Bedtime for the 32E


Hello all.

With my newly acquired HP-32E, how long should I recharge the 32E for the full cycle? And, is overcharging an issue?




Regular charging time may vary, but it is usually the ten hours 'rule of thumb'. I am not sure about it, but your calculator is probably being powered by new batteries, right? IIRC (here we go...) the original batteries were 650mAH, which gives an average 65mA charging rate. If you are using a new battery set, check for their ampacity and make the necessary adjustments. I usually go for no more than 12 to 14 hours when the batteries need charge.

I do not recall reading about overcharging in HP calculators. Trying to power the calculator with the adapter and no batteries is actually the worse case: NEVER TRY IT in some models/families. I'd not do that in Spices as well.


Luiz (Brazil)


Oh no! Not after the HP-67 scare I went through a couple of weeks ago! I learned that lesson once! Remember when I got my 67? Well, that mishap may have traumatized the card reader (or not). Fortunately, I've got quite a few 67 support and card reader rebuild options but, after that scare, I've made it a precautionary measure not to take for granted that batteries would be in the calcs I get from eBay or elsewhere.

Edited: 7 Apr 2012, 1:41 a.m.


Also, for Woodstocks in particular don't take it for granted that either
- the batteries are good or
- the batteries are making good contact with the contacts in the calculator.

A problem in either area can cause the delicate innards of the Woodstocks to be fried if connected to a charger.

Best to always charge the batteries outside the calculator.

Probably a good rule for any HP with red leds.




Well then. Where can I get a charging cradle to put the battery pack in?



There is an alternative NOT VALID FOR THE CONSTANT MEMORY UNITS, namely HP25C, HP29C and HP19C. Based on their main circuit, you can simply NOT turn the calculator ON while charging because once the calculator is turned OFF the battery line (hence the power line) is disconnected from the whole circuits. What I have been doing since I got the HP21 schematics is to put the batteries in their compartment and connect the calculator to the charger. Then I check if the batteries are getting warm (about 1/2 an hour). After some eight to ten hours I disconnect the charger and check if the calculator turns ON without the 'all-dots-on' sign of low battery. None of my three working Woodstocks (one HP21 and two HP25) had problems this way.


Luiz (Brazil)


Hi Luiz

Thanks, that's good to know. - you can use effectively use a 21 as a charging cradle for a 25C or other Constant Memory Woodstock.

Hi Matt,

When I got my 25C the battery holder had been modified by cutting away part of it so normal rechargeable AA cells could be used - presumably because the original rechargeables cells had given up. So I can take the cells out and recharge them in a normal AA recharger. Now I can just swap the battery holder into my 21.

Similarly my 34C had normal rechargeable AA cells when I got it so again I just take them of the metal clip that retains them when I need to recharge them as the power supply socket on my 34C is a bit iffy.

As for the classics, I was fortunate enough to get an original HP cradle to use off TAS. I think the original aim of the cradle was to allow a spare battery unit to be recharged so one would never be out of volts.




Hello Luiz,

What do you think of this ad?

“P.S> As calculadoros necessitam de reparos, pois ao liga-lás na forças elas acendem e apagam por isso estão sendo vendida no estado se sem garantia de funcionanento!!!”

(“P.S.: The calculators need repair because upon connecting them to the AC line their displays light on then off, so they are being sold "as is", with no guarantee they work!!!”)




Toasted ACT. :-(


Exactly! If I am not wrong, the only source of replacement is from a working Woodstock. I don't have any yet (looking for a 25C or 29C). If those only looked good...


Hi, Gerson;

this is a 'renewed' ad. The first one had a question of mine that has been removed: "Have you tested the calculators without the batteries?" The answer was "Yes, but they did not respond." Well, now they will never...

Thanks for your remind.


Luiz (Brazil)

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