I have bought a first-generation TomTom Multisport GPS watch, bundled with chest-strapped bluetooth HRM, about last year (mid 2015). It was on sale, big discounted, at Amazon. To give you context, this product originally launched on mid 2013. Everything went well, although I just used Running and Freestyle mode. No cycling and no swimming, just because I cannot swim and I do not have any bike.

One year later, around mid of 2016, it has a battery problem. It could not handle long runs. A month later, it even could not handle more than 2 minutes run. I thought it was discounted because it was too long in the shelves. Yes, it must be clearance sale, and lithium batteries are aging without have to be used. This is a risk of buying sale items: aged battery.

So, I need a quick solution. There is no TomTom official service center in Indonesia. I have contacted TomTom customer care through official website, and they said that I should claim to the store where I bought it. Which is Amazon in the America. This is not a valid option for me. Then, I bought another on-sale TomTom Multisport. But this time just the watch, without the HRM. But now, I know the risk and have to anticipate it.

Long story short, case closed and I am happy.

But, I am still curious. Can I buy the battery somewhere, and replace it by myself? Unfortunately, I cannot find any store that sells it on the internet. I continued my journey, and find this video: TomTom Runner Teardown.

At least, I know how to tear it down, and how the battery looks. I was expecting brand name, some model numbers, size/dimension details, voltage and capacity. But just can see the shape. Then, I have some conversation there with other YouTube viewers. A guy named Rolando Cook managed to find the specification: 3.7V, 190mAH lithium battery.

I tried to search the battery for Nike+ Sportwatch GPS, since it was also manufactured by TomTom. I thought it should be similar. And I found some sellers on the Ebay that sell battery for Nike+ Sportwatch GPS. Guess what? The dimension looks similar with TomTom’s, and it is 3.7V, 170 mAH lithium battery.

It should work, but it has less capacity. This should not be a problem. If the original battery can manage my 3 hours half-marathon on last Nike BajakJKT 2015, then I am expecting for at least 2.5 hours of run with connected bluetooth HRM and ocassionally backlight.

You probably already know that I bought a volt Nike Sportwatch back in 2012 and it has dead display on 2014. Yes, I have managed to buy another blue one after that. But, When I get TomTom Multisport, I put this blue Nike on the drawer. Nike Sportwatches were famous with its easily broken rubber straps. And yes, at the end of the day, both of my Nikes experienced this.

So, nothing to lose with those broken, useless Nikes. Tear it down!

Fortunately, iFixIt have done this. You can refer to their page on how to replace Nike+ Sportwatch battery. Since it is also a TomTom, the construction is relatively similar as well as the battery. Yay!

Follow the video that I shared earlier to learn how to tear TomTom down. Be careful on the vibrate motor. You will also need to release a black plastics from both batteries, and put TomTom’s black plastic to Nike’s battery.

Please mind the polarity. It actually have same polarity, but being a cautious engineer is must.

Although the size is similar, it is not identical. You will have to slightly trim the electrode, so it can fit and take place in the black plastic. Since the Nike’s battery is slightly wider, hence it cannot be placed well. This is very tricky. Just make sure the electrode are placed well, and the battery placement is not interferencing any other components.

Put the vibrate motor back, join the both parts, screw all those six bolts. Done!

Charge it using the USB dock cable. Let the battery filled up, make sure it is recognizable through the TomTom MySports Connect application on your computer. Then, take that watch for a run, bike or swim. Enjoy!

PS: This should be also applicable for first-generation TomTom Runner. And possibly applicable for TomTom Runner Cardio and TomTom Multisport Cardio. Have no idea on Sparks and Runner2, but I think it is still similar.

Please also note that this product was originally 5 ATM water resistant (you can swim with it). But if you are not good in disassembling and reassembling this product, you may lose the water resistance. So, please be careful, especially if you have a plan to swim with it.