Questions about Ti-58c power supply

[Doctor_Jacek]

Hi everyone,

Recently I bought a Ti-58c without AC adapter, battery pack needs to rebuild.

I have some questions to ask you:

a) Can I use the 5.0 V provided by USB to replace the AC Adapter?

b) Can I replace the BP1-A battery pack with a 3.7v Li-Po battery Or 3.6v Ni-Mh battery

c) Which is the most appropriate power for a new battery pack? 600mAh, 750mAh, 1300mAh or higher?

Thanks in advance for your response.

[Nigel (UK)]

(06-27-2019 09:30 AM)Doctor_Jacek Wrote:  Hi everyone,

Recently I bought a Ti-58c without AC adapter, battery pack needs to rebuild.

I have some questions to ask you:

a) Can I use the 5.0 V provided by USB to replace the AC Adapter?

b) Can I replace the BP1-A battery pack with a 3.7v Li-Po battery Or 3.6v Ni-Mh battery

c) Which is the most appropriate power for a new battery pack? 600mAh, 750mAh, 1300mAh or higher?

Thanks in advance for your response.

(a) Probably. There’s a bridge rectifier circuit connected to the input, so the 5.0 V from the USB goes through 2 diode drops, bringing it down to 3.8 V which should be close enough to the normal battery voltage to run the calculator.

(b) Yes. I’ve done this, soldering a Li-Po connector direct to the terminals and housing a 700mAh battery in an empty BP-1A case. I’ve also used Ni-MH battery packs that I originally bought for HP classic calculators. These work too, but the Li-Po solution is lighter and less cramped, although the capacity is less.

Just to be clear: I don’t recharge these batteries in the calculator. Your 5.0 V supply might work for the Ni-MH pack, but it won’t be optimal. It certainly wouldn’t recharge the lithium cell. I recommend using a proper charger for either battery type.

(c) Any will work, so long as it physically fits in the space available. My 700mAh fits easily. Differences in capacity don’t imply differences in power. The Li-Po cell I use in my TI-59 easily powers card reading and writing, and lasts for several hours.

Nigel (UK)

Edit: By the way, welcome to the forum!