HP41CX, corrosion on (-) of one battery

[Uli]

Hi Specialists,

within the last 3 weeks my mainly used hp41cx had corrosion on the minus pol of the left hand battery. It happened two times. I can't switch on the hp41cx. After cleaning the (-) pol on the battery, it works again.

This is my most loved calculator. I am afraid if there is a current the reason, when the calculator is switched off. Do you know this problem?

Greetings!

[Jlouis]

(11-01-2019 05:29 PM)Uli Wrote:  Hi Specialists,

within the last 3 weeks my mainly used hp41cx had corrosion on the minus pol of the left hand battery. It happened two times. I can't switch on the hp41cx. After cleaning the (-) pol on the battery, it works again.

This is my most loved calculator. I am afraid if there is a current the reason, when the calculator is switched off. Do you know this problem?

Greetings!

You have to worry about the calculator terminals. If it is clean, just replace the batteries. Your bateries are old, they can leak at any moment.

Cheers

[Uli]

„You have to worry about the calculator terminals. If it is clean, just replace the batteries. Your bateries are old, they can leak at any moment.“

Thanks for your idea. But that is to simple :-)
I have changed the batteries after this issue occured first time. The first batteries were fine and the actual batteries are very new.

Battery contacts in calculator are looking fine as well.

The corrosion on the battery is brown (not green) and it was not easy to clean it. It looks like corrosion from iron and not from copper .

[Jlouis]

Your calculator is fine, that's good news.

What bateries brand are you using?

I use Rechargeable 2/3 AAA, they are a little smaller, but fits goods and last long.

Some chinese N batteries can leak or corrode fast due poor material.

Cheers

[Uli]

I am also using rechargeable batteries. I have three hp41cx with these batteries.
Only one calculator has this issue.
I can't see any damages at these batteries.

The batteries are named as followed:
BlackFox
Ni--MH
BF-500N-Ni-MH-1.2V-500mAh

Maybe one of the four contacts in the calculator is not as good as the other three ones. But there is no different to see. There is no corrosion inside of the calculator. There was no battery leakage inside of the calculator.

I have had installed four modules.
CCD, math1, x memory, hp-41 advantage.
That is the only different to the other 41cx I have.

Now I make a test over the next couple of days without modules.

[AndiGer]

Maybe you try to spread the springs inside the battery case to get more tension of the batteries against the contacts?

[Jlouis]

(11-02-2019 03:26 PM)Uli Wrote:  I am also using rechargeable batteries. I have three hp41cx with these batteries.
Only one calculator has this issue.
I can't see any damages at these batteries.

The batteries are named as followed:
BlackFox
Ni--MH
BF-500N-Ni-MH-1.2V-500mAh

Maybe one of the four contacts in the calculator is not as good as the other three ones. But there is no different to see. There is no corrosion inside of the calculator. There was no battery leakage inside of the calculator.

I have had installed four modules.
CCD, math1, x memory, hp-41 advantage.
That is the only different to the other 41cx I have.

Now I make a test over the next couple of days without modules.

Your calculators are fine, don't worry. The problem is with the batteries.

Corrosion is a chemical reaction, oxygen mixing with metal molecules. If the calculators terminals are fine, and it is due to the high quality material used, they can't be the culprit for the battery corrosion. Blame the poor metal used in the batteries.

Try some qualty batteries, like Duracell, and you will see that they won't corrode.

Good luck.

Cheers

[Uli]

Thank you!

I have just ordered some Duracell batteries. I think you are right. The issue might be caused by the material of the minus (-) pol of my batteries.

I will try it with the Duracell and I will publish the results in ≈ 4 weeks.

Greetings!

[Uli]

After several months of use I can say that the changing of the accus to Duracell batteries has solved the issue. No more corrosion on the battery poles.