Can electric shaver charge batteries installed with reversed polarity?

AI Thread Summary
The discussion centers on issues with rechargeable batteries in a Braun electric shaver, specifically regarding potential reversed polarity during installation. The user initially soldered new batteries according to marked polarity but experienced a rapid decline in battery performance, leading to a suspicion of reversed polarity. The battery supplier indicated that the symptoms align with this issue, prompting questions about whether the old batteries could have also been reversed. Participants suggested testing the polarity with a voltmeter and speculated on the possibility of the shaver having circuitry to prevent reverse charging. The lack of available circuit diagrams for the shaver adds to the complexity of diagnosing the problem.
cjben
Messages
2
Reaction score
0
Hi,

I bought 2-AA (with pins tabs) rechargeable batteries for a Braun electric shaver. Checked the polarity of the old batteries, marked it on the board, and soldered the new batteries accordingly. (In series.)

First charge lasted 4 weeks. Next 3-4 charges lasted less and less. Now, batteries won't even hold a charge overnight.

Battery supplier claims that this symptom is classic for reversed polarity...

Does this make sense? Any thoughts? Could the old batteries have themselves become reversed in polarity? What can be tested at this point?

Thank you,
Ben
 
Last edited:
Engineering news on Phys.org
Well I don't explicitly know, but this is my thought about it =)
Battery cells store energy in a very interesting way. You have the two sides, the anode and cathode, which are made up of metals and between them lies a, usually, alkali solution. When you connect the end of the battery and complete a circuit. The anode dissolves forming positive ions, since it is a metal, and the electrons give you your current for whatever you have plugged the batteries into. When you recharge you reverse the process by supplying electricity which reforms the anode, but you effectively switch the anode and cathode doing this thus reversing the polarity. And the reason that they recharge less is because some of the ions from the previous anode and cathodes becomes atoms whilst still in the fluid so no longer carry a charge.
The way i would test this theory is by creating a battery myself, bigger, so I could see what happens... but I think the supplies would be difficult to get because you'd eed an appropriate anode, cathode and electrolyte. What do you think?
 
Check polarity of batteries with voltmeter.
Is polarity of batteries opposite that marked on batteries?
 
Its hard for me to imagine a consumer product whose batteries are not user replaceable (require soldering) accommodating arbitrary battery polarity.

How many consumer products where batteries *are* user replaceable work when batteries put in wrong way around?

My guess is that you got some inferior or wrong chemistry batteries.
 
Thanks for the thoughts. I'm out of town right now, but will check the polarity of the batteries with a volt meter. The "+" and "-" were hand-written in by the manufacturer, and both ends are identically flat, unlike store-bought batteries. So, perhaps they were written incorrectly? Or, if I have reverse-charged them, what will the voltmeter show?

I wonder if there is some circuitry in the shaver to prevent reverse polarity charging. The shaver seems to run 'hotter' than before while charging. It's amazing to me that there are no circuit diagrams to be found on the internet-- it's as if Braun has done a solid job to keep any technical information to themselves.
 
Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
Thread 'Beauty of old electrical and measuring things, etc.'
Even as a kid, I saw beauty in old devices. That made me want to understand how they worked. I had lots of old things that I keep and now reviving. Old things need to work to see the beauty. Here's what I've done so far. Two views of the gadgets shelves and my small work space: Here's a close up look at the meters, gauges and other measuring things: This is what I think of as surface-mount electrical components and wiring. The components are very old and shows how...
Back
Top