hp50g and power bank

[pier4r]

I tried a search but nothing useful was returned ( site:hpmuseum.org power bank 50g ).

Did someone try to keep the hp50g coupled with a power bank to handle intensive computations? (this because my 4 AAA batteries, ~700 mAh each, last very few hours and the calculator always complains about low battery)

I have a 2200 mAh power bank but it should be less helpful than the 4 AAA batteries, although I'll try. nevertheless if someone did tests already, would be nice to know.

[Dieter]

(03-27-2017 10:14 AM)pier4r Wrote:  Did someone try to keep the hp50g coupled with a power bank to handle intensive computations? (this because my 4 AAA batteries, ~700 mAh each, last very few hours and the calculator always complains about low battery)

If your 50g runs "very few hours" (say, 3 h) on a set of 700 mAh NiMHs this means that it permanently draws a current of something like 200 mA or more. Which sure is not typical. But then you say the calculator constantly shows a low battery warning. Both symptoms make me believe that the problem is at least one of your batteries.

I think you should try a set of quality (!) single-use batteries and see how long they last in your 50g. If this works fine simply get a set of high-quality NiMHs as well as a suitable processor-controlled charger. There have been several threads with recommendations for this.

What kind of batteries and what charger do you use now (manufacturer, exact type)?

Dieter

[Han]

Since the HP50G can run from USB power alone, I would imagine that any standard USB power bank should be sufficient for your additional power needs.

I would also recommend Dieter's suggestion to make sure that you don't have power issues that may not be battery-related.

[Vtile]

I use good quality NiMH "ready to use" re-chargeable batteries at 1000mAh capacity.

The powerbank should work as a plug-in. There is also somewhere on the net one blog post where person hacks one to the battery compartment of his/her 50g.

[Han]

Was it this one? http://hackaday.com/2009/03/06/new-batte...-an-hp50g/

The link in the article appears to be dead, but using the Wayback Machine, you can view an old snapshot here: HP 50G rechargeable battery pack hack

[Vtile]

(03-27-2017 01:55 PM)Han Wrote:  Was it this one? http://hackaday.com/2009/03/06/new-batte...-an-hp50g/

The link in the article appears to be dead, but using the Wayback Machine, you can view an old snapshot here: HP 50G rechargeable battery pack hack

Yep, it seems to be the "blog article" I referred. The down side is that you loose the "hot swap" ability of the AAA-cells, which for me are more important feature than a year worth of power at once.

PS. @pier4r do you have equipment to measure the real current draw of your 50g? There have been atleast one unit that had bad tantalum condensators in the mainboard that resulted excessive power consumption and also the big electrolytic capacitor glued to battery compartment (inside) might be leaky. Obviously if your normal use is 100% cpu time, then I can understand the "Few hours" battery life.


Hah, this answer and given solution is epic. (quote from hackaday)

Quote:Lessa says:
March 6, 2009 at 6:19 pm

The worst situation is the message “Low battery” in the middle of your final exam. this calculator should inform charge status of the batteries.
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Quote: Kerm says:
February 26, 2014 at 3:53 am

Put in fresh new batteries before your final exam? Maybe you’re not cut out for college after all?
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[Han]

(03-27-2017 02:26 PM)Vtile Wrote:  Yep, it seems to be the "blog article" I referred. The down side is that you loose the "hot swap" ability of the AAA-cells, which for me are more important feature than a year worth of power at once.

Yeah, given the power banks available these days (their relatively low price and how small they are in size), I would just go with batteries and a power bank. And even if one were to proceed with a hack, there are now pre-made USB charging boards that are much smaller than what the blog ended up using (which was pulled from some other device).

[pier4r]

Thanks for the replies!

(03-27-2017 10:36 AM)Dieter Wrote:  If your 50g runs "very few hours" (say, 3 h) on a set of 700 mAh NiMHs this means that it permanently draws a current of something like 200 mA or more. Which sure is not typical. But then you say the calculator constantly shows a low battery warning. Both symptoms make me believe that the problem is at least one of your batteries.

I think you should try a set of quality (!) single-use batteries and see how long they last in your 50g. If this works fine simply get a set of high-quality NiMHs as well as a suitable processor-controlled charger. There have been several threads with recommendations for this.

What kind of batteries and what charger do you use now (manufacturer, exact type)?

Dieter

The batteries are quite used. I would say they are 3+ years old and they were charged at least 20 times.

recharger, a cheap one. It states output "2.8V 150 mA
batteries, beghelli (quite good in Italy) and energizer, 750 and 850 mAh.

I will try what you say. Although I remember that when I used the 50g in 2013 and 2012, it was always quickly out of battery (I had similar AAA batteries back then, but different charger)

Pictures coming.
http://i.imgur.com/qLY0WGk.jpg charger
http://i.imgur.com/DnXfAjI.jpg batteries

About the hack. I would prefer a powerbank, since those are heavily developed for today's monster phones (well, since 2013 monster phones in terms of battery usage)

[Dieter]

(03-27-2017 03:22 PM)pier4r Wrote:  The batteries are quite used. I would say they are 3+ years old and they were charged at least 20 times.

No problem at all for high-quality batteries, carefully charged in a processor-charger. With decent treatment a few hundred cycles are possible. But...

(03-27-2017 03:22 PM)pier4r Wrote:  recharger, a cheap one. It states output "2.8V 150 mA
batteries, beghelli (quite good in Italy) and energizer, 750 and 850 mAh.

OK, no further questions. ;-)

Try quality single-use batteries first (high power alkalines, maybe even Lithiums – if approved by HP). If this works, replace both your batteries and your charger by, say, a set of Panasonic Eneloops and a BC700 charger.

Dieter

[Vtile]

I would stay away from enegizer, it have been proven poor brand in alkaline series (so I doupt the NiMH is any better) in several test around the net.

Varta ACCU or Eneloops are what I would go for.

[pier4r]

Oh, I did not know, TIL (today I learned). I will check those then, with a proper charger.

[franz.b]

I use only LSD (Low Self Discharge) batteries. the best batteries are eneloopm to also trony are excellent and cheaper.
it is important to upload them to appropriate currents (in two hours) and using a charger with individual channels.

[Dieter]

(03-27-2017 05:19 PM)pier4r Wrote:  Oh, I did not know, TIL (today I learned). I will check those then, with a proper charger.

Do you know what exactly makes a "proper" charger for AAA NiMHs ?-)
If you're not sure: get a BC700 or one of its siblings.

Dieter

[pier4r]

(03-28-2017 08:06 AM)Dieter Wrote:  Do you know what exactly makes a "proper" charger for AAA NiMHs ?-)
If you're not sure: get a BC700 or one of its siblings.

Dieter

I was hoping the price, but the plan B would have been "do a bit of searches" :guilty:. Now you are the second one mentioning the BC700.

[franz.b]

Powerex MH-C9000 is one of the best

[rprosperi]

(03-28-2017 10:26 AM)pier4r Wrote:  

(03-28-2017 08:06 AM)Dieter Wrote:  Do you know what exactly makes a "proper" charger for AAA NiMHs ?-)
If you're not sure: get a BC700 or one of its siblings.

Dieter

I was hoping the price, but the plan B would have been "do a bit of searches" :guilty:. Now you are the second one mentioning the BC700.

Consider me the 3rd. It's cheap, simple to use and works well, just be sure to also use quality batteries; as many have suggested Eneloops are excellent, and not too expensive.

[Dieter]

(03-28-2017 10:26 AM)pier4r Wrote:  

(03-28-2017 08:06 AM)Dieter Wrote:  Do you know what exactly makes a "proper" charger for AAA NiMHs ?-)
If you're not sure: get a BC700 or one of its siblings.

I was hoping the price,

I am not sure if I understand you here. What do you mean? It's the price that makes a "proper" charger? No, Sir.

(03-28-2017 10:26 AM)pier4r Wrote:  Now you are the second one mentioning the BC700.

Actually I have been recommending the BC700 here for years. You will even find posts in the old forum. The reason for this recommendation is the BC700 being a true processor-controlled charger with many useful functions – that you do not have to use if you do not want to. Without any manual setting it defaults to a charging current of 200 mA which is just fine for AAA NiMHs with their 800...1200 mAh capacity. Fast enough for convenience and safe end-of-charge detection, and slow enough for long battery life.

Dieter

[Dave Frederickson]

I recommend the BC-700 as well.

[pier4r]

(03-28-2017 05:22 PM)Dieter Wrote:  I am not sure if I understand you here. What do you mean? It's the price that makes a "proper" charger? No, Sir.

I try to explain. Normally, if one does not want to research enough, one assumes that prices convey the information about the quality of a product. Of course it is not always so, indeed companies exploit the statement above sometimes, but in general one could trim many of the "cheap but poor" choices using the price.

It does not work always, but it helps.

Quote:Actually I have been recommending the BC700 here for years. You will even find posts in the old forum. The reason for this recommendation is the BC700 being a true processor-controlled charger with many useful functions – that you do not have to use if you do not want to. Without any manual setting it defaults to a charging current of 200 mA which is just fine for AAA NiMHs with their 800...1200 mAh capacity. Fast enough for convenience and safe end-of-charge detection, and slow enough for long battery life.

Dieter

Thanks for the additional info.

[franz.b]

(03-28-2017 05:22 PM)Dieter Wrote:  Actually I have been recommending the BC700 here for years. You will even find posts in the old forum. The reason for this recommendation is the BC700 being a true processor-controlled charger with many useful functions – that you do not have to use if you do not want to. Without any manual setting it defaults to a charging current of 200 mA which is just fine for AAA NiMHs with their 800...1200 mAh capacity. Fast enough for convenience and safe end-of-charge detection, and slow enough for long battery life.

Dieter

the best charge current is C/2 where C is the battery capacity (it means that the charge time is 2h)
The BC700 charger maximum current is 700mA which could be insufficient in some cases (AA size batteries for example)