Thinking about an HP-41CL

[Dieter]

(07-27-2016 02:17 PM)Dave Frederickson Wrote:  Using the adapters above, the charger makes contact with the adapter, not the battery.

Argghhh... sometimes you don't notice the most obvious... #-) If the adapter is designed the way you described it should indeed work with both flat and button top batteries. On the other hand my homebrew AA-N-adapters are used the other way round: the adapter has the minus side and the plus side is the battery itself. ;-)

Edit: I just did a Google search for "adapter AA N" and found my picture of the mentioned DIY adapters in the 2011 forum thread. ;-)

Dieter

[Dave Frederickson]

(07-27-2016 05:49 PM)Dieter Wrote:  I just did a Google search for "adapter AA N" and found my picture of the mentioned DIY adapters in the 2011 forum thread. ;-)

One of my references when researching chargers and batteries.

[rprosperi]

(07-27-2016 03:45 PM)smp Wrote:  Did they indicate to you when about they will become available again?

Sorry, I thought I had posted that update, but I guess I only emailed Dave.

They are making a batch and should be ready within a week. You should sign-up (here) to be notified when they become available. I told them this was discussed here and to expect some more interest soon.

[smp]

(07-28-2016 02:32 AM)rprosperi Wrote:  

(07-27-2016 03:45 PM)smp Wrote:  Did they indicate to you when about they will become available again?

Sorry, I thought I had posted that update, but I guess I only emailed Dave.

They are making a batch and should be ready within a week. You should sign-up (here) to be notified when they become available. I told them this was discussed here and to expect some more interest soon.

Hi Bob,

Thanks very much for the info. Yes, I've already signed up to get notified when they are available again.

smp

[smp]

OK!

I now have a BC-700 charger and four 500 mA NiMH N size batteries on order. I am on the waiting list for the N size to AA size adapters that were recommended here. Hopefully, they'll be back in stock shortly.

Thanks very much to all you guys who offered up your thoughts, comments and advice. I really appreciate the support!

smp

[Dave Frederickson]

A few last comments:
Here's the GP50NH dartasheet: http://datasheet.octopart.com/GP50NH-GP-...549593.pdf

It should be noted that to fast charge the cells the BC-700 needs to have the charging current changed from the default of 200mA, otherwise the - delta T end-of-charge detection circuit may not work as intended.

A couple of questions. The BC-700 also detects end-of-charge by temperature, and the datasheet shows a DT/dt spec. Will the BC-700 end the charge cycle properly if the cells are charged at 200mA rather than fast-charging at 250 to 500mA?

Yesterday I received some 2200mAH AA flat top cells for use in Spice calcs. (No, they won't make contact with the charger without a washer.) Initial research turned up a 2200mAH Sub-C cell with a normal charge current of 220mA. Without buying the higher current BC-1000, what's the best charge current?

It would be nice if someone wrote an article about smart chargers and high-capacity cells.

Dave

[Dieter]

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  A few last comments:
Here's the GP50NH dartasheet:

Fine, but since the GP50NH is no longer available most probably a different type of battery will be used. ;-)
FTR: the datasheet for the X-Cell N battery seems to have some errors.

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  It should be noted that to fast charge the cells the BC-700 needs to have the charging current changed from the default of 200mA, otherwise the - delta T end-of-charge detection circuit may not work as intended.

"Fast charge" is not a term with fixed definition. The GP data sheet states 0,5...1 C for the small N cell, while other sources will define the same term as charging with a current of at least 1 C and higher, especially for larger cells with a different surface-volume ratio which influences the cell temperature and therefore the voltage drop at full charge.

The –dU detection of modern processor-controlled chargers usually detects voltage drops as low as 5 mV, so we can safely assume that a charge rate of 0,4 C should be fine. The GP datasheet even states this value as cut-off condition. The temperature detection essentially is an additional safeguard.

I am charging my 2000 mAh Eneloop AA cells with 450 mA, which is 0,22 C, and it works fine in a different processor-charger. Even thirty years ago the battery pack for my Metz flash was charged with 0,2...0,3 C, and a connected voltmeter cleary showed the characteristic peak on full charge with various types of NiCd cells.

So I do not think that the 200 mA setting should be changed. I think it's just right for this type of battery. That's why the BC700 is the recommended charger – it defaults to this current. I'd definitely avoid the next higher 500 mA setting for N-cells.

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  A couple of questions. The BC-700 also detects end-of-charge by temperature, and the datasheet shows a DT/dt spec. Will the BC-700 end the charge cycle properly if the cells are charged at 200mA rather than fast-charging at 250 to 500mA?

This can only be answered if we know the voltage drop of the battery in question (and the ambient temperature) at 200 mA charging current. But I think we can safely assume that there will be no problem – see above. Again: the main cut-off condition is the voltage peak resp. voltage drop (–dU). But where do you see a graph with dT/dt specifications? I just read the manual that can be downloaded from the LaCrosse website.

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  Yesterday I received some 2200mAH AA flat top cells for use in Spice calcs. (No, they won't make contact with the charger without a washer.) Initial research turned up a 2200mAH Sub-C cell with a normal charge current of 220mA. Without buying the higher current BC-1000, what's the best charge current?

My personal experience for the best compromise is something like 0,3 C or maybe a bit more (that's why I think 0,4 C for the N cells is perfect). This translates to about 700 mA for your 2200 mAh battery. But how do you want to squeeze a SC cell into a Spice, or even the BC700?

The BC1000's additional 1000 mA setting is a nice option for high-capacity AA cells (at least if their specs allows charging with this current, which should be the case for most decent cells of the last decade). On the other hand charging is just 30% faster than with 700 mA...

In general there is no "best" charging current if only the battery capacity is given. There are very different battery designs, some offer higher capacity, others are specially designed for rapid charge, etc.

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  It would be nice if someone wrote an article about smart chargers and high-capacity cells.

What high-capacity cells do you refer to?

Dieter

[Dave Frederickson]

(07-28-2016 05:51 PM)Dieter Wrote:  

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  Here's the GP50NH dartasheet:

Fine, but since the GP50NH is no longer available most probably a different type of battery will be used. ;-)

Agreed, but the datasheet is a representative example of a typical 500mAH NiMH N-cell, and it's what Sylvain recommended.

(07-28-2016 05:51 PM)Dieter Wrote:  

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  A couple of questions. The BC-700 also detects end-of-charge by temperature, and the datasheet shows a DT/dt spec. Will the BC-700 end the charge cycle properly if the cells are charged at 200mA rather than fast-charging at 250 to 500mA?

But where do you see a graph with dT/dt specifications?

There are some values for dT/dt in the GP50NH datasheet.

(07-28-2016 05:51 PM)Dieter Wrote:  

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  Yesterday I received some 2200mAH AA flat top cells for use in Spice calcs. (No, they won't make contact with the charger without a washer.) Initial research turned up a 2200mAH Sub-C cell with a normal charge current of 220mA. Without buying the higher current BC-1000, what's the best charge current?

But how do you want to squeeze a SC cell into a Spice, or even the BC700?

I simply found a datasheet for a SC cell. It provided some ballpark specs until I could find an AA datasheet.

(07-28-2016 05:51 PM)Dieter Wrote:  

(07-28-2016 04:41 PM)Dave Frederickson Wrote:  It would be nice if someone wrote an article about smart chargers and high-capacity cells.

What high-capacity cells do you refer to?

Any cell that is not practical to charge on the original ~50mA charger that came with the calculator.

Dave

[Dieter]

(07-28-2016 07:50 PM)Dave Frederickson Wrote:  Agreed, but the datasheet is a representative example of a typical 500mAH NiMH N-cell, and it's what Sylvain recommended.

Wait until you see the XCell data sheet. ;-)

(07-28-2016 07:50 PM)Dave Frederickson Wrote:  There are some values for dT/dt in the GP50NH datasheet.

The GP datasheet lists some cut-off conditions for different types of charge control. So if (!) the temperature gradient is evaluated, charging should stop at the given value. AFAIK the BC700 only checks the cell temperature as an additional safeguard: according to the LaCrosse manual it cancels charging at 53°C.

A better and IMHO more reliable way of charge control is the time-proven method of detecting the peak resp. drop of the cell voltage during charge. This is what is implemented in most processor-controlled chargers.

The idea is simple: While the battery is charged, its voltage increases. As soon as the battery is fully charged the voltage cannot increase further. The still flowing charging current now is transformed into heat, which – to a certain extent – is no problem as NiCd and NiMH batteries are usually designed accordingly. The increasing temperature in turn causes the voltage to drop (the higher the temp, the lower the voltage and vice versa). So this is a quite reliable and method for detecting the point where the battery is fully charged. All that's required is a sufficiently high charging current that will cause the battery to become warmer on full charge. Here 0,3 C usually is sufficient, sometimes even lower rates will do. At least if charger is able to detect the less distinct voltage drop.

(07-28-2016 07:50 PM)Dave Frederickson Wrote:  I simply found a datasheet for a SC cell. It provided some ballpark specs until I could find an AA datasheet.

SC and AA batteries can be very different. Sub-C is a common size for high drain applications, e.g. power tools or RC cars. The specs for AA size cells can differ significantly. I strongly suggest consulting the datasheet for exactly the type of battery you intend to use.

(07-28-2016 07:50 PM)Dave Frederickson Wrote:  

(07-28-2016 05:51 PM)Dieter Wrote:  What high-capacity cells do you refer to?

Any cell that is not practical to charge on the original ~50mA charger that came with the calculator.

OK, that's virtually any current battery type. ;-) Due to environmental restrictions NiCds are practically unavailable over here in Europe, so NiMH is what you get. Here the capacity for AA cells typically is 2000 mAh and more, compared to 500 mAh back in the days of the Spice series.

But let's not forget: the same charging time still yields the same operating time. If you charge your 2000 mAh battery with the original charger the same way you did 30 years ago, you'll still get the same usable capacity. ;-)

(No, of course that's not a serious option. I am using 2000 mAh Eneloops in my 34C, and these are charged in a decent processor-controlled charger).

Dieter

[Dave Frederickson]

(07-28-2016 08:41 PM)Dieter Wrote:  Wait until you see the XCell data sheet. ;-)

You mean Exell?

https://www.amazon.com/Exell-Size-2200mA...B00YHVB8UO

[smp]

(07-28-2016 11:25 AM)smp Wrote:  I am on the waiting list for the N size to AA size adapters that were recommended here. Hopefully, they'll be back in stock shortly.

I got an e-mail message from Ogaz/TNC today saying the N size to AA size adapters are now back in stock. I've placed my order. Now, all I have to do is wait for all the bits to arrive.

8-)

smp

[Sylvain Cote]

(07-28-2016 09:59 PM)Dave Frederickson Wrote:  

(07-28-2016 08:41 PM)Dieter Wrote:  Wait until you see the XCell data sheet. ;-)

You mean Exell?

https://www.amazon.com/Exell-Size-2200mA...B00YHVB8UO

I think Dieter is referring to my following comment

(07-24-2016 11:28 PM)Sylvain Cote Wrote:  Edit: after a research on the web I found that the GP 50NH is no longer produced but I have found a replacement in XCell X500NH.
Unfortunately, it seems that it is only available in Europe, all resellers that I found do not ship to USA or Canada.

The XCell X500NH is available here.

Sylvain

[Dieter]

(07-28-2016 11:48 PM)Sylvain Cote Wrote:  I think Dieter is referring to my following comment

Right.

(07-24-2016 11:28 PM)Sylvain Cote Wrote:  The XCell X500NH is available here.

Beware: the datasheet contains several errors, e.g. the hour ratings in the charge/discharge graphs are nonsense.

BTW Conrad claims they ship to 210 countries all over the world.

Dieter

[Sylvain Cote]

(07-28-2016 11:57 PM)Dieter Wrote:  BTW Conrad claims they ship to 210 countries all over the world.

That may be so, but choosing Canada or United State from their site we get the following message:

Unfortunately, we stopped shipping to both the US and Canada in 1991 due to high postage and insurance costs,
as well as the potential Product Liability issues arising from delivering to both countries. However, if you live in
the US or Canada, would like to purchase one of our products and have friends or acquaintance overseas, why
not ask them to order on your behalf?

Sylvain

[Dave Frederickson]

(07-28-2016 11:48 PM)Sylvain Cote Wrote:  

(07-28-2016 09:59 PM)Dave Frederickson Wrote:  You mean Exell?

https://www.amazon.com/Exell-Size-2200mA...B00YHVB8UO

I think Dieter is referring to my following comment

(07-24-2016 11:28 PM)Sylvain Cote Wrote:  Edit: after a research on the web I found that the GP 50NH is no longer produced but I have found a replacement in XCell X500NH.
Unfortunately, it seems that it is only available in Europe, all resellers that I found do not ship to USA or Canada.

The XCell X500NH is available here.

Sylvain

Whoops, sorry I missed that.

Here's a nice review of the BC-700: http://www.amazon.com/review/RK62EGS3P082I/

Dave

[smp]

Just to follow up with my current status:

I've now received my BC-700 and the N-size to AA-size adapters from Ogaz. Nice quality products on both counts.

My N-size NiMH batteries are still on their way to me with arrival hopefully tomorrow.

smp

[smp]

I've received my NiMH rechargeable batteries, and charged them overnight, and now I'm good to go.

Trying to get into HP-41C programming, I am running into many programs that have synthetic instructions in them. Not the best help to get familiar with programming when you cannot enter the instruction you come up to in the middle of a program.

I've been looking at snippets on synthetic programming and I'm getting confused by byte grabbers, byte jumpers, and byte loaders, and each needs to be generated by starting with a Memory Lost condition, so especially since I do not have any storage mechanism this seems interesting.

I'm wondering about simply obtaining one of the PPC ROMs. I believe it has a byte loader in it, so I would not have to worry about generating one, and I could get on with entering programs as I wish.

Is this a good idea, or should I simply cool my heels and wait until Monte has more 41CL boards available?

It appears that my HP-41C, along with my Quad Memory module, my Extended Functions/Memory module, and a PPC module might really be sufficient. Or, am I fooling myself?

Your thoughts would be most welcome.

smp

[smp]

BTW, somewhere I saw that someone is offering a 3D printed version of the HP-41 battery door/case. Of course, I cannot find it anywhere now. Can someone point me in the right direction?

Thanks!

smp

[Dave Frederickson]

(08-06-2016 05:35 PM)smp Wrote:  BTW, somewhere I saw that someone is offering a 3D printed version of the HP-41 battery door/case. Of course, I cannot find it anywhere now. Can someone point me in the right direction?

Thanks!

smp

Perhaps you were thinking of my shop on Shapeways: shapeways.com/shops/hpparts

BTW, models courtesy of Nate Martin and Hans Brueggemann. Prices are only for materials, there is no markup.

[smp]

(08-06-2016 06:27 PM)Dave Frederickson Wrote:  Perhaps you were thinking of my shop on Shapeways: shapeways.com/shops/hpparts

BTW, models courtesy of Nate Martin and Hans Brueggemann. Prices are only for materials, there is no markup.

Yes! Thanks very much, Dave.

You can be expecting an order from me.

smp