Braun Oral-B Sonic Complete 4729 Battery replacement

Written By: ndjenny
  • Comments: 17
Braun Oral-B Sonic Complete 4729 Battery replacement

Difficulty

Very easy

Steps

3

Time Required

5 - 10 minutes

Introduction

Important: This guide is ONLY for the Braun Oral-B Sonic Complete 4729!!! Not for ANY other toothbrush of the Braun or any other brand!!!

The battery of my toothbrush died and i have to replace it cause its a shame to throw away a electronic device just because the battery is death. I already opened it to see what kind of battery sits in there.

Now i ordered some replacement NiCd batteries and have to wait until they arrive. Probably NiMH batteries could be used too, at least they have same voltage but there might be some problems with the charger cause NiMH batteries can explode if overcharged.

NOTE: There are some very thin wires inside the toothbrush and you may destroy your device while "Repairing" it. But who cares if the manufacturer says your only option with a death battery is to bring the device to a recycling facility.

NOTE: Check your local regulations for recycling toxic waste (NiCd-Batterys)

  1. QaRBgdyMeVuwiLuD
    QaRBgdyMeVuwiLuD
    dFf6diU1Qqyrp5sa
    PVJkIGybWuZSMwsn

    • Push the bottom of the toothbrush against the knob on the back of the charger. Turn counter clock wise and the bottom should pop off. Put the toothbrush top down on a hard surface and push the inner part out.

    • Be careful with the thin wires connecting the bottom cover to the circuit board.

    If using a soldering iron, desoldering tool is useful. I was able to obtain the batteries and tab them together, shrink wrap, and resolder.

    Aaron Giesick -

  2. IjNDKyVLcoFNNnKm
    IjNDKyVLcoFNNnKm
    Y1bWtZSiwh12BFVx
    3QK1tCKSdgPUVHkK

    • Remove the old battery pack.

    • The Batteries are soldered to the circuit Board. You can use your soldering iron here if you like but i think its not really needed. And probably the minus is quite hard to work on because it lays under some other stuff (fig. 3; The circle marks the minus and the square the plus connection).

    • If you're not using a soldering iron you have to peel off the wire guard from the old batteries to remove them cause they are your connectors for the new batteries. The spring in the bottom cover provides enough tension to keep the battery in place and connected without soldering.

    The connectors (tags) are welded to the battery, not soldered. Do not try to use a soldering iron to detach the tags from the battery - it won't work, and the heat could cause the battery to burst and cause injury.

    Generally the new battery comes with new tags attached, so I think best practice is to unsolder the old tags from the circuit board.

    Michael Field -

  3. lQPHiVqwlkfI2Vid
    lQPHiVqwlkfI2Vid
    HJVguJiMVe1vmwEl
    caZWIwtwKgQGcwZk

    • Insert new battery pack.

    • If you unsoldered the old battery from the circuit board you have to solder the wire guards from the new Battery pack to the circuit board.

    • Otherwise just insert the new battery pack and reassemble the toothbrush. I used a pice of cardboard to make sure the plus gets proper connection (fig. 1).

Author

ndjenny

Member since: 20/03/13

1814 Reputation

15 comments

what is the replacement battery and where can

I get it?

Ron -

Hello Ron,

if you put: " Sanyo 2/KR-600AE 2/3 A Cadnica NiCd Battery Pack 2,4 V " into a search machine you should be able to find a replacement battery for this type.

At least thets how i got mine...

Kind regards Andy

ndjenny -

Do you need to buy 2 of these batteries? It looks like two separate batteries end to end.

Rob -

sorry for the late reply. No you don't need two batteries. Actually its a 2/3 A battery that means its 2/3 as long as a full A-size battery. in my case they delivered two 1/3 A batteries in one shrinking wrap but there are also 2/3 A batteries in one piece.

ndjenny -

I /think/ any "2/3 A" size battery should work - I've ordered some NiMH ones with nearly double capacity - I anticipate that these will hold more, but take longer to charge up.

Chris Murphy -

Keep in mind that the charger is not made for NiMH you must not overcharge a NiMH battery otherwise it may explode… So you do it at your own risk! Regards Andy

ndjenny -

NiMH charge at such a slow rate in this induction charger (24 hours is the norm for the first charge) that likely it will dissipate excess energy as heat.

unberger -

How has this fix been holding up for you over time?

Tom

viator -

Hello Tom,

the battery replacement worked very well but after sometimes the Toothbrush stopped working cause there was a crack where, i assume, moisture entered the housing and killed the electronics. So the new battery was still in good shape but the brush sometimes refused to turn on. It was to much hassle to finde the fault , thats why i replaced it last January.

Kind regards Andy

ndjenny -

Thanks for the response, Andy.

Could it have been because you didn't solder the connections?

Or are you fairly certain that it was a moisture intrusion issue?

viator -

Hello Tom,

i'm quite sure it wasn't caused by not soldering the battery in. It still worked but sometimes i had to push the button many times before it started stopped running and sometimes it started running by itself. there was also much of this white stuff all over the electronics which is a sign of water/moisture damage. I owned this brush vor over ten years and i not disappointed with it's quality taken in to account how many times it dropped to the ground. If you think about replacing the battery on yours, go for it. Its easy to do, inexpensive and if your brush has no cracks it should work until the replacement battery dies. I don't think its necessary to solder it to the board.

Kind regards Andy

ndjenny -

About the question NiCd batteries or NiMh; toothbrushbattery.com also use a NiMh battery in their tutorial.

I think the toothbrush does have an overcharging safety build-in. The toothbrush stops charging automatically after a few hours. The charging indicator light also stops pulsing then.

Peter Bakker -

I have a 4717 Sonicare Complete, would anyone know of I can go without using a Soldering iron, since I don't have one? Thank you in advance.

EricJL -

How do I know its the battery. Have not used the toothbrush for at least 15 years. When I plugged it in to charge for at least 17 hours the green light comes on solid for the entire time that the plug is in the receptacle. When I remove the toothbrush from the charger the light goes out and no power.

Marv -8-23-2021

Marvin Dubin -

If the battery is not used for 15 years it’s probably death. The charger is charging with very low power thus you cannot recondition it inside the device, you'd have to take it out and charge it with decent power and there would be a slight chance to revive it. But it’s still a very old battery and it’s probably not worth the effort.

In fact you know the battery is faulty but you can’t know if something else is gone bad to unless you change battery or power the device fro a different power source.

ndjenny -