Hello & Welcome to Just Answer,
I'm Greg and will do my best to assist you today.
Sorry I didn't see your question earlier and to hear of any issue you are having with your phones.
If you still need help you with this issue:
It looks like you are looking for a battery pack for a Panasonic cordless phone - with the part number supplied.
You can easily find the battery packs online, at shops such as Amazon.
I have a link (below) to a search for that particular part number.
HHR-P104 Search Results
NOTE: You do not necessarily need a "Panasonic brand" battery pack, but I do see at last one listed there at this time.
I hope this helps.
Please let me know what you find or if you have any more questions.
If this has helped answer your question(s), please take a moment to rate MY service level (5-star is my goal) so that I get credit for my time helping you with this question.
You should see some "stars" (and SUBMIT button) to do that, but please let me know if you do NOT see them (you may have to REFRESH your screen) or can not use them.
Thanks, ***** *****