Anyone changed the battery without buying the new gasket and have no issues? Am I asking for trouble if I plan on swimming with it and using the old gasket? I just don’t want to send it to Polar and need to replace the battery.
I think the rs400 was made so you could easily change it yourself, I have an rs200 and I have to send it in, I wish I had a 400.
Send it back to Polar. Let them deal with this. They check out the watch when they do a battery replacement.
Agreed. Also it may void the warranty if it isn’t replaced by polar.
I’ve done mine by myself without any issues.
I think they want you to use a Panasonic battery, don’t know why though.
jaretj
Have also done it myself without any issues.
You should not need a new “O-RING”, go for it and do it yourself.
I am trying to replace the battery on my rs400…the rear battery compartment only turns a little bit, then nothing happens. How can I get the battery compartment open?
It only turn about 1/4 inch. Did a quick Google search, this video is not an official Polar but will help. Never force the cover with a coin, metal wins over plastic 
After the initial turn pry the cover off with a pin or blade
looks easy enough, but this thing is not popping off… I turned the cover left so that the dot on the watch is between the two dots on the cover (just below where it says “open”) is the cover not open all the way? do the dots have to line up? thanks
Sounds like your doing everything correct but since it is your first attempt you may not have the feel and are afraid to cause damage. It may not be threaded to to the point of as you turn it screws off. Line up the points to OPEN and with the smallest blade, I do not know if a pin from running bib numbers is too fine will work. I the worst case scenario happens, Chris and I at Polar will take care of you, assuming you live here in the USA.
Agreed, I just didn’t want to damage it but I did get it open. I didn’t think it would take that much force. I’ll replace the battery and get intouch if there are any issues. Thanks for your help!
Sounds like your doing everything correct but since it is your first attempt you may not have the feel and are afraid to cause damage. It may not be threaded to to the point of as you turn it screws off. Line up the points to OPEN and with the smallest blade, I do not know if a pin from running bib numbers is too fine will work. I the worst case scenario happens, Chris and I at Polar will take care of you, assuming you live here in the USA.
A glasses screwdriver works well. Much better than a pin.
Hopefully this helped so you can train tomorrow and maintain your pro5 downloading. How great is slowstwitch.
Not necessary. You can do it yourself. Simple. Turn the slot. You may have to pry the back off if it has gotten tight with dirt and sweat.