Anyone know of an API I can get historical price time series for multiple coins I'd like to build some historical price charts, to use in my cryptocoin portfolio tracking app, using time series data (with HighCharts js). 

Anyone know of an API that provides this price data, preferably for multiple coins (btc, ltc, eth, etc)?
I am developing the ccxt cryptocurrency trading library, check it out on GitHub:

https://github.com/kroitor/ccxt

It is a library for cryptocurrency trading and e-commerce with support for many bitcoin/ether/altcoin exchange markets and merchant APIs. 

With it you can access market data and trade bitcoin, ether and altcoins with more than 70 (!!!) cryptocurrency exchanges. It is used to connect and trade with crypto markets and payment processing services worldwide. It provides quick access to market data for storage, analysis, visualization, indicator development, trading strategy backtesting, bot programming, building trading algorithms on top of it, webshop integration and related software engineering.

The codebase is in JavaScript / Python (2 and 3) / PHP. You can deploy it from PyPI, with npm (for Node.js) or by cloning the GitHub repository.

The ccxt library is under heavy development right now, but already offers a quick-start for trading and technical analysis with many crypto exchange markets out of the box. It is intended to be used by coders, developers and financial analysts to build algotrading strategies on top of it.