After my previous blog entry and photos on Sonicare Battery Replacement, I got an email from Ed Elliott, who detailed his own more successful attempt at replacing the batteries in his Sonicare 4100
:
Thanks for sharing the info on the Sonicare. Based upon your photos I was
able to take some measurements so that I could take a different approach.
Rather than splitting the case in half along the original seams, I removed
just enough of the case so the batteries could be removed and opened a small
area so that I could unsolder the battery connections from the PCB. Your
unit is probably beyond hope, but you might want to share the following info
on your site.
The cuts
c1da8ad1f39e567d6eb3bb25e178693e
The battery pack
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It works! Powers up. Runs for the full two minute cycle. I haven’t decided
how to close it back up. Epoxy? Silicone caulk + heat shrink tubing (may not
fit in charger base)? If it lasts until the new Nicads die, I’m doubt if
I’ll replace the Nicads again so making the process reversible is not a
concern.
Prior to this success, I tried this process with an even older model (it
even had a different model PCB). Failure. I used the same custom-made
battery pack that was subsequently used successfully in the newer Sonicare.
I also tested the older one unsuccessfully using 2.4V feed from a bench
power supply. I believe the problem was elsewhere on the PCB - the unit had
sat in an RV unused for over 4 years through heat/cold cycles and it had
been used for several years before that abuse. Given that my cutting
approach did not give full access to the PCB plus the fact that I already
have the re-batteried Sonicare and a new Sonicare 9500, I decided it wasn’t
worth the effort to track down the problem with no schematic.
View the Sonicare photos
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May 15th, 2007 at 5:38 pm
Just a tip - if the sonicare has a fast charge and if Nicads came out of it then Nicads will generally have to go back in, charging circuitry is different between nicads and NiMh - you said you had some 1800mah batteries - these will be nimh - cant get nicad this high. However if the sonicare is a slow charge (15 hours) then it wont matter, will just take longer to get a full charge ( but charge will last much longer)
August 27th, 2007 at 1:28 pm
I actually did this with mine over the weekend with great success. It would die every second or third day, needing a recharge. I left it charging all night with the new duracell rechargables and the light was a solid green in the morning and it works perfectly! I wrapped mine in electrical tape just to waterproof it until I come up with something to seal the “battery door” closed. My wife was skeptical at first, but she’s also sick of having hers die all the time, so I may get to do another one this week. Thanks for the great info…
Matt
March 11th, 2008 at 1:56 pm
The cutout dimensions for the battery compartment were perfect - thanks. My horizontal cuts were about 1/8 inch above the seam and parallel to it. One doesn’t have to cut the slot to access the solder connections on the on/off button side of the handle - when removing the old batteries use a long nose pliers to gently roll the wire back from the spot weld on the batteries and the replacement batteries can be directly soldered to those remaining wires.
Sincerely Appreciate Your Time and Effort - Thanks, Fred
May 6th, 2008 at 10:59 am
I cracked mine open along the seams using a flexible putty knife (screw driver to start). Desoldered the circuit board (8 spots - used a combination of solder sucker and copper braid). Cut the old batteries out with a knife attachment on a soldering gun. Replaced the batteries with standard AA NiCd. Tested fine. Sealed the body with 3M’s 5200 marine adhesive/sealant. Then realized the same model is on sale for $35 … but this experience was priceless. Thanks for the info! Steve
August 6th, 2008 at 9:44 am
You guys rock — I love the fact that there are others out there like me who will opt to change the battery instead of waste money on a new one and who are also willing to share their knowledge on the ‘net.
Thanks.
Love it!!!!!!