I have an A1/T31 heart rate monitor while easy to use and accurate, it is a nightmare when the battery goes in the transmitter unit. It is NOT designed to be replaced, and you just have to throw the transmitter away and buy a new one, and at today's price, I have to pay £25+postage and thats from Ebay! I paid only £29 for the whole unit a fews years back.
Why can't they design something which the user can open and have the battery changed I do not know, to boost their sales and profit?? They used a CR2032 battery and with normal use, they last about 1 year or so. I will never buy polar again, instead I bought a similar unit from Lloyd Pharmacy which costs £8, yes £8 !!! and you can change the batteries!!!!