Swollen Battery at 18 months

[Desert_Muldoon]

I have a severely swollen battery on my 18 month old Spectre x360-15.  It warped the case by over 1/4" and the touch pad was protruding outside the case.  Is it normal for the batteries on this model to fail so early?  This was an expensive notebook and my first HP purchase.  I had heard good things about HP reliability and didn't purchase an extended warranty.

[KS-X360]

I have 2 X360s with swollen batteries that happened in under 2 years.
HP Spectre x360 - 15-df0008ca
HP ENVY x360 - 13-ag0010ca

I replaced the battery in the Spectre15 with one from canadianbatteries.com that worked fine. It was hard to locate a match and it took close to 2 months to arrive.
I am in the process of replacing the Envy13 but again, it was really hard to find a replacement. It appears that HP does not carry these batteries.
I got the Envy battery and it is a perfect match (all numbers and form factor match) however it does not appear to be genuine HP as the Envy reports a POST error indicating that it is not a genuine HP product. This battery also appears to NOT report its charge properly for some reason. I am trying to trouble shoot it right now. It appears to report properly down to about 15% but under that the battery suddenly dies. I have adjusted my widows settings to put it into sleep at around 15% and that MAY be working. I have not done enough tests yet to be sure.
Both batteries were relatively easy to remove and reinstall but do require you to remove the bottom cover which has hidden screws (under the rubber pads) and is snap fitted. Care is needed in order not to damage the case.

I removed the batteries as soon as I noticed the case warping. On both machines, the case went back into its proper shape once the battery was removed. You can run on adapter only with the battery removed, until you get a replacement.