Electric Shaver - Battery Recovery

[dannstrait]

My shaver is in desperate need of a few good refreshing cycles and a balancing charge. It is a waterproof unit with two round metal bumps on the handle that make contact in the charging cradle. Powering the cradle is a 4 hour time-based wall-wart adapter w/ charging LED.

My intention is to to cut off the wall-wart and solder up a charge lead in order to connect the cradle to my iCharger hobby charger. My only reservation is regarding the ability to discharge the shaver using this setup. When I put my DMM probes onto the shaver's charging contacts, I get no reading. Is there a way these terminals only let power in and not out to prevent shocking the user's wet hand or something? My concern is that my charger may not be able to discharge the shaver during the refreshing process. Any thoughts?

 

[USSR]

try posting in some electronis repair forum.. u will get more response there.. or some rc forums..

yes it may have some protection to not allow input ports to be used as output..

have u tried measuring the voltage with the dmm probes reversed ?

 

[Norm]

It seems to make sense that you wouldn't get a reading from the contacts otherwise anything conductive is going to short the battery.

Norm

 

[czAtlantis]

You have to open the shaver to get access to the batteries. No consumer product I have ever seen had battery voltage accessible in reverse throught charging connector! There is always at least diode blocking or even complex charging electronics inside.

 

[march.brown]

Shavers generally get fairly well discharged before they are recharged , so I can't really see the need for any refreshing charges ... Do you know what type of batteries are installed ? ... My old shaver has two NiMh batteries soldered in , but my new one has a single Li-Ion fitted.

My old shaver (Panasonic ES7101) is now three years old and now only lasts 16 minutes (four shaves) ... It would cost about £14 to buy the genuine Panasonic replacement batteries and if I replace the batteries myself it might ruin the water-resistance of the shaver ... I have not replaced the foil or cutters during the three years and that would cost £26-75 ... So , to restore the shaver to its original performance would cost about £41 ... It would still have its original charging system , switch and motor ... However , I can buy a brand new identical one for £41 including postage and keep the old one as a spare.

I decided to buy a new (RF41) Panasonic shaver for less than £60 and will keep the old one as a spare ... I can now safely dispose of my old original spare (Braun) shaver.

My Son uses a wet shave and it costs him over £100 per year in those multi-bladed heads ... If I can get three years use out of my wet / dry Panasonic electric shaver then it is very cost-effective compared to my Sons wet-shaving costs.
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[czAtlantis]

Shavers have Ni-Cd, Ni-Mh or (newer ones) Li-ion. Replacing Ni-CD/Ni-Mh will be easier because it is just 2xAA. Li-ions will be hard if they are non-standard size (no 18650... - just some custom made size). I have 2xAA ni-cd and they still work fine after 3 years but when they fail I would have to find replacement. I will try eneloops - they are durable and can deliver high current but maybe some industrial high-current ni-cd would be better.

 

[march.brown]

Shavers have Ni-Cd, Ni-Mh or (newer ones) Li-ion. Replacing Ni-CD/Ni-Mh will be easier because it is just 2xAA. Li-ions will be hard if they are non-standard size (no 18650... - just some custom made size). I have 2xAA ni-cd and they still work fine after 3 years but when they fail I would have to find replacement. I will try eneloops - they are durable and can deliver high current but maybe some industrial high-current ni-cd would be better.

Shavers all seem to have batteries that are soldered in ... Can you get Eneloops with solder tags fitted ?

Two genuine Panasonic batteries (with tags) are about £14 for my Panasonic shaver.
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[czAtlantis]

no need for tabs - you can easily solder to the battery directly. But you must have proper tools (soldering iron with big tip and proper solder flux) and some skills to be able to solder without damaging battery by heat.

 

[Shadowww]

Shavers all seem to have batteries that are soldered in ... Can you get Eneloops with solder tags fitted ?

Yep, some European shops such as nkon.nl, voelkner.de (both ship to UK) have tabbed Eneloops in both AA and AAA flavour.

 

[march.brown]

Yep, some European shops such as nkon.nl, voelkner.de (both ship to UK) have tabbed Eneloops in both AA and AAA flavour.

I am well versed in the art of soldering , but I would certainly prefer to use tagged batteries rather than solder straight onto the battery direct ... I know that I can get two of the correct Panasonic (tagged) batteries for about £14 but I reckon that by the time I replaced the batteries and also the old foil and cutter , I could have a brand new (identical model) shaver at the same total cost ... If I had already replaced the foil and cutter recently , it would then be more prudent to change the batteries ... Most shavers apparently need a new foil about every 12 to 18 months plus new cutters every 18 months , so my three year old shaver is long overdue for both these replacements.

Anyway , the three year old shaver will be OK at the moment purely as a standby or reserve shaver ... The fact that the battery only lasts for four shaves (16 minutes) will mean that it will be OK to keep as a reserve shaver till I eventually get a cheap'ish new spare ... I suppose that I could get a modern multi-blade (old-style) wet shaver to keep as a spare , but I've never used a real wet-shaver before ... I think that at 74 years of age , I will stick with the electric ones.
.

 

[dannstrait]

You have to open the shaver to get access to the batteries. No consumer product I have ever seen had battery voltage accessible in reverse throught charging connector! There is always at least diode blocking or even complex charging electronics inside.

I should have mentioned originally that I have already taken the shaver apart to see if I could just put in some new cells or refresh them separately. Unfortunately, I found sealed and soldered cells as mentioned in some other posts here. The cells are very irregular in shape (almost square). I did not want to risk permanently damaging the electronics so I did not try to remove them.

Shavers generally get fairly well discharged before they are recharged , so I can't really see the need for any refreshing charges ... Do you know what type of batteries are installed ? ... My old shaver has two NiMh batteries soldered in , but my new one has a single Li-Ion fitted

I would generally agree with this assessment except for the fact that I have let the shaver sit for 6 months or so without any use. Now when I use it, I can hear an audible drop in the rpm's after about 1 minute and a quick decline from there. I get maybe about 4-5 minutes of usable power before it dies completely. When new, it would last for 15-20min easily.

At this point I suppose I'll try again to open it up and remove the batteries. Either way, I think I'm going to have to get a new one. At least I'll take a picture of these weird cells for posterity.

 

[WDG]

FWIW, my solution was a Norelco (no longer made) that takes standard loose AA cells, so I can use Eneloops in it. If I'm not mistaken, Braun, Panasonic, and some others have models like this, also.

 

[dannstrait]

Finally disassembled the unit to expose the battery. Lettering says VARTA V600HR. Made in Germany. Expandable thumbnail below.

 

[dannstrait]

Success! Using alligator clips and my iCharger to refresh and balance just like I wanted at the start of this thread. Thanks everybody!

 

[USSR]

so u refreshed the old battery pack ?
whats the result ?