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HP Forum Archive 14

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batteries for 48G+, 49G+, 48GII
Message #1 Posted by Eduardo Costa on 6 Feb 2005, 12:05 a.m.

Hi, people. I tried to buy batteries for Classpad 300, HP 49G+, HP 48GII, and HP 48G+ calculators. People told me that the best option would be Compit AAA rechargeable batteries KR 11 / 45 ˇ R 03, 1000 mAh, with an ultra fast recharger. The fact is that there is no such a brand in the town where I lived. I also searched Amazon, and they do not work with Compit batteries. In Walmart, I found Rayovac IC3 rechargeable batteries, with ultra fast charger (15 minutes), but they are 800 mAh models. Is this a good replacement for the Compit? Is 800 mAh enough to drive the foresaid calculators? Amazon has Accupower AP1000-5, that seems to be almost as good as Compit. Should I buy IC3 batteries from Walmart? Or order Accupower batteries from Amazon? Or try really hard to get Compit batteries? By the way, I bought 4 IC3 batteries just to test. They seem to be working quite well. Therefore, can I conclude that 800 mAh is enough?

      
re: batteries
Message #2 Posted by Tim Wessman on 6 Feb 2005, 1:32 p.m.,
in response to message #1 by Eduardo Costa

The mAh rating is a measure of the capacity of the battery, not the voltage. I imagine your batteries are 1.2v. The higher the mAh is, the greater the capacity is on the battery.

I had 750mAh rechargables in my calculators. In another I have 4-1950 mAh AAs. They work just fine. Just keep an extra set with you at all points as they tend to run out sooner.

TW

      
Re: batteries for 48G+, 49G+, 48GII
Message #3 Posted by Vieira, Luiz C. (Brazil) on 6 Feb 2005, 2:03 p.m.,
in response to message #1 by Eduardo Costa

Hi, Eduardo;

I wrote an additional post to this thread but somehow it was not added... I forgot to add my name in the proper field and the text was wiped out. No matter.

As Tim mentioned, I also use three 750mAh NiMH (SONYŽ, Cyber-shot 'STAMINA' DI HR 11/45) in my HP49G+. Considering the average of half an hour a day (I guess this is too much, but I actually powered it up with the purpose of testing batteries) the fully charged pack lasts for about one month. I also used the USB port some times, and this is a power-consumming operation. I did not upgrade the OS with the rechargeable batteries so far.

I also use the same type of NiMH in my HP49G (earlier model) and it lasts about two months. I use a pack of four NiCAD AAA, 650mAh, in my HP71B. These last more than two months, too.

Hope this adds a bit more.

Luiz (Brazil)

Edited: 6 Feb 2005, 2:05 p.m.

            
Re: batteries for 48G+, 49G+, 48GII
Message #4 Posted by Eduardo Costa on 6 Feb 2005, 7:36 p.m.,
in response to message #3 by Vieira, Luiz C. (Brazil)

Hi, Vieira. Aren't these new NiMH batteries supposed to last even longer than Alkaline batteries? Besides recharging in less than 15 minutes, of course. At least this is what the manufacturer claims. For instance, the manufacturer of IC3 says that it lasts more than 4 times longer than alkaline batteries. Another manufacturer even presents plots to the effect that his brand has the same low battery behavior as alkaline batteries.

                  
Re: batteries for 48G+, 49G+, 48GII
Message #5 Posted by Vieira, Luiz C. (Brazil) on 7 Feb 2005, 12:04 a.m.,
in response to message #4 by Eduardo Costa

Hi, Eduardo;

first of all, forgive me: I added a wrong information in my last post. Actually the 650mAh rechargeable batteries I use in the HP71B are NiMH, too. About discharging time, let me first compare the HP71B and the HP49g+:

1 - the HP71B uses four AAA instead of the three ones used in the HP49G+;
2 - I actually use the HP71B less than I use the HP49G+;
3 - the HP49G+ "eats" batteries; it has higher speed (internal clock) and this is, by itself, one of the reasons.

About the fact the NiMH rechargeable batteries live longer than Alkaline, I always took this based on their actual life, not each charging cycle. In fact, everytime I used alkalines instead of the rechargeables I know and use, their "life time" was a lot of times longer that a single discharge of the rechargeables.

I have not used the new NiMH ones yet; for example, I don't know the specs for this IC3 unit. Based on what you say, the newer NiMH are something to try out. I'm impressed!

Thanks for your information.

Best regards.

Luiz (Brazil)

                        
Re: batteries for 48G+, 49G+, 48GII
Message #6 Posted by Francesc Casanellas on 7 Feb 2005, 3:40 a.m.,
in response to message #5 by Vieira, Luiz C. (Brazil)

A standard AAA 1.5 V battery has a capacity of about 540 mAh. An alkaline-Mn AAA battery has a capacity of about 1200 mAh. A rechargeable NiMH metal hydride battery has normally a capacity of 750 - 800 mAh at 1.2 V, so will last less than an alkaline battery and more than a carbon-Zn battery.

Be carefull with super-fast chargers: Your battery will be dammaged in less charge cycles than if you charge it slowly.

                        
Re: batteries for 48G+, 49G+, 48GII
Message #7 Posted by Thomas Okken on 7 Feb 2005, 7:09 a.m.,
in response to message #5 by Vieira, Luiz C. (Brazil)

I recently bought half a dozen cheap NiMH cells (AA) with a cheap slow-charger; HEMA brand (that's a Dutch low-budget department store chain), spent about 25 euros for the whole set.

The batteries are 1900 mAh -- I charged two for 14 hours and put them in my HP-25. OK, I don't use the 25 a lot, I have it purely for nostalgia reasons, but even so, those batteries seem to last *forever*. Two months later, I'm still waiting for them to run down! Even without actual measurement, I can already tell they last several times longer than the original NiCd cells ever did, and maybe even as long as alkalines. And the price is right, too!

(With that kind of life, who needs a fast charger anyway? Even at 14 hours, they charge faster than the 25 can run them down. I bet with the 49 the situation is no worse.)


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