|Re: HP 33E Programable Calculator|
Message #7 Posted by Vieira, Luiz C. (Brazil) on 13 May 2005, 12:47 a.m.,
in response to message #6 by Paul Marin
I use a pair of rechargeables, and a small, flat piece of metal to connect them both. In fact, it's a cut from old 9V alkaline batterie...
The rechargeables avoid having to open the battery door to replace the batteries (I'm always affraid of breaking it when openning...), and the new rechargeables do not leak as easy as it used to happen to some of the eariler ones.
I tested a few different brands, either NiCad or NiMH, from 700mAh (currently in two HP38C) to 1700mAh (currently in my HP34C), and despite of the different discharging time, they work pretty fine, no complaints at all. I tested Panasonic NiCads of 850mAh, 1100mAh and NiMH 1600mAh, GP (Gamma Power) NiCad 700 and NiMH 1700mAh, all of them worked fine. I know that based on current consumption and estimated discharging time, one can 'predict' how long will a fully charged battery maintain a Spice working with a running program or simply with "led's on" stand by, but I'm not sure about how to use this information. I just wait till the 'low power' dot to come up so I plug the charger in. What I'd actualy like to know is how long should I wait till the more powerfull batteries are fully charged.
I once posted about this here, and I am aware of the fact that a battery with more miliamps (capacity) needs more time or a higher constant current to be fully charged. I also know (at least I think so) that the recomended charging current in most cases is about 10% the nominal battery current, so the Spices have their mains supply designed to charge their orignal rechargeables that are, IIRC, about 500mAh. If we take proportionaly, the 1600 mAh would need about 30 to 36 hours for a full-charge operation if charged by the original Spice circuits. I myself prefer using external chargers for two reasons:
1 - I don't like to think of having a Spice connected to the AC mains supply for that long;
2 - I take the recomended 10% charging current as the one to be used, and the charging Spice circuit is design to something closed to 50mAh (if I am wrong, guys, plase place the correct figures...), that is 1/3 the recomended for a 1500mAh. Would that be a good choice?
Yeap, I know, this way I'd be openning the battery compartment too often as well, and that's the main reason I choose using rechargeables with current capacity that's closer to the originals and, by doing so, I use them (the two HP38C) as I'd use with the original battery pack, no worries about excessive time plugged in the AC mains.
Wow! Too much words... It's been some time I don't write that much in here. And as this computer has no spell checker, there's a lot of typos, for sure...
Best regards, Paul.