That's excellent. I need to find some of those adapters on the US eBay. I'm sure somebody in Red China sells a set of 4 for $1.50 postage paid, but I don't see them.

In the US you can find N-Cell to AA Battery Adapters here, but it's more expensive than what you expect.

[Dieter]

(10-17-2018 08:23 PM)burkhard Wrote:  In your link from Akkushop, it does show the rechargeable N cells have a 500 mA·hr capacity, but the BC700 style charger has a minimum setting of 200 mA charging current. Isn't the rule-of-thumb that the charging current (in mA) should be limited to about 1/10 the nominal battery capacity (in mA·hr)? If so, it's about 4× higher than optimal.

No, there is no such rule, let alone is this the "optimal" charging current. Only if a dumb charger without any charge control is used and you don't know when to stop charging, these 0,1 C are recommended as most NiCds and many NiMHs can withstand an overcharge with such a low current. The charging time then is 12 hours or slightly more.

But were are talking about smart chargers here. 200 mA : 500 mAh means a relative charging current of 0,4 C which is almost perfect. It allows good –dU detection by the charger while it does not significantly heat up the battery. Take a look at the data sheets for the N-size NiMH cell of your choice. Often even a current of 1 C is allowed (i.e. here 500 mA) as long as there is a decent end-of-charge detection.

The BC-700 is one of the few smart chargers that allows a charging current as low as 200 mA. It even defaults to this setting when you turn on the device. This makes it very suitable for charging N-cells.

Dieter

[rprosperi]

(10-17-2018 08:23 PM)burkhard Wrote:  I need to find some of those adapters on the US eBay. I'm sure somebody in Red China sells a set of 4 for $1.50 postage paid, but I don't see them.

In USA, you can get the N-to-AA adapters here.

I've used them for several years w/o issues. Sometimes, you may have to wait a week or so as they make another batch, but the folks there are real nice and helpful.

[ijabbott]

These are advertised as low self-discharge: https://www.amazon.co.uk/dp/B07CMKWXC2

[HP67]

Thanks again to everyone for comments and links!

I saw the UK site but so far I have not found anything with a recognizable brand name. I'm concerned about nameless Chinese batteries (not that I have any illusions that the actual batteries aren't all made by one company and rebranded) just that without any reputation to worry about and no warranty, if it ruins an irreplaceable calculator it would be bad news.

Staying with the Duracell alkalines at this point until something more promising comes along.

Calculator arrived at local shipper today.. hopefully I will get it soon.

Thanks!

[Dieter]

(10-18-2018 07:19 PM)HP67 Wrote:  I saw the UK site but so far I have not found anything with a recognizable brand name.

While the GP 50NH (N-size 500 mAh NiMH battery) seems to be no longer available there is a substitute by Accucell, which I would say is a reliable brand for batteries and chargers. Here you can even get a complete set with four batteries, four N-AA-adapters and a suitable charger (looks like yet another version of the ubiquitous BC-700), for instance at Amazon or, even better, at akkushop.de.
(Edit: oops – I just noticed that Didiear already posted the akkushop.de link yesterday)

(10-18-2018 07:19 PM)HP67 Wrote:  Staying with the Duracell alkalines at this point until something more promising comes along.

If the above solution is not sufficiently promising, Alkalines are a good solution. At least as long you do not use a card reader or wand.

Dieter

[burkhard]

Thank you gentlemen for
1. ...allaying my fears about overcharging the N cells with my BC700.
2. ...passing along the sources for N adapters. I shall order up a set

[HP67]

(10-18-2018 07:44 PM)Dieter Wrote:  

(10-18-2018 07:19 PM)HP67 Wrote:  I saw the UK site but so far I have not found anything with a recognizable brand name.

While the GP 50NH (N-size 500 mAh NiMH battery) seems to be no longer available there is a substitute by Accucell, which I would say is a reliable brand for batteries and chargers. Here you can even get a complete set with four batteries, four N-AA-adapters and a suitable charger (looks like yet another version of the ubiquitous BC-700), for instance at Amazon or, even better, at akkushop.de.
(Edit: oops – I just noticed that Didiear already posted the akkushop.de link yesterday)

(10-18-2018 07:19 PM)HP67 Wrote:  Staying with the Duracell alkalines at this point until something more promising comes along.

If the above solution is not sufficiently promising, Alkalines are a good solution. At least as long you do not use a card reader or wand.

Dieter

Thank you, Dieter! I have had really bad experiences with GP batteries and I will never use them again. In 30+ years of using Duracell I had one unfortunate incident. So I trust them generally but will be careful not to leave them in anything that I'm not actively using and I try to remember to swap them out. I've converted to Eneloops for everything that uses standard size batteries.

If you say Accucell is known then I'll look into that brand, I had not heard of it before. Thanks to Didier for suggesting it and providing the initial link! Germany is the next country over, should be easy to deal with them.

Thanks again everyone!

[ijabbott]

(10-18-2018 07:19 PM)HP67 Wrote:  Thanks again to everyone for comments and links!

I saw the UK site but so far I have not found anything with a recognizable brand name. I'm concerned about nameless Chinese batteries (not that I have any illusions that the actual batteries aren't all made by one company and rebranded) just that without any reputation to worry about and no warranty, if it ruins an irreplaceable calculator it would be bad news.

I've tried a very similar Chinese brand TYBATT before (but AAA 1100 mAh size rather than LR1/N) and tested their capacity in a smart charger and they were fine. I can't vouch for the low self-discharge aspect yet. I wouldn't be surprised if EBL, TYBATT and similar brands come from the same manufacturer as they seem to have identical specs.

[Bill Duncan]

I just use a set of 4 Duracell alkaline "N" cells. They last a few years or more for me (but I haven't been using any attached peripherals much). Avoid Everready however; I've seen those leak.