Cheap Chinese shaver & Ni-Mh cell.

I

Ian Field

Guest
A while back I bought a cheap Chinese shaver, at best it only gave about 4
shaves per charge - when that deteriorated to 2, I opened it up and had a
look.

It has a single AA cell marked as Ni-Mh - 500mAh (I have higher capacity
Ni-Cd cells than that).

In the past I've tried replacing shaver Ni-Cd cells with higher capacity
Ni-Mh, only to find that the higher internal resistance results in not much
improvement on the worn out cells being replaced.

Since this shaver had a (marked as) Ni-Mh cell, I bunged in a 2300mAh low
self discharge type (brand new).

The shaver works, but seems sluggish - and no surprise, still only does 2 -3
shaves per charge.

So let the guessing games begin - did they fraudulently stamp Ni-Mh on a
Ni-Cd cell, or is the 500mAh cell optimised for high current at the expense
of total capacity?

Maybe I'll pull it apart again and stick a 600mAh Ni-Cd cell in it, but I'd
be interested to hear any opinions in the meantime.

Thanks.
 
On 5/22/2014 11:38 AM, Ian Field wrote:
A while back I bought a cheap Chinese shaver, at best it only gave about
4 shaves per charge - when that deteriorated to 2, I opened it up and
had a look.

It has a single AA cell marked as Ni-Mh - 500mAh (I have higher capacity
Ni-Cd cells than that).

In the past I've tried replacing shaver Ni-Cd cells with higher capacity
Ni-Mh, only to find that the higher internal resistance results in not
much improvement on the worn out cells being replaced.

Since this shaver had a (marked as) Ni-Mh cell, I bunged in a 2300mAh
low self discharge type (brand new).

The shaver works, but seems sluggish - and no surprise, still only does
2 -3 shaves per charge.

So let the guessing games begin - did they fraudulently stamp Ni-Mh on a
Ni-Cd cell, or is the 500mAh cell optimised for high current at the
expense of total capacity?

Maybe I'll pull it apart again and stick a 600mAh Ni-Cd cell in it, but
I'd be interested to hear any opinions in the meantime.

Thanks.
Click to expand...

Well I don't know, and I would be very disappointed in 4 shaves on a
charge. I have a Norelco (Philips) Aquatec, I have never tested it to
find out, but I be very surprised if I didn't get more than 10 shaves
before needing a charge.
I remember commenting to someone 25 years ago that I thought
rechargeable batteries were a great match for shavers. He didn't agree,
but I think he was a blade man.
Mikek
 
On Thu, 22 May 2014 17:38:43 +0100, "Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.

Peter



<gangprobing.alien@ntlworld.com> wrote:

A while back I bought a cheap Chinese shaver, at best it only gave about 4
shaves per charge - when that deteriorated to 2, I opened it up and had a
look.

It has a single AA cell marked as Ni-Mh - 500mAh (I have higher capacity
Ni-Cd cells than that).

In the past I've tried replacing shaver Ni-Cd cells with higher capacity
Ni-Mh, only to find that the higher internal resistance results in not much
improvement on the worn out cells being replaced.

Since this shaver had a (marked as) Ni-Mh cell, I bunged in a 2300mAh low
self discharge type (brand new).

The shaver works, but seems sluggish - and no surprise, still only does 2 -3
shaves per charge.

So let the guessing games begin - did they fraudulently stamp Ni-Mh on a
Ni-Cd cell, or is the 500mAh cell optimised for high current at the expense
of total capacity?

Maybe I'll pull it apart again and stick a 600mAh Ni-Cd cell in it, but I'd
be interested to hear any opinions in the meantime.

Thanks.
Click to expand...
 
On 5/22/2014 4:17 PM, Peter wrote:
On Thu, 22 May 2014 17:38:43 +0100, "Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.

Peter
Click to expand...
Might also want to measure the current draw of the razor under load.
Typical brand-name razor has two AA cells. That's more than twice
the capacity given the high load.
Twice 4 is 8. You're in the ball park.

How did you connect to the cell?
If you soldered on it, that might be your problem.
gangprobing.alien@ntlworld.com> wrote:

A while back I bought a cheap Chinese shaver, at best it only gave about 4
shaves per charge - when that deteriorated to 2, I opened it up and had a
look.

It has a single AA cell marked as Ni-Mh - 500mAh (I have higher capacity
Ni-Cd cells than that).

In the past I've tried replacing shaver Ni-Cd cells with higher capacity
Ni-Mh, only to find that the higher internal resistance results in not much
improvement on the worn out cells being replaced.

Since this shaver had a (marked as) Ni-Mh cell, I bunged in a 2300mAh low
self discharge type (brand new).

The shaver works, but seems sluggish - and no surprise, still only does 2 -3
shaves per charge.

So let the guessing games begin - did they fraudulently stamp Ni-Mh on a
Ni-Cd cell, or is the 500mAh cell optimised for high current at the expense
of total capacity?

Maybe I'll pull it apart again and stick a 600mAh Ni-Cd cell in it, but I'd
be interested to hear any opinions in the meantime.

Thanks.
Click to expand...
 
"Peter"
"Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.
Click to expand...

** I reckon you have nailed it.

That charger is meant to bring a 500mAh cell up to full capacity in about 12
to 24 hours and hold there it will a trickle of about 30mA.

If used with a 2300mAh NiMh cell, it will never become fully charged.



..... Phil
 
Fřlgende er skrevet af Phil Allison:
"Peter"
"Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.


** I reckon you have nailed it.

That charger is meant to bring a 500mAh cell up to full capacity in about 12
to 24 hours and hold there it will a trickle of about 30mA.

If used with a 2300mAh NiMh cell, it will never become fully charged.
Click to expand...
I would think the Chinese charger sense the voltage of the cell, not
counting the number of mAh put into it.

So the charger would still be able to charge the cell, it just takes
longer. Like about a week give or take.

Depending on shaving frequency and beard properties, the charger may
not be able to keep up with the usage.

I wouldn't know, I trim my beard every fortnight or so :)=

Leif

--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.
 
"Leif Neland"
Phil Allison:
"Peter"
"Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.


** I reckon you have nailed it.

That charger is meant to bring a 500mAh cell up to full capacity in about
12 to 24 hours and hold there it will a trickle of about 30mA.

If used with a 2300mAh NiMh cell, it will never become fully charged.


I would think the Chinese charger sense the voltage of the cell, not
counting the number of mAh put into it.
Click to expand...

** More likely, it does neither.


So the charger would still be able to charge the cell, it just takes
longer. Like about a week give or take.
Click to expand...

** Totally wrong.

2300mAh NiMH cells will not charge at all at 30mA.


Depending on shaving frequency and beard properties, the charger may not
be able to keep up with the usage.
Click to expand...

** ROTFL...




..... Phil
 
Phil Allison har bragt dette til verden:
"Leif Neland"

So the charger would still be able to charge the cell, it just takes
longer. Like about a week give or take.

** Totally wrong.

2300mAh NiMH cells will not charge at all at 30mA.
Click to expand...
What do you suggest happens with the 30mA, if it is not uset to charge
the NiMH? Does it just turn into heat?

Leif

--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.
 
"Peter" <peter@arin.htlm.com> wrote in message
news:d71tn9to94n9kknvdasskbdrk1bhce001s@4ax.com...
On Thu, 22 May 2014 17:38:43 +0100, "Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.
Click to expand...

The 2300mAh battery was charged for 24h in a regular charger before I fitted
it.

If I leave the shaver charging for more than the recommended 8h it gets
fairly warm.

If I get much more pissed off with it, I might tweak a 3.3V switcher down to
the right voltage and wire it for mains only operation.

It'd be a shame to give up on it just yet - it came with a spare foil &
cutter block.
 
"Phil Allison" wrote in message news:bu8p2vFd05dU1@mid.individual.net...

> 2300mAh NiMH cells will not charge at all at 30mA.

As far as I know, any current will reverse the cell's chemical state, however
slowly. Is there a lower limit for NiMH cells I don't know about?

I have plenty of NiMH cells and a charger that can go as low as 100mA. Is that
high enough to charge the cell?
 
"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:bu7sb2F7747U1@mid.individual.net...
"Peter"
"Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.


** I reckon you have nailed it.

That charger is meant to bring a 500mAh cell up to full capacity in about
12 to 24 hours and hold there it will a trickle of about 30mA.
Click to expand...

Its much more cheap & nasty than that! The recommended charge time is 8h, if
I left it charging for 24h the battery got pretty warm.

The 2400mAh battery gets fairly warm by 24h.
 
"Leif Neland" <leif@neland.dk> wrote in message
news:mn.bad17de5d96f54ed.130671@neland.dk...
Fřlgende er skrevet af Phil Allison:
"Peter"
"Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.


** I reckon you have nailed it.

That charger is meant to bring a 500mAh cell up to full capacity in about
12 to 24 hours and hold there it will a trickle of about 30mA.

If used with a 2300mAh NiMh cell, it will never become fully charged.


I would think the Chinese charger sense the voltage of the cell, not
counting the number of mAh put into it.
Click to expand...

My guess would be current regulating - there's no chip to sense voltage
change.

The old battery got pretty warm if left charging more than the recommended
8h - the 2300mAh one is warm-ish by 24h.
 
"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:bu8p2vFd05dU1@mid.individual.net...
"Leif Neland"
Phil Allison:
"Peter"
"Ian Field"

I would check first to see if the battery is being adeqautely charged
by the Chinese charger. Charge the battery in situ, and then
remove it, and do a discharge test, and see how many mAh it supplies.


** I reckon you have nailed it.

That charger is meant to bring a 500mAh cell up to full capacity in
about 12 to 24 hours and hold there it will a trickle of about 30mA.

If used with a 2300mAh NiMh cell, it will never become fully charged.


I would think the Chinese charger sense the voltage of the cell, not
counting the number of mAh put into it.

** More likely, it does neither.
Click to expand...

Its just a blocking oscillator with a TO92 transistor, no chip - no smarts.
 
"amdx" <nojunk@knology.net> wrote in message
news:llm0ao$ttd$1@dont-email.me...
On 5/22/2014 11:38 AM, Ian Field wrote:
A while back I bought a cheap Chinese shaver, at best it only gave about
4 shaves per charge - when that deteriorated to 2, I opened it up and
had a look.

It has a single AA cell marked as Ni-Mh - 500mAh (I have higher capacity
Ni-Cd cells than that).

In the past I've tried replacing shaver Ni-Cd cells with higher capacity
Ni-Mh, only to find that the higher internal resistance results in not
much improvement on the worn out cells being replaced.

Since this shaver had a (marked as) Ni-Mh cell, I bunged in a 2300mAh
low self discharge type (brand new).

The shaver works, but seems sluggish - and no surprise, still only does
2 -3 shaves per charge.

So let the guessing games begin - did they fraudulently stamp Ni-Mh on a
Ni-Cd cell, or is the 500mAh cell optimised for high current at the
expense of total capacity?

Maybe I'll pull it apart again and stick a 600mAh Ni-Cd cell in it, but
I'd be interested to hear any opinions in the meantime.

Thanks.

Well I don't know, and I would be very disappointed in 4 shaves on a
charge. I have a Norelco (Philips) Aquatec, I have never tested it to
find out, but I be very surprised if I didn't get more than 10 shaves
before needing a charge.
I remember commenting to someone 25 years ago that I thought rechargeable
batteries were a great match for shavers. He didn't agree,
but I think he was a blade man.
Click to expand...

As I mentioned in an earlier post, I've tried replacing Ni-Cd shaver
batteries with Ni-Mh before - they just can't handle the current draw.

The original battery in this one was a single AA cell marked Ni-Mh 500mAh, I
tried a low self discharge 2300mAh cell but it didn't work very well.

Its got a 600mAh Ni-Cd in it now - it works OK, but I've yet to find out haw
many shaves per charge.
 
Why do people need to sha where there ain't electricity /?
''''''''''nuts or something /?
 
On Fri, 23 May 2014 17:54:26 +0100, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote:

>Its just a blocking oscillator with a TO92 transistor, no chip - no smarts.

The TO92 package might be an LM317 playing NiCd charger.
<http://www.dprg.org/projects/1999-05a/>

I wouldn't try using an NiMH cell with such a crude charger. Without
proper EOC (end of charge) circuitry, you run a good chance of
overcharging and kill the NiMH battery.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
Jeff Liebermann har bragt dette til verden:
On Fri, 23 May 2014 17:54:26 +0100, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

Its just a blocking oscillator with a TO92 transistor, no chip - no smarts.

The TO92 package might be an LM317 playing NiCd charger.
http://www.dprg.org/projects/1999-05a/

I wouldn't try using an NiMH cell with such a crude charger. Without
proper EOC (end of charge) circuitry, you run a good chance of
overcharging and kill the NiMH battery.
Click to expand...

It's probably not designed to last more than the 14 days return
warranty from the chinese website.

Leif

--
Husk křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.
 
<jurb6006@gmail.com> wrote in message
news:8cfc3133-eaa8-43af-9a06-f986ffe5afb1@googlegroups.com...
Why do people need to sha where there ain't electricity /?
''''''''''nuts or something /?
Click to expand...

When the cheap Chinese one lets me down, I can fall back on the antique
Ronson 55 which has a mains frequency reciprocating armature.

Having to plug it in while I'm using it is a trivial hassle compared to the
weight of it - I have to keep changing hands when my arms ache!

I'm quite happy to use a wet shaver when I have to, and when odd whiskers
get missed by the trimmer and won't catch the foil.

An option that still hasn't been dismissed out of hand, is to modify a 3.3V
switcher down to 1.2V and have a "power brick" arrangement leaded shaver.
 
"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:t3q7o9t28umbcm2tjbg0i96qv9qouccs5n@4ax.com...
On Fri, 23 May 2014 17:54:26 +0100, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

Its just a blocking oscillator with a TO92 transistor, no chip - no
smarts.

The TO92 package might be an LM317 playing NiCd charger.
http://www.dprg.org/projects/1999-05a/

I wouldn't try using an NiMH cell with such a crude charger. Without
proper EOC (end of charge) circuitry, you run a good chance of
overcharging and kill the NiMH battery.
Click to expand...

The instructions say to take it off charge after 8h - it gets quite warm if
you don't!
 
"Leif Neland" <leif@neland.dk> wrote in message
news:mn.d9d57de5bc74055d.130671@neland.dk...
Jeff Liebermann har bragt dette til verden:
On Fri, 23 May 2014 17:54:26 +0100, "Ian Field"
gangprobing.alien@ntlworld.com> wrote:

Its just a blocking oscillator with a TO92 transistor, no chip - no
smarts.

The TO92 package might be an LM317 playing NiCd charger.
http://www.dprg.org/projects/1999-05a/

I wouldn't try using an NiMH cell with such a crude charger. Without
proper EOC (end of charge) circuitry, you run a good chance of
overcharging and kill the NiMH battery.

It's probably not designed to last more than the 14 days return warranty
from the chinese website.
Click to expand...

The one occasionally on "weekly offers" in Lidl cost 3x as much, and aren't
without their problems.

The problem with properly priced shavers is the foil doesn't last any longer
than cheap ones - and genuine replacements cost nearly as much as a complete
new shaver.

The cheap Chinese one came with a spare foil and cutter block - I'd like to
bodge it up for at least long enough to use up those consumables.
 
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