Batteries for a Sonicare?

[ifoxbox]

Hi,

I was wondering where I could find some NiCd AA cells with a true 1200Mah rating? I am replacing the batteries that were in my Sonicare toothbrush and am having trouble with how long they last before needing a recharge. Sonicare handles are supposed to last 14 day before needing a recharge. I am not 100% positive that Sonicare used 1200Mah cells, but I assume that did since that is the largest capacity for a NiCd cell that I know of. I tried the 1200Mah cells that battery junction sells, but the handle will only last for 5 days.

I also tried some higher capacity NiMh cells, but the Sonicare charger does not seem to charge the cells to full strength. I say this because before I installed the NiMh batteries in the handle, I fully charged them using my speedy box charger. The handle lasted for 21 days before it died. I let it sit on the Sonicare charger and when it said it was fully charged, it only lasted for 7 days. I tried this with many differnt brand NiMH cells and had the same result. Any sugestions?

Thanks!

 

[Mr Happy]

Hmmm, I don't know...doesn't the handle sit in the charging cradle when not in use?

I'm of the belief that the extraordinarily high prices of electric toothbrushes are 90% marketing and 10% substance, so I bought the e3000 model that takes two alkaline batteries and saved my money.

With two Eneloops it seems to last weeks or months between charges -- so long in fact that I can never remember when I last recharged the batteries, which is why I can't be more precise.

If your charger is not charging the batteries to their fullest extent, then I am not sure higher capacity batteries are going to help you.

 

[ifoxbox]

Hmmm, I don't know...doesn't the handle sit in the charging cradle when not in use?

I'm of the belief that the extraordinarily high prices of electric toothbrushes are 90% marketing and 10% substance, so I bought the e3000 model that takes two alkaline batteries and saved my money.

With two Eneloops it seems to last weeks or months between charges -- so long in fact that I can never remember when I last recharged the batteries, which is why I can't be more precise.

If your charger is not charging the batteries to their fullest extent, then I am not sure higher capacity batteries are going to help you.

Sonicare says that you can leave the handle on the charger all of the time, but I prefer to only charge the batteries when they need it. I agree that higher capacity cells will do me no good since the charger does not seem to fully charge them. I just did not understand why. I would think that it would eventually charge them to full capacity, but it seems like no matter how long I leave it on the charger the voltage never gets to what it does in my speedy box when fully charged. Any idea on where I can find some NiCd 1200mAh cells?

 

[Mr Happy]

I'm not aware that AA NiCd cells go up to a true 1200 mAh.

Here's a data sheet for a Sanyo Cadnica rated at 1100 mAh, and Cadnica is about the highest quality cell you are likely to find on the market: http://www.eneloop.info/fileadmin/EDITORS/BATTERIES/industrial/datasheets/nicd/KR-1100AAU.pdf

If you are buying NiCd cells, Cadnica is a good name to look for.

You may find some unbranded cells that claim 1200 mAh at places like batteryjunction.com, but they may not live up to their claims.

 

[electromage]

A charger designed for NiCad shouldn't have a problem with NiMH cells. Maybe the charger uses a timer, and it cuts off before the higher capacity cells are done charging. Can you test this? If you take two different capacity batteries, and discharge them both to the same voltage, they should take different times to fully charge. If they cut off at the same time, you'll know what's up.

 

[Mr Happy]

A charger designed for NiCad shouldn't have a problem with NiMH cells.

Well actually, that's not strictly true. The charger may not have a problem with the cells, but the cells may certainly have a problem with the charger. As likely as not, NiMH cells will get fried on a NiCd charger.

If it is a fast charger then the NiMH cells will not produce a large enough -dV signal for the charger to detect it and the cells will be overcharged. If it is a trickle charger then the constant trickle charge will overcharge the NiMH cells too and cause them to wear out quickly. If it is a fixed time charger then the timer is probably set for a much lower capacity than NiMH cells have and the NiMH will not get fully charged. Whichever way it goes, there is likely to be a problem.

 

[ifoxbox]

Well actually, that's not strictly true. The charger may not have a problem with the cells, but the cells may certainly have a problem with the charger. As likely as not, NiMH cells will get fried on a NiCd charger.

If it is a fast charger then the NiMH cells will not produce a large enough -dV signal for the charger to detect it and the cells will be overcharged. If it is a trickle charger then the constant trickle charge will overcharge the NiMH cells too and cause them to wear out quickly. If it is a fixed time charger then the timer is probably set for a much lower capacity than NiMH cells have and the NiMH will not get fully charged. Whichever way it goes, there is likely to be a problem.

Since it says you are supposed to charge the handle for 16 hours for a full charge, I am guessing that it is a trickle charger. Could the PC board that is in the handle possibly have a shut off for when it reaches a full charge? I have heard some people say that their handle lasted for over 6 years and they always kept it on the charger. Could a NiCd take that much abuse and last for 6 years without a shut off of some kind?

A charger designed for NiCad shouldn't have a problem with NiMH cells. Maybe the charger uses a timer, and it cuts off before the higher capacity cells are done charging. Can you test this? If you take two different capacity batteries, and discharge them both to the same voltage, they should take different times to fully charge. If they cut off at the same time, you'll know what's up.

I have the older handle which does not indicate when it is fully charged with the led. I have been basing my test on time. I let the higher capacity cells charge for over 2 days, and the voltage on the cells were still not fully charged. I am pretty sure that my brother has a dead one that has the blinking led feature when charging, and a steady led when fully charged. If I can get his handle, I will be able to test the times like you suggest. Being able to use NiMh cells as replacements would be nice, but it is not that big of a deal to me. If I can find some NiCd cells that will last for 14 days like the original Sonicare NiCd's did, I will be happy. I would really prefer NiCd cells since I know that the charger was designed for NiCads. Any idea on where I can purchase some Cadnica 1100Mah cells? I can't find the AA's anywhere.

 

[Mr Happy]

NiCd cells are quite robust when it comes to constant trickle charging (NiMH are not). So it is possible the charging base does have a non-stop trickle.

You might also look at voltages. If you leave the cells in the Sonicare charger for a day or so and then measure the voltage, how does it compare to the voltage off the external charger? Maybe the Sonicare charger has a voltage cut-off rather than a time cut-off?

I am afraid I do not know where to obtain Cadnica cells. Perhaps one of the electronic distributors like Digikey or Mouser?

There are these 1200 mAh cells from Battery Junction. I couldn't tell you anything about the quality but at the price there is nothing lost if they don't work out.

 

[SilverFox]

Hello Mr Happy,

Sanyo has either discontinued producing their NiCd cells, or they are no longer taking orders from them. The Cadnica line is no longer available from them.

If you want those cells, you will have to find a distributor that stocked up on them and has some left.

Tom

 

[Mr Happy]

Tom,

I guess the answer is they are not selling them through retail channels. There does seem to be plenty of information about them on the Sanyo web sites still, and every indication that they are available to industrial customers. I suppose this comment, found here tells the story:

NOTES

1. Industrials use batteries is not for sell to personal usage
2. For inquiry of product (Notebook computer etc.) which is used our battery, please contact its manufacture. (Including placing order for replacement of battery)

So there it is :sigh:

 

[Nubo]

...I am afraid I do not know where to obtain Cadnica cells. Perhaps one of the electronic distributors like Digikey or Mouser?

Batterystation has them for sale - Sanyo KR-1100AAU

 

[Mr Happy]

Batterystation has them for sale - Sanyo KR-1100AAU

Ah, good tip. They have a variety of Sanyo cells there.

 

[ifoxbox]

NiCd cells are quite robust when it comes to constant trickle charging (NiMH are not). So it is possible the charging base does have a non-stop trickle.

You might also look at voltages. If you leave the cells in the Sonicare charger for a day or so and then measure the voltage, how does it compare to the voltage off the external charger? Maybe the Sonicare charger has a voltage cut-off rather than a time cut-off?

I am afraid I do not know where to obtain Cadnica cells. Perhaps one of the electronic distributors like Digikey or Mouser?

There are these 1200 mAh cells from Battery Junction. I couldn't tell you anything about the quality but at the price there is nothing lost if they don't work out.

I will try the voltage test and see what I find.

I tried those 1200mAh cells from Battery Junction, but the handle only lasted for 5 days on a full charge. The handle is supposed to last for 14 days. That makes me question what capacity the original Sonicare batteries were? I do not know of a NiCd that has a larger capacity than 1200mAh, but we are talking about a 9 day difference. Do you think that the 1200mAh cells from Battery Junction are that far off their rated capacity?

Batterystation has them for sale - Sanyo KR-1100AAU

Thanks Nubo! I am going to check those out.

 

[Mr Happy]

I tried those 1200mAh cells from Battery Junction, but the handle only lasted for 5 days on a full charge. The handle is supposed to last for 14 days. That makes me question what capacity the original Sonicare batteries were? I do not know of a NiCd that has a larger capacity than 1200mAh, but we are talking about a 9 day difference. Do you think that the 1200mAh cells from Battery Junction are that far off their rated capacity?

I have no experience of those cells, but it is not unusual for unbranded cells to test below their nominal capacity. It is also not unusual for new cells to need some conditioning before they reach their best performance. This conditioning is why the instructions often say to put new devices on charge for many hours before first use. This long slow charge helps to redistribute the electrolyte in the cells and properly saturate the separator membranes, bringing the cells back to a good state after a long idle period. Without this conditioning, cells can significantly under perform their specifications.

 

[Minjin]

How did even take the Sonicare toothbrush apart in the first part? Mine is completely sealed. I don't see any way to take it apart without destroying it.

 

[Hoggy]

How did even take the Sonicare toothbrush apart in the first part? Mine is completely sealed. I don't see any way to take it apart without destroying it.

I'm wondering this too. I have both an old Sonicare and a newer Sonicare with a battery indicator window.

The new one is very new - about 4-5 months old. It's the newer one with the smaller brush(A-series?) and a battery indication window.
I would like to use them both... The bigger(older) one for when I know I won't gag, and the smaller(newer) one for when I know I will gag..

The 'old' one is the one with the bigger brush on it. It's about 3-4 years old or so. Since it was before I knew better about rechargeable batteries, I would often run it down - WAY down - by running it after it stopped, waiting, and running it down more, and repeating ad nauseum - thinking I was helping the NiCad's at the time.

It's that old one that I think has run into cell reversal and would like to bring back. I notice that if left on the charger continuously, it will get warm and last for a an entire brushing. Due to the warmth, I don't think the handle has any kind of charge termination built in whatsoever - I think it's just constant-current trickle.

I would like to try and take this apart myself and replace the batteries myself, but I don't see how because: A) I can't figure out how to take it apart, and B) If the batteries need any kind of 'welding' together, I don't think I have the right equipment - I only have a 25/35-watt soldering iron and a Cold-Heat soldering 'appliance'.

Sooo - I dunno..

 

[Closet_Flashaholic]

I also have the original sonicare. Nicad batteries just wore out after 3+ years.

The sonicare is put together using a type of "sonic" welding. Essentially the 2 halves of plastic are "melted" together. The original instructions show how to disassemble so that the batteries can be removed and recycled before disposing. Being very careful and patient, I was able to disassemble with minimal damage following Philips' instructions.. I also had to unsolder 4 wires that connect the induction charging transformer to the PCB so that the PCB could be removed. Once removed, I flexed the body enough to break the expoxy glue holding the batteries in the body. I used DAP sealent (see down further) to hold the new batteries in place.

I also could not find direct NiCad replacements. I ended up buying a two-cell NiMH pack from RadioShack (originally for cordless phone use). At this point I had already purchased a replacement Sonicare, but I wanted to see if I could refurbish the old one. So I didn't have much to lose.

The charger is a trickle charge - taking about 48 hours for the originals. The NiMH are 2200 mAH. Once they are charged I don't leave the charger on. I unplug it so that they aren't overcharged. As a previous poster stated, the original model had no end-of-charge indication, So I just charge it for 3 or 4 days and then plug in the charger only when it runs low.

When resealing you need to be very careful to maintain waterproof. (Lots of electronics inside). There's probably low-risk of electric shock, but the water would certainly short out the elecronics. I used 2 levels of waterproofing. 1st I used DAP Aquarium Water Sealant whick will seal but will not provide physical strength to hold the pieces together. For that I used a 1" shrink tube that covers the entire length of the body and cut out a hole in it for the on/off button. I left the bottom of the body clear so that it would still fit in the charger.

Working fine so far (about 2 months now). This is really a just an exercise anyways, as Philips has discontinued the brush replacements for this model and once I run through my stock, I will have to look for a new brand anyways. So I am not too concerned that I may be damaging the NiMH batteries. Who cares, they cost me a whole $6. Vs. $70 for a new Sonicare (at the time).

 

[Angineer]

Here are instructions for replacing the batteries in a Sonicare:
http://www.instructables.com/id/E99IBNEE70EP286VMM