Battery in old Dell Inspiron won't charge past 35%

I have a Dell Inspiron laptop that is about 3 years old. Recently, the battery will only charge to 35%. It then will stop charging though it remains plugged in. I have tried letting the battery die completely and recharging it. Again, it will charge, but only to 35%. Is this indicative of the battery being old?

Yes

See this link:
http://www.dell.com/content/topics/...sitelet/en/batteries_faq?c=us&l=en&cs=19#faq1

Yes time for a new battery.....

On average, laptop batteries for most computer brands and models do not last more than 12 to 15 months... Light use can perhaps mean they will last two years or so... but to have a reliable computer, you should replace the battery every year, so you can carry a known good one along with the older one which could fail at any time.
Take care with cheap foreign immitations as they claim a year or 18 months warranty, and seldom last that long.
A Dell battery will usually, but not always, last longer than an eBay battery from China... even though both are from China... you simply do not know how long ago the battery cells were replaced... and DELL DOES honor its warranty on all laptop batteries...